Studies of the strain distribution in wide plates during brittle fracture propagation

ssc-i 18

STUDIES OF THE STRAIN DISTRIBUTION IN WIDE PLATES

DURING BRITTLE FRACTURE PROPAGATION

by S. T. Rolfe T. M. Lynam

and

W. J. Hall

SHIP STRUCTURE COMMITTEE

MEMBER AGENCIES:

BUREAU OF SHIPS. DEPT. OF NAVY

MILITAPIY SCA TRANSPORTATION SERVICE. DEPT. OF NAVY UNITED STATES COAST GUARD. TREASURY DEPT.

MARITIME ADMINISTRATION 05Fr. OF COMMERCE

AMERICAN BuliCAu OF SHIPPIN8

SHIP STRUCTURE COMMITTEE

December 30, 1959

Dear Sir:

As part of its research program related to the improvement of hull structures of ships, the Ship Structure Committee is

sponsor-ing an investigation of Brittle Fracture Mechanics at the University

of Illinois. Herewith is a copy of the Fourth Progress Report, SSC-118, Studies of the Strain Distribution in Wide Plates During Brittle

Fracture Propagation by S. T. Rolle, T. M. Lynam, and W. J. Hall.

This project is being conducted under the advisory guidance of the Committee on Ship Structural Design of the National Academy of Sciences-National Re search Council.

This report is being distributed to individuals and groups

associated with or interested in the workof the Ship Structure

Com-mittee. Comments concerning this report are solicited.

Sincerely yours,

ADDRESS CORRLSPONDZNa 7: SECRETARY

SHIP STRUCTURE COMMIrrEE

U. S. COAST GUARD HEADQUARTER.

WAZHINSTON au, D. C.

E. H. Thiele

Rear Admiral, U. S. Coast Guard Chairman, Ship Structure Committee

Serial No. SSC-118 Fourth Progress Report

of

Project SR-137 to the

SHIP STRUCTURE COMMITTEE

on

STUDIES OF THE STRAIN DISTRIBUTION IN WIDE PLATES DURING BRITTLE FRACTURE PROPAGATION

by

S. T. Rolfe, T. M. Lynam and W. J. Hall

University of Illinois

Urbana, Illinois

under

Department of the Navy

Bureau of Ships Contract NObs-65 790 BuShips Index No. NS-73l-034

transmitted through

Committee on Ship Structural Desìgn Division of Engineering and Industrial Research National Academy of Sciences-National Research Council

under

Department of the Navy

Bureau of Ships Contract NObs-72046 BuShips Index No. NS-731-036

Washington, D. C.

National Academy of Sciences-National Research Council December 30, 1959

ABSTRACT

This report summarizes the results of a series of tests made as a part of the study of the propagation of brittle fractures in 6-ft wide steel plates. All plates were tested at an average net applied stress of 19, 000 psi, a temperature of about -10 F, and an impact energy of about 1000 fi-lb, which made it possible to superimpose the test data

and obtain contours of strain on the surface of the plate for a propagat-ing fracture. Contours of both the maximum principal strain, and strain measured with vertically oriented gages for various lengths of crack are

presented in this report. A study of all the applicable data from earlier tests made as a part of this program indicates that the strain contour

data presented here are also representative of the data fromthese earlier

tests.

The studies indicate that for the particular specimen geometry and associated test conditions, the strain field associated with the tip

of the advancing fracture remains essentially unchanged after traversing

about one-third of the plate width and extends only about 8--10 in, ahead of the crack tip.

CONTENTS

Page

INTRODUCTION 1

General i

Object and Scope. . . i

Acknowledgment . . 2

Nomenclature . . . . 3

DESCRIPTION OF SPECIMENS AND INSTRUMENTATION 3

Specimens and Material Properties

...,

3

Instrumentation 6

Data Reduction 17

Apparatus and Test Procedure . . 17

ANALYSIS OF TEST RESULTS 18

General ...18

Recorded Test Data . . 20

Computed Principal Strains

. ...

39

Discussion of Strain Traces 41

Maximum Principal and Vertical Strain Contours 45

Crack Path and Surface Texture 60

SUMMARY ... 62

BRITTLE FRACTURE MECHANICS ADVISORY COMMITTEE for the

COMMITTEE ON SHIP STRUCTURAL DESIGN Division of Engineering & Industrial Research

National Academy of Sciences-National Research Council Chairman:

N. J. Hoff

Head of Department of Aeronautical Engineering

Stanford University

Members:

D. S. Clark

Professor of Mechanical Engineering California Institute of Technology

Morris Cohen

Department of Metallurgy

Mas sac husetts Institute of Technology

J. Feely, Jr.

Esso Research & Engineering Company Martin Goland

Vice President

Southwest Research Institute R. Irwin

Head, Mechanics Division

Naval Research Laboratory

Egon Orowan

Department of Mechanical Engineering

Massachusetts Institute of Technology

W. R. Osgood

Department of Mechanics

Rensselaer Polytechnic Institute M. P. White

Head, Civil Engineering Department

INTRODUCTION General

Brittle fractures in riveted and welded steel structures have been

re-ported in the engìneering literature for many years. These fractures generally

are characterized 1) by a lack of the ductility usually associated with failures

of structural steel and Z) by a sudden occurrence with little or no previous

warn-ing.

The significance of the brittle fracture problem was not fully appreciated

until World War II, when a large number of welded merchant vessels failed in

this manner. Fortunately, through the use of improved geometrical layout, crack

arrestors, and improved materials and fabrication procedures, it was possible to

reduce greatly the number of major ship failures. In many cases, provisions have

been made to incorporate similar improvements or changes in the design of struc-tures other than ships in order to minimize the possibility of the occurrence of brittle fractures. Nevertheless, in spite of these improvements in design which

have resulted from the large amount of research completed during and since World

War II, brittle fractures still occur, and further studies are required if a better

un-derstanding of the brittle fracture problem is to be obtained

Object and Scope

The brittle fracture phenomenon is extremely complicated in that it involves

a consideration of materials and their behavior in various environments, This

par-ticular program is concerned with a study of the propagation of brittle fractures in

wide steel plates. The experimental approach followed in this investigation has

consisted of measuring surface strains and crack speed as the fracture traverses a wide steel plate to obtain fundamental data.

The primary purpose of these tests and studies was to obtain, sufficient data to establish representative strain contours on the plate surface during the time

a brittle fracture is propagating. Thus far, six major fracture tests of 6-ft wide, semikilled steel plates have been completed in which 34 channels of cathode ray

oscilloscope recording instrumentation have been utilized; in each test, 33 channels were used for il rectangular strain rosettes and one channel was used for speed

-2-detectors. The plates were tested at an average net applied stress of 19, 000 psi and at a temperature of about -lo F. The fractures were initiated from one edge

of the plate with the notch-wedge-impact method of fracture initìation. In

con-junction with the crack arrestor program (Project SR-134), one additional set of

records has been obtained for a plate tested at a higher stress level (28, 000 psi)

and at a lower temperature (-15 F). The results presented in this report are based

on the tests that are reported here for the first time, as well as on ali of the pre-vious applicable data obtained as part of this program. 1-4

Among the more important items presented in this report are the following:

strain gage traces from the component gages of the strain rosettes

principal strain curves computed from the component gage strain traces

discussion of the factors affecting the computed principal strain

magni-tudes and strain rates

representative vertical and maximum principal strain contours for

vari-ous crack lengths during the time the fracture is propagating, and

typical sets of maximum principal strain contours and vertical strain contours associated with a crack in the central portion of the plate,

The strain contours should be of considerable value in correlating the test

results and associated significant parameters with other experimental and analyti-cal results.

Acknowledgment

The work described in this report was conducted in the Structural Research

Laboratory of the Department of Civil Engineering, University of Illinois, The

project is under the general direction of N. M. Newmark, Professor and Head of

the Department of Civil Engineering. The program is sponsored by the Ship

Struc-ture Committee, and the members of the Brit.tle FracStruc-ture Mechanics Advisory Com-mittee under the ComCom-mittee on Ship Structural Design of the National Academy cf

Sciences-National Research Council have acted in an advisory capacity in. the planning of the programO

V. J. McDonald, Associate Professor of Civil Engineering, supervised the instrumentation and reduction of the test data from the photographic records, M

-3-the strain rosette computations, and F. W. Barton, Research Assistant in Civil Engineering, helped with the tests and preparation of the figures for the report.

Nomenclature

The following terms are used repeatedly throughout the text:

Dynamic strain gage--SR-4 Type A7 (1/4-in, gage length) strain gage whose signal is monitored with respect to time on an oscilloscope during the fracture test.

Static strain gage--SR-4 Type A7 (1/4-in, gage length) strain gage used to monitor the static strain level.

Component strain gage--One of the three individual strain gages of a rectan-gular strain rosette

Crack detector--A single-wire SR-4 Type A9 (6-in, gage length) strain gage

located on the plate surface perpendicular to the expected fracture path. A rough measure of the fracture speed may be obtained from a

knowledge of the distance between the detectors and the time interval corresponding to the breaking of adjacent detectors.

Initiation edge--The edge of the specimen at which the brittle fracture is ini-tiated.

Notch line--An imaginary straight line connectin.g the fracture initiation notches

on opposite edges of the plate specimen.

Test load strain--At any gage point, the strain corresponding to the applied test

load.

DESCRIPTION OF SPECIMENS AND INSTRUMENTATION Specimens and Material Properties

The plate material for the six major fracture tests outlined in Table 1 (Tests 33, 34 and 36 through 39) was a semikilled steel, USS heat No. 64M487, and was t.ested in the as-rolled condition.. _{The steel was from the same stock} that was used in the earlier tests made as a part of this program and its

proper-ties, typical of A-7 structural steels, are in agreement with those reported

ear-2

-4-TABLE 1. OUTLINE OF TESTS

With the exception of Test 35, all tests were conducted on 3/4-in, by 72-in, by 120-in, semi-killed steel plate specimens welded with E70l6 electrodes to l-in, thick pull-plates in the 3, 000, 000-lb Baldwin hydraulic testing machine. The brittle fractures were initiated by the notch-wedge-impact method with a nominal lateral impact of 1200 ft-lb.

The notch was l-1/8 in. long and consisted of a slot four hacksaw blades wide (-0. 141 in,) for the first 1 in., one blade wide (-0. 034 in.) for the next 1/16 in., and ended with a jeweler's saw-cut (0.012 in.) 1/16 in. long.

1000 19.0 0 Complete fracture--good strain records obtained from

7 rosettes.

1000 19.0 0 Complete fracture--good strain records obtained from

10 rosettes.

1475 28.0 -15 Plate specimen composed of 36-in, starter strake of

rimmed steel, 4-in. strake of T-1, 20-in. strake of rimmed steel, and a 12-in. strake of T-1 steel.

Specimen was 27 in. long. Fracture arrested at

lead-ing edge of final T-1 strake. Final load--85 kips. Good strain records obtained from 4 rosettes.

997 19.0 -10 Complete fracture--fair strain records obtained from

11 rosettes. Double fracture last two-thirds of plate width.

997 19.0 -8 Complete fracture--good strain records obtained from

11 rosettes.

997 19.0 -9 Complete fracture--good strain records obtained from

11 rosettes,

997 19.0 -6 Complete fracture--good strain records obtained from

11 rosettes.

Test No. Initial Avg. Stress on Avg.

(Plate No.) Load Net Section Temp. Remarks

(kips) (ksi) (F) 33 (XC -1) 34 (XF-l) 35 (RTRT-4) (Tested in coni unction with Project SR-I 34) 36 (X2B) 37 (X2F) 38 (X1B) 39 (X2E)

Specimen Ready for Testing

-5--Fig. 1. Typical Test Setup

the net width at the notch line was approximately 2-1/4 in. less than the gross

width because of the notches on each edge. Both ends of the specimen were

welded with double-V butt welds made with E7016 electrodes to l-in, thick pull-plates mounted in the testing machine; in welding the specimen to the pull-plates, care was taken to keep the warping and residual stresses to a

minimum. A line diagram of the specimen and pull-plates and a view of a

typi-cal test setup in the 3, 000, 000-lb hydraulic testing machine are shown in

Fig. 1.

The composìte plate specimen for the arrestor test (Test 35) _was

fabri-cated from, in order, 1) a 36-in, fracture starter strake of rimmed steel (the

plate on which the strain rosette gages were mounted), 2) _{a 4-in. strake of} T-1 steel, 3) a 20-in. strake of rimmed steel, and 4) a 12-in. strake of T-1

steel. Over all, the specimen was 3/4 in. thick, 72 in. wide, and 27 in.long.

Mechanical property tests were made on material taken from the

cen-tral portion of the plates after the plates had been fractured. The check ana-PULL HEAD i PULL PLATE SPECIMEN I' PULL PL A T E PULL HEAD t 76 je" 00" f 40 76 Line Diagram of Specimen 328"

20 80 40 0 IZO 80 80 40 o 120 80 40 o -40 40 80 TEMPERATURE - deg. F

lyses and the tensile test data for each of the rimmed and semikilled steel plates are presented in Tables 2 and 3. Charpy V-notch data are presented in Fig. 2.

Instrumentation

Until recently, it had been possible to obtain only a limited amount of

data from any one test because a maximum of only nine channels of cathode-ray

oscilloscope recording equipment had been avaìlable. Nevertheless, earlier

work on this program with both 2-ft wide and 6-ft wide plates produced much

valuable information concerning expected fracture speed and the strain

distribu-20 60 -6-. o >-o tAJ z w L) Q-80 4 o -40 TEST 39 (REEl SEMI-KILLED STEEL 40 80 120 60 TEMPERATURE - deg. F

Fig. 2. Charpy V-notch Curves

--Tests 33--39 TEST 3D IRTRT-41 RIMMED STEEL TEST 36 SEMI-KILLED 1.2Ml STEEL

Pl

20 80 40 TEST 33

SEMI-RLLEDRC-IlSTEEL

TEST 37 IRZFI SEMI-RILLEO STEEL '20 80 40 TEST 3S SEMI-KILLED Ix 1Ml STEEL EF - Il STEEL TEST 3E I SE MI. EIL L CD

-7-TABLE Z. CHECK ANALYSES OF STEEL PLATE MATERIAL

TABLE 3.TENSILE TEST DATA FOR STEEL PLATE MATERIAL (Standard ASTM 0.505-in. diem specimens)

*(L) Average of two specimens taken parallel to the direction of rolling. **(T) Average of two specimens taken transverse to the direction of rolling.

Test No. Material (Plate No.) Heat No. Lower Yield Strength (ksi) Maximum Strength (ksi) Elongation

in 2-in, Reductionof Area

33 Semikilled 64M487 (L)* 32.9 59.3 40.5 66.5 (XC-1) (T)**32.6 58.8 41.0 59.5 34 Semikilled 64M487 (L) 32.9 61.8 40.7 66.3 (XF-1) (T) 34.5 62.4 40.0 61.7 35 Rimmed 16445 (L) 34.7 68.1 36.5 57.6 (ZiA) (T) 35.2 68.7 31.2 51.6 36 Semikilled 64M487 (L) 36.5 67.2 36.0 63.5 (XZB) (T) 35.2 67.8 34.5 58.8 37 Semikilled 64M487 (L) 35.5 64.4 41.0 67.8 (XZF) (T) 35.0 64.2 36.3 _61.8 38 Semikilled 64M487 (L) 35.5 66. 8 36.5 64. 3 (X1B) (T) 35.6 66.4 36.8 59.8 39 Semikllled 64M487 (L) 34.3 61.6 39.5 65.3 (X2E) (T) 35.2 62.1 36.8 57.5

Test No. Material

C Mn

Chemical Composition in Per Cent

P S Si Cu Ni Al 33 Semikilled 0.17 0.71 0.019 0.028 0.058 0.02 0.0 0.03 34,37 Semikllled 0.20 0.76 0.019 0.028 0.052 0.02 Trace 0.03 35 Rimmed 0.18 0.42 0.013 0.031 0.02 0.23 0.14 0.003 36,38 Semikllled 0.21 0.82 0.018 0.030 0.058 0.02 0.0 0.03 39 Semikllled 0.20 0.76 0.019 0.040 0.03 0.04 0.16 0.002

- SPEEDOMAX CALIBRATING OSCILLATORS - FRANKLIN OSCILLOSCOPES

r

-8-OSCILLOSCOPES TEXTRONI X OSCILLOSCOPE

tion at various points on the plate surface as recorded by single strain gages. The results of the

work through the end of 1956 have

been reported in a paper5 and, in

more detail, in two technical

re-1,2

ports. In 1957, an additional

25 channels of cathode-ray oscillo-scope recording equipment were made available to the program by the Naval Research Laboratory

Fig. 3. Recording Equipment The latest 25 channels of

the cathode-ray oscilloscope

equipment were five-channel units manufactured by Franklin Electronics. The

nine earlier channels consisted of two DuMont Type 333 and two DuMont Type

322 dual-beam cathode-ray oscilloscopes, and a Tektronix Type 512 single

beam unit. The recording equipment, along with the calibrating oscillator that

supplied the time signals, is shown in Fig. 3; the cameras for the DuMont

equipment are not shown.

Six of the DuMont oscilloscope channels are sufficiently sensitive to

allow at least l-1/2 in. of trace deflection for 0.001 in./in. of strain. How-ever, the deflection scale used to record the test data on these DuMont scopes was limited by the size of the scope face and the maximum value of expected

strain. The other 28 channels only allowed about 1/2 in. of trace deflection for the same strain. In planning the recording of the test data, the equipment was arranged so that the strain gages that were expected to produce signals of

lowest electrical magnitude were connected to the six DuMont oscilloscopes as

they had the highest sensitivity. The frequency response of all oscilloscopes was flat up to at least 50 kc and therefore, they were considered to be adequate to record the strain signals. Portions of two typical strain records are presented

Franklin Oscilloscope Record

-9-Fig. 4. Typical Strain Records

calibrated by shunting gages with a resistance whose equivalent strain value

was known.

The time base for the records obtained from the DuMont and Franklin

oscilloscopes was supplied by continuously moving 35-mm film. Timing marks

on the traces from the Franklin units were energized by the oscillator and

re-corded as part of the strain traces; the DuMont units _{empl3yed intensity} modu-lation of the electron spot to define the time base. On all of the strain traces

a simultaneous "blip" was produced by a synchronizìng signal supplied from

the Tektronix oscilloscope circuit, immediately before and _{after the test. This}

signal made it possible to synchronize accurately with each other all the strain traces from a particular test. The synchronizing "blip" is visible on the records shown in Fig. 4.

The crack detector trace on the Tektronix oscilloscope was recorded on

a single frame of 35-mm film. _{The time axis was calibrated by putting a time}

signal of known frequency on the channel and photographing one sweep. This

was done immediately after the test was completed.

Since only 34 channels of strain recording equipment were available

(33 channels for 11 rectangular strain rosettes and _{one channel for crack speed} detectors) and the exact location of the fracture path was unknown prior to each

-lo-A .c 8 .0 Gond I 72

.AOSETTE -GAGE LAVOST A (SEE FIG 22(

O E (DETECTORS

FIG 5 INSTRUMENTATION LAYOUT AND CRACK PATh - TEST 33

test, it was decided to concentrate the strain rosettes in three general areas with respect to width on three of the plate specimens, and thereafter to super-impose the data to obtain the picture of the strain distribution associated with

a propagating crack.

The instrumentation layouts and crack paths for Tests 33 through 39 are

shown as Figs. 5--l].. The strain rosettes are located on only the first two-thirds of the plate, since it was felt that rosettes located in this region would yield the desired strain information. The strain rosettes were located at 7-in.

DYNAMIC STRAIN GAGES CRACK PATH

Rosette Strain Orlen- X Y Test Load Distance to X Y

No. Gage tation (in.) (io.) Strain Fracture (in.) (in.)

No. (in./in.) (in.)

A 1 V 22.0 0 .00067 0.7 1.1 0 2 H 22.3 0 -.00019 0.8 9 -0.2 3 0 22.3 0.3 .00024 0.5 15 0 s b V 22.0 3.0 .00067 -2.5 18 0.1 5 5 22.3 3.0 -.00019 -2.2 19 0.2 6 D 22.5 3.5 .00024 -2.6 22 0.7 C Î V 22.0 20.0 .00068 -19.0 24 1.2 8 a 22.3 20.0 -.00018 -19.0 28.5 1.9 9 0 22.3 20.3 .00026 -19.0 36 2.3 D 10 V 29.0 5.0 .00068 -1.1 45 3.2 11 5 29.3 3.0 -.00019 -1.0 t8 3.4 _12 D 29.3 3.3 .00026 -1.3 54 5.5 F 16 V 36.0 3.0 .00069 -0.5 3.7 17 5 36.3 3.0 -.00018 -0.5 66 3.9 18 D 56.3 5.3 .00029 -0.3 69 3.9 I 25 V 22.0 0 .00052 0.7 70 3.8 26 5 22.3 D -.00017 0.8 72 3.6 27 0 22.5 o. .00016 o.s J 28 V 36.0 0 .00053 2.5 29 H 36.3 0 -.00018 2.6 50 D 56.5 0.3 .00019 2.3

FIG 6

INSTRUMENTATION LAUT AND CRACK PATH - TEST 34

FIG. 7

INSTRUMENTATION

LAYOUT AND CRACK PATH - TEST

35 Rosette Strain Orlen-X Y Test Load. Distance to X Y 36" 5-1- 4 20" -No. Gage

tation (lo.) (in.)

Strain Fracture (irs.) (in.) No. (in/in.) (in.) A i V 22.0 0 .00o68 +.6 1.1 0 2 H 22.5 0 -.00018 +5.6 14 .2 3 D 22.3 +0.5 .00023 +s. 6 .14 B (4 V 29.0 0 .00066 +4.4 12 1.5 5 H 29.3 o -.000iß 4.4 16.5 2.5 6 D 29.5 +0.3 .00026 +4.1 18 2.6 C 7 V 29.0 +5.0 .00065 +1.4 22 5.6 DYNAMIC STRAIN (lAGEN CRACK PATh 8 II 29.3 5.0 -.00018 1.4 2(4 3.8 9 D 29.3 +5.5 .O0O19 +1.1 29 4.4 Rosette Strain Orlen-X Y Test Load Distance to X Y » 10 V 29.0 +6.o .00063 -i.6 36 (4.8 No. Gage

tattoo (in.) (in.)

Strain ?racture (In.) (in.) il H 29.5 +6.0 -.00018 -1.6 42 5.5 No. (10./lo.) (In.) 12 D 29.5 6. .00024 -1.9 1+8 54 Go 66 72

3.6 5.8 6.o 6.i 6.i

A 1 2 5 V 17.0 0 .00092 R 17.5 0 -.00024 D 17.3 0.3 .00035 -0.5 -0.5 -0.8 1.1 0 11 -.2 11s.5 -.3 17 -.5 20 -.6 23 -.8 50 -1.1 35 -1.1 40.4 -.9 1414 .3 E 15 ils 15 V 29.0 +9.0 3 29.3 +9.0 D 29.5 +9.5 .00o6ï -.00018 .00023 -4.6 -4.6 9 -4 F 16 17 18 V 36.0 o 5 36.3 0 D 56.3 +0.5 .00066 -.00018 .00021 4.8 +4.8 4jj B I 5 6 V 20.0 0 .00095 5 20.3 0 -.00022 D 20.3 +0.3 .000)6 -0.6 -o.6 -0.9 5 22 23 2(4 V 36.o +6.0 H 36., +6.0 D 56.5 +6.3 .00066 -.00018 .00015 -1.2 -1.2 -1.5 C 7 8 9 V 23.0 0 .00092 5 23.3 0 -.00022 D 23.3 +0.3 .000)8 -0.8 -0.8 -1.1 D 10 V 17.0 0 .0009(4 -0.5 I 25 26 27 V 56.0 +9.0 R 36.3 +9.0 o 6.5 +9.3 .00067 -.00019 .00019 -4.2 -4.2 -4.5 11 12 H 17.3 0 -.00026 D 17.3 -40.3 .00029 -0.5 .0.8 148.5 0 53 .3 57 0 Go -1.1+ J 28 V 22.0 0 .00057 +5.6 29 5 22.3 0 - .00017 3.6 62 Fracture SQ j) 22.3 -+0.5 .00021 +5.3 arrested K 31 V 36.0 0 .00057 +14.8 in T-1 52 s o -.000ii +4.8 33 D 56.3 +0.3 .00021 4.5 72 o Y Sønd J

ROSETTE - GAGE LAYOUT A

(SEE EIS 22)

E

.1

0

72

ROSETTE - OASE LAYOUT

A and D A (SEE e C F10. 22) RIMMED (DETECTORS) B Fond K 9 54 A (O'-*.4..-8 C 6" -4-7.5»-4*-O E (DETECTORS) T-I T-I C s e" e e

eJ

DYNA14IC STRAIN GAGES

CRACK PATh

FIG 8

INSTRUMENTATION

LAYOUT AND CRACK PATH - TEST

36

FIG. 9

INSTRUMENTATION

LAYOUT AND CRACK PATH - TEST 37

Rosette

No.

Strain Gage

No.

DYNAMIC STRAIN GAGES

Orlen-X

Y

Test Load

tation (in.) (in.)

Strain (in./in.) Distance to Fracture (in.) CRACK PATS X Y (in.) (in.) 1 1 (I 22 3 -.00018 -1.70 1.1 0 2 D 22.3 3.3 .00022 -2.10 3 0 3 V 22 3.3 .00065 -2.10 8 .2 2 6 II 15 3 -.000iß _2.140 15 .6 7 D 15.3 3.3 .00022 -2.70 20 1.1 8 V 15 3.5 .00066 -2.70 22 1.6 3 11 5 15 -3 -.00018 +1.65 25 1.8 12 D 15.3 -2.7 .00023 +1.35 29 2.2 13 V 15 -2.7 .00065 +1.55 32.5 2.6 14 16 a 8 3 -.00019 -2.80 35.5 2.6 17 o 8.3 3.3 .00023 -3.10 36 2.14 18 V 8 3.3 .0006i -3,10 39 2.14 5 21 H 36 6 - .00017 -3.65 149 3.5 22 D 36.3 6.3 .000214 -14.00 55 3.6 23 V 36 6. .00067 -14.00 614 3.6 6 24 H 22 6 -.00017 69 3.7 1 D 22.3 6.3 .00021 -5.10 70 3.6 5 V 22 6.3 .00067 -5.10 72 3.2 7 26 R 22 9 -.00017 27 D 22.3 9.3 .00027 -8.10 28 V 22 9.3 ,00Q66 -8.10 8 29 (1 15 6 -.00018 -5.140 32 D 15.3 6.3 .00026 -5.70 31 V 15 6. .00068 -5.70 9 25 It 22 0 -.00016 +1.35 9 D 22.3 .3 .00027 +1.00 )0 V 22 .5 .0006) +1.00 10 50 a 8 -3 -.00017 +2.20 114 D 8.3 -2.7 .O00i +1.90 15 V 8 -2.7 .00061, +1.90 U 33 5 36 0 -.0001't +2.35 19 D 36.3 .3 .00023 +2.00 20 V 36 .3 .00066 +2.00 Rosette No. Strain ((age No.

DYNAMIC STRAIN GAGES

Orlen-X

Y

Test Load

tation (In.) (in.)

Strain (in./in.) Distance to Fracture (in.) CRACK PATh X Y (in.) (In.1 1 1 It 22.0 3.0 -.00016 0.0 (Lower) 1.1 0 2 D 22.) 3.3 .00022 0.0 5 .2 3 V 22.0 3.3 .00070 0.15 10 .9 2 6 s 29.0 3.0 -.00017 0.15 15 1.9 7 D 29.) 3.3 .00026 0.50 20 2.6 8 y 29.0 3.3 .000714 0.55 22 3.2 3 11 II 36.0 3.0 -.0001? 1.35 25.0* 3.8 12 1) D V 36.3 36.0 3.3 3.3 .00027 .00070 1.80 1.70 (u) (L) (4 i6 It 29.0 6.0 - .000i6 0.0 (upper) 26 14.2 3.14 17 D 29.3 6.3 .00020 0.10 27 14.6 3.1 18 V 29.0 6.3 .00071 0.10 29 5.9 2.8 5 21 It 36.o 6.0 -.00017 2.60 30 6. 2.7 22 1) 36.3 6.3 .00026 2.15 35 8.1 1.9 2 V 6.o 6. .000.. 2.) 38 8.7 1.2 6 D 22.3 ..3 .00017 -3.00 Lover 145 10.3 0.7 5 V 22.0 6.3 .00070 -3.10 148 11.3 0.3 214 5 22.0 6.0 -.000i6 -2.80 52 11.8 0.3 7 26 H 29.0 9.0 - .00015 -3.00 (upper) 55 12.1 0.3 27 D 29.3 9.3 .00026 -3.10 57 12.3 0 28 V 29.0 9.3 .00072 -3.30 59 12.9 _l4 8 29 II 36.0 9.0 -.00017 -0.145 6 13.5 -0.9 32 D 36.3 9.3 .00027 -o.8o 66.5 13.5 -1.0 31 V 36.0 9.3 .00071 -0.75 69.5 13.5 -o.8 9 9 D 22.3 0.3 .00021 3.05 (Lower) 70 13.5 -1.0 10 V 22.0 0.3 .00068 2.90 72 13.6 -0.7 25 5 22.0 0.0 -.00017 3.25 10 il D 29.3 0.3 .00030 2.55 AC rack Itranclied 15 V 29.0 0.3 .00069 2.55

(u)- upper Crack

30 S 29.0 0.0 -.00011 2.85 (L) Lover Crack 11 19 D 36.3 0.3 .00027 1.15 20 V 36.0 0.) .00070 1.15 33 It 36.0 0.0 -.00017 1.65 72"

ROSETTE - GAGE LAYOUT if

(SEE ÌG. 22)

41

X (DETECTORS) Y3'_.f._ 1"__+__ " 7" -4.-- r 4, 72

ROSETTE - GAGE LAYOUT O (SEE FIG 22)

6 I0 A O C O E F (DETECTORS) cs"_.f.-_ 7"._.f.-_ c'_4.- 7-4.--7' . 4' -H

FIG, Io

INSTRUMENTATION LAYOUT ANO CRACK PATH - TEST 38

FIG

II

INSTRUMENTATION

LAYOUT AND CRACK PATH - TEST

39

DYNAMJC STRAIN

GAGES

CRACK

PATIO

DYNAMIC STI1AIN GAGES

CRACK PATh Rosette Strain Orien-X Y Test Load Distance to X Y Roeette Strain Orien-X Y Test Load Distance to X No. Gage

tation (in.) (in.)

Strain Fracture (in.) (in.) No. Gage

tation (in.) (in.)

Strain !'racture (in.) (in.) No. (in./in,) (in.) No. (in./in.) (to.) i i II 50 6 -.00017 -0.70 1.1 0 1 1 H 22 3 -.00017 +2.29 1.1 0 2 D 50.3 6.3 .00018 -1.05 5.0 .2 2 D 22.3 3.3 .00021 +2.10 6 0.7 S V 50 6.3 .000k6 -1.05 6.o .3 3 Y 22 3.3 .00062 +1.96 10 1.8 2 6 H I 6 -.00018 -1.05 10 .8 2 6 H 29 3 -.00017 +4.14 15 5.3 7 D 1o3.5 6.3 .00019 -1.30 22 2.9 7 D 29.3 3.3 .00019 +3.90 20 '4.6 8 V '43 6.) .00056 -1.40 24 3.2 8 V 3.3 .00061 +3.85 21 4.8 3 ii Ii 36 3 -.00017 +1.65 27 5.5 5 ].j 5 3. 3 -.00017 +4.50 25 6.3 12 D 36.3 3.3 .00018 +1.25 30 3.8 12 D 36.3 3.3 .00019 +4.22 28 7.1 i) V 36 3.3 .00050 +1.25 35 4.6 1 V 56 3.3 .00058 +4.12 32 7.0 ¿4 i6 H 43 9 - .00019 14.05 '40 4.9 s i6 II 29 6 -.000i6 +1.09 35 7.4 17 D 43.3 9.3 .00021 -4.30 45 5.1 17 D 29.3 6.3 .00022 +0.88 40 7.9 18 V 43 9.3 .0006 -4.40 50 5.4 18 V 2 6. .0006o +0.85 (#5 8.2 5 2]. H 36 6 -.00017 -1.50 54 5.4 5 21 R 36 6 -.00017 +1.55 50 8.4 22 D 36.3 6.3 .00014 -1.73 6 5.3 22 D 36.3 6.3 .00023 +1.14 55 8.5 2) V 36 6.) .000Eo -1.7) 60 5.4 23 V 36 6,s .0Q062 +1.12 60 8.5 6 24 H 50 9 -.00017 -3.70 6 5.5 6 24 10 22 6 -.00017 -0.73 65 8.6 4 D 50.3 9.3 .00015 -4.05 70 5.5 4 D 22.3 6.3 .00025 -0.90 69 8.4 5 V 50 9.3 .0006 -4.05 72 5.4 5 V 22 6,5 .00056 -i.oß 72 7.9 7 26 Ii i#3 12 -.00018 -7.05 7 26 II 29 9 -.00018 -1.76 27 D 43.3 12.3 .00018 -7.50 27 D 29.3 9.3 .00020 -2.07 28 V 4) 12.) .00044 7.140 28 V 29 9.3 .00061 -2,12 8 29 II 50 12 -.00018 -6.70 8 29 H 36 9 - .00018 -1.47 32 D 50.3 12.3 .00025 -7.05 32 D 36.3 9.3 . .00023 -1.80 3]. V 50 12.3 .00057 -7.05 51 V 56 9.) .00062 -1.85 9 25 H 50 3 - .00017 +2,55 9 25 R 22 0 -.00017 +5.27 9 D 50.3 3,3 .00021 2.10 9 D 22.3 0.3 .00022 +5.10 10 V 50 3.3 .00056 2.00 10 V 22 0.) .00059 +4.98 10 30 H 43 3 - .00017 1.95 10 30 H 29 0 -.00019 7.17 i4 D 43.3 5.3 .00028 1.70 14 D 29.3 0.3 .00019 +6.85 15 V 45 3.5 .00056 +1.65 15 V 29 0.) .00059 +6.89 11 33 H 36 0 -.00018 +4.65 U. 33 10 36 0 -.00017 7.50 19 D 36.) .3 .00009 +4.30 19 D 36.s 0.3 .00026 +7.20 20 V 36 .3 .0004 +4.30 20 V 36 0.3 .00060 +7.14 72"

ROSETTE - GAGE LAYOUT B

SEE Fn22( .7 .4 6 A) X A B C O E F (DETECTORSI -._.is"__..f.--- 7_.f.-_-7"__.4__7"_.4..-_V' -" -H 72"

ROSETTE - GAGE LAYOUT B

(SEE F10.221 o .7 '8 A1 4 .5 .2 .3 IO A B C O E F (DETECTORS) 7.5'-.-- 7-4.-- 7" -.4.-- i' -4.--- 7" - . 14

-14-intervals across the plate in order to obtain strain values at -14-intervals of one-tenth the net plate width. Since a double fracture occurred in Test 36, a duplicate test

(Test 39) was conducted,

Rectangular strain rosettes consisting of three SR-4 Type A-7 strain gages

were used to determine the principal strains at various locations on the surface of

each specimen. Since the component gages were of a finite size, it was obviously

not possible to measure the strain in three directions precisely at a point; however, since the three component strain gages of the rosettes had a 1/4-in, gage length, it was possible to mount the three gage elements within a 0.7-in, diameter circle, and this was consìdered to be satisfactory under the circumstances. In the tests reported here, two rosette layouts of the component gages were used, Photographs and drawings of both gage layouts are presented in Fig. 12. In layout A (Tests 33, 34, and 35), the diagonal gage was centered directly above the horizontal gage, and the vertical gage was mounted on the side near the initiation edge; in layout B (Tests 36 through 39), the vertical gage was centered directly above the horizontal gage, and the diagonal gage was mounted on the side away from the initiation edge.

The gages for dynamic measurements were connected in the customary

Wheatstone bridge circuit, Three similar electrical strain gages, which were iso-lated from the specimen, were used as resistances to complete the bridge circuit. These bridges were excited by direct current and their outputs fed to the recording oscilloscope channels. A diagram of typical circuits is shown in Fig. 13,

The crack speed was measured with a system of six surface crack

detec-tors which broke as the fracture traversed the plate; at each detector location in Tests 36 through 39, two 6-in, detectors (Baldwin SR-4 Type A-9 strain gages) were wired in series to give a 12-in, detector. The breaking of a crack detector opened an electrical circuit and caused a stepped change in voltage, A diagram of a typical crack detector circuit is shown in Fig. 14, From a knowledge of the spacing between detectors and the elapsed time between successive interruptions of the circuit, the speed of the fracture could be computed. This system gives an average surface speed of the fracture since the crack front location is not known precisely at the time the detector breaks. Thus, all calculated speeds were rounded off to the nearest 50 fps. Crack detector calibration was obtained

CA LIB RATION RESISTOR

Fig. 13. Strain Gage Circuits

-15-TYPI

STRAIN GAGE RTE USED IN TESTS 36, 37, 38, axd 39

<0.7 in.

Fig. 14. Crack Detector Circuits

Gage Layout A Gage Layout B

-16-SAT ICR! *

Iby

successively opening switches

ar-i- _{ranged in series with the various}

de-tectors and recording the trace steps.

J TRIGGCR

SIGNAL

TO SWE 000150TOR

The switch locations are indicated in

\AA___-4ç ) TIITRATRON

the circuit shown in Fig. 14.

A triggering device, referred to

as an external trigger because of its lo-cation, was utilized in these tests to activate the sweep and spot intensifying circuits in the recording equipment.

- \TRIOGCS 000SICO

FOIL This trigger consisted of a strip of

alumi-GGING num foil which was broken as the piston

device drove the wedge into the notch;

A_9 GAOC

-thus, the circuits in the recording de-Fig. 15. Trigger Circuit vices were energized just before the

fracture was initiated. To insure that

the circuits would be energized in the event of failure of the external trigger, a plate surface trigger (A-9 strain gage) was connected in series with the ex-ternal trigger. The trigger circuit is shown in Fig. 15.

Static strain gages also were located every 7 in. along the notch line on both faces of the plate and three sets of back-to-back gages were placed 18 in. above the notch line. However, to simplify the instrumentation draw-ings presented in Figs.5--ll, the positions of the static strain gages are not

shown. Strain readings showed that in each test there was a fairly uniform

static strain distribution across the plate during application of the test load; in addition, bending strains were noted to be less than 0.0002 in./in. in all

tests.

The temperature of the specimen was continuously recorded during cool-ing by means of a Leeds and Northrup Type G "Speedomax" recorder and

copper-constantan thermocouples located in 1/4-in, deep holes at various points

-17-A more complete description of the instrumentation may be found in reports

and papers previously issued as a part of this program.1, 2, 5

Data Reduction

Reduction of the strain data recorded on 35-mm strip film was facilitated with a decimal converter and the University of Illinois high-speed digital

com-puter, the ILLIAC.

A brief summary of the data reduction procedure is presented below. The

35-mm film strips were enlarged and the calibration and timing marks scaled on

the enlargements. With the aid of the decimal converter, values of component gage strain versus time were simultaneously punched on IBM cards, plotted on

an X-Y plotter, and typed in tabular form. The strain-time values were then

transferred from IBM cards to punched paper tape and processed through the

ILLIAC which computed values of the principal strains. The ILLIAC results

con-sisted of tabulated principal strain data, as well as scaled oscilloscope displays of component gage and principal strain traces. The scaled oscilloscope displays

were photographed for later enlargement and processing. Apparatus and Test Procedure

In most respects, the apparatus and test procedure used for these tests was similar to that used in earlier tests made as a part of this program.

The notch-wedge-impact method of fracture initiation was used in these tests. A closeup view of the 1-1/8 in0 deep notch and the wedge is shown in Fig. 16. A view of the gas-operated piston device that provides the external im-pact is shown in Fig. 17. The theoretical output energy of the piston device was 1200 ft-lb, but calibration tests indicate that the device actually delivered about 1000 ft-lb.

Crushed dry ice was used to cool the plate specimen. Photographs of the dry ice containers, as well as a diagram showing the thermocouple locations for the specimens, are presented in Fig. 18. Typical cooling curves for Tests

33--39 are presented in Fig. 19.

After the instrumentation was mounted on the plate and the plate speci-men had been welded to the pu1l-heads, the specispeci-men was stressed at room

-18-Fig. 16. Closeup of Notch and Tip Fig. 17. Piston Device Used for

of Wedge. Fracture Initiation.

temperature to the test load to check the behavior of the strain gages; at the same time, it was possible to ascertain the static strain distribution in the specimen and to obtain the test load strain values for each dynamic gage. Any

gages that displayed faulty or questionable response were replaced and the newly installed gages were checked by another test load cycle.

In Tests 36--39, wiring between gages and oscilloscopes was double

checked by shunting each gage with a resistor and noting the direction of trace

movement on the face of its respective oscilloscope. This gave a positive identification of the scope trace corresponding to each gage and the direction of the compression calibration for each gage.

At the time of test, the cooling tanks were filled with crushed dry ice; when the test temperature was approached, the plate was stressed to the test

load. After loading, the recording equipment was calibrated, and the gas

op-erated piston device pressurized. When the desired specimen temperature was

obtained, the recording cameras were started, and the gas-operated piston de-vice was fired to drive the wedge into the edge notch to initiate the brittle

frac-ture.

ANALYSIS OF TEST RESULTS

General

ob-'2

I I

L L IO

Thermocouple Locations

Individual Cooling Tank

Fig. 18. Thermocouple Locations and Cooling Apparatus

TIME - min.

Fig. 19. Average Cooling Curves--Tests 33--39. -19--20 60 40 20 -20

Cooling Tanks Mounted Prior to

Te sting

200

TEST 36

lEST 37

EXTRA ICE ACOTO

TEST 38 TESI 39 î 60 40 00 Li. -20 ØJ 60 -a 40 20 w 0 D 4 20 W 80 Q-60 w p- ₄₀ 20 o 20 Ui p cl: W a_ u p--TEST 33 20 40 60 80 lOO 120 TEST 34 20 40 60 80 00 120 TEST 35 40 80 ISO 60 200 240 20 40 60 80 lOO 120 TIME - min. 5 5" I 5" 5" 6"-3 5 7 9 60 40 20 o 20 60 40 20 60 40 20

.0030 .0020 OCIO O - 0020 °' .0010 o .0010 0

20-tamed as a part of this program. The extensive strain data obtained in Tests 33--39 are presented in this report for the first time. The use of strain rosettes in the latter tests permits the plotting of

contours of maximum principal strain, as

well as contours of vertical strain, on the surface of the plate as the fracture propagates across the plate. The data

obtained in earlier tests1' Z support the

results of the more recent tests which are presented here.

Recorded Test Data

Typical strain traces for

com-ponent gages located at various

dis-tances from the fracture may be seen in Fig. 20; the three rosettes are from one plate and are mounted directly above one another at distances of 1.1 in., 4.1 in., and 7.1 in. from the fracture. The strain traces shown are representative of the strain-time curves obtaìned from all tests conducted as a part of this program. The decrease in maximum

strain magnitude and the change in pulse shape as the distance between the

gage and fracture changes may be clearly noted.

The vertical and diagonal gage traces exhibit a general shape character-ized by a fairly steady and rapid increase in strain to a maximum (peak) strain value as the fracture propagates past the gage; the peak strain is followed by a decrease to a strain level associated with the removal of external load. For gages located close to the fracture, the peak is very sharp; for gages located

away from the fracture, the peak is of a lower magnitude and the pulse extends

over a longer time.

c.

----TOlETTE II-TEST 59

S.T_--_

05 IO 1,50 05 Io

TIME - nTiIlIS.Cond,

FIG 20 TYPICAL STRAIN TRACES ANO COMPUTED PRINCIPAL STRAINS

FOR ROSETTES LOCATED AT VARIOUS DISTANCES FROM THE FRACTURE

-21-The horizontal gage traces are characterized by three major changes in strain. The strain trace first exhìbits an initial relaxation of compressive strain, and this is followed by a compression pulse corresponding to the ten-sion peak of the vertical gage. Finally, the trace exhibits another relaxation of compressive strain before leveling off at the final strain value.

The strain-time curves of the component gages obtained from Tests

33--39 are presented in Figs. 21--85. All strain traces are plotted such that the strain at zero time is the initial test load strain.

The second peak occurring in the component gage traces (and principal

strain traces) in Figs. 43, 45, 47, and 50 was attributed to electrical effects associated with the recording equipment (although there is still some ques-tion regarding this matter), and not the double fracture of the plate specimen

in Test 36.

The crack speed detectors were used to measure the approximate surface

fracture speed and to aid in determining the location of the surface fracture at any time during the brittle fracture test. The average surface speeds of

propa-gation of the brittle fracture for Tests 33--39 are presented in Table 4. It will (Text continued on page 39)

O000

STRAIN TRACES FROM

COMPONENT OASES PRINCIPAL STRAINS ANO DIRECTION IRe 0F £m Ye 0030 ISO 0020 I 120 J,- \ . __\__--_______

'

Luììì

°°

/

/'

0 _0tR

._/

\____.--- _D'__ _._-Is o 'I OSlO 30 _0O2O 05 IO IS 200 05 IO IO 20

TIME mIIII,ecR,d. TIME

FIG 21 STRAIN TRACES FROM COMPONENT GAGES NOS 2 AND 3

-zz-TABLE 4. FRACTURE SPEEDS

All distances are measured along the crack path.

Speeds are rounded off to nearest 50 fps.

DIstnce Distance

Breaking Time Breaking Time

Detector between Speed Detector between Speed

Time Interval Time Interval

Dete ctors Dete ctors

(in.) (milliseconds) (fps) (In.) (milliseconds) (fps)

A TEST 33 A TEST 37 0.76 0.96 12.02 0.36 2800 7.02 0.14 4200 B 1.12 B 1.10 13.16 0.37 2950 7.10 0.18 3300 C 1.49 C 1.28 6.02 0.22 2300 6.50 0.22 2450 D 1.71 D 1.50 6.05 0.25 2000 6.97 0.28 2100 E 1.96 E 1.78 13.60 0.62 1850

TEST 34. Fracture Passed above crack Detectors F 2.40

TEST 35 TEST 38 A 0.77 A 0.34 8.00 0.23 2900 7.14 0.15 3950 B 1.00 B 0.49 8.00 0.14 4750 7.16 0.16 3750 C 1.14 C 0.65 8.00 0.24 2800 6.71 0.20 2800 D 1.38 D 0.85 8.00 0.20 3350 6.94 0.22 2650 E 1.58 E 1.07 13.84 TEST 36 F A 0.31 TEST 39 7.10 0.13 3500 B 0.44 A 0.06 6.64 0.15 4150 6.73 0.19 2950 C 0.59 B 0.25 7.32 0.23 3050 7.18 0.44 2700 D 0.82 C 7.15 0.20 3000 7.18 E 1.02 D 0.69 14.47 0.52 2800 7.24 0.26 2300 F 1.54 E 0.95 14.0 0.46 2550 F 1.41

.0030 .0020 oo: 00GO STRAIN TRACES COMPONENT FROM GASES PRINCIPAL AtOo DIRECTION 0F Ep STRAINS lOO ISO ou 30 200 1

-_____

0010 O020 05 FROM ROSETTE GAGES TIME NOS B IO - ,,%TIisecD,Os 4, 5, - TEST IS AND 6, 33 OS IO IS 000 TIME - mIIOseco,d; FIG. 22 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS .0030 0020 .0040 STRAIN TRACES COMPONENT FROM SAGES PRINCIPAL AND DIRECTION 0F 6,n STRAINS _Yo ISO 50 120 30

iOoI:D..:

TiITt

0010 -00200 0 OS FROM ROSETTE GASES TIME -NOS C IO nilbsecond. 7 8 - TEST 5 2.00 ANO 9, 33 05 IO 5 20 TIME - mIIlitecond. FIG. 23 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS 0040 0030 STRAIN GRACES COMPONENT I I CIAGES jI 00031 PRINCIPAL AND DIRECTION 0E 6ffa STRAINS t 4000) lOO ; 50 60 22P IO ¡ -0010 0020o 110 S \\ J Lt3° AND le, 33 I: OS FROM ROSETTE GAGES TIME -NOS F ID IS oIIrAeCondS 16, Ii, - TEST 55 IO IS 200 TIME - mOIitPCoodi FIG OS STRAIN TRACES FROM COMPONENT ANO PRINCIPAL STRAINS .0030 0020 _-0010 0040 STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL STRAINS AND DIRECTION OF C,,, 4 _YIe'\x

ISO ISO IDO

:

30

2

J

"1\L___

V----iii

V'

::

FIG OS IO IS 200 TIME - mIIII,.cDnd. 24 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS FROM 05 IO 5 2I TIME - m)IiSeçond. GAGES NOS IO, Il, AND 12, ROSETTE o - TEST 33

0000 STRAIN TRACES COMPONENT FROM SAGES PRINCIPAL ANO DIRECTION OF STRAINS 80 50

j

s, 0030 00GO 2O 30 200 ::: 0010 _OO2O o

1I1\j

OS FROM ROSETTE GAGES TIME -NOS. J IO 84.0000, 28 29 - TEST IS AND 30, 33 05 IO IS 200 TIME - ,"lI'ttAOnds FIG. 27 STRAIN TRACES FROM COMPONENT ANO PRINCIPAL STRAINS .0040 STRAIN TRACES FROM COMPONENT GAGES PRINCIPAL STRAINS ANO DIRECTION 180 0F E,,, yeR,'x 50 5 .00 30

::

.11:

:

2e-W -E _o 1/ R 'i 30 Dolo 0O2O 05 0 5 2GO TIME - mAlOtoOndi OS IO 5 200 TIME - 455,000db FIG. 26 STRAIN TRACES FROM COMPONENT GAGES NOS, 25, 26 AND 27, AND PRINCIPAL STRAINS FROM ROSETTE I - TEST 33 0000 0030 0020 ¿2010 STRAIN GRACES COMPONENT FROM GAGES PRINCIPAL STRAINS ANO DIRECTION 0F L 4 YIe\x ISO ISO 20 30 20 / o -0010 00200 -05 IO IS 200 05 IO IS TIME - RRIISSARRd TIME - II'dI,,.COOAI FIG. 29 STRAIN TRACES FROM COMPONENT GAGES NOS 4, 5, AND AND PRINCIPAL STRAINS FROM ROSETTE B - TEST 6, 34 0040 0030 .0020 i00bO 0010 _OO200 , STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL AND DIRECTION OF E,,. STRAINS 4

lOO ISO 1GO 30

S G B: FIG 05 1.0 IS 200 00 IO IS TIME ---,oRI,StCOodI TIME - ,,MNIRO.dS 28 STRAIN TRACES FROM COMPONENT GAGES NOS. I, 2 AND 3, AND PRINCIPAL SIRAINS FROM ROSETTE A - TEST 34

0030 0020 00*0 STRAIN TRACES COMPONENT FROM SAGES PRINCIPAL AND DIRECTION 0F C, STRAINS f YIe\ lAO

i

Izo 30 001G -00200 e-R _- e- ___---05 FROM ROSETTE GAGES TIME -NOS. C IO mMAs000nd. 7, 8, - TEST 5 200 AND 9, 34 05 IO IS 200 TIME - mIllIsecond. FIG 30 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS 0040 0030 0020 AGIO 0010 _0020o STRAIN TRACES COMPONENT i FROM GAGES PRINCIPAL ANO DIRECTION OC STRAINS 'RO ISO ¡ I IO

-"r,1I°

0 S 60 0 _J 30 20? ,ov -IIU -b.S __- _--FROM ROSETTE 05 GAGES TINE -NOS. D IO ,,,Or,seco,,d. IO, II, - TEST IS AND 12, 34 05 1.0 IS 2GO TIME - mIIIIetAoVd. FIG 31 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS 00*0 0030 0020 ¡0010 STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL AGO DIRECTION 0F CIoN STRAINS 1GO ¡I'\ ISO 20 60 30 0010 _0020o FIG 05 IO IS 200 05 1G IS 20? TIME - ,niIÌIs.Rn,Id. TINE - ,,*Ii.100nd. 32 STRAIN TRACES FROM COMPONENT GAGES NOS. 13, 14, AND IS, AND PRINCIPAL STRAINS FROM ROSETTE E - TEST 34 0030 0040 STRAIN TRACES COMPONENT i FROM GAGES PRINCIPAL ANO DIRECTION OF E STRAINS 4 _YIe GO ISO 520 60 30 0 0020 GOI0 O -.0010 -0020 0 05 IV IS 300 05 TIME - mIllisecond. TIME FIG 33 STRAIN TRACES FROM COMPONENT GAGES ANO PRINCIPAL STRAINS FROM ROSETTE IO IS 0.0 - m*Ii5000,,dS NoS. 6, 7, AND IO, F - TEST 34

0040 0030 STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL AND DIRECTION OF ClA__ STRAINS

/

\ / ISO I20 / / I .0020 2ó1 00200 II, FROM ROSETTE 05 GAGES TIME -NOs. IO R%Ir,,RcodS 25 26, - TEST IS AND 27, 34 05 IO 5 200 TIME - lnRinco,.d. FIG. 35 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS 0040 0030 ::: STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL STRAINS AND DIRECTION OF C,p,R f _Y161\x 60 --ISO 30 200 / -1 0010 00200 'J '----FROM ROSETTE 05 GAGES TIME -NOS H IO mïIi.eto@dS 22, 23, - TEST IS AND 24, 34 FIG 05 IO 15 200 TIME - plIIittAO,,dI 34 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS 0040 0000 .0020 0010 STRAIN TRACES COMPONENT FROM DACES PRINCIPAL AND DIRECTION OF E,,, STRAINS ye 150 ISO 120 60 ' f 0010 0020e --.-3O 05 IT 5 200 05 0 IS TIME - mlIIi,.co,,d$ TIME - .,ATR.CO,d. FIG 36 STRAIN TRACES FROM COMPONENT GAGES NOS 22, 23, AND 24, -ANO PRINCIPAL STRAINS FROM ROSETTE J - TEST 34 0040 , STRAIN TRACES FROM PRINCIPAL STRAINS 1GO COMPONENT GAGES AND DIRECTION 0F C f _Yje\ 50 .0030 .0020 120 0010

__.a

.-::

60 RAN A ___ -j 3, 'J OOIO 30 o -OO20 05 IO 5 200 OS IO IS 200 TIME - mI,ecDpd, TIME - .,,AIISRc0,,d$ FIG. 37 STRAIN TRACES FROM COMPONENT GAGES NOS. 31, 32, AND 33, ANO PRINCIPAL STRAINS FROM ROSETTE K - TEST 34

0040 0033 0020 STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL AND DIRECTION OF CflF STRAINS $ 00 50 120 9O AO 30 200

000:

0010 -0020o / FROM ROSETTE 05 GAGES TIME NOS A IO ,,,AI,SeCOodi I 2, - TEST IS AND 3 35 OS ID 13 200 TIME - mIllISecond. FIG 38 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS A' .0030 0040 I STRAIN TRACES COMPONENT FROM OASES PRINCIPAL STRAINS AND DIRECTION 01' lAC iso 42G AO G J 30 200 .0020 0010 o 0010 5O \! / V A ./ ---u ¡---u _-1 T'.,,.,, SR j s-T,4_____ -/ _I O OES FRON ROSETTE GAGES TIME NOS, B IO mArIsecAnd. 4, 5, TEST 5 AND 6, 35 05 IO 1.5 20 TIME ndIiSecondS F113 39 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS 0030 0020 .0010 Is o 00I0 _0O2T 3040 STRAIN TRACES ÇOMPONENT , FROM GASES , PRINCIPAL STRAINS ASO DIRECTION 0F E 4 _YIe'\x GO o 15G 120 60 30 '°

i.

I'TI V4 _{-JL_} 42 _' J ¡\p II

II

_-,I -I-__.. V '-_. 05 lO 5 200 OS IT IS 20 TIME mIllIseconds TIME I,,dliseoAnds F10 40 STRAIN TRACES FROM COMPONENT GAGES NOS. 7, 8, ONO 9, AND PRINCIPAL STRAINS FROM ROSETTE C TEST 55 R -0042 0030 STRAIN

j

064PGNENT TRACES FROM OASES PRINCIPAL STRAINS AND DIRECTION 0F Cmsy1 I\ TORCh 100 L 150 ROO 60 30 TIP 0020 0010 150 e A -12-R -''I! ,A / 7I _e_ -2

/

A i' I _/ II / 0010 _002O OS FROM ROSETTE GAGES TIME NOS D IO nArRecond. IO, II, TEST IS AND 12, 35 FIG 05 IO 5 200 TIME 'nillise,ondl 41 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS

0040 0030 0020 ¡00I0. STRAIN TRACES COMPONENT FROM GASES

PRINCIPAL ONO OIRECTION OF

STRAINS 4 180 150 120 30 ₂₀₀ ,/I/ I II t! 'i -'I -0010 _0020o I t! IS I.' ,_ ,N, FROM ROSETTE 05 GAGES TIME - IRÎII..Po,d; NOS. 2 IO 6 7 TEST IS AND 8 36 FIG 05 IO IS 200 TIME - ,,,III.,cond. 43 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS 0040 0030 0020 -0010 STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL STRAINS ANO DIRECTICN OF yel'\-x 50 i 20 3Q ₂₀ W I I__J' I , i ---. _.. I ¡ R...'...J,f'I

/I'

!._..,{' -0010 -0020

--/ -SS FROM ROSETTE GAGES Ill.004l TIME NOS I IO 15 mA,s.CAnd$ I 2 TEST AND 3 36 O OS IO IS 200 TIME ,flHIIRCOfldl FIG 42 STRAIN TRACES FROM OMPONENT AND PRINCIPAL STRAINS 0040 .0030 .0020 0010 _-0O2O STRAIN TRACES COMPONENT FROM GASES PRINCIPAL AND DIRECTION OF C,_ STRAINS ye lBS ISO 0 E _t; Í

OoIDNZ/;L

20 90 3G

0J

!6S

FIG 45 05 1.0 iS 20 0 0.5 I S I 5 2 TIME P1AII.Rc0n4. TIME -Ii..cod. STRAIN TRACES FROM COMPONENT GAGES NOS IS 17, AND 8, AND PRINCIPAL STRAINS FROM ROSETTE 4 TEST 36 0040 STRAIN rRACES FROM PRINCIPAL STRAINS lAO COMPONENT OASES ANO DIRECTION 0F L 4 _Ye\ 0030 ISO 0020 I 420

TP'!-_.:

7_) \ I, II --..; . --ODIO 30 t; 05 IO IS 200 05 IO IS 2.8 TIÑE InIIIINRcAP,d TIME F113 44 STRAIN TRACES FROM COMPONENT GAGES NOS II 12, AND 3, AND PRINCIPAL STRAINS FROM ROSETTE 3 TEST 36

0040 .0030 0020 So: OCIO -00200 STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL ANO DIRECTION OF E STRAINS 4 _YIe\ RO /

ì';4:::c:i>

50 _{IO 30}

Nr""\t'-/

'i

I-FIG 05 IO IS 200 05 IO IT 2d5 TIME - mUIIflCOfldI TIME - nAISICOFId; 46 STRAIN TRACES FROM COMPONENT GAGES NOS. 21 22, ANO 23, ANO PRINCIPAL STRAINS FROM ROSETTE 5 - TEST 36 0040 STRAIN TRACES FROM COMPONENT GAGES i PRINCIPAL STRAINS AND DIRECTION 18° E,p .0030 j ! ISO / i i .0020 I 20 0 I i SOlO

J

l

0/L

A5, _I I! ir I p I II I 4! s' 5 0010 3Cl F j "j .0020 05 IO IS 200 0.5 IO 5 21? TIME - miIII.,CAsd; TIME - MAflnPond$ FIG. 47 STRAIN TRACES FROM COMPONENT GAGES NOS. 24, 4 , AND 5, AND PRINCIPAL STRAINS FROM ROSETTE 6 TEST 36 .0030 OOIO -00200 .0040 STRAIN TRACES COMPONENT FROM GAGES

PRINCIPAL ANS DIRECTION OF Cpp

STRAINS 4 lAO 50 30 200 ZD

/'

»

-'..---A' ''ZI2'so OS FROM ROSETTE GAGES IT IS TIME - mASseco,,ds NOS, 29, 32, 8 - TEST AND 3F, 36 05 IO IS 200 TIME - ,,IIIincRnds FIG. 49 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS 0040 0030 0020

Io:I: -Solo _OO2O

STRAIN

TRACES

COMPONENT

FROM

GAGES

PRINCIPAL ANS DIRECTION OF C,,,,

STRAINS ye A 160 so lOO '30

It

1,

05 FROM ROSETTE GAGES TIME -NOS 7 IO ¡ It 200 AIIiSeAosds 26, 27, AND 26, - TEST 36 FIG 55 IO IS 200 TIME millinlAnds 48 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS

0040 STRAIN TRACES COMPONENT FROM GASES

PRINCIPAL AND DIRECTION OF Emo

STRAINS RO ISO O O 0030 0020 0010 t\ ! O _{90 60 30} 6

'A

''I

IRV ._'\/ ' / -D -O 0010 _0020o

j'

---FROM ROSETTE 05 GAGES TIME -NOS IO IO 30, 14 - TEST IS 28 AND IS 36 FIG os IO IS 200 TIME - fll,III.COdA 51 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS 0030 0020 _{_0020o} 0O40 STRAIN TRACES COMPONENT FROM GASES PRINCIPAL AND DIRECTION OF ,, STRAINS j 80 150 s E ---r---' 20 ₂₀₀

°j/\I\/'

0 OS FROM ROSETTE GAGES TIME -NOS, 9 IO mAfl.eARndS 25 9 - TEST IS AND IO 36 05 1.0 IS 20 TIME - ,AIitCOfldA FIG 50 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS .0040 STRAIN TRACES COMPONENT FROM RAGES -PRINCIPAL ANO DIRECTION 0F E STRAINS 4 ING ISO .00 50 0020 o 0010 -0o20o 90 30 200 A , E 120 OS FROM ROSETTE GAGES TIME -NOS I IO mAD..AOd. I 2 - TEST IS AND 3 37 FIG 05 IO IS 200 TIME - mIIIIItCA,0S 53 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS 0040 .00 30 .0020 , STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL ASO DIRECTION OF E1, STRAINS 4 _Yle\ 1RO ISO 5 o 120 30

r'

d,1.

I '--\, 0010 _0O2O FIG 05 IO 5 200 05 IO IS 200 TIME - INAI..00Rd, TIME - nIArMCDnd. 52 STRAIN TRACES FROM COMPONENT GAGES NOS. 33 , 9, AND 20. AND PRINCIPAL STRAINS FROM ROSETTE II - TEST 36

00GO _{0030 0020 00} : 0010 _OO2C STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL STRAINS AND DIRECTION O; CIflOyt1_X 1GO A 50 lOO 30 28 /

-;L

iïï:-OS FROM ROSETTE GAGES lIME -NOS 2 10 mAIi,eto,1G. & 7 - TEST ID AND $ 37 FIG 05 IO IS 200 TIME - mflllflcond. 54 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS 0030 0020 0010 0040 STRAIN TRACES COMPONENT FROM SAGES PRINCIPAL AND DIRECTION OF E STRAINS 4 00 15G 20 90 30 28 O JI

"I's

-.0010 ----'.1. 05 FROM ROSETTE GAGES TIME -NOS 3 0 IS ,,,ÎrIltCnnd. II 12 - TEST AND 13 37 05 IO ID 200 TIME - ITlIllitecOnd, FIG. 55 STRAIN TRACES FRON COMPONENT AND PRINCIPAL STRAINS 0040 .0030 002G 0010 O STRAIN TRACES COMPONENT FROM SAGES

PRINCIPAL AND DIRECTION 0F E

STRAINS 4 _YId\ lOO G E 150 12G 90 60 3G

91

,-__-op__._.__ -021G _{_0020o} ---05 FROM ROSETTE GAGES TIME -NOS IO mirIIecAnd, 16, 17 4 - TEST 5 200 AND IR, 37 F10 05 IO IS 200 TIME - ollilIsecond, 56 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS .0040 .0030 0020 I STRAIN TRACES COMPONENT FROH GAGES PRINCIPAL AND DIRECTION 0F Cn,. MO ISO 120 30 200 O STRAINS 4 _yI&IR'-x R I J V -0010 _{_0020o} FROM 05 GAGES ROSETTE TIME -NOS 5 IO ITlilIluIlOOndS 21,22 - TEST IS ANO23, 37 FIG OS IO IS 200 TIME - mIiIincond, 57 STRAIN TRACES FROM COMPONENT ANO PRINCIPAL STRAINS

0040 .0030 .0020

i

Gol: STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL ANO DIRECTION OF STRAINS f YIe 1GO 50 120 30 ₂₀₀ I2 'H ¿ / . 0010 _00200

II

05 FROM ROSETTE GAGES TIME NOS 7 IO - .,IOncond. 26, 27, IS _TEST / AND28, 37 FIG 05 IO IS 200 TIME - mMR..00,,d. 59 STRAIN TRACES FROM COMPONENT ANO PRINCIPAL STRAINS 0040 STRAIN TROCES COMPONENT FROM GAGES PRINCIPAL ENO DIRECTION OF E,pp STRAINS f 140 0030 ISO

-IÍH

:

lj

I, 30 -ODIO _0020o OS IO 5 200 05 IO 15 2.00 FINE - mlIII4.00.dt TIME - ,,,AIAecOd. FIG. 58 STRAIN TRACES FROM COMPONENT GAGES NOS 24 , 4 , AND S AND PRINCIPAL STRAINS FROM ROSETTE 6 - TEST 37 DORO .0030 0020 , STRAIN TRACES COMPONENT FROM GAGES , PRINCIPAL AiRAINS ANO DIRECTION OF C,,._ f _yIOAI'-x lOO j . _/ ' /

t:

ISO 20 30 0010 FIG OS I O IS 2 0 O 0.5 I O I 5 TIME - mRIIItCOndt TIME - .,ïI14Rco6. 60 STRAIN TRACES FROM COMPONENT GAGES NOS 29 .32 AND 31, ANt) PRINCIPAL STRAINS FROM ROSETTE 8 - TEST 37 0040 .003: .0020 7.0010 STRAIN TRACES COMPONENT FROM GAGES ' PRINCIPAL ANO DIRECTION OF E.fly\ STRAINS f Ç 80 ISO 420 30 3 II :1 0010 OO2O ° ---OS IO 15 200 05 IO IS 2 TINE - ,nRA*RcORO. TIME - ,.II1GRFR.,dA FIG. 61 STRAIN TRACES FROM COMPONENT GAGES NOS 25, 9, AND IO AND PRINCIPAL STRAINS FROM ROSETTE 9 - TESI 37

Z .0050 0020 0010 0010 _.00200 0040 STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL AND DIRECTION OFCrNy1\ STRAINS -80 o 5 r o ISO 20 90 60 30 200 e 'I ISR L

-- __

'T " I--J p7 \i '-0 OS FROM ROSETTE SAGES TIME NOS IO UAESRc0,ld. 301 14 O TEST IS ANO IS, 37 05 1.0 IS 20 TIME mUII,000nd. FIG 62 STRAIN TRACES PROM COMPONENT AND PRINCIPAL STRAINS 0040 -STRAIN TRACES COMPONENT FROM GAGES . PRINCIPAL STRAINS NNO DIRECTION OF L I _YIo' ISO ISO NO 30 6E 0030 o 001G -OO2O OS_V -NS - O _.." \ il _\ --'I / OS IO IS 200 05 TIME miIIiI.conds TIME FIG 63 STRAIN TRACES FROM COMPONENT GAGES AND PRINCIPAL STRAINS FROM ROSETTE IO IS 'RAritcoods NOS. 33, 19, ANO 20, II TEST 37 0040 .0030 0020 0010 STRAIN TRACES COMPONENT FROM SAGES PRINCIPAL AND DIRECTION OF L,,., STRAINS _YO x IT. ISO 12G 6O 30 200 t.' !\ I \ I R0 0010 _-0D2O0

\

000 05 FROM ROSETTE GAGES TIME NOS, I IO mARfloRRds I 2, TEST 15 ANO 3, 38 FIG OS IO IS 200 TIRE mIlIlsecoRd. 64 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS .0040 0030 ::: STRAIN TRACES COMPONENT I FROM SAGES PRINCIPAL STRAINS AND DIRECTION 0F Ln,, Y105\x SO ISO 30 2E? e .0010 _OO2Oo OS FROM ROSETTE GAGES TIME -NOS 2 IO OlTI5100ndI 6, 7, TEST IS ANO 8, 38 FIG OS IO 15 200 TIME ZSIIflCR041 65 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS

0000 STRAIN TRACES FROM COMPONENT SAGES PRINCIPAL STRAINS ANO DIRECTION OF £p. 4 _Yte'\ 0030 IsO f \ 0020 1 '\ ODIO OO

-GO o

,-'---.,

---NA \..__-000 30 -0020o OS 1.0 15 200 05 IO IS 200 TIME - FfliIGMAAfl4N TIME ,,,AONRCOnÓS FIG 67 STRAIN TRACES FROM COMPONENT GAGES NOS. 6

Il, ANO IB,

AND PRINCIPAL STRAINS FROM ROSETTE 4 TEST 38 .0040 0030 STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL STRAINS ANO DIRECTION 0F E 4 180 150 I: 30 od2 -f' L -ODIO _0020o

o/I

0 OS FROM ROSETTE SAGES TIME NOS. 3 IO mÎÇ$,OCATAN II , IS, TEST IS AND 13, 38 FIG 05 IO IS 20 TIÑE mIIS.OcA046 66 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS 0030 0020 0010 _OO2Oo .0040 STRAIN TRACES COMPONENT , FROM SACOS PRINCIPAL STRAINS ANO DIRECTION OF C,,., 180 ISO I' 20 30

ooI:/7\

J1T

05 FRON ROSETTE GAGES TIME -NOS. 6 ID mIlIlUTOnAN 24, 4, - TEST 15 -28 AND 5, 38 FIG 05 IO IS 200 TIME - R1IIINOA004N 69 STRAIN TRACES FROM COMPONENT ANO PRINCIPAL STRAINS 0040 , -80 STRAIN TRACES FROM PRINCIPAL STRAINS COMPONENT GAGES AND DIRECTION 0F CI] .0030 ISO

t\

t\

: i

0020 ODIO

A

-G0 u .0010 30 000O OS IO IS 200 OS IO IS 28 TIME ITGIIN*AAdN TIME - .,Idhi.EcondS FIG. 68 STRAIN TRACES FROM COMPONENT GAGES NOS 21, 22 ANS 23, ANO PRINCIPAL STRAINS FROM ROSETTE 5 TEST 38

.0050 0030 0020 .0010 STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL ANO DIRECTION OF C STRAINS

yx

RO ISO TOO 30 28

£I1

O:,,:çI

05 FROM ROSETTE OASES TIME -NOS. 7 0 IS ,,srs.c004s 26 27, - TEST ANO 28, 38 FIG 05 0 IS 200 TIME -AllIlItcond. 70 STRAIN TRACES FROM COMPONENT ANO PRINCIPAL STRAINS 0040 .0030 0000 oOI: _.0010 _00000 STRAIN TRACES COMPONENT FROM GAAES PRINCIPAL STRAINS AND DIRECTION OF CFy1e5\x lAO 90 30 28 0 OS FROM ROSETTE GASES TIME -NOS. 8 IO nAIlSICAndI 29, 32, 15 AND 31, _TEST 38 FIG OS IO IS 20 TIME - mIlIlItcond. 71 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS .0040 .0030 STRAIN TRACES COMPONENT FROM GASES PRINCIPAL STRAINS AND DIRECTION 0F E 4 _Yje'\x AO ISO 30 E

J:

IR-A I' I; _ _---\ k / 14D O 0010 00200 SR-A 7 V .,

/

'I /1

Í---05 lO IS 200 OS IO IS TIME - mIllisecond; TIME - nAlisecond. FIG. 73 STRAIN TRACES FROM COMPONENT GAGES NOS 30, 4 , AND 5, AND PRINCIPAL STRAINS FROM ROSETTE IO - TEST 38 0040 .0030 .0020 7 STRAIN TRACES COMPONENT FROM GASES PRINCIPAL AND DIRECTION 0F C, STRAINS 4 RO 150 120 GO o -30 -O 0010

DOl0/

t

i

-'"

AR_S , T f \ J "i--c AA I \ 'c f\ 47 .-OS IO IS 200 OS TIME - ,nIlII;ecccd$ TIME FIG. 72 STRAIN TRACES FROM COMPONENT GAGES AND PRINCIPAL STRAINS FROM ROSETTE O IS - mAlisleAnd; NOS 25, 0, AND IO, 9 - TEST 36

.0040 0030 0020 OOIO 0010 .00200 -STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL AND DIRECTION 0F STRAINS 4_{Yi e\} ISO 50 IZO 30

-.---.

I. FROM ROSETTE 05 _GAGES TIME -NOS. I IO I 2 - TEST 5 2& AND 3 39 OS IO IS 200 TIME - mIIIi,IcondI FIG. 75 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS 0040 0030 STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL STRAINS ANO DIRECTION OF E,,, Ye x ISO ISO g t; p'

:

60 30

A

I'

!PI

\ S -ODIO _0020o 33-H FIG OS IO IS 20 0 05 IO IS TIME - ,,,IIIIIRCOPÓ. TIME - ,.AT1..coAdS 74 STRAIN TRACES FROM COMPONENT GAGES NOS 33, 9, ANO. 2Q AND PRINCIPAL STRAINS FROM ROSETTE II - TEST 38 0040 .0030 .0020 0010 _0020o STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL ANO DIRECTION 0F Ca STRAINS 80 ISO ₉₂₀

:

30 g t; i 's

;00011

-f \_ FIG 0.5 IO 5 200 05 TIME - IRGII..coRd. TIME 77 STRAIN TRACES FROM COMPONENT GAGES AND PRINCIPAL STRAINS FROM ROSETTE ID 15 2O - mAr..00nd. NOS II , IS , AND 13, 3 - TEST 39 0040 .0030 .0020 Dolo o .0010 _OO2Oo STRAIN TRACES COMPONENT , FROM GAGES PRINCIPAL ANO DIRECTION OF Ep STRAINS 4 _{Yl o\} RO 150 20 90 GD 30 _2.00 2 t;

r

N

J

\ -FROM ROSETTE 0.5 GAGES TIME -NOS ID m3Tm.eA,,d, 2 6 , 7 - TEST 15 ANO 9, 39 OS IO IS 200 TIME -nHIIItCOfld3 FIG. 76 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS

.0040 003G

::

-Dolo -00200 STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL STRAINS AND DIRECTION OP Ep Yt2\x lAO ISO 6G 30

11111

z

05 FROM ROSETTE GAGES TIME -NOS IO mAliseconds 16 lT 4 - TEST39 5 28 ANGlA, 05 IO IS 200 TIME - ,,4IIIIRcond$ FIG, m STRAIN TRACES FROM COMPONENT ANO PRINCIPAL STRAINS 0040 STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL AND DIRECTION or c STRAINS

yx

80 0030

-"

-A t

\\.\

-15G 120 SO 3G 28

0020 DOlO 0IO 0G20o

-'í'l;' T's-_---_ --T DR_____ V I. f FROM ROSETTE 05 _GAGES TIME -NOS 5 IO mSG$econd, 21 22, - TEST IS AND 23, 39 05 IO IS 200 TIME - ,nIlIiflco,,d, FIG 79 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS .0030 .0020 004G STRAIN TRACES COMPONENT , FROM GAGES 4_II PRINCIPAL AND DIRECTION OF C,, STRAINS 1RO ISO 20 3G 2.8 G t I l'O ,

!irrÍì\:

jOGIoi

-GOlD -0020 OS FROM ROSETTE GAGES TIME -605.24 6 IO mAiseconaC , 4 , - TEST IS AND 5, 39 05 1G IS 20G TIME mIIIi*eçRnd, FIG. 80 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS .0030 .0020 0010 _-0010 _00200 0040 STRAIN TRACES COMPONENT , FROM AAGEG PRINCIPAL ANO DIRECTION OF £,o,o I STRAINS _Yle\ RO ISO 12G 30 T60 200 t .,

trII

I

---*:

05 FROM ROSETTE GAGES TIME - nAlsecond, NOS. 7 1G 26, 27, - TEST IS ANO 28, 39 05 IO IS 2GO TIME - milliecond, FIG. el STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS

0080 .0030 0020 0010 STRAIN TRACES COMPONENT FROM GASES PRINCIPAL AND CIRECTION OF Cn,,._0 STRAINS 4 80 CO ITO 60 30 2TP O ti

'1ii_°

o 0010 _ -FROM ROSETTE 05 GAGES TINE NOS o IO ,,Ijrm.RoIa. 25 9 - TEST IS ANGlO 39 FIG OS 0 15 200 TIME -flGlII.ttofldl 83 STRAIN TRACES FROM COMPONENT ANO PRINCIPAL STRAINS 0040 .0030 0020 1000 STRAIN TRACES COMPONENT FROM OASES -PRINCIPAL STRAINS ONO TIREETION 0F E Yt.QX.,x /\ J RO ISO 1 ' J \ 14 i S 20 0 :, 50

íVH:

0010 FIG 05 0 IS 200 05 IO 15 2I TIME - rflhIIincRfldl TIME - muliSeConds 82 STRAIN TRACES FROM COMPONENT GAGES NOS 29 32 ANS 31, ANO PRINCIPAL STRAINS FROM ROSETTE 8 - TEST 39 0040 0030 0020 STRAIN TRACES COMPONENT FROM GAGES PRINCIPAL AND DIRECTION OF STRAINS 1GO ISO -20 30 28

:L0OI0,.1,1:

0010 FROM ROSETTE 05 _GAGES TIME -NOS lO mIRlecoflAs 33 II 19 - TEST IS AND2O, 39 05 0 IS 200 TIME - IflIlIlI000RdI FlOE 85 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS 0040 .0030 Rozo 0010 0 .0010 00200 , STRAIN TRACES COMPONENT FROM GASES -PRINCIPAL AND DIRECTION 0F C STRAINS 4 _Yje'\ ISO ISO 42G SE 30 ₂₀₀ -I lo-u ____/ -___/ ----S 100M ROSETTE 05 GAGES TINE NOS ID nurse000di 30, 14 , o - TEST IS AND IS, 39 FIG 05 ID IS 200 TIME AIiOtC0fldl 84 STRAIN TRACES FROM COMPONENT AND PRINCIPAL STRAINS

be noted that these speeds ranged from 1850 to 4750 fps, and are thus in the same range as those reported for earlier tests. 1, 2

Computed Principal Strains

To compute the principal strains from the rectangular strain rosette equa-tions, it was necessary to determine strain values from the three component gage traces at selected times; the times were selected arbitrarily at points correspond-ing to changes in strain in the component gage traces.

The rectangular strain rosette equations used in computing the principal strains and the direction of the maximum principal strain are as follows:

where: E 1 max = -E min = Q -39-E + E

+Jz

(E - e )2 + Z(E - E )2 y h h d d y

E+Eh_J2(E -E )2+2(e

-E h d d y 2E - E - E 1 -1 d h y = - tan z _{Eh_Ev}

Emax _{= maximum principal strain}

E = minimum principal strain

min

Q = angle between E and the positive X-axis

max

Ev = vertical (Y) component gage strain

Ed = diagonal component gage strain

Eh = horizontal (X) component gage strain

40-The resulting curves of the principal strains (E and E ₎ and the direction

max min

of

maxwith respect to the positive X-axis () for Tests 33--39 are presented

in Figs. 21--85.

There are several important details that should be noted with respect to the time--alignment of the component strain traces for any particular rosette

gage. In the case of strain records obtained with gage layout A (Fig. 12), the

vertical gage peaked before or at the same time as the horizontal and diagonal gages for about 80 per cent of the rosettes. A detailed study of the component gage traces and the principal strain computations indicated that changes in the vertical and horizontal strain values have the greatest effect on the principal strain magnitudes; thus in Tests 36--39 it was decided to center the vertical

and horizontal gages above one another in the manner shown in layout B (Fig. 12).

For records obtained with gage layout B, the vertical and horizontal gages peaked before or at the same time as the diagonal gages in the case of about 85 per cent of the rosettes. Typical component gage traces from both layouts are shown in

Fig. 86; the offset in peaking times may be noted clearly.

It was believed initially that a refinement in the results could be ob-tained by shifting the recorded component gage traces to a position where the maximum strain values would occur at the same time. However, later studies

showed that there was only a small change in the principal strains as a result of this shifting of the component gage traces. This is illustrated in FLg. 87, which

shows the principal strain traces for a typical rosette computed 1) for the

com-ponent straìn traces as-recorded and 2) for the comcom-ponent strain traces shifted to make the peaks occur at the same time. It will be noted that shifting the trace does not change the shape or magnitude of the maximum principal strain

trace markedly. For most rosettes it would be necessary to shift the trace by

less than 0. 1 milli seconds to make the maximum strain values occur at the

same time. This time dìfference is of the same order of magnitude as the inherent

time error that accompanies matching of the trace times during a reduction of the

original 35-mm strip-film record. It should be noted that many other factors also

tend to affect the strain traces, such as the discontinuous nature of the fracture, the deviation of the crack path from the notch line, and inherent variations in

Fig. 86. Typical Strain Traces from Component Gage Layouts A and B. 0 0020 -41-00!5 0.0020 -00 Q_o (mn

Fig. 87. Effect of Shifting Component Gage Traces on Principal Strains.

to shift the traces; therefore, all of the principal strains have been computed

from the as-recorded component gage traces. Discussion of Strain Traces

In general, the maximum principal strain trace for each rosette is of es-sentially the same shape as the vertical component gage trace. The magnitudes

of the peak strain for the vertical gage trace and for the principal strain trace are also nearly equal for any rosette. This is shown in Fig. 88, in which a comparison is given of the maximum principal and vertical peak strain

magni-tudes; it will be noted that there is nearly a one-to-one correspondence in strain values, irrespective of the distance from the fracture path. Almost all peak strain values fall into a range between 0.0008 in./in. _{and 0.0030 in./in.}

The minimum principal strain traces _{are characterized by a shape that}

I /1

iROSETTE

LAYOUT TEST B 3S I

J//'\I

-L_AY0JT TEST ROSETTE A 50 ---, 0 i' --- -05 .0 1.5 20 25 TIME - miUisecorlds 0.5 IO I-5 20 as TIME - n,iIlisconds 0.00 20 0.0010 O -0,0010 0.0010 C a, 0

Q z O-0.0060 0.0050 0.0040 z I n 0.0030 0.0020 C 0.0010 o o strain

-42-//

exhibits a slight peak in tension,

followed by a fairly sharp

com-pressive pulse occurring as the fracture propagates past the rosette; this compressive puise corresponds to the tension peak

of the maximum principal strain.

The traces then return to the final strain level of the rosette.

In the case of rosettes located close to the fracture path,

the magnitude of the strain peak

is relatively large. As the dis-tance between a rosette and frac-ture increases, the peak principal

magnitude decreases rapidly. This may be seen clearly in Fig. 20, in

0.0010 0.0020 0.0030 0.0040 0.0050 0.0060

MAXIMUM VERTICAL STRAIN - In./ In.

Fig. 88. Comparison of Maximum Prin-cipal and Vertical Strain Magnitudes.

which typical principal strain traces for rosettes located at various distances from the fracture are presented. When the distance between the rosette and the fracture exceeds about Z in., the rate of decrease of the peak strain

magni-tudes is somewhat less. Figure 89 is a plot of all the peak maximum principal

strains versus distance between the rosette and the fracture. This figure gives

the impression that there is a wide scatter; however, if the curves are plotted for rosettes located at varying distances from the initiation edge (8 in., 15 in., etc.), the individual curves move to the right with increasing distance, as may be seen in Figs. 90 and 91. Thus, there is an increase in the peak maximum principal strain with increasing distance from the initiation edge; this increase is noticeable to a distance from 22 to 29 in. from the initiation edge, after which there is no apparent change. Thus, the strain field associated with the propagating fracture appears to reach a "steady state" condition at about 22 to 29 in. from the initiation edge.