Welded reinforcement of openings in structural steel members: Room and low temperature tests of plates with reinforced, openings

Studiecentrum T. N. Scheeps d. Sche C', 9 c) N-.

z

o o 0 Third PROGRESS REPORT (Project SR-119) on

WELDED REINFORCEMENT OF OPENIN3S

IN STRUCTURAL STEEL MEMBERS: Room and Low Temperature Tests of Plates

with Reinforced Openings

by

D. Vasarhelyi and R. A. Hechtman

UNIVERSITY OF WASHINGTON

Under Bureau of Ships Contract NObs-50238 (BuShips Project NS-731-034)

for

SHIP STRUCTURE COMMITTEE

Convened by

The Secretary of the Treasury

LA&ORATOR!LM

_VOOR

ChEEP.CO

_RUCTES

Member AgenciesShip Structure Committee

Bureau of Ships, Dept. of Navy

Military Sea Transportation Service, Dept. of Navy United States coast Guard, Treasury Dept. Maritime Administration, Dept. of Commerce American Bureau of Shipping

JUNE 30, 1953

0312

SERIAL NO. SSC-55

Address Correspondence To:

Secretary

Ship Structure Committee U. S. Coast Guard Headquarters Washington 25, D. C.

SHIP STRUCTURE COMMITTEE

Jurie

30, 1953

Dear Sir:

As part of its research program related to the improvement of hull structures of ships, the Ship Structure Committee is sponsoring an investigation on the "Welded Reinforcement of Openings in Structural Steel Members" at

the University of Washington. Herewith is a copy of the

third progress report, SSC-55, of the investigation,

en-titled "Welded Reinforcement of Openings in Structural

Steel Members: _{Room and Low Temperature Tests of Plates} with Reinforced Openings" by D. Xîasarhelyi and R. A. Hechtman.

Any questions, comments, criticism or other matters pertaining to the Report should be addressed to

the Secretary, Ship Structure Committee.

This Report is being distributed to those

individuals and agencies associated with and interested _in

the work of the Ship Structure Committee0 Yours sincerely,

K. K. COWART

Rear Admiral, U. S. Coast Gu.rd Chairman, Ship Structure

C olTunit tee.

MEMBER AGENCIES: ADDRESS CORRESPONDENCE TO:

BUREAU OF SHIPS. Dipl. or NAVY SECRETARY

MILITARY SEA TRANSPORTATION SERVICE. DEPT. OF NAVY _{SNIP STRUCTURE COMMITTEE} UNITED STATES COAST GUARO, TREAUURY OPT. U. S. COAST GUARD HEADQUARTERS

MARITIME ADMINISTRATION. DEPT. or COMMERCE WASHINGTON 25. D. C.

Third

PROGRESS REPORT

(Project SR-ll9)

on

WELD REINFORCEMENT OF OPENINGS

IN STRUCTURAL STEEL MEMBERS:

Room and Low Temperature Tests

of

Plates

with Reinforced Openings

by

D0 Vasarhelyi and R0 A, Rechtman

UNIVERSITY OF WASHINGTON

und e r

Department of the Navy

BuShips Project No. NS-73l-O3

4

Bureau of Ships Contract MObs-50238

f or

TABLE OF CONTENTS

Pa ge

IINTRODUCTION

o o o o o o e o o o o e o o 1

IIQ OBJECT AND SCOPE OF THE INVESTIGATION e e e e e o 2

lilo

TESTSANDTESTMETHODS00

0O oe000.00e.o

3

l Specimen Steel and Welding Electrodes . . 3

2 Details of the Test Specimens . e ₇

Method of Loading 7

Cooling of the Specimen . . o o 12

5 Gaging and Measurements 12

1V0 RESULTS OF TESTS o o e o o o o o o e o e o e e o o 13

l, Introduction and Definition of New Terms . 13

2 Distribution across Plate of the Elongation on a

Gage Length Equal to the Width of the Specimen0 0 16

3 Comparison of Load on Specimen and Elongation on

Gage Length Equal to Width of Specimen0 o o o o o 22

General Yielding of Specimen e o o e 30

5' Ultimate Load and Ultimate Strength 30

32 7° Comparison of Energy Absorption to Ultimate Load

with Ultimate Strength and Elongation to Ultimate

Load . , . , .

8 Percentage of Reinforcement e o o o o e o o o o

9° Efficiency of the Plates with Openings . 53

100 Unit Strain Concentration in the Region Around

the Opening at Room and at Low Temperature0 O

11 StrainAging Effects and Incidental Causes of

Failure e u o o o e o o o o e e o o o 61

V0 CONCLUSIONS o o o o o o o o o o e o o o o o o o o e 6+

VI0 ACKNOWLEDGEMENTS0000000000..°.000

65

VII0 BIBLIOGRAPHY o o u o u e o o o o e o o o o e o o o o 66

LIST OF TABLES

No.

T1ç

Page

I Mechanical Properties of Plates of Different

Thickness Semi-Killed Steel U As Rolled

Ii Description of Specimens with 9 in. x 9 in.

Openings 'with ii/8 in. Corner Radius

0.0

0 o 8

III LISt of Plates Used for Fabrication of Each

Specimen 9

IV Strength and Energy Absorption of 36 in, x

1/1+

In0

_{and +8}

in0

x l,'2 in. Plates with

Openings at Room and at Low Temperatures. 17

V Average Unit Strain Energy and Average

Elonga-tion to Ultimate and to Failure for All

Specimens . . 19

VI General Yielding and Fractures of the Specimens

35

LIST OF FIGURES

No. Title Paze,

1. Charpy Keyhole

Notch-Impact

Test Results for

Steel U as Rolled o o o o 5

2 Body Plates of

36

in0 x i/ in0 and +8 in. x

1/2 1n, Specimens0 Location of Slide Wire

Resistance Gages and Thermocouples. 10

30 Details of the Face Bar, Doubler Plate and

In-sert Plate Types of Reinforcement. o 11

Location of SRF 'Gages Around the Opening of

the Specimen

o o o o o o o o o

5 Location of SRF Gages Around the Opening of

the Specimen0 O

15

6 Distribution Across Plate of Elongation on a

Gage Length Equal to the Width of the Plate,

Specs0 No0 9 and 990

20

Distribution Across Plate of Elongation on a Gage Length Equal to the Width of the Plate,

Specs0 No3

lOand 310..

00 000

000

20

8 Distribution Across Plate of Elongation on a

Gage Length Equal to the Width of the Plate,

Specs0

No0 15and320

20

90 Distribution Across Plate of Elongation on a

Gage Length Equal to the Width of the Plate,

Specs0 No0 21 and 3 . . . o o o 20

1O Distribution Across Plate of Elongation on a

Gage Length Equal to the Width of the Plate,

Specs0 No39and 50

21

110 Distribution Across Plate of Elongation on a

Gage Length Equal to the Width of the Plate,

Specs0 No0 51 and 52 o 21

i2 _{Distribution Across Plate of Elongation on a}

Gage Length Equal to the Width of the Plate,

Specs0No055and560003000000000

21

7o

Te

l3

Distribution Across Plate of Elongation ori a

Gage Length Equal to the Width of the Plate,

Specs0 No0 70 and 7l 21

Comparison of Load and Average

Elongation on

a

Gage Length Equal to the Width of the

Plate,

Specs0

No0 9 and

99° 0 0 23

150

Comparison of Load and

Average Elongation on a Gage Length Equal to the Width of the Plate,

Specs0 No0 10 and 31 w o 23

i6 Comparison of Load and Average Elongation on

a

Gage Length Equal to the Width of the Plate9

Specs0 No0

15and320

000000000000

2+

l7

Comparison of Load and Average Elongation on a

Gage Length Equal to the Width of the Plate9

Specs0 No0 21 and 3+ o o o 2+

l8

Comparison of Load and Average Elongation on a

Gage Length Equal to the Width of the Plate, Specs0 No0 )+9 and 50

l9

Comparison of Load and

Average Elongation on a

Gage Length Equal to the Width of the

Plate,

Specs0 No0 5land 520 w o

o woo w

o o o e e 25

20 Comparison of Load and Average Elongation on a

Gage Length Equal to the Width of the Plate9

Specs

No0 55, 55A

and 56 o w 26

2l Comparison of Load and Average Elongation on a

Gage Length Equal to the Width of the Plate,

Specs0 No0 70 and 7l 0 0 0 0 0 0 o o o 26

22. Average Elongation to Ultimate Load at Room

and at Low Temperature w o 0 29

23 Load and Average Stress on Net CrossSection

at General Yielding at Room and at Low Tempera

turc 31

21F0 Ultimate Load and Ultimate Strength at Room

and atLow Temperature0

000

31

rage

25 Energy Absorption to Ultimate Load at Room

and at Low Temperature0 o o 0 ₃₃

26 C.mparison of Energy Absorption to Ultimate

Load with Ultimate Strength. o

26a0 Relation between the Energy Absorption to

Ultimate Load of Plates with Openings and

the Notch Acuity of the Opening0 o 1f1

27 Comparison of Average Unit Strain Energy

and Average Unit Elongation to Ultimate

Load at Room and at Low Temperature0 o o

28 Comparison of Ultimate Load and Percentage

of Reinforcement. .. . o e. .

29 Comparison of Ultimate Strength and Percent

age of Reinforcement. OOe o

o os

oso

o o

Comparison of Energy Absorption to Failure

and Percentage of Reinforcement . Lf7

30a0 Comparison of Average Net Stress at General

Yielding and Ultimate Load with Same Prop

erties of Tensile Coupons o ).f7

Unit Strain Concentration in the Region of

the Opening in 36 in. x l/+ in0 plate0 Face

Bar Reinforcement0 Specs. No0 9 and 99. .

32 Unit Strain Concentration in the Region of

the Opening in 36 x 1/1 in0 plate0 Face Bar

Reinforcement0 Specs0 No0 10 and 3l o o o o

33. Unit Strain Concentration in the Region of

the Opening in 36 x l/+ in0 plate0 Doubler

Plate Reinforcement. Specs0 No. 15 and 32 50

3- Unit Strain Concentration in the Region of

the Opening in 36 x i/-i- in0 plate0 Insert

Plate Reinforcement0 Specs. No3 21 and 3+ 0 ₅₀

35 Unit Strain Concentration in the Region of

the Opening in +8 x 1/2 in. plate at Low and

at Room Temperature0 Face Bar Reinforcement0

Specs0No..9and5O.000

00000

0000

V

36

Unit Strain Concentration in the Region of

the Opening In

)3

x 1/2 ir±0 plate at Low and

at Room Temperature0 Doubler Plate Reinforce

men Specs0 Nc ₉ and 5O. G 5'l

37

Unit Strain Concentration in the Region of the

Opening in 8 x 1/2

in0

plate at Low and at

Room Temperature0 insert Plate Reinforcement0

Spec0 No0 55

55A and 56 52

38

Unit Strain Concentration in the Region of the

Opening in +8 x 1/2

in0

plate at Low and at

Room Temperature0 Insert Plate Reinforcement0

Specs0 No 70 arid

7l.

e e

00

o o o o o e 52

390 Photographs of Specimens After Fracture0 56

Photographs of SpcImenis After Fracture0 O e 57

1f10 Photographs of Specimens After Fracture0 58

Nature of the Fractured Edges of the Specimens o 59

ROOM AND LOW TEMPERATURE TESTS OF PLATES WITH HE1N.iORCED OPENINGS

L INTRODUCTION

This report continues the work described previousiy in which the investigation of various room temperature prop-erties of selected types of are-welded reinforcement for openings in plain-carbon structural steel plates loaded un-der uniform tension led to the conclusion that from the standpoint of performance the square opening with rounded corners having a i 1/8-in0 radius and the circular opening

appeared to give the best properties0 Since this

investi-gation covered only the behavior of specimens at room tem-perature, the problem of their behavior in the more

criti-cal low temperature range was unknown. Moreover, it was

desirable to parallel the previous tests of 36-in by

l/+-in. plates wIth tests of

+8-in,

by 1/2-in, plates In

order to use thicker plate which would have a higher transition temperature0

This progress report Includes tests of four specimens

36 In, by l/-i- in. and nine specimens +8

in0

by 1/2 in. in

cross-section, four of the former and four of the latter

being tested at low temperatures. All specimens had a

9-in0 by

9-in0

square opening with rounded corners

rein-forced by a welded face bar, single doubler plate, or

distribution and. concentration in the vicinity of the open-ing, and the total energy absorption were studied for all

specimens0 The results of the lcw temperature tests were

compared with those obtained in the room temperature tests0

Another phase(2) of this research investigated the

dis-tribution of unit strain energy and stress in the plastic range of the materiaL

For brevity., the two previous reports will be referred

to hereafter as the First ogress Report and the Second

Progress Beport(2).

IL OBJECT AND SCOPE OF THE INVESTIGATION

This part of the experimental program on welded rein-forcement of openings in structural steel members was planned primarily to find information concerning the be-havior at low temperature of plates with a square opening

with rounded corners and various types of reinforcement and

to test plates of greater thickness0 The influence of low

temperature on such factors as general yielding, ultimate strength, energy absorption unit strain distribution, and mode of failure was investigated0

This investigation was a continuation of the work

re-ported in the First Progress Report. The results of the

tests in that report are compared with the room and low tem perature tests in thIs report0

1110 TESTS AND TEST METHODS

L pecimen St

eldi lectrode.

All specimens were fabricated from the same steel used

in the previous tests0 Steel U is a plain-carbon

semi-killed grade meeting ASTM Specification A7 - 1+9T and was

used in the as-rolled condition0 The chemical analysis for

l/+-in0

Plate No0 2 gave

C Mn P S Si

0G23

0O

₀₀₅₃

_005l

₀₀₇

and for 1/2-in0 Plate I 1f,

Ni Cr Cu

O22

0+7

00010

0028

005

₀₀₇

TR

_0O66

The only significant difference in these two analyses, which were made by different laboratories, occurred in respect to the amount of phosphorus and sulphur.

The tensile properties at room temperature as determined by tests of ASTM standard flat specimens at -20° and J+6°F0

as determined by tests of

l-in0

wide flat specimens are

given in Table L. It was necessary to use a tensile

spei-men with a reduced width for the low temperature tests in order to utilizTe fixtures made for this type of test0

The Charpy keyhole notch-ipact test resuits are

shown in Fig0 i for 1/2-in0 Plate No0 The transition

temperature range feil between temperatures of about _LI00F. and some temperature in excess of 160°F0, the maximum at

1LBI.

I

CHANICAL PROPERTIES OF PlATES OF DIIIYERENT THICKNf3E SEMI-KILLED STEEL U AS ROLLED

*

_{Cut from pirmanent1y strained specinn and norra1ized.}

Plath

No,

Thicknss

in.

Temp.

Dg. F,

Upper

Uitinat

JLlong,

Yield

Strength

Point

_p;i

r)oT_Tenprature Tet

n 8 in,

er cent

Red, of

Area

per

ent.

lear-Test

Transition

Deg, F,

5 6* 10 15; 16 17 18 19 21 214 25; 26 3 1/2 1/2 1.

1/4

i/h

1,'Ii. 1/14 1/14 1/14 1/2 1/2 1/2 1/2 1/14

27,1

27)4 32,6

27.8

29,5

29th

29 2 28,2

286

293

31.2

297

29.1

32 1

27,9

WJ

W,6

50 8

SL?

149,7 55; .3 56.3

503

220 -146 -20 -146 39,900 61,900 38,800 59,50e 32,800 61,100 L,20O _63,L.00

U,ioo

65,300 hh,300 65,200 h5;, 100

65,800

U.4,000 65,900 LIJ!,5oO 66,000 b14, Boo 65; ,800 36,500 61,OO 36,900 62,300 Lcm Tempratur9 Tes t

t1,'i0o

71,1400 ).0, 700 66,330 55,100 73,600 i L'

C, w

z

w

2.

Fig.

i

.

Charpy Keyhole NotchImpact Test Results for Steel U

as Rolled.

50

40

30 20 lo o o o o o o 2 o 2 o 2 o 5 FT.LB. _{AT 24° F.} 2 o

080

40

0 40 80 120 160

6-which tests were made0 The transition temperature for 50

per cent of maximum energy absorption would appear to be

about 20°F0 The temperature for an energy absorption of

l5 ft0-1b0 was about -2+°F0

The transition temperature as determined by the Navy tear test for specimens of full plate thickness and the

av-erage ASTM grain size were found to be as follows:

The rnicrostructures of these plates were shown in the First Progress Report

These data were used in selecting the temperature for

the low temperature tests. Except for Specimen No, 50,

which was tested at -20°F0, all specimens were loaded at -+6°F., which temperature was considered low enough to give

a predominantly cleavage failure even in the 1/+-in. plates.

This latter temperature was also about the lowest which the refrigerator equipment could maintain constant while absorb-Ing the heat given off by the specimen during plastic deforma-tion0

The same coated welding electrodes, 1/8 and 5/32 in0 in

diameter meeting AWS Specification E-6010 were used as in

the first group of tests0 The properties of the weld metal

were not especially investigated.

Plate Plate Thickness

No0 inches Transition Tern-perature, °F0 Average ASTM Grain Size 18 1/'+ 8 1/2

0

6

lo

i

120 ₅

2 Details of the Test pecimens

The

l/4-Irie

plate specimens tested at low temperatures

exactly duplicated the types tested at room temperature as

reported in the First progress Report(1)o The same method

of fabrication was carefully followed0 Table II gives the

program and Table III the plates from which the specimens

and details were cut0 Sketches of the specimens including

the dimensions of the welds are shown in

Figs0

2 and ₃

It was necessary to make the +8-'In0 wide specimens from

+8-In, plate0 In order to increase the length of the butt

weld joining the specimen to the pulling plates of the test

ing machine, wing plates of the same thickness and ₃ In0 by

8 In0 in size were welded to the four corners of these

specimens. These plates after the completion of the weld

ing were flame-cut and ground to the shape shown In Fig0 2 In order to minimize the possibility of fracture0

No specimen was tested until at least seven days after the welding of the reinforcement0

30 Method of

The specimens were tested in a 2,+OO,OOOlb. capacity

universal hydraulic testing machine0 They were butt welded

to the pulling plates, which in turn were free to swivel on

the pins of the devises of the testing machine0 The center

line of the specimens was aligned within 1/16 in. of the line joining the centers of the devis pins.

-8-TABLE II

DESCRIPTION OF SPECIMENS WITH 9 in. x 9. in. OFENINGS WITH 1-1/8 in. CORNER RADIUS

Spec.

Size of Reinforcement

Percentage

Cross-Section

Test

No,

cf Reinforce-

Area - cq. in.

Temp.,

I.

36 in. x :L/1 in, Body Plate

A.. Opening Reìnforced by a race Bar.

9

2 x 1/

Lo 9.13 7.Th 72

99

2 x i/1

1O

9,00

7,7LL -1.6

10* _{1 x 1/L.} 16

9.ÌS

722

7

31

1 x i/Li

16

9.00

7,22

.-6

B,

Opening Reinforced by a Single Doubler Plate.

18 x 18

i/Ia. 103 9,13

9,16

76

32

18 x 18 x l/L

103

9,00

9,16

46

C. Opening Reinforced by an Insert Plate.

2]?

i1) x 1/2

62 9,02 8 .17 77

3

]$D x 1/2

62

9,00

8 ,)7 -b6

II,

b8 in. x 1/2 in, Body Plate

Opening Reinforced by a Face Bar,

1L9

2 x 1/2

33

2I,32

21,2I

70

2 x 1/2

33

2L37

21.2 20

Opening Reinforced by a Single Doubler Plate

18x18x1/2

96 2L.17 2Ii.01 7Lt

18x18x]J2

96

2b.00

21i3O1 -IL6

C. Opening Reinforced by an Insert Plate,

J5D x 1

66 23,63 22,09 70

lSD x 1

67

23.58

22.10 69

56 15D x 1 66 2IL.,00

22.09

-146

70

12-3/IL x 12-3/iL x 1

39 2IL.00 21.38 76

71

12-3/Ii x 12-3/14 x 1

39 21i.00 21.38 -146

ment _{Gross Net}

_{Deg, F.}

in

-9-TABLE III

Mechanical properties of these plates

ax'e given

in Table I,

LIST OF PITES USED FOR FABRICATION OF ACR SPECThIEN

Spec. No,

Plate No. Used For

ody

1ate

Reinforceint

9 19 19

io

18 18 35 21 21 21 3.7 ₂₅ 31 16 21 32 1.5 21 3h 3.5 26 1i.9 6 25 So 6 25 51 6 ₂₅ 52 .5 26 55 26 10 2.5 10 56 .5 10 70 _{3 10} 7]. _{3 10} 99 3$ 21

SLIDE WIRE SPACING SAME ON BOTH FACES 3,.. 0

3"

/4 48" p w w

P

O

-LOCATION OF THERMOCOUPLES SLIDE WIRE i SPACING SAME ON3 BITH ACES

II.I'

I 11/4 I._. 113/4",

a

;iH

Wa 48"

-a a

Fig. 2

.

Body Plates of 36-in. x 1/4-in, and 48-in. x 1/2-in. Specimens. Location

of Slide-Wire

Resistance Gages and Thermocouples.

-w

w

w

SPEC. NO. 10,3

h

9..

SPEC. NO. 9, 99

SPEC. NO. 49,5O

SPEC. NO. 55, 55A, 86

r#

600 SPEC. NO. 15, 32 SPEC. NO. 51,52 12 SPEC. NO. 70,7!

Fig. 3

.

Details of the Face Bar, Doubler Plate and Insert Plate

Types of Reinforcement,

the load was applied

slowly nd readings of the gages

were taken at frequent intervals0 &wugh time was aiLy'Ted

in the low temperature tests to absorb the heat developed

by the plastic stretching of the plate and to

maIntain a

constant test temperature0

ool1g of the Spec 1mm.

In order to cool the specimens for the low temperature

tests the specimen and the devises of the testing machine

were enclosed In

an almost airtight canvas bag, over which.

four layers of woolen blankets were wrapped0 Air chilled

to the required temperature wa. circulated contInuously through the bag from a combined mechanical and dry'ice re

frigerating system0 The regulation of the air flow provided

a control of the testing temperature which was maintained

within 2°F0

The temperature of the specimen

was measured at fre

quent intervals by copperconstantan thermocouples at the

sIx points shown on Fig0 2

The thermocouples were solO

dered to the clean steel surface and covered with

l/+In

thick felt pads. The thermocouples at the different

loca-tions did not show a temperature difference greater than 3°F0

5 Gj

a

asrems0

The gaging and measurements were so designed as to ai

l3

temperature and were remotely controlled, since no direct observations on the plates could be made in the low tem perature tests.

The principal measurements of the elongation were made straddling the region around the opening by s1idewire gages located on both faces of the plate on four equal spacIngs

across the width as

shown In Fig0

2. Since the gage length

was equal to the width of the specimen, a gage length of

36

in0 was used for Specimens

No0 9, 10, 15, 21, 31

32, 3)+,

and ₉₉ and of +8 in. for Specimens No0

9 to 52 and 55,

5'5'A,

56, 71, and 72.

The unit strain distributIon was determined by SR+ gages applied to both faces of the plate to remove the ef

feet of bending0 The locations of

the SR-

gages for the

different types of specimens are shown in Figs. + and

_5.

The SR+

gaging of Specimens No0 70 and 71 followed the

pattern of Specimens

No0 51 and 52.

IV. RESULTS 0F TESTS 1. Introduction and Definition of New Terms.

Three factors

were varied in the tests reported herein the body plate width and thickness9 the type of reInforee

ment, and the testing temperature.

The shape of tie 9in.

by

9-in,

opening was the same for all specimens, square with

C)

SPECS. No. 9 & IO

SYMBOL

GAG E TYPE A-12

A-7

A R1

SPECS. No. 31 & 99

Y 2

KK

4.

SPECS. No. 49 8 50

3' c'J

SPEC. No. 5

SPEC. No. 32

SPECS. No. 51 & 52

Xnot on reverse side

SPEC. NO.52

Fig. 4

.

co

SPEC. No. 55

SPEC. No. 21

SY M BO L k'

I

GAGE -TYPE

AI I

A-12

Â-7

AR-I

-SPEC. No. 34

SPECS. No. 55A&56

Figs0

6 to +3 and Tables IV to VI.

Most of the terms used .th this report were previously

defined.

Several new terms require explanation or

clari-f ication. The percentage of cleavage in the fracture was

taken as the ratio in per cent o the cleavage portion of

the riet cross-section of the specimen along the fracture

line including any unbroken part of the plate width0 The

percentage of shear was determined in the same manner0

In computing the percentage of reinforcement, the ratio in per cent between the net cross-section area added by the reinforcement at the critical section and the cross-section

area of the a'teriai removed from the body plate by the

opening was used. Thus the percentage of reinforcement as

it is defined here gives identical values for similar types of l/- and l/2in. thick specimens0

The average unit strain energy is defined as the total energy absorption within the gaged area divIded by the

vol-ume between the gage lines0 The unit elongation was equal

to the average elongation within the gage length divided by

the gage length.

2. Distribution across Qte ation on a ge

Le to the WIdth 01' the men.

The distribution across plate cf the elongation on a gage length equal to the width of the plate for both room

Spec, No.

STRFJJGTH AND ENEROY ABSPTION OF 36" x i/li" and

1j8" x )J2"

PLATES VITH OPENINGS

AT ftOOM AND AT LOW ThMPERATÏJRFS

Per Test Cent Temp. cf Re!nf. Dcg.F.

Frac ture* Per Cent

C S Un-broken kipa kai kai kips Joel TABLE 1V General Yielding Load

Ayo. Stress Gross

Net 9 140 72 0 1414 56 319 99 140 -146 97 3 0 3140 10 16 75 0 69 31 313 31 16 -146 75 25 0 3614

36" x 1/Li" Bcdy Plate.

Single Doubler 15 103 76 o 65 35 362 140.2 140.2 32 103 -1.i6 63 22 15 149.0 )i8.1

Ultimate Strength Load Ave, Stress

Gross Net kai 35,5 141.8 1451.0 50.1 59.2 37,8

)4o

507,0 56.14 65.5 314.8 143.9 ¿i67.0 51.9 65.5 140.14 50.ti 527.0 58.6 73.0

Energy Abs orp .**

Yo

To

Ulti-Failure

mate Load 1000's in-lb Nature of Final Fracture

Proportion in

pe1'

cent of total net cr.ss-section area at fracture surface

including

fracture and unbroken section, if any,

C = Cleavage.

S

Shear.

36-in, gage length for 36"

x ]Jli" plate.e.

148in,

gage length for 148" x 1/2"

plates.

36" x i/Li" Body Plate.

Face Bar Reinforcement.

/ 7147 -, 1063 Weld to Reinf. 1062 1019 Through opening. 12]li iSoli Through opening. 1857 1880 Through opening. Plate Reinforcement. 522.5 58.1 58.1 729 1099 Through opening. 5148.0 60.9 59.8 89t. flOh Through opening.

TABlE IV (Cont,)

STR}NGTH ANT) EN1±RGY ARSORPTION 0F 36" x 1/14" and 148" x

1/2" PLATES WiiH ÖPfNIN0S

!T WOM ANP í.T LT TE!PETPRF

General Yie1d

Ultimate Seth

Load

Ave. Stress

Load Ave. Streß8 Groas Net Gross Net kips

ksi

kei

kips

ksi

ksi

Energy Absorp.-3H1

-

Ulti-Faj1

mate Load

1000's in-lb

Nature of

Final

Fracture

# Initial failure in pulling plate0 Spec.

No. 51 reloaded after 3 days, Spec. No.52 after 9 days,

and Spec. No, 55 after

10 days0

1.x ]Jh"

ody Plate.

Insert Plate ReinforcementQ

21 62 77 o 66 314 300 33,3 36,14 1478,0 53,1 57,9 11% 114814 Through opening. 314 62 -146 96 14 o 376 14i.8 146.0 551,5 61.3 67.5 1652 15142 Through opening. 148" x 1/2" Body Plate.

Face Bar Reinforcement.

149 33 70 0 77 23 7140 30.14 314.8 3255 51.6 59.0 3510 4710

Weld to reînf,

50 33 -20 99 1 0 880 36,6 141.5 11410 58,8 66.8 5892 5610 Through opening.

148" x 1/2" Body Plate. Sin1e Doubler Plate Reinforcement,

51 96 714 0 8]. 19 770 31.9 32.1 1385 57.14 57,7 14730 5360

Weld to reinf/

52 96 -146 100 0 0 950 39.6 39.6 11460 60.8 60,8 14303 14187

Throu:h bocbr

plate

146" x 1/2" Body Plate

Insert Plate Rainforcement

55 66 70 57 28 15 800 33,8 36.2 1275 514.0 57.7 142140 14660 Through opening j'V 67 69 0 79 21 800 33,9 36,2 1288 514.8 58.3 14082 14328 Through opening. 56 66 -146 100 o o 900 38,2 140,8 1360

57.6 615

314214 3220

Through body plate,

70 39 76 1 50 149 BoO 33,3 37.6 1276

53.l

59.7 3362 3699 through opening 71 39 -146 100 O o 800 33.3

376

1176 li8.8

55,0

20814 20814 Through opening Spec. Per

Test

Frac ture* No. Cent Temp. Per Cent,

of

C S Un-Re

f,

broken Deg .F.

Studiecentrum T. N. O. Scheepsbouw

_{en Navgatie}

19

fd. Scheepsbouw _DELFI

TABLE V

AVERAGE UNIT STRAIN RNERGY AND AVERAGE ELONGATION TO ULTLVJAfl

AND TO FAILUIE FOR ALL SFECThIENS

55

Ir

70 69 76 )46 cL.

358

3,58

3.97 309)4 3.05

32

) ,,2 8 ¿4 2 O 2q75 ¿4000 2,GO 383)4 ¿43)45 3)496 3)496

¿48" x 2"r Plate,

Insért Plate ReinorccdLent,

3518 2951 2960 1831 ¿4o16 3750 277)4 ¿4016 1831

x 1/L Dod

Plate,

Face Bar Reinforcement,

72 1.97 2,73 23)40 3329

4i6

2,55

2,38

3326 3193

75 3,Oh ¿4.00 3909 ¿48)43

1x6 _{1.93 5980 7h00}

Spec Test Temp,,

Average Elongation

Average Unit Strain

No To To Ener

Ultimate

Failure

ajiure

Dog. F.

in,.

in.

1b,in / cu.in

x i/)4" Body Plate, Sin:le Doubler Plate Reinforcement

15 76

1,70

2,70

1999 3013

32 _{-)46 1.93 2,39 2)451 3090}

36

_{x 1/)4"BodyPlate.}

Insert Plate Reiriforcemeíit,

2]. 77 2b86

372

3519 ¿521

3)4

46

3.55

3,l

_{5630 5255}

¿48" x 1/2" Dod

Plate,

Face Bar Reinforcement,.

¿49 70

3,36

5,08

3082 _¿4136

50 -20 14,90 517)4 ¿4938

x 1/2" Bc

Plate,,

Sing,e Doubler Plate Reinforcement0

9

99

lo

ai 4,5 40 35 3.0 °' 20 o I'S 1.0 05 o

Fig. g . Distribution across Plate of Elongation on a Gage Lngth Equal to the Width of the Flute,

Specs. 9 and 99. 4.5 40 35 30 25 o t, 20 o g 'o 0.5 -20-3.0 -J 25 to s, 20 o 15 w 4.5 40 3.5 1.0 05 o

Fig. i . Distribution across Plate of Elongation on a Gage Length Equol to the Width of the Plate, Specs. lt and 31. 4.5 4.0 35 3.0 o o Room - Low temp. temp.

i

EDGE PLATt 3O_1..

:

.,,

diii

'

EDGE O 340 PLATE u I4

i.

EDGE F PLATE

//

2_ MAX

--- ---

--,4

ìj

_-

:

S00

iL°

-ìiI.

Fig. 8 . Dcotribution across Plate of Elongation un a

Gage Length Equal to the Width of the Plate. Fig. . Distribution açrosn Plate of Elongation on u

Specs. 15 and 32. Gage Length Equal to the Width of the Plate. Specs. 21 and 34.

o .5

t

W o w 6 56 4.8 40 3.2 2,4 1.6 08 0 -21-6 0.8

Fcg. 11 . Distributloc across Plate of ElongatCon ott a

Gage Length Equal to the Width of the Plate, Specs. 51 and 52.

o

öoK

. Distribution Across Plate of Elongation on a

Gage Length Equal to the Width of the Plate, Specs. No. 70 and 71.

EDGE 0 PLATE I i

O.--

\

. 's.-.-. t200_.._ _::-.._, -EDGE O PLATE .-4 EDGE OF PLATE D -. 1276 MAX. 1130 1200 lOO 150 900 900 64 6. 56 5. EDGE 0F 4.8 4. -J -J 40 C, 4. W W

t

3.2 o W _3. D l 2 _{_1MI--._.} 2 w w -I2Q íO 6 I. 08______.,f,00' 0. 1000 -0

Fig. IS . Diatribution across Plate of Elongation on a Fig. 13

Gage Length Equal to the Width of the Plate, Specs. 55 and 56. 6.4 0.6 4.8 -i t,

t

4.0 W o 3.2 w 2.4

Fcg. 10 Distribution across Plate of Elongation on a Gage Length Equal to the Width of the Plate. Specs. 49 and 50.

22

values for low temperature are shown with solid lines; those for room temperature, with dotted lines0

The elongation in both temperature ranges followed the

same general pattern0 It remained fairly syrnmetrical about

the vertical centerline of the plate until fracture began

at, or just before the ultimate load. The elongation was

maximum in the center cf the plates0 The distribution pat

terns did not show any characteristics which couid be at tributed to the particular type of reinforcement0

At equal loads the elongation of the room temperature specimens was greater than for those tested at low tempera

ture even for Specimens No0 52 and

56,

although the

frac-ture in both of these plates passed completely outsIde the reinforcement

3 is on. .f Load on and ggt ion on

Length Egi

WI _Qr.

The five elongations at the given gage locations across

the plate were averaged0 The relation between the applied

load and this average

elongation is shown in Figs0

1+ to 21

for the various specimens0 The

principal

data from these

figures are stmmarized in Table IV.

The shapes of the loadelcngation curves for identical specimens tested at room and low temperature were similar up to the ultimate load9 except that the strength level for the

600 500 400 600 500 400 00 300 300 200 200 lOO o o

I

o.--. SP -0- SPE EC. NO. IO C. NO.31 o 75°F -46°F O o

23--..e.-. SPEC. NO.9 72°F -e-- SPEC. NO.99 -46°F

13 o

Average Elongation on 36-in. Gage Length - Inches

Fig. 4 _{. Comparison of Load and Average Elongation on a Gage Length Equal to the Width}

of the Plate, Specs. No. 9 and 99.

2 3 4

Average Elongation on 36-in. Gage Length - Inches

5

Fig. 5 . Comparison of Load and Average Elongation on a Gage Length Equal to the Width

of the Plate, Specs. No. 10 and 31.

600 500 400 300 200 100 600 500 400 o 300 200 loo

--o--. SPEC. NO. 15 76°f

Cl--- SPEC.NO.32 -46°F

Fig. 7 . Comparison of Load and Average Elongation on a Gage Length Equal to the Width

of the Plate, Specs. No. 21 and 34.

o 2 3 4 5

Average Elongation on 36-in. Gage Length - Inches

Fig. . Comparison of Load and Average Elongation on a Gage Length Equal to the Width

of the Plate, Specs. No. 15 and 32.

2 3 4 5

1600 1600 1400 1200 1000 800 600 -2 5L 560 460 cl498

£

___

ii

O SPEC. NO.51 G SPEC. NO.52 74°F 46cF I

1..

J o 2 3 4 5 6

Average Elongation on 48-in. Gage Length - Inches

Fig. 8 . Comparison of Load and Average Elongation on a Gage Length Equal to the Width

of the Plate, Specs. No. 49 and 50.

2 3 4 5

Average Elongation on 48-in. Gage Length - Inches

Fig. 9 . Comparison of Load and Average Elongation on a Gage Length Equal to the Width

of the Plate, Specs. No. 51 and 52. 400

200

600 1400 200 1000 800 000 600 400 200 o 1200 800 600 400 200 o O SPEC. NO. 70 76°F O SPEC. NO.71 46°F j

Fig. 21 . Comparison of Load and Average Elongation on a Gage Length Equal to the Width of

the Plate, Specs. No. 70 and 71.

. 1316 2 75

O

If' 00

I-¿w

Ii

UI! -O- SPEC. - SPEC. 5PC. NO.55 WO.55A69°F t-40 56 -46°F 70°F I-' o o o 2 3 4 5 6

Average Elongation on 48-in. Gage Length -- Inches

Fig. 2C . Comparison of Load and Average Elongation on a Gage Length Equal to the Width of the

Plate, Specs. No. 55, 55A, and 56.

o 2 3 4 5 6

verage Elongation on 48 -in. Gage Length -- Inches

1600

the ultimate load the shape of these curves depended prima ruy upon the percentage of cleavage in the fracture.

Specimens

No0 99, 3)+, 50,

5'2

56,

and 71, all having be

tween 96 and

loo

per cent cleavage, suffered sudden

frac-tures at the ultimate load with no additional elongation

beyond that point0 As a shear fracture developed beyond

the ultimate load in Specimens

No0 319 32,

and

_55,

all hav

ing between ₅₇ and

₇₅

per cent cleavage5 the load fell off

gradually to the point where a sudden cleavage fracture

oc-curred and the load dropped off sharply. The more ductile

behavior of Specimens No

_9,

10, 15, 21, +9, 5l and 55A

with zero per cent cleavage and Specimen _{No0 70 with i per}

cent cleavage was apparent in the gradual reduction _{of the}

load as the shear fracture progressed _{across the plate0}

The amount of elongation occurring after ultimate _{load in}

this last group of specimens depended largely _{on the por}

tion of the width of the specimen which remained unbroken

and therefore bore no close relation to _{the amount of}

elongation up to the ultimate 1oad

Specimens tested both at room and at low _temperature

exhibited a noticeable necking in the direction of _{the width}

of the plates and a simultaneous reduction _{of the thickness}

over the affected area'. _{The ones which failed by a shear}

1ng the fracture0 This localized reduction of thickness of coursa was not present wherever the crack was of the cleavage type

Figures

39 to

.3 show the nature of the fracture for

the various specimens0

Several of the l/24ri specimens. Specimens

No0 51,

52, and

_55,

were subject to strainagi.ng during the course

of the test0 Cleavage failures occurred in the pulling

plate and time elapsed before these plates were again

loaded0 The history of these specimens is given in

Figs0

19

and 20 Since the remaining specimens were not affected by

str.inaging, a

ftv

comparison could be made only by re

moving this effect from the results of these three testee Figure s 19 and 20 show the actual and the assumed 1oad

elongation curves for Specimens No 51, 52, arid ₅₅ The

values of ultimate load, ultimate strength and energy to

ultimate load and to faIlure given in Table IV were computed on

the basis of these assumed values0 A discussion of the

strainaging effects in these three specimens follows in

Section 100

A comparison of the average elongation to ultimate

toad for identical specimens at room and low temperature is

shown in

Fig0

22 The average elongation to ultimate load

was greater in each case for the low temperat.ure specimen ex

5 4 3 2 _O o o Di (D 1

0

t-00

o.

(D _!:_

,

t-o

2Ø

)

o (D 1 o (D

t--0

p

I

j

I

p

SPEC. NO. 9 99 IO 31 IS 32 21 34 49 50 51 52 51 55A 56 70 7 I TYPE OF REINFORCEMENT FACE RAR DOUBLER INSERT FACE BAR DOUBLER INSERT INSERT 36X ,'4" BODY PLATE 48" X '2" BODY PLATE

and 7l it is sIgnificant that Specimens No0 52 and 56

broke through the body plate, while ali other plates failed either through the opening ùr in the weld at the outer edge

of the reinforcement0 The average elongation to ultimate

load of Specimen No0 71 was the smallest sustained by any of

the plates in this report.

+. of imens0

The load and the average stress on the net

cross-section at general yieldIng are shown in

Fig0

23 and Table

1V0 When the average stress at generai yielding for each

low temperature specimen was compared with that of the iden

tical specimen at room temperature, the values of the ratios

ranged from 127 to 105' per cent for the

1/+-in0

plates and

from 123 to 100 per cent for the 1/2-In0 plates0 If the

results of Specimens No0 70 and 71 are disregarded, a

gen-erai, though not very distInct trend was indicated, As the

dimension of the reinforcement at the edge of the opening in the direction of the body plate thickness increased, the value of this ratio tended to decrease0

5 Ultimate Load and Ultimate

njj0

The ultimate load and ultimate strength developed by

the various specimens are shown In

Fig0 21+

and Table IV0

Among the l/1+-1n0 plates, the ultimate strength ranged from

000 800 600 400 200 O SPEC.N0. 80,000 e 'D 'D

I-i

i

Fig. 23. Load and Average Stress

n Net Cross-Section at General

Yielding at Room and at Low Temperature.

1600 200 800 400 80,000 60,000 40,000 20,000 O TYPE OF RE IN F ORCE MENT o D e N

i

kØ

'DID

t-'

ID e 'D O o

e'

D o 0V * O * W t--, ?. D,,_ p-O p-'D 'D W * FACE BAR DOUBLER INSERT

FACE BAR DOUBLER

INSERT

INSERT

36"X

/4' BODY PLATE

48'X I,.. BODY PLATE

Fig. ¿4 .

Ultimate Load and Ultimate Strength at Room and at Low Temperature.

9 99 IO SI 15 32 21 34 49 50 51 52 55 55A 56 70 71 o è 'D N ID 'D I 4' 'D *

I-li i

i

ii

o SPEC. NO. TYPE 0F 49 50 SI 52 5555A56 70 71 SPEQ P40. 9 99 IO SI IB 32 21 34 4950 5152 5555A56 7071 SPEC. NO. 9 99 lO SI IS 52 21 34 49 50 SI 52 55 SSA Si 70 lI 20,000 40,000 ID z -J w -J 4 X w z I-. 4 INSERT 9 99 IO 31 IS 32 21 34 FACE BAR DOUBLER INSERT FACE BAR DOUBLER INSERT REINFORCEMENT: 36" X I,, BODY PLATES 4B X '2" BODY PLATES

=32=

598 to 730

ksi for the low temperature tests0

The same

variation for the 1/2-in0 plates was from

5707 to 597

ksi

and

550

to 668 ksL

Thus

with respect to

ultimate

strength also, the differences in the

geometry of the

specimens were more accentuated at

the lower temperature0

The ultimate strength of each specimen tested at low

temperature was greater than that of the identical specimen

at room temperature except

for SpecImens No0

70 and

7l

The ultimate strength of the plate material for the

body plates and reinforcement ci' Specimens

No0 9, 99

10,

and 31, as given In Table I, was essentially the same0

However, a distinctly higher strength was developed by

Specimens No.

10 and 31, which had a l-in0

by

l/+-In0

face

bar

A 2in0 by l/1+-1n0

face bar

was used In

Specimens Nc0

9 and 99

6

gy AbsortIon

The energy absorption to ultimate load and to failure

is given in Table IV. Figure 25 compares the values of the

energy absorption to ultimate

load for the room and the low

temperature tests. .mong the

i/4-in.

plates a greater en=

ergy absorption

to ultimate load was developed by each low

temperature specimen than by the identical specimen at room

temperature

6000

z

«L

5000

w

I-4000

3000

2000

w

z

w I 000 o o

o

N

Fig.

25.

Energy Absorption to Ultimate Load at Room and at Low Temperature.

36" X 1411 48" X o 1.-o (D e

r-0.,

w

0

o

r-o (.0 1 I r-. l:o o (D t o o w O

ii!ii

9 99 IO 31

1532

2134

49 50

51 52

55 55A 56 7071

o .v

was apparent. Specimens No0 52 and 56 which failed through

the body plate outside of the reinforcement, developed less

energy to ultimate load than did their corresponding plates

at room temperature0 The failure of these plates was

per-haps somewhat premature but still occurred at a stress level

at which a failure through the opening was imminent-. Of the

pairs of specimens, which failed through the opening

Speci-mens No0 1+9 and 50 followed the trend of the 1/1+-inh plates,

and Specimens No 70 and 71 followed exactly the opposite

trend. While the relative energy absorption of the l/1+-1n0 plates at the two temperatures followed a simple pattern,

it appeared to obey a more complex relation for the 1/2-In0

plates0

The random behavior of the 1/2-in0 plates as compared to the consistent trend of the 1/1+-in0 plates suggests that the thickness of the plate was becoming a significant

fac-tor in governing their behavior It should be noted that

1/2-in0 Specimen No0 70 and 71 were the same in type as

l/1+-in0

Specimen No0 22, which developed the lowest energy

absorption of all the

l/1+-in0

plates with the square

open-ing with rounded corners(1)c These two specimens were also

lowest in energy absorbing capacity among the 1/2-inc plates.

The energy absorption to ultimate load of Specimen No0 71

3

-TABLE VI

GENERAL YIELDING AND FRACTURES OF THE SPECIMENS

Spec.

Load in Kips at

Percentage

Location of First Luders

No. First

General

First

Ultimate of Cleavage Lines, First Crack, Max.

Luders Yielding Crack

Load

in Fracture Unit Strain Concentration,

Lines

and Lateral Buckling*

9 60 319 451 451 0

99 340 507 507 97

36 x 1/4 in. Body Plate

180*

10 60 313 467 467 0 I0Q.

31 364 527 527 75

Studiecentrum T. N. O. Scheepsbouw en Navigatie

Afd. Scheepsbouw, DELFI

* Legend:

Max. unit strain concentration according to SR-4 gage readings

Luders lines appearing before general yielding of specimen.

(/f

Lateral buckling of plate in regions of compression stress.

4--

_{Point of first crack.}

Fracture

-36-TABLE VI (C ont.)

GENERAL YIELDING AND FRACTURE OF THE SPECIMENS

Spec.

Load in Kips at

Percentage Location of First Luders

No. First

General First

Ultimate of Cleavage Lines, First Crack, Max.

Luders Yielding Crack

Load

in Fracture Unit Strain Concentration,

Lines

and Lateral Buckling*

15 362 362 522.5 522.5 0 32 441 548 548 63 21 100 300 478 478 0

220

120

34 49 50 700 376 740 880 551.5 551.5 96

48 x 1/2 in. Body Plate

1255 1255 0

-3?-TABLE VI (C ont.)

GENERAL YIELDING AND FRACTURE OF THE SPECIMENS

Spec.

Load in Kips at

Percentage

Location of First Luders

No. First

General

1rst

_{Ultimate of Cleavage Lines, First Crack, Max.}

Luders Yielding Crack

Load

in Fracture Unit Strain Concentration1

Lines

and Lateral Buckling

51 500 770 1300 1385 0

52 950 1560 1560 100

56 900 1360 1360 100

55 700 800 1275 1275 57

-38-TABLE VI (C ont.)

GENERAL YIELDING AND FRACTURE OF THE SPECIMENS

Spec.

Load in Kips at

Percentage

Location of First Luders

No. First

General

First

Ultimate of Cleavage Lines1 First Crack, Max.

Luders Yielding Crack

Load

in Fracture

Unit Strain Concentration,

Lines

and Lateral Buckling

70 700 800 1276 1276 17

.03 9

Specimen No.

_56,

which had the next lowest energy absorption0

It would appear that any l/2in. plate with a higher stress

concentration factor or any plate

3/+ in0

or greater in

thickness could be expected to develop a relatively lower energy absorption at room temperature and to suffer a large reduction in energy absorption at low temperatures.

Any comparison of the energy absorption of the various specimens must take into account the dimensions of the dff

ferent types of specimens. Three cross-section sizes were

used: 36

in0

by i/p-i- in., 36 in. by 1/2 in0, and -8 in. by

1/2 in. The gaged area was 36 in. long for the 36 in0 wide

and +8 in. for those +8 in, wide. It was found for these

similar types of specimens that the total energy absorption was more or less proportional to the volume of the gaged region.

In the First Progress Report(1), the energy absorption

to failure was used as the basis of discussion, while in this report the energy absorption to ultimate load is used0 This change in viewpoint came about from two factors:

The energy absorption at ultimate load corresponds to the maximum load-carrying capacity of a member and the point beyond which its structural useful-ness is questionable.

In these tests, the energy absorption beyond ulti-mate load was as much a function of the portion of

the plate width which was fractured as of the geome

try of the pecimen0

70 Coiprisor! of Ener to Ultimate Load with

Ultimate

nth and

to Ultimate Load0

The First Progress Report(1) found,

1 That the ultImate load increased in proportion to

the logarithm of the elongation to ultimate load0

2 That the specimens which reached the highest ultimate

load and ultimate strength also absorbed the most energy0 A clearer picture of these relations has been established in

this report0

Figure 26 shows the linear relation between the loga rithm of the energy absorption to ultimate load and the

ultimate strength0 The results of all tests from the First

and Second Progress and this report are

in-eluded in this figure0 Four conclusions may be drawn from

these data0

10 The rate of increase of the energy absorption to

ultimate load became greater as the ultimate strength increased0

2 The values for the

l/-i--in0

specimens with the higher

stress concentration factors fell to the left on the plot, those with the lower factors to the rîght0

3 Lowering the testing temperature moved the values

7000 5000 1000 500 200 6000 4000 2000 1000 800 600 400 200 2 4 6 8 IO 20 40 60 80 00 144

RATIO 0F HALF- WIDTH 0F OPENING TO NOTCH RADIUS R0 / RN

Fig.26a. Relation between the Energy Absorption to Ultimate Load of

Plates with Openings and the Notch Acuity of the Opening.

O O TEST . U A SI ©______ 50 C. C. Q COLO CIRCULAR SQ.,SHARP 55 70 !1 38 -SO,R0UND il 21 o II o _Il 99 © 5 o J B 9 12

4fl6

22 .. A20 ZI3 A3 .-0 48--f. 70

r

CIRcULAR ;-0 SQ.ROUNDC. D 4i. SQ. ROUNDC. A A 4 @34 'Np O COLD TEST JI '7 :

-2 p99 32 . 6 IS

k

22 F 2OL TA A I3 3L I4 'SA 45 50 55 60 65 70 75

ULTIMATE NET STRESSKSI

and unreinforced 1/2in0 plates, but had a random effect upon the values for the reinforced 1/2-in0 plates

The increase cf energy absorption as

the size of

the specimen was increased was not linearly propor tional to the increase of volume in the gaged area0

The 1/2-in0 reinforced specimens absorbed about 7

times as much energy to ultimate load as the

i/+-in0

plates0 The volume of the gaged section for

the

former was approximately 2O times and of the latter approximately 309 times the same volume for the

l/-i--in0

plates0 This increase of energy appeared to be independent of the stress concentration prevailing in the particular specimen

These four conclusions have a significant meaning when

applied to design0

Any improvement in

the design of the re

inforcement, such as a reduction of the stress concentration factor or a better distribution cf the reinforcing material which brings about a greater ultimate strength, increases

the energy absorbing capacity of the detail in more than

direct proportion0 Moreover, it would appear that the

ap-plication of the results of these tests to the design of

reinforcement for plates over 1/2

in0

in thickness may lead

to an overly optimistic estimate of their energy

absorbing

In the First Progress Report(1), the energy absorption R

to failure was plotted against the notch acuity the

N

ratio of the halfwidth of the opening to the correr radius

of the opening0 Figure 26(a) compares the energy absorption

to ultimate load and the ratio The width of the scatter

bands in the latter fIgure as smaller than in the plot us

ing the energy absorption to failure0 The relation between

R

the energy absorption to ultimate load and the ratio, for

N

the l/1fin0 plates at 6°Fe and the unreinforced 1/2iri0

plates at room temperature was similar to that for the 1/+ R0

In0

plates at room temperature0 Since the ratio was

N

not varied for the remaining specimens no definite trend

for them was established,

When the unit strain energy to ultimate load was com pared in Fig0 27 with the unit elongation to ultimate load9

for the reinforced plates, the points for both the room and

the low temperature tests fell along the same line and a

method was provided for comparing the energy absorption of

the similar specimens of different sIzes, All the plates

considered in this figure had a square opening with a

rounded corner0 The data for this figure are given in Ta

ble V0

80 Ec ee

The importance of the percentage of reinforcement is indicated In Figs0 28 to 309 where it is related to the

e

z

5000

o

w 4 w w 6000 4000 3000 2500 2000 1500 4 5 6 7 8 9 IO H 12 13

AVERAGE UNIT ELONGATION TO ULTIMATE LOAD - PER CENT

Fig.27

.

Comparison of Average Unit Strain Energy and Average

Unit

Elongation to Ultimate Load at Room and at Low

Temperature.

034

-BIo

o

38A

38

MD

Z9

990/

Io

55 215?A

o

_460 76° A56

IO37

e

02/

22

1600 1000 600 400 o PERCENTAGE OF REINFORCEMENT I I I j 6.75 7.20 7.65 8.10 8.55 1/4 Spec. Net CrossSection Area Sq.In. I I I 19.5 20.4 21.3 22.2 23.1 240 Spec Net CrossSection Area Sq. In. 40,000 o 31 34 76o TI p 21 085A O 055 15( '51. 036'X 1/41 R.. 36' X 1/4 R... 48"X I/2 R.. 4e_X R.... 76°F 46°F 76°F 46°F .80 052 .86 si ci 049070 55 TI O 5'X /Ç R.. 36XY4"R..-4GDEG.F 7G DEG. F 76 DEG. F -DEG.F 4e'X'/' R.. 4e'x-'íR.._4e SI

'

52 18( 010 09 021 Fig. 2

-Comparison of Ultimate Load and Percentage of Reinforcement.

Fig.

29. Comparison of Ultimate Strength and Percentage of Reinforcement.

20 40 60 80 loo Percentage of Reinforcement I I I I 6.75 7.20 7.65 810 8.55 9.00 /4 Spec.

Net CrossSection Area Sq. In.

I I ¡9.5 20.4 21.3 22.2 23.1 24.0 Spec.

Net Cross- Section Area - Sq. In.

20 40 60 80 75,000 70,000 65,000 60,000 55,000 5000O 45,000 loo 9.00

ultimate load, ultimate strength9 and energy absorption to

ultimate load0 In FIg0 30 the points plotted as A and B

were comput;ed for a +8in0 by 1/2-in0 body plate size with out reinforcement on the assumption that the unit strain

energy absorption at ultimate load wa.s occurring at the same rate as for the 36.-in0 by 1,12in0 plates, Specimens No0 37

and 38 Some justification for this procedure may be found

in Fig0 27 These two points were added to help clarify

the behavior of the 1/2-in0 plates0

Due to the fact that the test series included a wide

variety of types of speeimen and no duplicates were tested,

any comparison of the test results is somewhat crude0

How-ever, some observations have been drawn from these figures0 Increasing the percentage of reinforcement,

l Decreased the ultimate strength, the rate of de

crease being greater for the tests at J6°F0 than

for those at room temperature0

2 Increased slightly the energy absorbing capacity of

the 1/2-in0 plates

30 Reduced the ene:rgy absorbing capacity of the l/+-in0

plates at +60F

Made little change in the energy absorbing capacity of the i/+-In0 plates at room temperature0

In consideration of the generally opposite effects for the two plate thicknesses of increasing the percentage of

80,000 70,000 60,000 50,000 40,000 30,000 E7l

58

5000 4200 3400 2600 :800 1000 600 o A34 ASS A 56 52 A 32 50 6.75 9.5

Fig. 30. Comparison of Energy Absorption to Failure and Percentage of Reinforcement. ULTIMATE STRENGTH OF C OUF O N 36A PLATES PLATES SS A 49 3? 51 Í8 SI D 055 52 O OSA 490 JA TOD I06 3ex I4 76°F 39°X A-49°f 46X 4SX R.. 76°F R..-46'F 551 534 0 Io 099 021 14 09 32IS 20 40 60 Percentage of Reinforcereent 60 loo 7.20 hi4 _Spec. 765 BiO

Net CrossSection Area

-8.55 Sq. In. 9.00 20.4 Spec. 21.3 22.2 Net CrossSection Area

23.: - Sq. In.

24.0

PLAI' E S

031

0 32 _{LPPEft YIELD POINT OF}

034 COUPON

PLATES

SO

'71 _.39

60 40 20 0 20 40 60 80

TESTING TEMPERATURE DEi F

Fig.50a.. Comparison of Average Net Stress at General Yielding and Ultimate Load _{with Same} Properties of Tensile Coupons.

TENSILE COUPONS

UPPER YIELD STRESS ULTIMATE STRESS LARGE PLATES

II

V'

AT GENERAL YIELDING UT ULTIMATE LOAD WHITE - J4 PLATES NLACK - - PLATES OS . A

reinforcement, it must be remembered that the transition

temperatures determined by the Navy tear test were +O0F0

for the l/in0 plate and +OF0 for the l/2in0 plate0 The

testing temperature for the plates with openings of 6°F0

was in the vicinity of the transition temperature of the i/inQ plates arid weil below that of the 1/2-in0 plates0

Since the

l/+-in0

and the 1/2in0 plates did not re

spond to changes in the percentage of reinforcement in the same rnanner the former cannot always be used to forecast

the behavior of thicker plates0 In any scale model test to

investigate cleavage fracture, the transition temperature should be scaled downwards as well as the dimensions of the specimen0

The forthcoming Fourth Progress Report will show

that the principal effect of properly proportioned rein forcement in the plastic stress range, as compared with no reinforcement is

l To reduce the maximum stress concentration factor

around the opening0

2 To reduce the high rate of strain energy absorption

concentrated around the opening0

The plots of the unit elastic strain concentration fac

tors in the First Progress Report and this report in

Figs0

31 to 38

showed that the strain-raising effect of the opening, whether reinforced or not, was closely concentrated

064 036 o 0.85 0.8 J SPEC. 99 46°F SPEC. 9 72°F 4.90 0.94

Fig.31 - Elastic Tirilt Strain Concentration in the Region of the Opening in

36 x 1/4 in. Plate. Face Bar Reinforçement. Specs. No. 9 and

99.

o

Fig.32 . _{Elastic. Unit Strain Concentration in the Region of the Opening In}

36 x 1/4 in. Plate. Face Bar Reinforçement. Specs. No. 10 and 31.

1.08

0.63

T:-;-

ini

- SPEC. NO. IS 76°F SPEC. NO.32 - 46°F

3,70

Fig33. Elastic Unit Strain Concentration in the Region of the Opening in 36 x 1/4 in. Plate. Doubler Plate Reinforcement. Specs.

No. 15 and 32.

O

-- :::: ::

Fig.34. Elastic Unit Strain Concentration in the Region of the

Opening in 36 x 1/4 in. Plate. Insert Plate Reinforcement.

Specs. No. 21 and 34.

.0 .i4 .r r'';';

ivsi/1 r

1.06 2.80 -20°F 2.52

.ii.Iiu.i&

p9

I.450O -0.96 SPEC.50 -20°F SPEC.49 70°F

Fig.35. Elastic Unit Strain Concentration in the Region

of the Opening in 1+8 x 1/2 in. Plate, at Low and

at Room Temperature. Face Bar eirSorcernent.

Specs. No. 1+9 and 50.

SPEC.52 46°F

--SPEC51 74°F

Fig.36. Elastic Unit Strain Concentration in the Region _{of the}

Opening in 1+8 x 1/2 in. Plate, at Low and at Room

Temperature. Doubler Plate Reinforcement. Specs.

No. 51 and 52.

Studecentrum T. N. O.

-51-Scheepsbouw en Navigatie ifd. 5cHeepstouw, DEFT

.22 0.96 0.89

-o

-

SPEC. 55 SPEC. 56 -46°F 700F --SPEC.55A 69°F

-52-Fig.37.

Elastic Unit 3train Concentration in the Region of

the Opening in )3 x 1/2 in. Plate at Law and at Room Temperattre. Insert Plate Reinforcement.

Specs. No. , 5Á and 6.

Fig.38.

Elastic Unit Strain Concentration in the Region

of the Opening in +8 x 1/2 in. Plate, at Law and at Room Temperature. Insert Plate

around the opening0 A consideration of these facts aids in analyzing the greater Improvement in the ultimate strength

resulting from the lower percentages of reirjforcement The

specimens in this program with less than about +O per cent reinforcement were of types which tended to concentrate

the reinforcement around the edge of the opening in the region where the greatest stress and energy concentration

occurreth Thus, the reinforcement was concentrated where it

appeared to be most beneficial0

It would seem at this stage of the investigation that the best reinforcement for any opening operating at tempera tures well below the transition temperature for the steel should be of a type which concentrates the reinforcing ma terial fairly close to the edge of the opening without its breadth in the direction of the plate thickness becoming too

great

90 ciefl of the Plates with

No direct basis of comparison between plain plates without openings arid the plates with openings was available

for the low temperature tests of the l/- and 1/2-in0 speci

mens arid the room temperature tests of 1/2-in0 plates0

ow-ever, the results of the tensile coupon tests in Table I were compared with the results of the plates with openings

having the same thickness of body plate as shown in

Fig0

5i

the plates with openings, whether at general yielding or ultimate load, was always less than. the strength cf the

tensile coupons at the same temperature0 It is Interesting

that the points for the 1/2-Inn plates at 6°F0 fell

fur-ther below the tensile upper yield point arid ultimate strength than those for the 1/2-in0 plates at the higher temperatures, further evidence that the temperature was be

Ing approached at which low-energy cleavage fractures would occur

An estimate of the effectiveness of this present series with respect to energy absorption cannot be made directly0

However, the maximum efficiency o about 25 per cent found

in the

specimens in the First cgress Report would not

be exceeded by any considerable margin, if at ali, by any

of the specimens in this report since the energy absorption

in the more recent tests as of the same order of magnitude

as that of the previous tests0

lO Unit Strain Concentration in t Around the

at Room and Lobi Temrature0

Elastic strain concentration curves based on the data

of SR- strain gage readings are shown on

Figs0

31 to 38

The results of the room and low temperature tests for the two identical specimens are shown on each figure (dotted

lines for room temperature, plain lines for low temperature)0 The unit strain concentration on these figures Is presented

as follows:

l The unit

strains

in the vertical direction, on a

horizontal line passing through the point of tan gency between the vertical, edge of the opening and the corner arc0

2 The unIt strains tangential to the edge of the

open-ing on the cIrcumference of the openopen-ing0

The unit strain concentrations were computed from the

gage readings

In

the same manner as described

in

the

First Progress Report(1)o They are the ratlos of the slope

of the strain plots at a particular point on the specimen to the slope of an identical plot in the region of the plate remote from the opening, where uniform stress conditIons would prevail0

The general shape of the unit strain concentration curves for the p1atewas the same, both at room and low temperature, when the plates with the same type of

rein-forcement are compared. HOwever, for every pair of

identi-cal specimens except Specimens No0 9 and 99, the maximum

unit strain concent;ration at the corner of the opening

was

greater at the lower temperature. Since no measurable

change In the modulus o elasticity of steel takes place

between room temperature and -'6°F0, It seems reasonable to conclude that the maximum elastic strain concentration, and therefore the stresses as well, would be somewhat greater

Specimen No. 99

Specimen No. 32

Specimen No. 49

-56-Specimen No, 31

Specimen No, 34

Specimen No. 50

Specimen No. 51

Specimen No. 55

-57-Specimen No. 56

Specimen No0 52

Specimen No. 55A

-58-5pcin3n NOQ 70

Specinn No. 71

SPEC. NO. 9 99 IO 31 32 2I 34 GLEAVAG E a/4

59--'5 SHEAR III. '2 NOT FRACT.IRED

I.0

b

71/" 4%

Fig.42

.

Nature of the Fractured Edges of the Specimens.

49 50 5I 52 55 55 A 56 70 CL EAVA G E

-60-2"

. 2l

k 12" SHEAR

0

Fig.43

Nature of the Fractured Edges of the Specimens.

NOT FRACTURED

L-94

-61-at lower temper-61-atures in pl-61-ates with openings than -61-at room

temperature. The Second Progress Report has already

shown that higher relative energy

absorption in

the plastic

stress range occurred around the opening in the test at the lower temperature, and this evidence is substantiated by

the

results of

the forthcoming Fourth Progress Report

It seems therefore that lowering the testing temperature for plates with reinforced openings tended to intensify the

concentration cf stress and energy around the opening. This

finding constitutes evidence that the behavior of identical plates with openings is not the same at room and at low tem-peratures, either in the elastic or the plastic stress state.

Further test data are needed

to

fully verify these comments.

The unit strain dIstribution near the outer edge of th' body plate ir. the +8-i..n, by 1/2-in, plates more nearly approaches uniformity than in the 36-in, by l/-ir. plates. At this greater ratio of plate width to hole diameter,

(5.3 :1),

the strain

distribution

near the edge of the plate

in the elastic range was approximately that predicted by

the assumption of infinite plate width.

11G

StrairAgig Effects and Incidental Causes

Fa1ure

Three 1/2-it. specimens suffered premature failures in

the puUing

plate, were

rewclded, and retested. Tue history