LABORATORIUM VOOR
SCH EEPSCONSTRUCTI ES
TECHNISCHE HOGESCHOOL
-
DELFT
RAPPORT Nr.
Results of tensile- and bend-tests with G.R.P.-specimens representing bulkhead - deck or - shell connections.
SSL 119
LABORATORIUM VOOR
SCH EEPSCONSTRUCTI ES
TECHNISCHE HOGESCHOOL
-
DELFT
BETREFFENDE:
Results of tensile- and bend-tests with G.R.P.-specimens representing bulkhead - deck or - shell connections.
LABORATORIUM VOOR
SCHEEPSCONSTRUCTIES
TECHNISCHE HOGESCHOOL
-
DELFT
RAPPORT Nr.
119
BETREFFENDE:
Results of tensile- and bend-tests with G.R.P.-specimens representing bulkhead - deck or - shell connections.
2.2.2. Construction methods for big G.R.P. ships.
Op pagina 6 staat: " in de voorschriften van Lloyd's Register of Shipping worden voorgeschreven". Hieraan moet worden toegevoegd: "Een samenvatting van de
proefresultaten wordt gegeven in
Strength of connections made with "hand lay-up" or "spray-up' techniques.
In section 2.2.2. it is suggested that connections between orthogonally placed plates could effectively be made by use of a spraying technique. The advantage over the "hand-lay-up" method abviously is that much time can be saved.
A provisional investigation has been carried out in order to get an idea of the
relative strength which can be obtained with both methods. The specimens are shown in figure 1. They represent the connection between shell - or deckplating and a bulkhead. The "shell" strips have been glued on plywood backings in order
to eliminate bending of these strips during testing. In this way the loading condition at the crossing is clearly defined. Of course it is not completely realistic but it approximates reality sufficiently well for the purpose of the
investigation. In the near future the influence of bending of the "shell"-strip will also be incorporated.
In table I the fracture-loads are given for two loading conditions. The results of the tensile tests which were carried out in the Kunststoffeninstituut T.N.O.
at Deift are given in the bottom part of the table.
The bending tests were carried out in the Ship Structures Laboratory at Delft. The fracture loads are given in the upper part of table I; the deformations of
the specimens can be studied in figures 2 and 3. Each curve represents the average of the results of all specimens of one type. In figure 2 load-displacement curves are given applying to points situated 50, 100 and 180 mm from the corner. In figure 3 the lines of deflection are drawn for various loads.
The first conclusion from these tests is that the spraying technique was very succesfull. Specimen types C and D were significantly better than type A for both loading conditions. Type B in which the throat-height was only 10 mm behaved better in the "pull-out" (tensile) test but worse in the bending test.
The bent specimens of type D have fractured in two ways: three of them cracked at the corner and two in the bulkhead material along the borderline of the sprayed-up laminate. (This bulkhead itself also constituted of sprayed laminate.) This proves that the connection was very good not, only as compared with a "hand-lay-up" connection but also in an absolute sense. For the cracks in the "virgin" bulkhead material occurred at a point where the bending moment was only half of that at
the corner. Consequently the bending strength of the sprayed connections D was about two times as large as the bending strength of the bulkhead plate. In the pull-out specimens all fractures seem to have started at point P in figure 1. For the bent specimens the crack-origin was situated either at P or somewhere at
Q.
The results of this investigation are very promising and therefore an extension of it would be welcome. The most important aspects of strength to be considered are the fatigue-strength and the impact-strength. In particular the impact-strength of specimens containing minor fatigue-cracks might be of great interest.
In the near future the Ship Structures Laboratory will undertake investigations of this kind under the sponsorship of the Netherlands Ship Research Centre.
Fig. 2 D.f 0.otion I mm) Ao.,og. 9700 100% L Tened. Load Laminato; 6 nrO!. Fig. i
Average defO.ctlon of bulkilead at
_ 180mm from Innorsid. nf sheltplate
(
---100mm from rnnersido of shelOp)otn I
Lar -o---- Sh.L (p PLywood =Pt,ee.a - 6h .LL F Tgb)e. I Sp odIn en kf Ao.rag. Fructur. cod (kg) logo 1150 1240 1360 loon 12100131% I.n.l. cod Sprayed Loar Throat. l5nrrn 8. 1V V1 i- '° 59.0 rrn.n. Type A
II 1IIJ
lP" I
Ví! i
in...'..
iuauu
11...
1I!IUIU
Sp.cirn.n NO A y. ro g Frootur. Load L kg I 1162 1185 1200 1320 1340 1260? 130°/a len.i(e load [j Sprap.d Lam Throat OOmmrt
¿X O.tL.00an (Otto) Contour of specImens. Sp. aim, ne Typ.. o loi-s)p
Ip;
I.
ria uI
tIIIIUIIIU
!UUUUU
Sp.crm.n57 Fracture Load(kg) Sp.cim.nN! rocrrur. 100dkg)
1 OtO 1 040
2 020 2 1011
3 983 3 1006
4 101O 4 1120
N 1010 5 1170
Sp.cim.ns Typ.. A Specimens Type B Specirn.ns Type. C Specimens Type. D
Sp.y N! Fr001. lood (kg) Span NO Front. Load kg) Opon. NO Front Load (kg)
190
Sp.o N! Front load (Log) -to lot 141 132 lIt 173 324 ltd 146 lei 2eS 172 Ita 200 275 166 5 125 162 250
Av.rog. 1800 100°/a Au .t 0g e 1390 Ol°/a Au r o g 1810 1)35% Ay. rag 2820 1O6(o
B.ndng Load Barrdlrg 6.rtdAg Spray.d Loro. Load tptoy.d (arr Lo rn irr od e
t nrate T (oro od 10 nr rs Throot llmrn
L.
