F.6 TESTS OF CHAIN TENSIONED
OVER CURVED SURFACE
An experimental program was conducted £0 determine the load 21 which stud link chain breaks
when tensioned over a curved surface. Specimens from two samples of nasn-welded grade-2 steel
stud-link chain from different manufacturers were tensioned around pins having surface diameters
ranging from 2.3 to 14 limes the chain diameter. Tlley were loaded until they faiJed. Properties
of the chain specimens arc given in Table F.I.
Sample A Sample 8Type of chain Grade 2 stud-link Grade 2 stud-link
Diameter 35 mm 1-i-in. 32 mm 1 tin.
Certified proof load 490 kN 111,000 Ib 410 kN 92.200 Ib
Certified breaking load 690 kN 155,000 Ib 570 kN 129,000 lb
Actual breaking load 830kN 186,000 Ib 700 kN 156,500 Ib
Metallurgical coupon test results:
Yield strength at 2% oNset 415,000 kPa 60,200 psi 373,000 kPa 54,100 psi
Ultimate strength 568,000 kPa 82,400 psi 555 ,000 kPa 80,500 psi
Elongation. 2 in. gauge length 340,i) 29%
Reduction in area 73% 70%
Hardness Rockwell B 81 Rockwelt B 84TABLE F, 1: CHAIN TENSIONED OVER CURVED SURFACE, PROPERTIES OF CHAIN SAMPLESA typical test set up is shown in Figure F8, Load was applied by a large hydraulic cylinder
moumed horizontally. One end of (he chain specimen was attached [0 the cylinder head by a
detachable Iin.k.
The other end was run over the (est pin, mounted with its ax is horizontal between two plates
extending from a stationary frame and connected through a detachable link to a chain swivel bolted
to a strong rail in the test floor.
A lotal of 24 tests were conducted. Tne set-up and results of each test is summarized in Table F .2.
The first 17 tests were conducted wilh chain A. TIle results of these tests indicated tbe chain
specimens might be untypically ductile. Therefore chain B was obta.ined and spec.imens from it
were tested.F.7 RESULTS OF CHAIN TESTS
When loaded in straight le.n sion, both chain samples broke at loads significantly higher than their
rated break test loads, These straight break strengths were used as the basis for defining percent of
stseogth for tbose chains loaded on the curved surfaces. There was very good agreemc[)[ between
identical tests with chain A. Thus tests were not repeated with chain B.There was wide scatter of results depending on the geometry of the chain in relation to the surface.
When interlocking chain links were arranged to contact tbe surface at angles near 450 , the chains
broke at the interlocking point at loads somewhat lower than the str.aigbt break test load. When
the interlocking cbain lin.ks were alternating upright and Oat to the surface, as happens with smaller
surface diameters, chain strength was not significantly reduced. Somelimes the straight chain links
free of [he surface broke before the bent chain links did.Figure F9 sbows the tests results. The lowest brea,king load Obtained for each diameter ratjo divided
by t.he straight breaking ~treng1h is ploued as a function of the surface diamerer 10 chain diameter
ratio. In tbe case of idemjcal tests, (he average of tbe two loads is plotted.