Results and conclusions from static torsion tests on various crank and shaft test pieces.
| Identifier | ExFiles\Box 42\2\ Scan056 | |
| Date | 11th November 1919 | |
| R.R. 235a (500 T) (S.D. 408. 26-4-17.) Bm. 2/156/13. EY/Btn1/P1.11.19. - 3 - test piece are capable of standing approximately the same static twisting moment. A copy of these diagrams is attached. In the case of test pieces A, B and B,B the fracture indicates a certain amount of temper shortness, but this is quite absent in test piece A, which shows quite the best fracture from a material point of view. Test piece C, C1, was broken at two attempts. It was the first tested and distorted the key in the adapter, owing to inefficient bedding, thus giving a false start. This was remedied and the second diagram obtained, which was only taken as far as the initial fracture. It was found necessary to carry this further in order to get the test pieces out of the machine. In all the other cases loading continued until the two main halves separated. The chief conclusion we can draw from these tests is, that the crank is weak where the web joins the journal. It would appear that this method of testing could be of considerable use to us in checking the design of such parts, particularly as there is a remarkable similarity between the fracture, such as test piece A, and the fractures we have obtained in service. We do not consider that this method of testing will give us a numerical value of the strength of the shaft, as the stress in this case applied is statically, whereas in service it is one of fatigue. We do, however, consider that this will help us to pick out the weakest point in a shaft and to make comparisons of different shafts. contd. | ||
From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).