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).
Letter to Dunlop Rim & Wheel Co. Ltd. discussing stress analysis results of a wheel rim.
| Identifier | ExFiles\Box 159\3\ scan0075 | |
| Date | 22th June 1939 | |
| - 2 - Messrs. Dunlop Rim & Wheel Co.Ltd., COVENTRY. These tests confirm the results of the stress analysis made by our Mr. Bower, who handed a copy of his investigation to your representative (Mr. Chatterton) on the occasion of his visit to these Works on May 17th. For example, the calculated stress at the inside face at B. is 10 tons/sq.in., that at the outside face at B is 8.7 tons/sq.in., and that at the outside face at A is 9.4 tons/sq.in. The latter two figures agree with the experimental results. The inside face of the metal was, of course, inaccessible with the tyre in place, so that the stresses here could not be checked by the lacquer method. The fairly high stress at D is also of interest, as this is the point where failure has been known to occur in a previous model Bentley rim, a failure which was attributed at the time to corrosion due to water lodging in the hollow bead rim, but now seems to have been probably due to corrosion and stress fatigue. It should be realised that the stresses at present under consideration are very localised, and therefore, in a ductile material, do not show up in an ordinary overload test, but cause ultimate failure by fatigue. The effect of fatigue is very largely increased by the fact that similar concentrated stresses will be caused by the cornering and other variable loads on the tyre, and such stresses will be superimposed on those due to inflation, which are already high. It should be possible to determine these additional stresses by the lacquer process. It is very evident that the increase in section thickness mutually decided upon is essential to safety. Yours faithfully, FOR ROLLS-ROYCE LIMITED. R M Harvey Bailey CHIEF ENGINEER - CHASSIS. | ||