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).
Analysis of stress, load, and deflection in parallel spiral springs using mathematical formulas.
| Identifier | ExFiles\Box 56\2\ Scan098 | |
| Date | 28th August 1930 guessed | |
| -4- considerable increase in the stress in the fully compressed position is allowable — the initial deflection in the set up position being considerably reduced to keep the stress the same in that position. Now, whatever is done in this direction, and assuming for the moment that we are keeping to parallel spiral springs, it appears that it can be done as already stated by increasing d or reducing k or D.{John DeLooze - Company Secretary} It becomes therefore, desirable to enquire as to which of these three possibilities, either separately or in combination, it is expedient to adopt. To enable us to arrive at this we may utilise the fact that it is probably required to retain the same load in the set up position. Now, as already given, the load W = (Cd⁴δ)/(8D³k) = (dδ)/(kD²) x (Cd³)/(8D) If, therefore, we are working on the principle of having kept the stress for a given deflection the same by increasing d/kD² and reducing the initial deflection to the same extent it follows that dδ/kD² has remained the same, and since also the load (Cd⁴δ)/(8D³k) has remained the same it follows that d³/D must have remained the same or that d must vary as D¹/³. | ||