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).
Bending and torsion tests on a piece of ash wood to determine its modulus of elasticity.
| Identifier | ExFiles\Box 19\4\ Scan066 | |
| Date | 25th June 1930 guessed | |
| -2- (4) Btn. writes Ap.30 and later - "Further to my letter of Ap.16 we have, with considerable help from Mr. Ingham, now made some rough tests on a piece of ash to determine the direct and transverse modulus of elasticity. "A bar was made true and square of the section 1" x 2" x 48" long. "In bending - Between supports 45" apart with short side vertical, this bar was loaded at centre up to 300 lbs. The deflection curve was a good straight line averaging a deflection of 1.100 at centre for 250 lbs. load. "This gives a figure E = 2.59 x 10^6. (See curve SK 401 attached). "Text books I have give 1.5 x 10^6 and in your letter you use 1.6 x 10^6, so apparently we obtain a figure rather higher than the accepted figure. "In torsion - The same piece of ash was held in a dividing head clamped down to the marking-off table. The other end was supported and fitted with a 12" arm with a spring balance on the end. A point 42" from the chuck was taken as a datum and dividing head turned through a definite angle. The anchor of the spring balance was adjusted in every case to bring this datum line back to horizontal. Readings are plotted in SK 402 attached, which indicate a twist of 32° for 70 lbs - feet twisting moment in 42". "For a computation of elasticity, I have taken the formula - deflection = θ = (40J / A^4) x (T.L / N) where J is polar moment of inertia = bd{Mr Berend} (b^2 + d^2) / 12 = 10 / 12 A = Cross sectional area = 2. T = Twisting moment = 840 lbs.ins. θ = Deflection = 32° - .558 rad. L = Length = 42". cont'd.{John DeLooze - Company Secretary} | ||