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).
Fundamentals of body construction, load distribution, and bending moments.
| Identifier | ExFiles\Box 14\8\ Scan289 | |
| Date | 23th June 1930 | |
| (C O P Y) Btn-1 June 23, 1930. To: Mr. Olley Cc- Mr. Beck Mr. Ainsworth From: Mr. Burton FUNDAMENTALS OF BODY CONSTRUCTION We are now experimenting with some bodies supported only on two points each side - Forward - 15" behind dash - using standard subframe mounting brackets. Rear - as near as possible to axle - using the same brackets. An investigation of the loads on the sill gives figures shown on SK-403 and SK-404. We believe that our fundamental requirement is to produce a sill that under existing conditions of loading will take up when deflected a uniform curvature throughout its length, and that this condition will produce in general the least destructive strains on the coachwork structure. This condition is satisfied by keeping the factor - M -- EI constant throughout the length of the sills, and this is the basis on which the following investigations were carried out. Distribution of load. As basic assumptions we take - Body weight - 1500 lbs. } Total 2400 lbs. Passengers - 900 lbs. } Body base - 120" Points of support - 15" and 91" from front end. If we assume a uniformly distributed load, this will give us a rating of 20 lbs. per inch run. On this basis we have plotted on SK-403 - (a) Bending Moments as shown in curve I reaching a max. +9400 lbs. ins. at 48" back - concave upward and -8400 lb. ins. at 91" back - concave downward, crossing the zero line at 0, 18-1/2, 79 and 120" from the front. (b) The cube root of the bending moment - curve II - expressed as a percentage of the max. value of this i.e. at 48" this curve is made to read 100 and all the other ordinates are in proportion, but at the same time making all values positive. - continued - | ||