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, including load distribution and bending moments.
| Identifier | ExFiles\Box 14\8\ Scan290 | |
| Date | 23th June 1930 | |
| ( C O P Y ) Btn-1 June 23, 1930. To: Mr. Olley From: Mr. Burton Cc- Mr. Beck Mr. Ainsworth 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 - | ||