Published online by Cambridge University Press: 28 July 2016
The problem of determining the distribution of stress over the various components of a structure such as an aircraft frame is one which has always presented considerable difficulty. For a large proportion of the components calculations of the stresses can only be carried out on the basis of assumptions and approximations, the effects of which cannot be estimated with any degree of accuracy and, since considerations of size and weight impose limitations upon the employment of a large safety factor, there has always existed a need for some practical means of checking the results of calculations or of obtaining more reliable estimates of the stresses.