1021. A Procedure for Calculating the Weight of Wing Structures With Increased Service Life

Paper

Abstract

This report describes a method for computing the weight of wings which are subjected to severe fatigue loads. The method is based on the procedure developed by M.E. BURT and L.E. RIPLEY in Great Britain. After an extension of the load assumptions by several load cases, proposals are made for estimating typical load spectra. In addition, a basic procedure for taking account of elasto-dynamic effects is discussed. The influences of different materials and types of construction are included in the computation of the allowable compressive, shear,and tensile stresses. Furthermore, the damage accumulation hypothesis according to MINER is applied as well as classical NACA test evaluations. An improvement of the computational accuracy is reasonable only if all weight components – dependent on their share in overall weight – are included in the prediction. Therefore the original methods were revised in some details and several new partial procedures were introduced. Apart from calculating the wing weights at an advanced project stage, individual sections of the method can also be used for estimating the allowable stress levels in important cross sections. On account of the relatively great numerical efforts involved, however, complete wing weight computations can only be effected with the aid of a computer. As regards practical work, the introduction of display units is extremely helpful.