Designing of minimum mass airframes under several loadings

We discuss the features of optimal force transfer in a thin-walled structure and use them to develop a method for defining the distribution of material over the structure elements for minimizing its volume. The suggested method works with one or several external loadings and allows one to determine the optimal structure and to recognize the phenomenon of Razani in which a structure with unequal stresses due to several loadings is more light-weight than a fully- stressed one. Using the developed method, we solved the original Razani problem and applied it for the optimization of the wing structure of a novel hypersonic airplane. It is shown that the determined material distribution is 8.78% lighter than that in a conventionally fully-stressed structure.