Research Of Structural Layout Optimization Method Based On The Load-carrying Path

In the design of aircraft structures, the lightweight design of aircraft with the main component of force bearing is very critical. Currently, the layout optimization technique is one of very effective mean to carry out the design of structural lightweight. In layout optimization technique, topology optimization is a kind of important method, are being more structural designers attention. In fact, whether topological optimization or other layout optimization technology, its essence is seeking the most direct load-carrying path, namely the shortest load-carrying path.This paper, based on the research significance of load-carrying path, we first studied Michell truss criterion, introduced concept of structural load-carrying factor, took the structural load-carrying path as the design variables, by the integral to internal force of structure in the load-carrying path, corresponding load-carrying factor is obtained. As the load-carrying factor is the functional of structural load-carrying path, then we derived differential equation of the shortest load path of the corresponding structure with variational method, and solving the differential equation with the Ritz method, obtained the shortest load-carrying path structure. Compared with the result by Michell truss theory, proved that we put forward the quantification model is effective.Then, the paper analyzed the force transfer of fuselage bulkhead, respectively by analytical method and numerical optimization method based on the load-carrying path, optimized and got the best outline of edge strip and optimum the internal force distribution ratio of bulkhead. Through comparing the optimization results, the maximum error is less than 5%, proved the validity of the model theory.Finally ,adopt size optimization method optimized the half frame finite element model under the same shape and loads, we obtained the same load-carrying factor with the analytical model, Proved the validity of analytical model is put forward in this paper. Meanwhile through comparing the optimization results and analytical calculations of the structure minimum quality, show that the proposed analytical model can estimate the minimum quality of the force transmission structure also provided a reference goal for designers when they reduced weight in structure design.