LOAD PATH VISUALIZATION USING U* INDEX AND PRINCIPAL LOAD PATH DETERMINATION IN THIN-WALLED STRUCTURES

U* index is used to express the load transfer inside a structure from a global perspective. Typically, a load path is defined as the ridgeline of the U* contours. However, it is cumbersome to directly locate the load paths by numerical approaches. This paper presents a streamline method with the fourth-order Runge-Kutta algorithm to visualize the load paths in thin-walled structures. The load paths can be consistently plotted on the surfaces of two-dimensional plates or three-dimensional shells by path projection. A new concept of principal load path is also introduced by evaluating the importance of load paths using statistical means. The principal load path is conceived as the “spine” of the structure that transfers the greatest internal force. A case study of a simplified vehicle body is presented. It is found that the structural stiffness can be greatly improved by reinforcing the set of principal load paths, which gives engineers an important insight into the development of weight-efficient structures.