Conjugate Gradient Back Analysis of Mechanical Parameters of Box Structure Based on Layered Shell Element

摘要

Emphasis has long been put on mechanical analysis of box structure and some computational codes besides general FEM software have solved it well. Before mechanical analysis of box structure, mechanical parameters are necessarily input, which indicates the importance of back analysis of mechanical parameters of box structure. Compared with mechanical analysis, little attention has been paid to the back analysis problem. The objective of this present study is to carry out conjugate gradient back analysis of mechanical parameters of box structure based on layered shell element. Firstly from degraded shell element theory, layered shell element is deduced and the displacement function is obtained. Then dynamic Bayesian error function of mechanical parameters of box structure is founded and the corresponding formulas of dynamic Bayesian expectation and variance are derived. After the method of solving the automatic search of step length is put forward, the back analysis computing formulas are also obtained by adopting conjugate gradient method. Then the steps of conjugate gradient back analysis of mechanical parameters of box structure are listed in detail and the corresponding code is compiled. Through analysis of a classic example, the criterion of judging the precision of the known information is gained as well as some other important conclusions about conjugate gradient back analysis of mechanical parameters of box structure.