Study On The Load-Relieving Device And Analysis Theory Of Load Relieving System

Load Relieving System was a new type of structure, which was put forward by a British scholar in 1980's. Its basic conception is that the structure achieves the goal of self-adjustment and self-protection by introducing some kind of movable device. Load Relieving System is different from the general rigid structure and the flexible structure.Firstly, the up-to-date researches in domestics and international were summarized, some types of load-relieving device was innovated, and then two kinds of analysis methods were developed - force density method and non-linear finite element method. The main content included as follows:On one hand, several kinds of devices had been brought forward: four-bar-linkage structure, spiral pressing structure, spring structure, structure body device and shape memory alloy device. And then, spring bar structure, spring ream structure and spring four-bar-linkage structure are further studied the effects of load relieving.On the other hand, the analysis method was discussed:Force density method was based on the relationship of geometry, the force density value of each element and each node coordinate, then the linear equations about the nodal coordinate was set up and solved. Practice showed that force density method was highly efficient and could control the precision of convergence arbitrary.The steps of non-linear finite element method were to adopt the virtual material parameters, split the outside loads to a comparable small increment, and revise the geometry model every time to get the final shape. The key of this method was to keep the invariance of each element force in the whole process. Example showed that this method can analyze the Load Relieving System efficiently, but there were some problems need to be solved.The characteristic of spring was explained in details, and there were three kinds of applications in Load Relieving System: spring bar structure, spring ream structure and spring four-bar-linkage structure. Research showed: although very great displacement took place in spring bar structure, each element force did not change much with the increase of external force. But the precondition using spring bar structure was: when the dummy displacement was corresponded to the outside load directions, the newly structure should be propitious to bear the increased external loads. Spring four-bar-linkage structure was also studied in this paper.In the end, some conclusions were summarized and the problems that should be studied further were put forward.