基于界面单元的子结构协调技术

该文提出一种用于协调子结构的界面单元方法。基于广义变分原理，将两子域的刚度与界面单元刚度组装成耦合结构的整体刚度矩阵，求解新的平衡方程即可得到各个耦合子域的位移。界面单元的意义是对子域引入边界力，并建立边界上平衡关系和位移协调关系。该文利用悬臂梁单轴受拉案例验证了界面单元方法的精确性。为了使得界面单元能够应用到子结构混合试验中，引入静力凝聚与BFGS方法，这样只需通过提取边界上的力与位移即可实现多子域不共节点的边界协调问题。该文最终以悬臂梁案例验证了界面单元在解决非线性静、动力加载工况下的正确性。

A METHOD TO COORDINATE SUBSTRUCTURES BASED ON INTERFACE ELEMENTS

Proposed in this paper is an interface element method for coupling multiple subdomains. Based on the general variational principle, it is feasible to formulate the overall stiffness matrix of a coupled structure by assembling the stiffness matrices of subdomains and the stiffness matrix of interface elements, thus being possible to solve the new equilibrium equation to obtain the displacements of each subdomain. The interface element method essentially introduces boundary confinement forces to substructures, and builds up the equilibrium and compatibility on the common boundaries between subdomains. An example of a cantilever beam under uniaxial tension was used to demonstrate the accuracy of the interface element method. In order to apply the interface element method to a substructure hybrid test, the static condensation technique and the BFGS method are further introduced. Only boundary forces and displacement are implemented to realize the coordinating between subdomains, while the common nodes between subdomains are not necessary. Finally, the nonlinear static analysis and the nonlinear time history analysis were conducted on the cantilever beam, which fully demonstrate the feasibility and accuracy of the interface element method.