面向组合结构刚度非线性特性的等效模型

Non-Linear Characters of Stiffness of Combination Structure Based on Equivalent Model

针对组合结构轴向载荷下呈现的刚度非线性特性难以计算的问题,提出了梁-双弹簧等效计算模型,研究了在包含不同材料垫片的组合结构中螺栓预紧力以及部分几何尺寸对轴向刚度非线性特性的影响.结果表明:采用铝合金垫片时,该连接组合结构的非线性特性主要表现为其轴向载荷-位移曲线在拉压状态改变时出现明显拐点;而该结构采用石墨垫片时,位移曲线在拉压阶段分别表现出非线性.相比于垫片厚度,螺栓预紧力、法兰厚度以及螺栓位置对轴向拉压刚度的影响更显著,且影响规律与所受载荷方向、垫片材料属性有关.

In the case of different axial loads,a combination structure shows its non-linear axial stiffness,which is hard to calculate. To solve this problem,an equivalent model,bending beam-double springs,was proposed. The influence of bolt pre-tightening force and geometric parameters on the non-linearity of joint axial stiffness of combina-tion structure with different material properties of gaskets was discussed. Results indicate that when aluminum alloy gasket is used,inflection point occurs in axial load-displacement curve between the stages of stress and ten-sion. When graphite gasket is used,displacement curve demonstrates apparent non-linear stiffness in the stages of both stress and tension. Compared with the thickness of the gasket,bolt pre-tightening force,flange thickness and position of the bolt play a more significant role on axial stiffness,and the influence law is related to loading direction and material properties of gasket.