计算曲面壳体等效节点热载荷的新方法

提出了一种利用平面壳单元计算曲面壳体热应力问题等效节点热载荷的新方法, 具有较高的计算精度. 首先在平面壳元的理论基础上, 在壳单元切平面建立局部坐标系; 然后根据提出的理论, 利用单元节点整体坐标直接计算壳单元等效节点热载荷积分方程中所需的未知量, 如: 形函数对局部坐标的导数、从对局部坐标积分转换到自然坐标积分时的雅可比行列式等; 最后, 根据提出的算法求出从局部坐标转换到整体坐标的转换矩阵, 进而求出整体坐标系下壳单元等效节点热载荷. 通过与商用软件ANSYS 的计算结果进行对比分析, 证明提出的方法是正确而且精确的.

A NEW METHOD TO COMPUTE THERMAL EQUIVALENT NODAL LOADS ON CURVED SURFACES

A new method using flat shell element to compute thermal equivalent nodal loads on curved surface is presented. Firstly, the local Cartesian coordinate system is established on the tangential plane to the element surface. Then, the unknowns included in the integrand about thermal equivalent nodal loads are computed in terms of the theory proposed in this paper, which include the derivative of shape functions with respect to the variables of local coordinate system and the Jacobian of the transformation from the local three-dimensional coordinate system to the intrinsic two-dimensional coordinate system of the surface patch. Finally, a matrix transformation formulation is derived from the local Cartesian coordinate system to the global one, based on which the thermal equivalent nodal loads in the global Cartesian coordinate system can be found. Comparison with the results from FEM analysis shows that the proposed method in this paper is correct and accurate.