本文在T．L．坐标下，利用能量原理，同时导出了空间杆元精确的割线刚度矩阵和切线刚度矩阵显式。
In this paper, the tangent stiffness matrices and the secant stiffness matrices of space trusses are derived with the energy principle in the Total Lagrangian coordinates.
采用拖带坐标系下的退化壳单元，以及动态显式有限元方法求解管材在弯管机上的弯曲成型问题。
A dynamic explicit finite element method is used to pipe bend forming processes on bender in this paper. The degenerated shell element and co-rotational coordinate system are employed.
并建立了相应的薄壁单元刚度方程，从而得出了局部坐标系下单元刚度矩阵的显式。
And the corresponding thin-walled element stiffness equation was formulated. The apparent formulation of element stiffness matrix under the local coordination was attained.
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