ANALYTICAL ELEMENT FOR BAR SUBJECTED TO COMPRESSION AND TORSION CONSIDERING THE LARGE DISPLACEMENT

To improve the accuracy and efficiency in calculating the inter force and deformation of bar under compression and torsion, the shape function was determined by considering the section warping and the effect of large displacement, based on Vlasov restrained torsion theory and according to the displacement controlling equation for bar. Potential energy functional of bar subjected to compression and torsion was established by applying potential energy principle. Analytical element formulations for bar were received and element stiffness matrix was obtained via variational principle of potential energy stationary value. Comparisons among the calculation results of proposed element, theoretical solution, and interpolation polynomial element are conducted, and the results show that the solution of analytical element by one element number is in accordance with the theoretical solution. The analytical element can satisfy the high accuracy and efficiency requirement and can be applied in practice.