Elastic-Plastic Local Deformation and Collapse of Shells in Contact

本文用数值方法和实验方法研究了相互接触壳体的弹塑性大变形和破坏过程。本文建立了壳体与刚体或壳体接触或碰撞时所受损伤的基本知识，发展了一种有限相互滑动接触问题的数值分析算法，并将罚函数法用于建立基于有限元法的数值计算程序，对壳体与刚体或壳体接触或碰撞时所受的损伤进行了数值模拟，结果表明，该算法是有效的，且计算量小球壳和圆柱壳的接触屈曲和崩溃过程的细节进行了讨论。对壳体接触损伤的研究结果表明：（1）接触表面的摩擦条件起着非常重要的作用。(2)如果摩擦系数不是那么小，则在粘附（没有相互滑动）下的变形继续达到相当大的量，并且结果，两个主体（壳体）遭受显著的损坏。(3)如果摩擦系数小，则在接触表面上发生相互滑动，并且其中产生弹性卸载的物体在滑动后表现为刚性物体，并且对另一物体造成严重损坏。(4)本文通过球壳和圆柱壳接触屈曲的实验观察，讨论了非对称变形对屈曲过程稳定性的影响，这是很难用理论分析来估计的。

Large elastic-plastic deformation and collapsing process occurred in shells in contact with each other have been examined numerically and experimentally. Basic knowledge to estimate the damage suffered by the shell on the occasion of contact or collision with the rigid body or the shell has been established.An algorism of numerical analysis for the contact problem involving finite amount of mutual sliding has been developed and the penalty function method is used for the algorism to build in the numerical procedure based on the finite element method.The numerical simulations of the contact problems of spherical and cylindrical shells were performed and the details of the contact buckling and collapse process were discussed. The following results have been obtained concerning the damage of contact of the shells: (1) The condition of friction on the contact surface plays very important role. (2) If the frictional coefficient is not so small, deformaion under sticking (without mutual slide) continues up to the considerable amount and as a consequence, the both bodies (shells) suffer remarkable damage. (3) If the frictional coefficient is small, mutual sliding on the contact surface occurs and the body in which the elastic unloading results behaves like the rigid body after sliding and the serious damage is caused to the other body. (4) Therefore, the estimation of the damage necessitates to know the local rigidity of shear deformation of the body resisting the frictional force in the contact surface.From the experimental observations of the contact bucking of the spherical and cylindrical shells, the role of the non-symmetric deformation is discussed on the stability of the buckling process, which is very difficult to estimate by theoretical analysis.