线弹性动力学的某些一般定理及广义与广义分区变分原理

Some General Theorems and Generalized and Piecewise Generalized Variational Principles for Linear Elastodynamics

从四维空间思想出发,在四种时端条件下,系统地推导得出了弹性动力学有关的一般定理,如:可能功作用量原理,虚位移原理,虚应力一动量原理,互易定理及由此导出的位移互等定理与始末时刻条件关系定理等;得出了线弹性动力学的位能作用量变分原理,余能作用量变分原理,动力问题的胡-鹫原理,H-R原理及本构关系变分原理.Hamilton原理,Toupin原理及有关文献如[5]、[17]～[24]的工作均可作为文中一般结果的特例.对应于有限元分析.在空间分区,时间分区及时空均分区情况.给出了动力学问题的分区位能作用量原理.分区余能作用量原理,分区混合能作用量原理及相应的分区广义变变分原理.导出了分区原理的一般形式.若去掉时间维及有关量,文中有关结果可转化为静力问题中有关的相应结果.

From the concept of four-dimensional space and under the four kinds of time limit conditions, some general theorems for elastodynamics are developed, such as the principle of possible work action, the virtual displacement principle, the virtual stress-momentum principle, the reciprocal theorems and the related theorems of time terminal conditions derived from it. The variational principles of potential energy action and complementary energy action, the H-W principles, the H-R principles and the constitutive variational principles for alastodynamics are obtained. Hamilton's principle, Toupin's work and the formulations of Ref. [5],[17-24] may be regarded as some special cases of the general principles given in the paper. By considering three cases: piecewise space-time domain, piece-wise space domain,piecewise time domain, the piecewise variational principles including the potential, the complementary and the mixed energy action fashions are given. Finally, the general formulation of piecewise variational principles is derived. If the time dimension is not considered, the formulations obtained in the paper will become the corresponding ones for elastostatics.