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arXiv 0907.1833cond-mat.mtrl-sciphysics.class-ph
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对称和非对称弹性力学中的应力和应变

Stress and strain in symmetric and asymmetric elasticity

Albert Tarantola

摘要:

运动概念的简单介绍并不能很好地适用于后来的严格张量弹性理论。考虑任意坐标系来表示实验室中的点和材料点(共动坐标),可以发展一个简单的老式理论,其中只需要引入可测量的量-如柯西应力。该理论解释了非对称应力(Cosserat弹性介质)的可能性,但是,与理论的通常发展相反,基本变量不是微旋转,而是更基本的微旋转速度。这里引入的变形张量是通常理论中定义不好的变形“张量”的适当张量等价。它通过矩阵与变形速度张量有关。应变是变形张量的对数。由于该理论解释了一般的Cosserat介质,应变不一定是对称的。胡克定律可以适当地引入材料坐标中(因为刚度是材料点的函数)。该理论的一个特殊性是,在材料(共动)坐标的刚度张量的组件是不依赖于时间。位形空间被标识为李群GL(3)+的一部分,其测地线连接到群的原点。

英文摘要:

Usual introductions of the concept of motion are not well adapted to a subsequent, strictly tensorial, theory of elasticity. The consideration of arbitrary coordinate systems for the representation of both, the points in the laboratory, and the material points (comoving coordinates), allows to develop a simple, old fashioned theory, where only measurable quantities -like the Cauchy stress- need be introduced. The theory accounts for the possibility of asymmetric stress (Cosserat elastic media), but, contrary to usual developments of the theory, the basic variable is not a micro-rotation, but the more fundamental micro-rotation velocity. The deformation tensor here introduced is the proper tensorial equivalent of the poorly defined deformation "tensors" of the usual theory. It is related to the deformation velocity tensor via the matricant. The strain is the logarithm of the deformation tensor. As the theory accounts for general Cosserat media, the strain is not necessarily symmetric. Hooke's law can be properly introduced in the material coordinates (as the stiffness is a function of the material point). A particularity of the theory is that the components of the stiffness tensor in the material (comoving) coordinates are not time-dependent. The configuration space is identified to the part of the Lie group GL(3)+, that is geodesically connected to the origin of the group.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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