内应力假说和脆性材料特性参数的尺寸效应(Ⅱ)

Hypothesis of interior stress and size effect of mechanical parameters of brittle materials (II)

根据弹性力学、能量守恒定律以及内应力假说的基本原理,从材料的非均一性、多相性出发,建立了一组描述脆性材料强度指标和弹模指标尺寸效应的方程.利用本假说的理论公式与实验数据Weibull 理论作了对比,结果表明本假说的理论公式在描述材料强度尺寸效应时具有良好精度,可很容易地说明为什么尺寸效应在试件尺寸大到一定程度会消失.该假说认为内应力会受到试件边界面的释放, 称为内应力的边界效应,试件尺寸越大则边界面相对越小, 因而内应力场或者说内应力能会随试件尺寸加大而加大,边界效应在引起材料强度指标随试件尺寸加大而减小的同时,

Based on the theories of elasticity, energy conservation law and the basic principles of the hypothesis of interior stress, a series of equations describing size effect of the strength and elastic modulus of brittle materials are set up. In this article, the size effect equations are used for calculating experimenting data of the strength of concrete specimen of different sizes. The results prove the precision of the theoretical equation in describing size effect of material strength. The theory can easily explain why size effect disappears when the specimen is big enough. The hypothesis holds that the interior stress field or the interior stress energy increases with the increase of the size of the specimen, which causes decrease in strength with the increase in size of the specimen causes increase as well in elastic modulus.