三维应力计的工作原理及误差分析

常规应力状态由3个正应力和3个剪应力共6个分量组成，因此,确定一点的应力状态至少需要6个单向应力计。基于三维应力状态理论，以单向应力计或压力计为基本元件，设计了一种能测试受力体内部三维应力状态的装置。该测试装置由6个单向应力计组成，且应力计的轴线构成四面体的6个棱。考虑测试装置对稳定性、合理性、便利性等技术要求，该四面体的形状可以设计为正四面体和由正方体截取的正三棱锥。根据某一方向上正应力与常规应力状态表示方法中6个应力分量之间的关系，建立了三维应力计各分量与常规应力分量之间的映射关系，并进一步导出了由三维应力计计算常规应力状态的方法及产生误差的原因。

Principle and errors analysis of the three-dimensional stress apparatuses

The traditional stress state is composed of two normal stresses and a shear stress in the two dimensional space, and three normal stresses and three shear stresses in the three dimensional space. Therefore, six stressometers at least are necessary to determine the stress state at a point in space. Based on the stress state theory, a stress apparatus that can detector the three dimensional stress states is devised. The apparatus is made up of six one-way stressometers which are disposed at the edges of a tetrahedron. The tetrahedron is regular of all even arbitrary shaped in theory considering rational, logical, stability and conveniently. The mapping transformation, from the traditional stress state to the stress state illustrated by the edges of the tetrahedron is constructed. Furthermore, the traditional stress state can be derived from the data collected by the three-dimensional stress apparatus, and causes of errors are analyzed.