基于能量原理的动态加载下材料力学性能分析

Energy-Based Mechanical Properties Analysis of Materials under Dynamic Loading

材料的基本力学性能,如刚度和强度等,通常是在准静态加载条件下测定的,即加载速度限制在不对结果产生影响的程度,但实际上该条件并没有明显的界限,工程中材料常常处于动态加载情况,其刚度和强度与静态存在明显的区别。不仅如何获得材料的动态性能是一个重要的技术问题,明确低速情况下刚度、强度等材料性能的表现特征,探讨造成材料动态性能与静态性能不同的物理机制也是一个具有理论意义的课题。本文从能量守恒的角度,对材料在动态加载情况下的变形与加载速度的关系进行了分析,基于材料力学性能与加载过程无关的认识,本文研究说明在动态加载情况下,材料变形速度造成材料细观变形机制发生变化,从而影响了材料宏观性能。上述结论与现有文献中的实验结果相比较,二者体现的规律呈现一致性。

The basic mechanical properties of materials, such as stiffness and strength, are usually measured under quasi-static loading conditions, i.e., the loading speed is limited to the extent which does not affect the results, but in fact there is no obvious boundary between the conditions. In engineering, materials are often under dynamic loading, and their stiffness and strength are obviously different from that in static state. Not only how to obtain the dynamic properties of materials is an important technical issue, but also it is of theoretical significance to clarify the performance characteristics of materials such as stiffness and strength at low speed, and to explore the physical mechanism that causes the difference between the dynamic and static properties of materials. From the perspective of energy conservation, this paper analyses the relationship between deformation and loading speed of materials under dynamic loading. Based on the knowledge that mechanical properties of materials are independent of the loading process, this paper shows that under dynamic loading, the deformation speed of materials changes the micro-deformation mechanism of materials, thus affecting the macroscopic properties of materials. The above conclusions are consistent with the experimental results in the existing literature.