机械材料热变形的微观数值模拟研究

Microscopic Numerical Simulation and Experimental Study of the Rmal Deformation of Mechanical Parts

热特性是机械材料非常重要的物理特性。为了研究不同形体结构的热变形规律,文章针对铝材料进行微观层面的数值模拟和宏观的热变形实验。在原子尺度上分别构建立方体和空心圆柱体的3D纳米单晶铝模型,采用分子静力学理论与数值算法对模型热变形,得到模型升温后的变形量和热膨胀系数。微观模拟和数值模拟的结果均表明:立方体升温后,表面不同位置的热变形量不一样,中间的热变形量大于边缘处,即机械材料热变形具有非相似性特征;内径尺寸一致、外径尺寸不同的一组空心圆柱体升温后,外径和内径的热膨胀系数均不同。这说明机械形体的形状与结构参数对材料热变形规律影响重大,该现象在精密机械工程中不可忽略。

Thermal characteristic is one of the most important mechanical properties of materials. The paper studies the thermal deformation characteristics of mechanical parts by using the microscopic numerical simulation and macroscopic experiment. The paper takes a set of 3D aluminum crystal models as the objects of study and gets the thermal deformation data by the molecular statics method. Meanwhile, series of macroscopic thermal deformation experiments of aluminum sample are also carried out. The consistency of microscopic simulation and macroscopic experiment results demonstrate that with the body worming, the thermal deformation of the different position of surface is not the same, and the thermal of the middle is larger than the edges, namely, mechanical deformation is not similar. After heating the hollow cylinders with the same inner diameter size and different outer diameter size, the coefficient of thermal expansion of the outer diameter and the inner diameter is different. It proves that the thermal deformation of mechanical part is obviously affected by its shape and structure parameters, which should not be ignored in precision machinery engineering.