Dynamic contact mechanics with friction

本课题涉及机械部件的动态接触力学研究。预测动态接触力的一些应用包括预测管/管支架和机构接头的磨损率；水下遥控车辆、机器人系统远程遥控控制及培训软件；以及金属切削工艺的优化。提出了两个研究项目：(1)球面低速斜弹性碰撞的研究；(2)切削过程中切屑-刀具界面的研究。这两个项目都有分析、数值和实验方面。最近的低速斜碰撞实验和分析结果与部分滑移模型一致，即接触区中心有一个粘着区域，周围有一个发生滑移的环区。将使用一种改进的仪器进行进一步的实验测试。利用ABAQUS有限元软件对弹性球体与刚性表面斜碰撞进行瞬态仿真。剪应力和变形结果将与新开发的分析模型进行比较。部分滑移接触动力学模型有望在梁动力学仿真软件中取代粘滑算法。管状梁的实验结果将与预测的力/运动波形进行比较。利用ABAQUS/Explicit有限元程序建立了正交加工过程的平面应变热弹粘塑性模型，该模型具有温度相关的物理性质。最新的模型使用任意拉格朗日-欧拉（ALE）公式，允许工件材料流过弹性工具。在提出的工作中，将探讨材料模型和工具几何参数的变化。将与文献和实验进行比较。要回答的基本问题是与切屑-刀具摩擦模型和材料模型之间的关系有关。

The proposed research involves the study of dynamic contact mechanics of mechanical components. Some applications for the prediction of dynamic contact forces include prediction of wear rates at tube/pipe supports and mechanism joints; remote teleoperation control and training software for underwater remotely operated vehicles and robot systems; and optimization of metal cutting processes.    Two proposed research projects are described: (1) Studies of low-speed oblique elastic impact of spherical surfaces, and (2) Investigations of the chip-tool interface in machining. Both projects have analytical, numerical and experimental aspects.    Recent experimental and analytical results of low-speed oblique impact are consistent with a partial slip model where the contact zone has a central sticking region surrounded by a ring area undergoing slip. Further experimental tests will be carried out using a refined apparatus. ABAQUS finite element software will be used to do transient simulations of an elastic sphere obliquely colliding with a rigid surface. The shear stress and deformation results will be compared with a newly developed analytical model. The partial-slip contact dynamics model is expected to replace the stick-slip algorithm in beam dynamics simulation software. Experimental results for a tubular beam will be compared to the predicted force/motion waveforms.    Plane-strain thermo-elastic-viscoplastic models of orthogonal machining processes have been developed recently using the ABAQUS/Explicit finite element code with temperature-dependent physical properties. The latest models use an Arbitrary Lagrangian-Eulerian (ALE) formulation that allows the work-piece material to flow past an elastic tool. In the proposed work, variations in the material model and tool geometrical parameters will be explored. Comparisons will be made to the literature and with experiments. The fundamental questions to be answered are related to the relationships between the chip-tool friction model and the material models.