Characterisation on the effects of workpiece microstructure and process parameters on resiudal stresses generated during machining

长期目标是对工件微观结构和工艺参数对单点车削后加工表面产生的残余应力的影响进行数值模拟。短期研究包括：a)开发一种结合数值和实验的方法来确定沿刀具-切屑界面的摩擦系数，并研究该方法的操作边界；b)设计使用任意拉格朗日欧拉公式技术来模拟顺序切削、切削刃半径和进给对残余应力的影响；C)建立一个数值模型来模拟工件微观结构和相变对残余应力的影响，d)通过数值和实验研究侧面磨损长度、切削刃半径与进给比、刀具涂层和工艺参数对残余应力的影响。本研究将开发一种独特的方法，通过数值和实验方法来获得加工过程中产生的实际摩擦系数。在切削过程中，刀柄对刀具偏转的影响也将被建模。分析了顺序切削对最终残余应力分布的影响。用于预测残余应力的F.E.模型将基于隐式求解器或解析方法，这将大大减少计算时间。还将开发模型来预测相变和工件微观组织对残余应力的高度复杂影响。本研究的重要意义在于增强了残余应力建模的知识，这将使研究人员能够优化航空航天，医疗和汽车行业中疲劳载荷部件的加工参数，以最大限度地提高压缩残余应力的大小和渗透深度。此外，该技术将有助于设计制造方案，减少后加工阶段，如喷丸强化，提高疲劳性能，减少由残余应力引起的零件变形。残余应力研讨会将在麦克马斯特大学为机械、材料和制造工程师组织，以介绍这项资助的研究发现。

The long term objective is to numerically model the effects of workpiece micro structure and process parameters on residual stresses generate in the machined surface after single point turning. Short term research is comprised of studies on a) develop a combine numerical and experimental method to determine the friction coefficient along the tool-chip interface and investigate the operating boundary for this method, b) design using the Arbitrary Lagrangian Eulerian formulation technique to simulate the effects of sequential cut, cutting edge radius and feed on residual stresses, c) develop a numerical model to simulate the effects of workpiece microstructure and phase transformation on residual stresses and d) numerically and experimentally investigate the effects of flank wear length, cutting edge radius to feed ratio, tool coating, and process parameters on residual stresses. This research will develop a unique methodology to acquire actual friction coefficient induced during machining by using both numerical and experimental approaches. The effect of tool holder on tool deflection during the cutting process will also be modeled. Influence of sequential cut on the final residual stress profile will also be analyzed. The F.E. model developed to predict residual stresses will be based on either an implicit solver or analytical approach, which will reduced computational time substantially. Models will also be developed to predict the highly complex effects of phase transformation and workpiece micro structure on residual stresses. The significant of this research is to enhance the knowledge on modeling of residual stresses, which will enable researchers to optimize machining parameters for fatigue loaded components in the aerospace, medical and automotive sectors in terms of maximization of compressive residual stresses in both magnitude and penetration depth. Furthermore, this technology will assist design for manufacture protocol in reduction of post machining stages like shot peening, improved fatigue performance and reduce part distortion induced by residual stresses. Residual stress seminar will be organised at McMaster for Mechanical, Materials & Manufacturing engineers to present research discovery from this grant.