PhD - Characterisation of machining induced damage in composite materials

博士 - 复合材料加工引起的损伤的表征

• 批准号: 1942015
• 金额: --
• 依托单位: University of Sheffield
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1942015
• 关键词: PhD; Characterisation; machining; induced; damage

Carbon fibre reinforced polymers (CFRP) are widely used in the aerospace and automotive industry due to their superior mechanical proprieties such as a good strength to weight ratio, high resistance to corrosion and excellent fatigue resistance. Machining of CFRP is important as the manufactured part needs to meet geometrical constraints having an excellent surface quality required for specific engineering applications. Typical machining induced problems such as delamination, fibre pull-outs, matrix cracking and fibre breakage arise due to the incorrect configuration of machining parameters in correlation with material properties. To avoid the machining induced damage, a better understanding of the tool-material interaction is needed, which in literature is investigated experimentally through orthogonal cutting tests. The present work proposes a new perspective in analysing the orthogonal cutting process of UD CFRP laminates using an on-line, in situ analysis method: High Speed Digital Image Correlation (HS-DIC) and a specially designed rig for experimental cutting tests. The creation of strains, which is known to affect the integrity of the newly finished surface is monitored and strain maps are generated and correlated with the cutting force and chip formation mechanism. The material properties such as compression strength, shear modulus and shear strength are strain rate dependent properties which governs the plastic deformation during cutting. An in-depth assessment of the relation between strain values and cutting forces, chip formation and cutting parameters is done to optimize the cutting process and safeguard against the premature failure of machined parts under in-service loading conditions.

碳纤维增强聚合物（CFRP）由于其上级的机械性能如良好的强度重量比、高耐腐蚀性和优异的抗疲劳性而广泛用于航空航天和汽车工业。CFRP的机加工很重要，因为制造的零件需要满足几何约束，具有特定工程应用所需的优异表面质量。由于与材料性能相关的加工参数配置不正确，导致了典型的加工引起的问题，如分层、纤维拔出、基体开裂和纤维断裂。为了避免机械加工引起的损伤，需要更好地了解工具-材料相互作用，在文献中通过正交切削试验进行了实验研究。本工作提出了一个新的角度在分析正交切割过程中的UD CFRP层压板使用在线，原位分析方法：高速数字图像相关（HS-DIC）和专门设计的实验切割试验台。应变的产生，这是已知的影响新完成的表面的完整性进行监测和应变图生成和相关的切削力和切屑形成机制。压缩强度、剪切模量和剪切强度等材料特性是应变率相关的特性，这些特性决定了切削过程中的塑性变形。对应变值与切削力、切屑形成和切削参数之间的关系进行深入评估，以优化切削工艺，并防止在使用载荷条件下加工零件过早失效。