Mechanics and dynamics of machining advanced composite materials

复合材料具有出色的强度重量比以及抗疲劳和耐腐蚀性能，因此在从消费产品到航空航天的广泛产品中的应用都有了极大的增长。为了适应复合材料应用的激增，该行业需要高生产率的制造方法来将材料转化为最终产品。钻孔、铣削和修整等加工操作通常是制造复合材料的关键步骤。这些操作通常用于精加工和装配阶段，因此较差的加工条件可能会导致成品刮伤。该计划的最终目标是开发高性能加工(HPM)系统，通过a)基于模拟的过程优化，b)适当的过程控制和监控，以及c)开发智能机器人加工系统来提高复合加工过程的生产率和稳健性。实现这些目标将对目前的复合材料加工方法产生革命性的影响。例如，在制造商用飞机的复合材料结构时，70%以上的钻探操作是人工完成的；此类操作可以使用自动化机器人系统进行，以优化生产的速度和健壮性，还可以避免因钻头振动而导致的工作场所健康和安全危害，如白指症。 这项研究将有助于通过描述复合材料加工中的切屑生成过程，并对由此产生的切削力和振动进行建模，从而开发出高功率加工系统。这些模型将长期用于过程的优化、控制和自动化。在接下来的五年中，将通过追求以下目标来研究该过程的数学建模：i)表征材料的失效模式(剪切、断裂等)这导致了纤维增强聚合物(FRP)中切屑的产生；ii)根据进给量、速度、刀具几何形状和材料的本构模型建立了切削力的数学模型；iii)在切削力模型中加入了刀具和工件的结构灵活性，以模拟加工操作中的振动。尽管未来五年的研究重点将集中在FRPS上，但由于其更广泛的工业应用，从长远来看，建模将扩展到其他类型的复合材料。 除了该计划的科技贡献外，还将培训几名高素质的人员(HQP)，他们将接受工程基础和应用领域的培训，如断裂力学、动力学、振动、有限元建模、动手实验、信号处理和实验结构动力学。这项培训将为他们在学术界和工业界担任领导角色做好准备。

Composites offer an outstanding strength to weight ratio and fatigue and corrosion resistance, therefore their application has grown tremendously in a broad spectrum of products—from consumer to aerospace. To accommodate the surge in the application of composites, the industry demands high productivity manufacturing methods to convert the material into the final product. Machining operations such as drilling, milling and trimming are usually a critical step in manufacturing composites. These operations are commonly used in finishing and assembly stages and thus poor machining conditions may lead to scraping of the finished product. The ultimate goal of this program is to develop High Performance Machining (HPM) systems to enhance the productivity and robustness of composite machining processes by a) simulation-based optimization of the process, b) appropriate process control and monitoring and c) developing intelligent robotic machining systems. Achieving these objectives will have a transformative effect on current methods of machining composites. For example, in manufacturing the composite structure of a commercial aircraft, more than 70% of the drilling operations are performed manually; such operations can be carried out using automated robotic systems to optimize the speed and robustness of production, also to avoid workplace health and safety hazards such as white finger syndrome due to drill vibrations. The proposed research will contribute to developing HPM systems by characterizing the chip generation process in composite machining and modeling the resulting cutting forces and vibrations. These models will be used in the long term for the optimization, control and automation of the process. Mathematical modeling of the process will be studied by pursuing the following objectives in the next five years: i) characterizing the material failure modes (shear, fracture, etc.) that lead to chip generation in Fiber Reinforced Polymers (FRP), ii) developing the mathematical models of cutting forces in terms of the feed, speed, tool geometry and material’s constitutive model, and iii) incorporating the structural flexibility of the tool and workpiece in cutting force models to simulate the vibrations during machining operations. Although the focus of the study in the next five years will be on FRPs, because of their broader industrial applications, modeling will be extended to other types of composites in the long term. Scientific and technological contributions of the program will be complemented by training several Highly Qualified Personnel (HQP), who will receive training on fundamental and applied fields of engineering such as fracture mechanics, dynamics, vibrations, Finite Element Modeling, hands-on experimentation, signal processing and experimental structural dynamics. This training will prepare them to take on leadership roles in academia and industry.