4. Numerical modeling of LFRP machining

Abstract

This chapter presents some considerations for modeling long fiber reinforced polymer (LFRP) composites machining. The composite components are usually made to the desired product's final size. However, some machining operations are required to achieve dimensional tolerance and assembly requirements. LFRP composites are considered difficult to cut due to the presence of hard fibers, being especially vulnerable to machining-induced damage. Numerical modeling of machining can help in analyzing the process; however, it is a relatively new approach to the study of composite cutting. In this chapter, main contributions dealing with LFRP modeling of cutting are summarized. Recent contributions by authors in this field are included, giving the reader information on the development of numerical models that cover mechanical and thermal aspects of different cutting processes. IntroductionLong fiber reinforced polymer (LFRP) composites have been extensively used in structural components. Their attractive properties -fatigue and corrosion resistance combined with light weight, high specific stiffness and strength -made this family of materials suitable for a wide range of applications in aeronautical, automotive, marine and sporting industries.The problems associated with precision and efficiency in cutting LFRP composites have become important issues in the manufacturing field. Although the components are usually made to the final size of the desired product, machining processes (mainly trimming, milling and drilling) are needed to achieve dimensional tolerance and assembly requirements. LFRP composites are considered difficult to cut materials due to the presence of hard fibers, being especially vulnerable to damage, mainly delamination, fiber pull-out and matrix thermal degradation [1].Machining-induced damage has significant importance in industrial applications; for instance, poor hole quality in composite drilling accounts for an estimated 60 % of all parts rejection. The workpiece's surface integrity is critical for the subsequent assembly stage and, of course, during the service life of the component. In fact, recent calls for international projects deal with this unsolved problem: drilling holes in high responsibility composite components, hole quality improvement, non-destructive inspection techniques and other aspects showing the importance of high value machining operations previous to final assembly of the components.