With increasing environmental awareness and ecological risk, green composites have gained more and more research attention, as they have the potential to be attractive than the traditional petroleum-based composites which are toxic and nonbiodegradable. Because of their lightweight, friendly processing and acoustic insulation, green composites have been used widely ranging from aerospace sector to household applications. The end-of-life concern with many polymeric composites has also limited their application spectrum. The green composites not only replace the traditional materials such as steel and wood but also challenge certain nonbiodegradable polymer composites. The present research initiative aims at highlighting the issues and challenges in the development and characterization of poly lactic acid-based green composites. A few of these important composites and their mechanical properties (tensile, compressive, flexural, and impact strength) have been reported in this study. The focus is the identification of the possible areas for their novel applications. A study has been conducted to categorize the various types of green composites on the basis of their physical, chemical, and mechanical characteristics.

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In this study, natural fiber reinforced polylactic acid composites have been developed by hot pressing through film-stacking procedure. The reinforcement materials used are nettle, Grewia optiva and sisal fibers in the plain weave form. For comparison purposes, polypropylene-based composites using the same fibers have also been developed. Mechanical properties (tensile, compressive, flexural, and impact properties) of all the developed composites have been evaluated through standard test procedures. It has been found that the polylactic acid based composites have superior mechanical properties and can be a potential substitute for traditional synthetic fiber composites in many application areas. Polylactic acid/sisal composite showed overall the best performance in terms of mechanical behavior. The morphological study of the fractured surface during mechanical testing has been done using scanning electron microscopy, which provides the mechanism of failure of composites during different types of mechanical loadings.

Natural fiber-reinforced composite materials are finding wide acceptability in various engineering applications. A substantial increase in the volume of production of these composites necessitates high-quality cost-effective manufacturing. Drilling of holes is an important machining operation required to ascertain the assembly operations of intricate composite products. In the present experimental investigation, natural fiber (sisal and Grewia optiva fiber)-reinforced polylactic acid-based green composite laminates were developed using hot compression through film stacking method. The drilling behavior of green composite laminates was evaluated in terms of drilling forces (thrust force and torque) and drilling-induced damage. The cutting speed, feed rate, and the drill geometry were taken as the input process parameters. It was concluded that all the three input process parameters affect the drilling behavior of green composite laminates. The drill geometry was established as an important input parameter that affects the drilling forces and subsequently the drilling-induced damage.

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In this study, a surface wear prediction methodology for spur and helical gears is proposed. The methodology employs a finite elements-based gear contact mechanics model in conjunction with the Archard’s wear formulation to predict wear of contacting tooth surfaces. An iterative numerical procedure is developed to account for the changes in the gear contact as the gears wear. A methodology is developed to import gear coordinate measurement machine data into the gear contact model in order to analyze gears with actual manufactured surfaces with profile and lead modifications. Results of an experimental study are presented for validation of the methodology. A set of simulations is also included to highlight the differences between gear pairs having modified and unmodified tooth surfaces, with and without manufacturing errors in terms of their wear characteristics.

Recently, natural fiber-reinforced composites are becoming a viable alternative to synthetic fiber composites in many applications. Secondary processing in terms of hole making in composites is an almost unavoidable operation for facilitating the assembly operations. In the present experimental investigation, the drilling process of natural fiberreinforced thermoplastic bio-composites has been evaluated in terms of the drilling forces. The cutting speed, feed rate and the drill point geometry have been taken as the input process parameters. Two types of drill geometries (solid and hollow in shape) have been used for drilling in the present work. The cutting mechanism of solid and hollow drill point geometry are substantially different which consequently affects the drilling forces and drilling-induced damage.