Environmental and sustainability issues coupled with increased awareness have urged researchers to focus on natural sources that can substitute several forbidden materials. Fiber‐reinforced hybrid polymeric composites have succeeded in attracting global attention toward its suitability to replace conventional materials. Hybrid fibers have recently become immensely popular with polymer composite reinforcements for various automotive parts. Hybrid composites are developed by blending natural, synthetic, or a combination of natural or synthetic fibers in a single matrix. Hybridization allows enhancements in physical, mechanical, and thermal properties of the composites. Hybrid composites assist in achieving an optimum combination of properties than individual fiber composites. In this paper, a comprehensive review of the properties of composite reinforcement natural fibers for the application of automobile components is presented. Recent articles on emerging fiber types are reviewed and fabrication techniques required for hybrid polymer composites are discussed. A prospective study is also presented and discussed of future trends in natural fiber applications as well as needed innovations for extending their applications.

This article presents a thorough review of biofiber-based hybrid composites along with the discussion on its mechanical and tribological performance in the polymeric matrix. Emphasis is centered on plant fibers as animal fibers are not frequently used and mineral fibers possess serious health issues. All five types of plant fibers and their hybrids are reviewed. Hybridization of plant fibers synergetically combines individual benefits while eliminating the limitations of single fiber use. Study regarding fiber origin, processability and extraction techniques, composition, chemical surface treatments, and applications are presented. Finally, the results obtained are summarized and future developments are discussed. The review concludes that biofiber hybrid composites possess great potential in several applications provided that satisfies design constraints and polymeric matrix compatibility issues.

As an additive manufacturing (AM) technology, fused deposition modeling (FDM) is widely used to fabricate highly complex components. Polymer components fabricated by FDM technique have weak mechanical properties. To enhance the mechanical properties, 3D printing of polymer composites is done by reinforcing particles, nanomaterials, short and continuous fibers into thermoplastic polymers. The thermal, flame retardant, and impact properties of a continuous kevlar fiber-reinforced onyx 3D-printed composite are investigated in this study. Additionally, the effect of fiber arrangement and orientation (0 , 90 , 0 /90 , and +45 /À45 ) on the impact strength of 3D-printed composites have been investigated. The impact strength of the 3D-printed composite specimens was determined using izod impact testing. It was found that specimens with fiber arrangement having fiber and matrix layer configuration as 21O| 20K|20O|20K|21O have a higher impact strength and specimens with fiber arrangement as 31O|40K|31O have lower impact strength. Furthermore, specimen 3D printed with a unidirectional 0 fiber angle had the highest impact strength, while specimen 3D printed with a unidirectional 90 fiber angle had the lowest impact strength. Furthermore, flammability tests and thermogravimetric analysis were performed to investigate the flame retardant and thermal properties of 3D-printed composites. Morphological study of onyx and kevlar fiber filament was also done using scanning electron microscope (SEM).

Electrochemical machining (ECM) is a preferred advanced machining process for machining Monel 400 alloys. During the machining, the toxic nickel hydroxides in the sludge are formed. Therefore, it becomes necessary to determine the optimum ECM process parameters that minimize the nickel presence (NP) emission in the sludge while maximizing the material removal rate (MRR). In this investigation, the predominant ECM process parameters, such as the applied voltage, flow rate, and electrolyte concentration, were controlled to study their effect on the performance measures (i.e., MRR and NP). A meta-heuristic algorithm, the grey wolf optimizer (GWO), was used for the multi-objective optimization of the process parameters for ECM, and its results were compared with the moth-flame optimization (MFO) and particle swarm optimization (PSO) algorithms. It was observed from the surface, main, and interaction plots of this experimentation that all the process variables influenced the objectives significantly. The TOPSIS algorithm was employed to convert multiple objectives into a single objective used in meta-heuristic algorithms. In the convergence plot for the MRR model, the PSO algorithm converged very quickly in 10 iterations, while GWO and MFO took 14 and 64 iterations, respectively. In the case of the NP model, the PSO tool took only 6 iterations to converge, whereas MFO and GWO took 48 and 88 iterations, respectively. However, both MFO and GWO obtained the same solutions of EC = 132.014 g/L, V = 2406 V, and FR = 2.8455 L/min with the best conflicting performances (i.e., MRR = 0.242 g/min and NP = 57.7202 PPM). Hence, it is confirmed that these metaheuristic algorithms of MFO and GWO are more suitable for finding the optimum process parameters for machining Monel 400 alloys with ECM. This work explores a greater scope for the ECM process with better machining performance.

Non-exhaust brake dust and pollution arising from metal, semi-metal, and ceramic brake pads have made recent research consider their replacement by potential natural fibers such as hemp, flax, sisal, etc. These natural fibers are lightweight, biodegradable, and cheap. This paper discusses the wear and friction analysis of hemp fiber reinforced polymer brake pad material. Three test specimens viz. HF4P20, HF5P20, and HF6P20 were prepared per ASTM G99 standards for the pin-on disc tribo-test. The test trials and validation were done using the Taguchi design of experiments and ANOVA. The optimum result showed a consistent coefficient of friction and lowered specific wear rate for HF6P20 brake pad material. Worn surface morphology was done using scanning electron microscopy.