The laser shock peening (LSP) process using a Q-switched pulsed laser beam for surface modification has been reviewed. The development of the LSP technique and its numerous advantages over the conventional shot peening (SP) such as better surface finish, higher depths of residual stress and uniform distribution of intensity were discussed. Similar comparison with ultrasonic impact peening (UIP)/ultrasonic shot peening (USP) was incorporated, when possible. The generation of shock waves, processing parameters, and characterization of LSP treated specimens were described. Special attention was given to the influence of LSP process parameters on residual stress profiles, material properties and structures. Based on the studies so far, more fundamental understanding is still needed when selecting optimized LSP processing parameters and substrate conditions. A summary of the parametric studies of LSP on different materials has been presented. Furthermore, enhancements in the surface micro and nanohardness, elastic modulus, tensile yield strength and refinement of microstructure which translates to increased fatigue life, fretting fatigue life, stress corrosion cracking (SCC) and corrosion resistance were addressed. However, research gaps related to the inconsistencies in the literature were identified. Current status, developments and challenges of the LSP technique were discussed.

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In this study, natural fiber epoxy composites were prepared using palmyra sprout fiber and red matta rice husk ash(RHA) biosilica. This paper mainly aims to investigate the mechanical, wear resistance, thermal stability as well as water absorption behaviour of naturally obtained novel fiber with red matta biosilica in epoxy based composites. The fiber’s surface was treated by base, while the biosilica particles were treated by amino-silane. The composites were fabricated by hand lay-up process and characterized based on ASTM standards. According to the results the highest tensile and flexural strength observed for the composite is about 147 MPa and 211 MPa for 3 vol. % of biosilica with 30 vol. % of fiber. Izod impact toughness reveals the maximum impact resistance up to 5.82 J. Increment in reinforcement vol. % shows increased hardness. Wear properties represents the composite designations EPB3 retains good wear resistances for 3 vol. % of biosilica. Similarly, thermal stability improved by the addition of biosilica of 3 vol. %. Water absorption results reveal that, the addition of reinforcements marginally affects the contact angle. Such mechanically improved, wear resistible and thermally stable natural composites could be used in automotives, industrial and defense applications as well as in household appliances.

The water droplet erosion (WDE) performance of laser shock peened (LSP) Ti-6Al-4V was investigated. LSP condition using two or three peening impacts per unit area induced compressive residual stresses. However, LSP treatment showed a mild increase in microhardness and no observable changes in the microstructure. The effect of LSP and its associated attributes on the WDE performance was studied according to the American Society for Testing and Materials Standard (ASTM G73). Influence of the impact speed between 150 and 350 m/s on the WDE performance was explored. Two sample geometries, T-shaped flat and airfoil, were used for the WDE tests. For the flat samples, LSP showed little or no beneficial effect in enhancing the WDE performances at all tested speeds. The peened and unpeened flat samples showed similar erosion initiation and maximum erosion rate (ER max). The LSP airfoil samples showed mild improvement in the WDE performance at 300 m/s during the advanced erosion stage compared to the as-machined (As-M) condition. However, at 350 m/s, no improved WDE performance was observed for the LSP airfoil condition at all stages of the erosion. It was concluded that compressive residual stresses alone are not enough to mitigate WDE. Hence, the notion that the fatigue mechanism is dominating in WDE damage is unlikely.