Leaf spring plays a significant role in the riding comfort of an automobile. Thermoplastic composite materials are replacing many metallic parts in an automobile system. The main objective of the present work is to identify the scope of thermoplastic composite material for leaf spring application. Emphasis is given to understand the effect of reinforced fibre length on the leaf spring performance. In all, 20 per cent discontinuous long and short glass fibre reinforced polypropylene (PP) materials were considered for the development. Prior to the development and evaluation of leaf springs, the influence of reinforced fibre length over leaf spring material behaviour has been investigated. With the increase in reinforced fibre length, crystallinity of the base matrix structure, thermal characteristics, and mechanical behaviour under static and dynamic loading conditions were found to be improved. Mono, discontinuous fibre reinforced thermoplastic leaf spring of varying width is designed and injection molded. A servo-hydraulic fatigue testing facility coupled with linear guide ways is utilized to evaluate the preliminary leaf spring performance parameters, namely load deflection, strain rate sensitivity, hysteresis, and damping behaviour. Preliminary test results on composite leaf spring confirmed that long glass fibre reinforced PP leaf spring is able to carry three times the load for a design deflection than short glass fibre reinforced PP leaf spring. This improved spring rate behaviour results in significant improvement of the energy-absorbing capability. The influence of strain rate over the load deflection behaviour of long fibre reinforced leaf spring is found to be less than that of short fibre reinforced leaf spring. However, the damping behaviour of short glass fibre reinforced leaf spring is found to be superior to that of long glass fibre reinforced leaf springs.

This study investigated the effect of adding fly ash on the mechanical and durability characteristics of coconut shell (CS) concrete. Two different mixes were developed, one with CS and the other with conventional aggregate and CS as coarse aggregate. Cement was replaced with Class F fly ash in terms of weight at 0, 10, 20, and 30% in both mixes. Test result showed that the CS concrete with 10% fly ash replacement level exhibited the highest compressive and tensile strength. The addition of fly ash decreased the porosity of CS concrete due to its fineness and increased hydration products in the matrix at later ages. Additionally, it also improved the weak aggregate interfacial transition zone of CS lightweight concrete. Thus, the fly ash addition in CS concrete showed lower values of water absorption, permeable voids, sorptivity, and chloride permeability. Furthermore, the increasing content of fly ash addition improved the durability characteristics of CS concrete considerably.

The aim of this study is to investigate the effect of polypropylene fibre addition into eco-concrete made with fly ash, an industrial by product, as partial cement replacement material, and coconut shell, an agricultural waste,  as coarse aggregates, on the mechanical properties of the concrete. Two different mixes were developed, one with coconut shell only as coarse aggregates, and the other with the combination of both conventional aggregates and coconut shell as coarse aggregates. The cement content was replaced with class F fly ash at 10% by weight in the concrete mixes. The volume fractions of polypropylene fibres used in this study were 0.25%, 0.5%, 0.75% and 1.0%. The addition of polypropylene fibres slightly reduces the slump and density of coconut shell concrete. As the volume fraction of fibres increases, the compressive strength and modulus of elasticity of coconut shell concrete also increases by up to 0.5% of fibre volume fraction. The split tensile strength and flexural strength of coconut shell concrete were also enhanced with fibre addition. The addition of 0.75% and 1.0% volume fractions of polypropylene fibres slightly reduces compressive strength. Results of this study show that polypropylene fibres may be used in coconut shell concrete to improve the mechanical properties of the composite.

This study investigates the effect of steel fiber addition into eco‐concrete made with fly ash, an industrial by product, as partial cement replacement material, and coconut shell, an agricultural waste, as coarse aggregates, on the mechanical properties. Two different mixes were developed, one with coconut shell only as coarse aggregates, and the other with both conventional aggregates and coconut shell as coarse aggregates. The cement content was replaced with class F fly ash at 10% by weight. Steel fibers of 0.25, 0.5, 0.75, and 1.0% by volume of concrete were used. The properties investigated were slump, density, ultrasonic pulse velocity, compressive strength, split tensile strength, flexural strength, and modulus of elasticity (MOE). The findings indicated that the addition of steel fibers resulted in a reduced slump and slightly increased density in the fresh concrete mixes. Meanwhile, enhancements of up to 39% compressive strength and 17% MOE were also obtained. A substantial improvement in split tensile strength and flexural strength were also observed. Steel fiber addition also significantly reduced the brittleness of concrete containing coconut shell. The outcomes of the experiment revealed that steel fiber addition yielded a positive result on the mechanical properties of coconut shell concrete.

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