The present work deals with the characterization of interwoven roselle/sisal fiber fabric reinforced epoxy composites. All the composites are manufactured using the hand layup technique, and the physical (density), mechanical (tensile, flexural, and impact) and dynamic mechanical characteristics are determined as per ASTM standards. The findings reveal that roselle fabric composite has superior mechanical properties than interwoven roselle/sisal fabric composites. The tensile and impact strengths of the sisal fabric composite are lower than those of the roselle fabric composite. However, the roselle fabric composite and sisal fabric composite have similar flexural properties. The sisal fabric composite yields the highest peak value of the loss factor. The loss factor peak height for the roselle/sisal fabric composites increases with increased sisal fiber content. Morphological analysis revealed proof of yarn pullout and matrix damage near the yarn, indicating inadequate stress transfer between the fabric and epoxy. The property map is presented in comparison with available literature.

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The influence of weaving architecture on mechanical and dynamic mechanical properties of woven roselle fiber epoxy composite has been investigated. Plain, twill, satin, and basket type weaving patterns are considered for this study.Hand lay-up process is used to produce the woven composites. Mechanical tests (tensile, flexural, and impact test) and dynamic mechanical analysis are conducted according to ASTM standards for material characterization. Results revealed that basket type architecture of woven roselle fiber epoxy composite has better tensile, flexural, and impact strengths. Woven composites have improved storage modulus in comparison with neat epoxy. Woven composites have 3% to 15% lower glass transition temperature than that of neat epoxy.Scanning electron microscopy (SEM) analysis is carried out to correlate the experimental findings. SEM images showed evidence of fiber pullout and cracks near fiber bundle, which indicates non-uniform transfer of stress from fiber to the matrix.

The effect of roselle fabric weave pattern on water absorption and thickness swelling behaviour of woven roselle fibre composites has been investigated. Roselle fabrics with various weaving design such as plain, twill, satin and basket are used in this study. All composites are produced using hand layup process. The water absorption and thickness swelling behaviour of all composites are studied as per ASTM standards. The test samples were immersed in distilled water at room temperature and change in weight and thickness of the test samples recorded at every 24 hour time interval. For all composite samples, saturation in water absorption and thickness swelling was observed after 264 hours of water immersion. Result revealed that the plain-woven composite yields higher resistance to water absorption and thickness swelling than other types of composites.

Exposure of human body to vehicular vibrations in transit may lead to the human discomfort. Ride comfort is one of the major issues in design of automobiles. Magneto rheological (MR) dampers are emerging as most feasible solution for various applications in controlling vibrations. An MR damper is a semi-active device, which will offer the advantages of both active and passive suspension. In this study, the MR damper based semi-active suspension system for a car is analysed for ride comfort of 7 degrees of freedom model human body lumped mass, considering head, upper torso, lower torso and pelvis, seated over a seat of a quarter car model and is compared with that of similar system using passive damper. A MR damper is fabricated and is filled with MR fluid made of Carbonyl iron powder and Silicone oil added with additive. Modified Bouc-Wen Model developed by Spencer is used to model the behaviour of MR damper. All the parameters of this model are identified using data acquired from experiments conducted to characterise MR damper. Further, using the Spencer model of MR damper, the human body seated over quarter car is simulated by implementing a semi-active suspension system for analysing the resulting displacement and acceleration of the human body. The ride comfort performance of vehicle model with passive suspension system is compared with corresponding semi-active suspension system. The simulation and analysis are carried out using MATLAB/SIMULINK.