Dynamic Mechanical Characterization of Woven Natural Fiber Polymer Composite

Abstract

Natural fiber composites with improved mechanical properties can be successfully used to replace the environmentally hazardous synthetic fiber composites in low and medium structural load applications. Detailed investigation on possibilities of improving mechanical characteristics of woven natural fiber fabric polymer composite is very important. Main objective of the present work is to investigate effect of various important parameters such as nature of weaving architecture of a woven fabric, intra-ply hybridization of two different natural fibers in a fabric, intra-ply hybridization of synthetic and natural fibers in a fabric, chemical modification of natural fabric, nanoclay as secondary reinforcement and stacking sequence of woven fabrics with different weaving architecture on mechanical, dynamic mechanical and free vibration characteristics of the composite. Jute woven fabrics with five different types of weaving architecture namely plain, basket, stain, twill and huckaback are considered to analyze the effect of weaving pattern of woven fabric reinforcement on mechanical, dynamic mechanical and free vibration characteristics of a polymer composite. Results revealed that weaving pattern influences the mechanical behaviour of the composite and fabric with basket type weaving pattern enhances the properties of composite material. Due to less interlace and lower crimp in the warp and weft directions of the basket type woven fabric its composite carries more load compared to the composite with other weaving patterns. Further effect of intra-ply hybridization of two different fibers in a woven fabric on mechanical behaviour of the composite has been analyzed. For this purpose, fabrics are prepared ivby orienting banana and jute yarn in the warp and weft direction of basket type woven fabric in different combinations. Results reveal that orienting relatively stronger jute fiber yarns in the warp direction enhances the properties of composite material. Further synthetic-natural fiber intra-ply hybrid woven fabrics are prepared by orienting synthetic glass fiber and natural fiber such as banana and jute in the warp and weft direction in different combinations to analyze the effect on the mechanical behaviour. Results reveal that synthetic-natural fiber intra-ply hybridization can be effectively used in structural members subjected to impact loading compared to the structural members subjected tensile or bending loads. In order to investigate the effect of pre-surface treatment of woven fabric on mechanical behaviour of the composite basket type woven jute-banana intra-ply fabric is treated with four different chemical solutions such as alkali, potassium permanganate, benzoyl chloride and silane. Results reveal that benzoyl chloride surface treatment enhances the properties of composite material to the largest extent when compared to all other cases. It is also found that addition of nanoclay as secondary reinforcement enhances dynamic mechanical behaviour of the basket type woven jute-banana intra-ply fabric composite for the 2 weight percentage of nanoclay. From the studies on comparison of woven fabric made of conventional simply twisted yarns and braided yarns it is found that braided yarn fabric reinforcement results in significantly higher dynamic mechanical properties of the composite due to the braided nature of yarns. However it is also observed that intra-ply hybridization of jute and banana yarns in braided fabric is not improving the dynamic mechanical behaviour. These results are compared with knitted fabric composites also which reveals that knitted fabric composites have better damping capability but very poor mechanical properties due to the higher gap naturally available between the yarns in the knitted fabric. Mechanical properties of the composite increases with number of layers of the fabric due to increase in the fiber loading and four layered basket type woven fabric composvite has better dynamic mechanical behaviour. From the studies on sequence of layer of fabric with different weaving pattern, it is found that composites with relatively strong fabric as skin and relatively weak fabric as core have better dynamic mechanical properties due to the sandwich effect. Buckling and free vibration characteristics of woven natural fiber laminated composite beam under the axial compression load are analyzed experimentally. Jute-plain, jute-basket and jute-herringbone fabrics are considered for the analysis on effect of number of layers and nature of weaving pattern on the buckling strength and free vibration behaviour of the beam. It is found that the buckling strength is influenced by number of layers of the fabric and nature of weaving architecture of the fabric. Natural frequency of the composite beam reduces with increase in the axial compression load while modal damping increases with axial compression load in the pre-buckled region. However this trend in natural frequency and modal damping with increase in axial compression load changes in the post-buckled region which is clearly observed for the fundamental vibration mode.