Performance Evaluation of Flexible Jute-Natural Rubber Composites for Impact Behaviour

Abstract

A composite material is made from two or more constituent materials with significantly different physical or chemical properties which are combined to produce a material with characteristics different from the individual components. ‗Flexible composites‘ is a term coined to identify the composites making use of elastomeric polymers as matrix. These flexible composites exhibit usable range of deformations which are much larger than conventional stiff composites. The ability of flexible composites to undergo larger deformation and still provide high load carrying ability makes them suitable for many engineering applications. Flexible composites are better energy absorbers compared to conventional stiff composites subjected to impact loading. The objectives and scope of the present study includes proposing, developing and characterizing the flexible ‗green‘ composite for impact applications. An extensive literature review was carried out to explore the potential constituent materials for impact applications and accordingly the present study is carried out to explore the possible use of jute and rubber for impact applications. Initially, the feasibility of using natural rubber (NR) as a constituent material in composite is studied using commercially available finite element (FE) package. Further different stacking sequences of the flexible green sandwich composite are optimized and the three stacking sequences are selected for experimental study. These three optimized stacking sequences of the proposed flexible green sandwich composite are prepared using compression moulding technique and are characterized for their physical and mechanical properties. Further, the proposed flexible green composites are studied for their abrasive behaviour under two body environments and erosive behaviour under slurry environment. Finally, the impact behaviour of the proposed flexible composites is studied under low velocity impact (LVI) and lower ballistic impact. The mechanical characterization of the proposed flexible composites revealed that the composite with jute/rubber/jute (JRJ) exhibits better tensile and tear strength compared to jute/rubber/rubber/jute (JRRJ) and jute/rubber/jute/rubber/jute (JRJRJ) with JRJ exhibiting 57.7% and 64.47% higher tensile strength compared to JRRJ and JRJRJ respectively. Also, the tear strength of JRJ is found to be 0.4% and 2.38%higher than JRRJ and JRJRJ respectively. The interlaminar shear strength (ILSS) studies shows that short beam strength of JRJRJ is better compared to JRRJ and JRJ with JRJRJ exhibiting nearly 2.1 times and 2.75 times better ILSS compared to JRRJ and JRJ respectively. The proposed flexible green composites are further studied for their abrasive behaviour under two body environments and erosive behaviour under slurry environment, the outcome of which reveals that JRJ provides better results compared to its counterpart JRRJ and JRJRJ. Various factors affecting the wear behaviour of the flexible composites are also studied from which it is clear that abrading distance and sand concentration affects the weight loss of the proposed flexible green composite in case of two body wear and slurry erosion respectively. Flexible ‗green‘ composites of different stacking sequences are further subjected to impact tests at low velocity and lower ballistic velocity at different impact energies. The results of low velocity impact reveals that flexible green composite with JRJ stacking sequence exhibit better energy absorption and the stacking sequences JRJRJ exhibit better resistance to damage with no appreciable variation in specific energy absorption of the composites. The lower ballistic impact study reveals that the flexible composites are better energy absorbers with JRJRJ exhibiting better lower ballistic response compared to JRJ and JRRJ. The ballistic limit of JRJRJ is enhanced by 39.7% and 6% compared to JRJ and JRRJ respectively. The energy absorption at ballistic limit of JRJRJ is more compared to JRJ and JRRJ by 97.7% and 12.7% respectively. The energy absorption of JRRJ is enhanced by 75.5% compared to JRJ. The specific energy absorption (SEA) of JRJRJ is enhanced by 52% and 2.7% compared to JRJ and JRRJ respectively. The proposed flexible green composite can be a potential material for sacrificial structures in order to protect the primary structural components.