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Crash-box is an essential passive safety device in an automobile that absorbs the kinetic energy of an external impact during an accident, thereby improving passenger safety. Selecting a suitable material for fabricating a crash-box to maximize its crashworthiness performance is a critical issue and is a multi-attribute decision-making (MADM) problem. This study focuses on choosing an appropriate aluminium alloy for a crash-box out of 16 different frequently used wrought aluminium alloys considered as alternatives based on eight crashworthiness performance indicators used as attributes by taking the opinions of three decision-makers (DMs). The effect of varying the material of thin-walled circular crash-boxes with identical geometry is first examined by simulating their axial quasi-static collapse using ABAQUS/Explicit. Various crashworthiness performance indicators obtained from these simulations are used for the decision-making process. While taking a decision, the opinions of several DMs from varied backgrounds are generally considered. A systematic approach is proposed to determine the importance of each DM involved in group decision-making situations by considering their credentials, such as educational qualification, work experience, etc., using a ranking based MADM technique known as 'R-Method'. Opinions of multiple DMs are then combined to come up with a single final decision, called a consensus. The application of the R-Method is discussed in detail to derive consensus in a group decision-making environment. The aluminium alloy AA 7075 T6 is the best, while AA 3003 H12 is the least preferred material for manufacturing a crash-box of the considered geometry as per the proposed method. [ABSTRACT FROM AUTHOR]

Fibre waviness is frequently observed manufacturing defect which leads to a reduction of mechanical performance of the fibre reinforced polymer (FRP) composites. The current study investigates the effect of out-of-plane fibre waviness as a manufacturing defect on the flexural performance of carbon fibre reinforced polymer (CFRP) composites. Specimens with the non-uniform hump and non-uniform indentation waviness were fabricated using the transverse strip method. Experimental tests were conducted in the three-point flexural configuration using specimens with and without fibre waviness to investigate the flexural behaviour. Each of the above type of non-uniform waviness was investigated to evaluate the effect of the extent of the wave for three severity levels. Load-displacement response and digital optical microscopy were used to identify typical failure modes and damage initiation and progression in flexural specimens under test. Fibre kinking leading to delamination and fibre fracture were observed as prominent failure modes in hump as well as indentation waviness. Experimental investigation revels 12–30% reduction in flexural strength with increase in wave severity for the range considered in this study. [ABSTRACT FROM AUTHOR]

In the current study an analytical model to determine fundamental frequency of perforated plate with circular perforation is formulated. Circular holes are replaced by equivalent square hole and non homogeneity in Young's modulus and density due to equivalent square perforation is expressed by using unit step functions. Analytical formulation is based on Rayleigh-Ritz method. In present study boundary condition considered is clamped at all edges. The deflected middle surface of the plate is approximated by a function which satisfies the boundary conditions. Proposed approach is validated by comparing numerical analysis results with Finite Element Method (FEM) modal analysis results. [ABSTRACT FROM AUTHOR]

In the current study an analytical model to determine fundamental frequency of perforated plate is formulated. Non homogeneity in Young's modulus and density due to perforation is expressed by using unit step function in Rayleigh's Quotient. In the present analysis the boundary condition considered is clamped at all edges. Perforated plate is considered as plate with uniformly distributed mass and holes are considered as non-homogeneous patches. The deflected middle surface of the plate is approximated by a function which satisfies the boundary conditions. The proposed approach is validated by comparing results with finite element method modal analysis. [ABSTRACT FROM AUTHOR]