Papers by Keyword: Energy Absorption

Abstract: This article focuses on the Finite Element (FE) analysis of the ballistic performance of the polymer composites consisting of natural rubber (NR), glass-epoxy (GE) and glass-rubber-epoxy (GRE) sandwich of different thicknesses (3, 6 and 9 mm) under the impact of the conical nose projectile for a velocity variation of (180, 220 and 260 m / s). FE modeling was carried out in direction to forecast the energy absorption, ballistic limit velocity and failure damage mode of the target materail. The significant influence of thickness, interlayer and sandwiching effect was studied: the lowest ballistic limit was obtained for 3 mm thick GE. Energy absorption capacity of GRE sandwich was highest among the natural rubber and GE. In future, the work can be extended for the experimental validation purpose, so that these polymer composite materials could be utilized to defence sector for bullet-proofing.

Abstract: Filling the thin-walled tubes with a foam core is a typical method to enhance the energy absorption performance and stabilize their crushing responses under impact loading. Recently, auxetic foam material with negative Poisson’s ratio has gained remarkable popularity as an effective candidate to enhance the energy absorption capability of structures. In this paper, polyurethane auxetic foam is suggested as a foam core with the negative Poisson’s ratio of-0.31. Numerical simulation was performed to quantify the crush characteristics of auxetic foam-filled square aluminum tubes for variations in initial width of tube under quasi-static axial loading using the nonlinear finite element (FE) code LS-Dyna. Based on the numerical results, the influence of tube width was quantified in terms of energy absorption (EA), specific energy absorption (SEA), initial peak force (P_max) and crush force efficiency (CFE). It is found that the progressive collapse and deformation modes of auxetic foam-filled tube (AFFT) is pronouncedly affected by varying the tube width. Furthermore, the SEA of AFFT is remarkably sensitive to the tube width variations, yet show low sensitivity to the EA of AFFT. The present study provides new design information on the crush response and energy absorption performance of auxetic foam-filled square tube with varying tube width.

Abstract: A novel rectangular tube with circumferential anti-symmetric local self-surface nanocrystallization (CALSSN) layouts is designed for energy absorption. The effects of stripe numbers on the energy absorption performance is investigated. Results reveal that the 8-stripe CALSSN model exhibits the best buckling modes, which is more regular and stable than the untreated ones. It is also found that the stripe numbers highly depend on the structural sizes, unsuitable stripes number may reduce the buckling stability and periodicity. Besides, five CALSSN models with stripe numbers from 6 to 10 are selected to find the optimized size which has the highest specific energy absorption (SEA). A new 7-stripe CALSSN model which has optimal buckling modes and energy absorption performance is achieved.

Abstract: Energy absorbers in the form of hollow profiles are used in automobiles to mitigate energy transfer to passenger cabin during a crash event. A similar event is carried out in this research work to study the progressive compression behaviour of aluminium tubes with triggering mechanisms in the form of cut-outs. Various hollow profiles are used as energy absorbing elements. In this work, square aluminium tubes of 50x50 mm side and 150 mm length with wall thickness of 1.5 mm with cut-outs are tested under axial compression loading and the results are compared with tubes without any cutouts. Crash parameters like minimum compressive force required to fail the aluminium tube, energy absorption, peak load and progressive collapse behaviour are studied. Results reveal that tubes with slots exhibited better crash parameters than plain tubes and tubes with circular cutouts.

Abstract: Lightweight and strong composite material beams are increasingly sought to quickly, easily, and cost-effectively transport and setup a variety of constructions such as bridges, cabins/ stores/shelters, vehicles etc. For structural beams produced as conventional laminated composite materials, their weak areas tend to occur at intersections such as web-flange junctions due to absence of fibres bridging the interconnections. This drawback can however be overcome with development of profiled 3D textile reinforcements having combination architectures and constituent web-flange parts inherently mutually interconnected through fibre interlacement. In addition to general strength improvement, beams containing such novel reinforcement architectures also show increased energy absorption capability due to the mutual web-flange integration at the junctions. An ‘I’ and a ‘flanged-triangle’ cross-section beams were produced by a novel non-conventional weaving method, using carbon fibres as reinforcement, and their energy absorption capabilities were tested. These beams respectively absorbed over 50% and 300% more energy per weight in bending, compared to metal counterparts. This paper presents some relevant aspects of these innovative beams.

Abstract: This study investigated the effects of the reinforcement positions and the number of shape memory alloys (SMAs) on the structural characteristics of highly intelligent hybrid fiber reinforced concrete (hereinafter, HIHFR) beams. First, tests were conducted under monotonic loading conditions. To examine such structural characteristics, the load-deflection curve relationship and crack patterns, temperature and energy absorption, temperature and displacement ductility, displacement ductility and energy absorption, and the relationship between the displacement ductility and resilience were compared and analyzed. The reinforced concrete beam (RCB) exhibited somewhat excellent values in terms of displacement ductility, but showed the lowest values in terms of strength, resilience, and energy absorption capacity. HIHFR1 exhibited the most excellent results among the test samples in terms of resilience and energy absorption capacity. Therefore, SMAs were partially substituted for the compressive, tension, and shear reinforcement of the existing RCBs. As a result, the substitution for the compressive and tension reinforcement exhibited the best results, confirming the possibility of using SMAs as a substitute for steel reinforcement.

Abstract: Carbon fibre composite tubes have high strength to weight ratios and outstanding performance under axial crushing. In this paper, square CFRP tubes and aluminium sheet-wrapped CFRP tubes were impacted by a drop mass to investigate the effect of loading velocity on the energy absorption of CFRP/aluminium tubes. A comparison of the quasi-static and dynamic crushing behaviours of tubes was made in terms of deformation mode, peak crushing force, mean crushing force, energy absorption and specific energy absorption. The influence of the number of aluminium layers that wrapped square CFRP tubes on the crushing performance of tubes under axial impact was also examined. Experimental results manifested similar deformation modes of tubes in both quasi-static and dynamic tests. The dynamic peak crushing force was higher than the quasi-static counterpart, while mean crushing force, energy absorption and specific energy absorption were lower in dynamic tests than those in quasi-static tests. The mean crushing force and energy absorption decreased with the crushing velocity and increased with the number of aluminium layers. The impact stroke (when the force starts to drop) decreased with the number of aluminium layers.

Abstract: Ballistic qualities of the material are important for the military defence barrier application for protection of military persons, their vehicles and equipment. In the present investigation ballistic performance of Kevlar29 fibre reinforced polyester composite (KPC) is analysed. A definite parametric study, taking into account various shape of projectiles (Flat-F, Spherical-S and Conical-C) impact on the composite target of different thicknesses (12, 16 and 20 mm). Impact velocity of the projectile considered for analysis 100-400 m / s. Ballistic parameters such as residual velocity, deformation and penetration behaviour are predicted. Conical projectile has more effect on the composite target compared to other projectiles. Composite thickness influenced the energy absorption. The thickness increase from 12 mm to 20 mm which leads to increase in energy absorption by almost 20%.

Abstract: Recent research findings on the mechanical behavior of metal foams are summarized in this work. Thanks to their properties in compressive tests, a wide range of foamed materials has been considered for energy-absorption applications such as Al, Fe, Ti, Ni and its alloys. The main parameters affecting energy absorption are focused and presented: cell size, relative density, strain rate, hybrid foam (Al-Cu, Al-Ni), base metal, and composites structures (Al-foam filled tube and sandwich). Metal foam response, impact resistance and failure are discussed in many configurations and test conditions. The results of finite elements modelling and its validation by means of mechanical tests are discussed too.

Abstract: The behaviour of aluminium matrix syntactic foams (AMSFs) with homogeneous and graded structures have been studied under quasi-static compression and impact. Particle size of ceramic microspheres and impact velocity had significant effects on the static and impact responses. Smaller microspheres led to higher strength but lower toughness. The compressive yield stress, plateau stress and specific energy absorption of the graded AMSF specimens were approximately the averages of the constituent layers, following the rule of mixture, although the order of the layers had some influence on the compressive behaviour. The syntactic foams were brittle under impact, no matter whether they were brittle or ductile in quasi-static compression. They had higher peak stresses and absorbed more energy in impact than in quasi-static compression. The location of the most brittle layer of the small ceramic microspheres had a significant effect on the impact failure pattern and sequence of the three-layer graded AMSFs.