The peel test is a popular test method for measuring the peeling energy between flexible laminates. However, when plastic deformation occurs in the peel arm(s) the determination of the true adhesive fracture energy, G c , from the measured peel load is far from straightforward. Two different methods of approaching this problem have been reported in recently published papers, namely: (a) a simple linear-elastic stiffness approach, and (b) a critical, limiting maximum stress, σ max , approach. In the present article, these approaches will be explored and contrasted. Our aims include trying to identify the physical meaning, if any, of the parameter σ max and deciding which is the better approach for defining fracture when suitable definitive experiments are undertaken. Cohesive zone models Fracture mechanics Laminates Peel tests Plastic deformation
Solar selective absorber materials have been the focus of much research and development over the last 60 years as the functionality of solar thermal collection devices relies considerably on these coatings and their operation and deposition specifications are complex. This article reviews the solar selective absorber coatings which have been patented and covers a wide variety of materials and techniques including metal/ceramic composites (cermets), semiconductors, paint coatings, electroplating and vapour deposition processes. The cermet class of materials has emerged as the most utilised with the recent selective coatings based on nanoscale particulates. As the operating temperatures in solar devices increases so demands on reliability, thermal stability and durability continue to grow. Furthermore, there is pressure to reduce costs and the advances in nanoscale technologies and thin film deposition seem to offer the greatest potential for new selective coatings.
This paper presents finite element simulations of axial crash behaviour and energy absorption characteristics of thin-walled tubes with variable cross-sections and different materials to investigate the design of an optimised energy absorbing street pole. With the conclusion of the desired variables for the design of an energy absorbing thin-walled tube, the tubes are placed 90 degrees to that of the base of the model street pole. Simulation of frontal impact of a vehicle and street pole are analysed and compared to that of the energy absorbing street pole concept. Studies are carried out by numerical simulation via the explicit finite element code LS-DYNA. Results compare the absorbed energy and the deflection of each variable, and recommend best design for the tube structure which improved vehicle crashworthiness.
The blast and impact behaviour of structures are dependent on many factors, such as the type of loading and the behaviour of constituent materials at high strain rates. Blast can be defined as a large scale, rapid and sudden release of energy. For example, in physical explosions, energy may be released from the catastrophic failure of a pressure vessel, or from the chemical interaction of two or more liquids. Structural impact deals with the behaviour of structures and components subjected to large dynamic loads involving contact, which could be the outcome, for example, of a high velocity projectile or a high speed crash. The prediction of the effect of a blast load on a structure is an important step in designing advanced blast protective structures. Blast energy is released within a very short period of time, which can be less than 1ms, making it challenging for protection material to absorb a majority of the blast energy. For blast impact analysis, the complexity of the problem can be attributed to the high speed wave front propagation, the flow of materials under these conditions, and the large structural deformation. Researchers are actively pursuing all these issues related to blast and impact analysis and means of developing protection against blast and impact forces. Since an explosion is a hypervelocity impact, numerical simulation is an attractive method to
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