Shape memory alloys (SMAs) possess inherent superior properties that make their applications in active disassembly an emerging and interesting field of research. This is because extremely large forces can be generated repeatedly using a small compact-sized element, such as an SMA actuator. To ensure the ability of the SMA actuator to generate a repeated large force or withstand repeated load, several factors should be considered. These include factors that affect the value of the generated recovery forces, such as the amount of strain used, activation temperature, activation time, and cross-sectional area of the SMA element. In general, the compressive strain can be considered as the most influential factor that affects the value of the generated recovery force. The present research investigates the possible use of the SMA actuator in large-force active disassembly applications. To the best of the authors' knowledge, all the studies conducted in this field are concerned with implementing active disassembly in applications requiring small disassembly forces. The present research was conducted in three phases. First, the behaviour of the SMA element upon exposure to different repetitive compressive strains was studied, and the generated recovery force and strain hardening induced in the material were considered to ensure the continuous generation of large recovery forces with the least amount of residual strain induced in the material. Second, the optimum value of the compressive strain required to generate the maximum force with the least amount of residual strain induced in the material was estimated. Third, a practical case study was presented to validate the possible implementation of SMA actuators in large force active disassembly applications. The study successfully estimated the optimum compressive strain value that generated the required recovery force to disassemble the conducted case study using active disassembly technique.
Active disassembly is an emerging field in the research of design for disassembly, that enables a cost effective and nondestructive separation of product components. It enables the self-disassembly of products without any direct contact between the product and the operator through using active joints and fasteners, that were inserted in the product throughout its design and manufacturing phases. Active disassembly is based on using smart materials such as shape memory alloy actuators to generate the necessary disassembly forces to complete the disassembly process. Most of the exerted effort in this field was focused on products requiring small disassembly forces either in the electronic or automotive sectors. All these active disassembly applications were based on using shape memory alloy snap fits, clips or wires that are characterized by their ability to generate small forces with large displacements. As, up to the authors knowledge none of the exerted efforts were concerned with applying active disassembly in products requiring large disassembly forces or have large structures. Consequently, the presented research aimed to examine the probability of applying active disassembly with products requiring large disassembly forces, having tapered surfaces and large mechanical structure. Thus, two case studies were presented to validate the probability of using active disassembly with large force applications. In addition, the presented case studies investigated the capability of using shape memory alloy actuators having either a concentric or eccentric assembly with the product structure.
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