Design for Disassembly With High-Stiffness Heat-Reversible Locator-Snap Systems

Abstract

Recent legislative and social pressures have driven manufacturers to consider effective part reuse and material recycling at the end of product life at the design stage. One of the key considerations is to design and use joints that can disengage with minimum labor, part damage, and material contamination. This paper presents a unified method to design a high-stiffness reversible locator-snap system that can disengage nondestructively with localized heat, and its application to external product enclosures of electrical appliances. The design problem is posed as an optimization problem to find the locations, numbers, and orientations of locators and snaps as well as the number, locations, and sizes of heating areas, which realize the release of snaps with minimum heating area and maximum stiffness while satisfying any motion and structural requirements. The screw theory is utilized to precalculate a set of feasible orientations of locators and snaps, which are examined during optimization. The optimization problem is solved using the multi-objective genetic algorithm coupled with the structural and thermal finite element analysis. The method is applied to a two-piece enclosure of a DVD player with a T-shaped mating line. The resulting Pareto-optimal solutions exhibit alternative designs with different trade-offs between the structural stiffness during snap engagement and the area of heating for snap disengagement. Some results require the heating of two areas at the same time, demonstrating the idea of a lock-and-key.

Review and future of active disassembly

“…This concept is quite simple, but the modelling of the system can be quite complicated because the constraints of the material must be taken into consideration to ensure the desired behaviour is reached. Luckily tools, such as FEA, have already been incorporated to show the validity of smarter designs with more control (Shalaby and Saitou 2008a, 2008b, 2009. Currently, these smart designs with more control are only focused on eliminating accidental triggering and increasing disassembly reliability, but they do not attack other deficiencies with ADSM most notably mechanical limitations with SMMs.…”

Analysis of Guidelines and Identification of Characteristics Influencing the Deconstruction Potential of Buildings

“…According to Crowther [9,15], there are four end-of-life scenarios (also recognizable as recycling strategies) to building materials and components or to the whole building:…”

“…Materials are seen as the basic parts of buildings. The materials could be connected to form sub-assembly: "component" [9]. Construction components can be connected to form higher-level assembly: system [16,17].…”

“…In recent years, progress has been made in the field of building deconstruction, both in terms of research development and in practical terms, with several buildings being deconstructed or designed for this purpose. Several works [9][10][11][12][13][14] have established guidelines for orienting designers towards incorporating characteristics that can influence both the extension of a building's lifecycle and the development of techniques for the reutilization of construction materials and for the building's future deconstruction.…”

“…Several lists of DfD guidelines are provided in research papers [9][10][11][12][13][14], resulting in a comprehensive set of principles that provide a basis for the modern DfD process. However, these lists do not point out the characteristics that are related to these guidelines and how they ought to be considered in a deconstruction viability analysis.…”