Disassembly Tree Research Articles

Spatial and in-product density characterization of in-use copper stocks in Japan for stock recyclability assessment

In-use metal stocks comprise various products, and their recyclability is determined by several factors. Hence, a comprehensive characterization of in-use stocks is required for stock recyclability assessment. We characterized in-use copper stocks in Japan by introducing two indicators to represent stock attributes relevant to recyclability: spatial density (SD) and in-product density (PD). SD is based on the spatial distribution of in-use stock, which is estimated by material flow analysis. PD is quantified based on the disassembly tree and level concepts and input-output analysis framework. Infrastructure-related products exhibited a relatively weak correlation with population and low SD, suggesting relatively large efforts required for collection. In contrast, information and communication electronics exhibited higher SD but lower PD, suggesting relatively large efforts required for preprocessing and recovery stages. Furthermore, integrated density characterization demonstrated a trade-off between three aspects related to recyclability: the amount of in-use copper stock, SD, and PD.

Accelerating Benders decomposition for closed-loop supply chain network design: Case of used durable products with different quality levels

Durable products are characterized by their modular structured design as well as their long life cycle. Each class of components involved in the multi-indenture structure of such products requires a different recovery process. Moreover, due to their long life cycle, the return flows are of various quality levels. In this article, we study a closed-loop supply chain in the context of durable products with generic modular structures. To this end, we propose a mixed-integer programming model based on a generic disassembly tree where the number of each sub-assembly depends on the quality status of the return stream. The model determines the location of various types of facilities in the reverse network while coordinating forward and reverse flows. We also consider the legislative target for the recovery of used products as a constraint in the problem formulation. We present a Benders decomposition-based solution algorithm together with several algorithmic enhancements for this problem. Computational results illustrate the superior performance of the solution method.

A Case-based Green Design Support System for Customization Product

Decisions taken in the early design phases can influence the outcome of a design exercise far more significantly than any optimization steps later on in the design process. Hence, in a green design approach an early recognition of favorable product solutions is great importance. However, during the early design phases, only functional requirements and product concepts are available for customization product. Therefore, how to propose a product scheme integrating environmental qualities in this stage is noteworthy. This paper proposes a green design method that supports designers making decision in the early design phases. The proposed methodology is composed of four steps. Firstly, demand analysis is utilized to transform the subjective and qualitative customer’s requirements into objective and quantitative constraints. And then, the case representation model and matching algorithm are designed to search the similar case according to the demand constraint conditions. Next, a kind of product information model called disassembly tree model is construct for analyzing the environmental attributes of these similar cases. Fourthly, the fuzzy analytic hierarchy process combined with fuzzy restriction analyzing technique is applied to evaluate the candidates integrating environmental aspects and choose the optimum product. The feasibility and applicability of the method are demonstrated through a green design support system for push-pull door. The method is flexible and can be applied to other customization products. As long as rebuild product the information model, evaluation factor set for a specific product and customer’s needs.

분해우선작업을 가지는 페트리 넷 기반의 분해순서계획모델

This paper presents a Petri Net (PN) based disassembly sequence planning model with precedence operations. All feasible disassembly sequences are generated by a disassembly tree and a disassembly sequence is determined using the disassembly precedence and disassembly value matrix, The precedence of disassembly operations is determined through a disassembly tree and the value of disassembly is induced by economic analysis in the end-of-life phase. To solve the disassembly sequence planning model with precedence operations, a heuristic algorithm based on PNs is developed. The developed algorithm generates and searches a partial reachability graph to arrive at an optimal or near-optimal disassembly sequence based on the firing sequence of transitions of the PN model. A refrigerator is shown as an example to demonstrate the effectiveness of proposed model.

Determining optimal disassembly and recovery strategies

We present a stochastic dynamic programming algorithm for determining the optimal disassembly and recovery strategy, given the disassembly tree, the process-dependent quality distributions of assemblies, and the quality-dependent recovery options and associated profits for assemblies. This algorithm generalizes the one proposed by Krikke et al. (International Journal of Production Research 1998; 36(1):111–39) in two ways. First, there can be multiple disassembly processes. Second, partial disassembly is allowed. Both generalizations are important for practise.

Disassembly sequence generation: A Petri net based heuristic approach

The generation of a set of optimal or near-optimal disassembly sequences is an important task associated with the study of disassembly planning. This task encapsulates actions at the required disassembly depth to reach maximum net revenue while satisfying economic constraints. The Petri net modelling, combined with heuristic search procedures developed in this study, offers an efficient procedure for disassembly sequence generation. The heuristic generates and searches a partial reachability graph to arrive at an optimal or near-optimal disassembly sequence based on the firing sequence of transitions of the Petri net model. The proposed methodology reduces the search space in two areas: (1) pruning the disassembly tree (DT) and, (2) selective tracking of the reachability graph. The efficacy of the proposed methodology is demonstrated by using two examples from the literature.

Optimal Disassembly Sequence Using Genetic Algorithms Considering Economic and Environmental Aspects

In this paper, a genetic algorithm (GA)-based approach for an optimal disassembly sequence considering economic and environmental aspects is presented. All feasible disassembly sequences are generated by a disassembly tree or an AND/OR graph. Using the disassembly precedence and the disassembly value matrix, a disassembly sequence is optimised. The precedence of disassembly is determined through a disassembly tree or an AND/OR graph and the value of disassembly is induced by considering both economic and environmental aspects in the disassembly, recycling, and disposal phases. Economic and environmental factors can be compared by the same measure through converting environmental factors into economic cost. To solve the disassembly sequence problem, a heuristic algorithm based on GAs is developed. The proposed GA can search for and dynamically explore the disassembly node through the highest disassembly value, keeping their precedence in order to identify an optimal disassembly sequence. It can also help to explore the search space, and an optimal solution can be obtained by applying the optimisation criteria. A refrigerator is used as an example to illustrate the procedure.

Disassembly sequence plan generation using a branch-and-bound algorithm

This paper presents an approach to generate disassembly sequence plans (DSP) automatically for product recycling and remanufacturing. An algorithm is defined first that generates a geometrically based disassembly precedence matrix (DPM) from a CAD drawing of the product. The DPM is then used to generate a hierarchical disassembly tree (HDT) that represents the feasible DSP. Generation of the HDT, i.e. generation of all feasible DSP, is NP-complete. Thus, to keep the size of the HDT manageable, the branching and bounding processes are controlled using two user-defined variables. The first, w , controls the enumeration of the HDT, while the second, v, controls the bounding procedure in the HDT along with an evaluation function. The evaluation function incorporates tool changes, changes in direction of movement during disassembly along with individual part characteristics (e.g. high-valued parts, parts with hazardous content, etc.). The resulting HDT is called the reduced HDT (RHDT) since it only represents as many (near-) optimum DSP as the size of v. Experimental results demonstrate the applicability and effectiveness of the methodology.

Disassembly analysis for electromechanical products: A graph-based heuristic approach

Original equipment manufacturers are facing more pressure to improve the recyclability of their products. The concept of environmentally conscious design and manufacturing has been adopted in an effort to improve the environmental compatibility of manufactured goods. This new trend requires that environmental considerations be incorporated into design strategies. This paper presents a graph-based heuristic approach to perform disassembly analysis for electromechanical products. The components of a product and their assembly relationships are represented using a component-fastener graph. A cut-vertex search procedure is used to split the graph into sub-graphs representing modular sub-assemblies. Disassembly precedence analysis is then applied to generate a disassembly tree, from which a disassembly sequence can be derived. The results of the analysis can be used by designers to evaluate the 'disassemblability' and 'recyclability' of products they are designing. Desirable changes can then be made at the early stage of design.

ANALYSIS OF DESIGN EFFICIENCY FOR THE DISASSEMBLY OF MODULAR ELECTRONIC PRODUCTS

In this paper, we present a technique for analyzing the design efficiency of electronic products, in order to study the effect of end-of-life (EOL) disassembly and disposal on the environment. The design efficiency is measured using a Design for Disassembly Index (DfDI). DfDI uses a disassembly tree (DT) which relies on the product's structure. The DT can be used to identify the precedent relationships that define the hierarchy of the product's structure (which in turn, represents the order in which components can be retrieved). DfDI can be used to analyze the merits and drawbacks of different product designs. The index offers designers with an important measure to help improve the future products. We provide a comprehensive procedure for developing the index and demonstrate its application through an example.

Automated analysis of 3-D polyhedral assemblies: Assembly directions and sequences

Abstract Some issues concerning the automated analysis of three-dimensional (3-D) assemblies consisting of polyhedral components (that is, components with plane faces) are studied. The product is assumed to have been modeled in a boundary representation environment. An algorithm for mating surface identification is first developed. Noting that previously published work on the automated determination of assembly directions has largely been confined to the 2-D domain, a new approach to the automated determination of the feasible range of assembly directions in the 3-D domain is proposed. This consists of the concept of principal disassembly directions (PDD) that lie on the boundary of the region defining all feasible assembly directions. Finally, an algorithm for determining the translational freedom of components during assembly is presented. These two algorithms enable a rapid construction of the disassembly tree that forms the basis for the automated generation of assembly sequences in the 3-D domain.

Automatic Disassembly and Total Ordering in Three Dimensions

Generating a sequence of motions for removing components in a three-dimensional assembly, one at a time, is considered—the robot motion being strictly translational. We map the boundary representation of a given assembly to a tree structure called Disassembly Tree (DT). Traversing the DT in pre- and post-order yields a minimal sequence of operations for disassembly and assembly, respectively. In this paper, an assembly is classified by the logical complexity of its DT (an ordered graph whose nodes are components of the given assembly) and by the geometric complexity of the nodes in DT (in terms of the number of motions needed to remove a single component). Next, whether a component can be removed in one motion is described as a predicate. This predicate is then used in an algorithm for constructing the DT. For a class of assemblies that exhibit total ordering, the algorithm decides whether each component can be removed in a single motion, by constructing a DT in O(N log N) time, on the average, where N is the total number of mating faces in the assembly.