Christian Mascle

Algorithmic selection of a disassembly sequence of a component by a wave propagation method

Abstract The design of a product for its entire life-cycle is becoming more and more important. Nowadays, a product is designed with significant considerations for its manufacturability, serviceability, its functionality and even for its disassemblability. This is due to the fact that the modern consumers demand products that are not only functional, but also reliable, easy to repair and also environmentally friendly. For maintenance and re-use, the operation sequencing in disassembly process planning needs of reversible operation selecting. We present a new wave propagation disassembly algorithm of the determined component of a product; the given data are the immediate predecessors of each component. We show that the solution exists and that she is unique in the following conditions: the binary matrix of the immediate predecessors is non-symmetrical and the data does not contain a cycle. A tracked down cycle method in the data is also proposed.

Product design analysis based on life cycle features

In this research, we effectively integrate the downstream activities of the design process and present a product model representation. Using an extended definition of feature, the product model is represented by its life cycle features, design for X attributes, geometrical and topological information, material features, etc. The relationship between the product features defined makes possible the use of an object-oriented approach to represent the product model with the complete description of the life cycle applications such as the assembly, disassembly, recycling, maintainability, environment, etc. In this way, the designer is able to assess the design performance regarding each life cycle application and redesign the product model accordingly. Since current CAD systems cannot represent the proposed life cycle features, life cycle feature system is implemented using OpenCascade, a geometry kernel and C++ programming. The representation of a product model that integrates the product life cycle features, the geometry and topology of the product and the product model design analysis based on the downstream design activities make our study different from many product design models presented earlier.

A new method for evaluating the best product end-of-life strategy during the early design phase

The choice of an appropriate end-of-life (EOL) destination for discarded products is becoming an important issue for most manufactured products, given the current problems of environmental waste impact and landfill saturation. To address these issues, the design of a product must be optimised with a view to incorporating in that product an environmentally sustainable EOL scenario that respects economic and legislative constraints. The new EOL scenario evaluation method (ELSEM) that we propose in this paper takes these fundamental aspects into account, and provides a method for evaluating the various options for the EOL scenario of a product during early design phase. The ELSEM provides a simple and intuitive tool for designers to help them construct arguments for the EOL decision-making process. It is built using the fuzzy technique for order preference by similarity to ideal solution method, a multi-criteria decision process that is highly appropriate in the uncertain and subjective environment in which the designer works during the early stages of product development. Our method is illustrated with a case study involving a vehicle engine.

Geometric and form feature recognition tools applied to a design for assembly methodology

The paper presents geometric tools for an automated Design for Assembly (DFA) assessment system. For each component in an assembly a two step features search is performed: firstly (using the minimal bounding box) mass, dimensions and symmetries are identified allowing the part to be classified, according to DFA convention, as either rotational or prismatic; secondly form features are extracted allowing an effective method of mechanised orientation to be determined. Together these algorithms support the fuzzy decision support system, of an assembly-orientated CAD system known as FuzzyDFA.

Feature-based assembly model for integration in computer-aided assembly

Abstract This paper proposes a real good approach for a computer-aided assembly (CAA) system, which makes use of software agent technology and deals with a representation of assembly features. The context of our work is the study of the engineering and manufacturing system based on the assembly features. The system never thinks like an assembly engineer, but makes it possible to support engineers in doing creative methodology, and producing new ideas better than the conventional CAA.

A database for the representation of assembly features in mechanical products

This paper deals with a representation of assembly features. Modeling the product at each stage of the assembly process, taking into account all pertinent geometrical, technological and functional data, distinguishes our model from the ones described in the literature. A representation such as this also greatly contributes to the designing of a system that includes the various stages in the development and manufacture of a product. To reach our goal, we let the user interactively input a set of features that cannot be supported by a solid modeler. The system automatically deduces other features pertaining to faces, parts and subassemblies. Given the object-oriented structure that we chose, the different features can be abstractly represented as object attributes. This can assist the method engineer in the automatic generation of assembly sequences or resources. Examples are given to validate the concept.

Sustainability assessment using fuzzy-inference technique (SAFT)

A fuzzy-inference method was introduced to evaluate product/process sustainability.The proposed methodology does not require generation of rules.A comparison with fuzzy rule-base technique was done.Results were satisfactory and indicated the applicability of the proposed technique. Green products are increasingly becoming the center of attention for policy and decision makers worldwide not only because of environmental and eco-systems crisis but also to satisfy the current competitiveness in the markets. With this aim, it is highly attractive to count with mathematical tools that allow assessing the sustainability of the products. In this regard, fuzzy techniques have been broadly used in different studies due to uncertainty and vagueness associated with sustainability problems. However, these studies are mostly based on fuzzy rules generation which is time consuming and also can lead to redundancy and inaccuracy. In this study, we introduced a fuzzy-inference system to evaluate product/process sustainability (SAFT). The proposed method does not require generation of rules which simplifies the procedure and makes it more precise. Furthermore, fuzzy analytic hierarchy process accompanied by Shannons entropy formula was employed to determine the relative importance of each element in the hierarchy. The methodology SAFT was compared with fuzzy rule-base technique and impressively pretty the same results were obtained. The method introduced in this paper was built as a user interface platform which can be used as a fuzzy expert system to facilitate the sustainability assessment of products/processes in different manufacturing industries.

Application of a fuzzy decision support system in a Design for Assembly methodology

Concurrent engineering in product modelling aims at developing a comprehensive practical model capable of driving design, manufacturing, assembly, maintenance and recycling activities. In this paper, an application of fuzzy logic to a Design for Assembly methodology is introduced. The main objective is to compute the assembly efficiency of a product from boundary representation geometric models and a minimal technological database. This work is based on the well-known Boothroyd–Dewhurst methodology for studying manual and automated assemblies. The use of a fuzzy decision support system involves the representation of this method by fuzzy sets. Each part of a product has to undergo computation of its handling and insertion efficiencies, as well as an evaluation of its relevance to the assembly. This evaluation process depends on geometric and technological criteria. The designer may experience difficulties in making a choice when there are several adequate solutions for every part. This paper demonstrates that a decision support system approach significantly improves the Boothroyd–Dewhurst methodology. The proposed approach is flexible and it can be applied to specific products.

Assisting designer using feature modeling for lifecycle

This paper presents a product dynamic model and design for X solution (DFX) developed in C++ with the OpenCASCADE geometric kernel, allowing the designer not only to get feedback on the viability of his design choices but also to collect data for process and task planning, maintenance and end-of-life strategy planning. The implemented method evaluates automatically both the efficiency factors and the incompatibilities between development characteristics in order to optimize the design of the product for multiple domains. The framework of this DFX solution, based on the product data structure, consists of imposing integration constraints concerning the development process during the entire design product process. In this paper, simple assemblies are used as brief examples to demonstrate the application of the proposed integrated design solution, its effectiveness to improve the design for X and collecting useful data for entire lifecycle duration. The method developed has been formalized with the NIAM model.

Automatic a priori, a posteriori or appropriate determination of subassemblies

In the industrial field, the idea of subassembly must be distinguished from the subset one, when considering subassemblies as the only subsets in which all parts are stable. An original approach using the disassembly method, the logical reverse chronology of assembly, and the introduction of a mathematical model describing the liaisons allow us to determine the problems related to the automation of assembly sequences. To do so, the modelling of functional liaisons between parts helps to distinguish a simple contact from an attachment, and subsets from subassemblies. Liaisons between components are described by matrices of half degrees of liaison. These liaisons are extracted automatically from a B-rep model of a mechanical product on CAD. Subassemblies are determined automatically just in time during the determination of disassembly sequences. A limitation of this approach is that as soon as a relation is no more orthogonal to the basic referential, a new referential has to be introduced. An expert will c...