V.P. Agrawal

Optimum Selection of a Composite Product System Using MADM Approach

The paper describes a methodology for evaluation, coding, ranking, and optimum selection of subsystems for composite product used directly by its manufacturers. This method is important from the point view of development of a reliable database, virtual design, customization, developing cutting-edge technology, and meeting the challenges of global competition in composite industry. The 77-attribute electronic coding scheme and the evaluation techniques presented in this paper are useful to the designer during all the phases of design process, and manufacturer for the selection of optimum subsystems, which meet global market requirements. Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) is a Multiple-Attribute Decision Making (MADM) approach, used for selection of subsystems for a composite product development in order of preference for given application. Two graphical methods of MADM approach for evaluation and comparison are also introduced. The proposed 3-stage selection methodology is explained with an illustrative example.

Structural Modeling and Analysis of Composite Product System: A Graph Theoretic Approach

An attempt is made to develop an integrated systems model for the structure of the composite product system in terms of its constituents and interactions between the constituents and the molding processes, curing kinetics, etc. using graph theory and matrix algebra. The composite product system is first modeled with the help of a graph theory, then by a variable adjacency matrix and then by a multinomial known as a permanent function. The permanent function provides an opportunity to carry out structural analysis of the composite product in terms of strength, weakness, improvement, and optimization by correlating the properties of a composite with its structure. A physical meaning has been associated with each term of the permanent function. Different structural attributes of the composite product are identified to develop a graph theoretic model, a matrix model, and a multinomial permanent model of the composite. A top-down approach for complete analysis of any composite product system is also given. A general methodology is also presented for characterization and comparison of two composite product systems. Usefulness of the present methodology is also illustrated.

Design for ‘X’-abilities of RTM Products - A Graph Theoretic Approach

The resin transfer molding (RTM) process has been widely accepted for fabricating automobile, aircraft, and spacecraft components with high strength and stiffness to weight ratios of the composite products. This process is widely acceptable in various industries, i.e., wherever low manufacturing cost with high mass production is required compared to other processes like compression molding and hand lay-up. Designing the composite products requires a lot of skill with multidisciplinary knowledge. Considering the design and the manufacturing strategies as well as the product development, every aspect of the design is to be considered in a single approach without losing any information. The present approach gives a new methodology for combining all the design aspects together in concurrent design methodology, which finally leads to the achievement of the six-sigma limits i.e., almost defect-free products from the RTM technology. The present paper utilizes the advantages of the graph theoretic approach to considering all the design aspects together in a single methodology with the help of matrix algebra and permanents. It is basically a virtual design methodology, which decides the process, the product strength, and the weakness with the help of a multinomial defined by using the matrix algebra. The design index, developed using the proposed methodology, really decides if the overall design is acceptable or not by considering all the aspects of the design related to the product, process, environment, etc. Finally, a step-by-step procedure is proposed to help generate a new algorithm for software coding.

Quality Evaluation of Resin Transfer Molded Products

The present study introduces a new procedure to evaluate the quality of composite products using the graph theoretic approach, and a composite screw rotors process is considered (manufactured by the Resin Transfer Molding (RTM)). The composite product coming from the manufacturing processes must have good surface finish and high quality without any defects. There are several factors which affect the quality during design and manufacture of the RTM products like screw rotors. These factors form a quality digraph based on the interactions existing between them. Hence, we considered the quality digraph by defining fuzzy crisp scores for the degree of interactions between the factors. A quality index derived from quality permanent function is helpful for quality inspectors on the shop floor to decide whether the product is within benchmark limits. The benchmark limits obtained for the composite product, manufactured by the RTM process by considering the strong and weak interactions existing between the factors defined for quality, are considered as upper and lower bounds in deriving the indices. Therefore the present work proposes a quality index, which is a useful numerical index for quality assurance groups to take proper decisions on the shop floor for the manufacturing process adapted to composites (composite molders).

Concurrent Design of a Computer Network for x-abilities using MADM Approach

Organizations are deploying well-designed computer networks supporting converged applications of data, audio, and video. Use of different applications demands computer network to have various abilities — performance, resilience, security, maintainability, etc. called x-abilities — in varying degree of importance depending on application requirements of an organization. To facilitate design of computer network simultaneously for all x-abilities in an integrated way, a concurrent design methodology using multi attribute decision making (MADM) approach is proposed. This concurrent design methodology is aimed at reducing design time considerably and makes use of expertise of experts from different specialized fields in a single design team. MADM approach provides technique for selection of best computer network for the application under consideration.

DFX Analysis Applied to Composite Products

The concept of concurrent engineering (CE) has changed the traditional process of design to an integrated process, comprising all aspects of design, manufacturing, costing, process control etc. In composite product development, CE is adopted to enhance quality, to reduce time of production, and to reduce cost. There have been several models that consider design for minimal weight, design for cost, design for quality, design for manufacture, design for reliability, design for metal inserts, design for environment etc., separately for composite product development. In the present paper, we apply the graph theoretic approach to DFX analysis methodology for design of composite products. The DFX methodology is new to composite design, and is applied to study the various DFX components, like design for cost (DFC), design for manufacture (DFM), and design for minimal weight (DFMW), simultaneously. In this study, an example for development of fiber reinforced polymer composite (FRP) drive shafts is taken up. Several material combinations like E-glass/epoxy, E-glass/polyester, and HM-carbon/epoxy composite materials are compared in light of their performance with conventional steel material. The concurrent graph theoretic approach with a permanent function is used to account for the interdependencies existing among the design parameters in studying DFMW, DFM, and DFC.

Reliability Modeling and Analysis of Composite Product System - A Systems Approach

In the present scenario application of composite products has been extended enormously in Naval, Military, Civil aircraft structures, in addition to more exotic applications on unmanned aerial vehicles, Space launchers and Satellites. Selection of suitable composite products to the given application has become an important aspect in composite industry. The present paper describes a methodology for the reliability analysis of composite product system as well as optimum selection based on reliability. A detailed procedure for the reliability analysis of polymer matrix composite product system is suggested through a reliability function. The approach is based on graph theory and matrix algebra, and this takes into account complexities and interrelations of subsystems existing in polymer matrix composite product. Exhaustive and useful reliability analysis of a system is carried out based on reliability-based tests for the composite product system. Coefficients of similarity or dissimilarity, which compare two composite product systems based on reliability, are developed. Quantitative evaluation of the reliability of a system through the reliability index is proposed in this paper. This aids in the optimum selection of a composite product system at the initial stages of design. The methodology is flexible and general in nature and can be used by the designer and manufacturer on the basis of its selected subsystems and reliabilities related to them at the conceptual stage of design. The proposed methodology is illustrated through an example of a Resin Transfer Moulding (RTM) composite product system.