Weighting of dependent and target-based criteria for optimal decision-making in materials selection process: Biomedical applications Ali Jahan a,⇑ , Kevin L. Edwards b a Faculty of Engineering, Semnan Branch, Islamic Azad University, Semnan, Iran b School of Engineering & Applied Science, Aston University, Aston Triangle, Birmingham B4 7ET, UK article info Article history: Received 27 November 2012 Accepted 23 February 2013 Available online 7 March 2013 Keywords: Biomaterial selection Target-based criteria Multi-attribute decision-making Continuous improvement in product development Quality tools in engineering design Dependent criteria in material selection abstract The selection of the most appropriate material, or combination of materials, is a demanding intellectual process that takes a lot of time and experience. There are a large number of established and newly devel- oped materials, and their associated materials processes, necessitating the simultaneous consideration of many conflicting criteria. This has highlighted the importance of the developing field of multi-criteria decision-making (MCDM) to the material selection process which is especially useful for high technology market where product differentiation and competitive advantage are often achievable with just small gains in material performance. It is clear that decision-making techniques that address target criteria as well as cost and benefit criteria can help engineering designers make better informed choices of mate- rials. Despite the progress has been made in the ranking of materials for target-based criteria, there is no formalized technique for calculating the weighting dependency when target criteria must be taken into account in material selection problems that usually deals with databases. Therefore, to overcome this shortcoming, the strategy of using dependent weightings is extended in this research. Also, an alternative method is proposed to incorporate the correlation, objective, and subjective weightings effectively when there is uncertainty in the importance of three types of weights. This issue is very important for inexpe- rienced designers. The updated procedure is validated through biomedical applications. The first example demonstrates the importance of dependency weighting in amalgam tooth filling material selection and the second one is a hip joint prosthesis material selection problem, which includes target criteria. Fur- thermore, a model of continuous improvement in product development is outlined, and it is highlighted that the material selection/development is a permanent and endless task for sustainable and profitable growth. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction From the perspective of engineering design and manufacturing, there is a need for optimal selection of materials for reasons of cost reduction, product reliability improvement, manufacturing process yield enhancement and for replacing obsolete, restricted access, or barred materials [1]. The selection of the most appropriate mate- rial, or combination of materials, is a demanding intellectual pro- cess that takes a lot of time and experience, and it is associated with all but the most simplest of design and manufacturing prob- lems [2]. The problem is further compounded by the need to also consider indirectly manufacturing process constraints that might eliminate the use of certain high performance materials depending on their application. Materials selection and materials process selection follow similar, but interrelated, routes in that a number of potential options need to be reduced to a final choice to best meet the constraints of the intended design. Considerable technical and commercial benefits can therefore be gained by the use of appropriate material(s), compensating for the time taken in their identification. There are a large number of established and newly developed materials, and their associated materials processes, necessitating the simultaneous consideration of many conflicting criteria. This has highlighted the importance of the developing field of multi- criteria decision-making (MCDM) to the material selection process. The technique has the potential to improve all areas of decision- making in engineering, from design to manufacture, but is espe- cially useful for high technology market sectors such as aerospace, electronics, motorsports, nuclear, and biomedical applications, where product differentiation and competitive advantage are often achievable with just small gains in material performance. The biomedical market sector is large and growing rapidly with ageing populations worldwide and the need to provide prosthetic implants and rehabilitation equipment to injured personnel, par- ticularly resulting from war conflicts. As well as a great demand 0261-3069/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.matdes.2013.02.064 ⇑ Corresponding author. Tel.: +98 2313322034. E-mail addresses: iranalijahan@yahoo.com, a.jahan@semnaniau.ac.ir (A. Jahan). Materials and Design 49 (2013) 1000–1008 Contents lists available at SciVerse ScienceDirect Materials and Design journal homepage: www.elsevier.com/locate/matdes