Metric for Disassembly and Reuse Decisions: Formulation and Validation

Design for disassembly and reuse focuses on developing methods to minimize difficulty in disassembly for maintenance or reuse. These methods can gain substantially if the relationship between component attributes (material mix, ease of disassembly etc.) and their likelihood of reuse or disposal is understood. For products already in the marketplace, a feedback approach that evaluates willingness of manufacturers or customers (decision makers) to reuse a component can reveal how attributes of a component affect reuse decisions. This paper introduces some metrics and combines them with ones proposed in literature into a measure that captures the overall value of a decision made by the decision makers. The premise is that the decision makers would choose a decision that has the maximum value. Four decisions are considered regarding a component’s fate after recovery ranging from direct reuse to disposal. A method on the lines of discrete choice theory is utilized that uses maximum likelihood estimates to determine the parameters that define the value function. The maximum likelihood method can take inputs from actual decisions made by the decision makers to assess the value function. This function can be used to determine the likelihood that the component takes a certain path (one of the four decisions), taking as input its attributes, which can facilitate long range planning and also help determine ways reuse decisions can be influenced.

Development and Design of a Cost-Efficient Tire Mechanics Testing Apparatus

Most tire models need experimentally obtained data as input for simulation purposes. The study of tire mechanics requires the accuracy and repeatability of a controlled environment. However, the accessibility and cost of tire testing machines make it prohibitive for exploring tire mechanical properties for academic studies. Moreover, most industrial tire testing machines are designed for general tire testing, and would require an extensive amount of time and resources to adapt for academic research. To study tire mechanical behavior for modeling purposes, a tire mechanics test apparatus has been developed at the Center for Vehicle Systems and Safety (CVeSS), Virginia Tech. The tire mechanics test apparatus has been designed as an interchangeable attachment to an existing modular quarter car test rig developed at the Institute for Advanced Learning and Research (IALR) in Danville, Virginia, to save on cost, as well as to maintain repeatability of testing. The physical limitations of maximum tire vertical load for various tire testing machines are also among the main motivations for developing the tire mechanics test apparatus. The current configuration of the tire mechanics test apparatus provides the capability to study the vertical load - deflection characteristics of the tire, as well as the static footprint of the tire under various vertical loads. Future planned enhancements to the setup include the addition of a soil bin and an instrumented rolling drum for tire shear force studies.

Assessing Product Lifecycle Sustainability Using Uncertain Design Information at Conceptual Stage

This paper presents a hierarchical fuzzy evaluation approach to product lifecycle sustainability assessment at conceptual design stages. The purpose is to advocate the emerging use of lifecycle engineering methods in support of evaluation and selection of design alternatives for sustainable product development. A fuzzy evaluation model is developed with a hierarchical criteria structure to represent different sustainability considerations in the technical, economic and environmental dimensions. Using the imprecise and uncertain early-stage product information, each design option is assessed by the model with respect to the hierarchical evaluation criteria. Lifecycle engineering methods, such as lifecycle assessment and lifecycle costing analysis, are applied to the generation of the evaluation criteria. This would provide designers with a more complete lifecycle view about the product’s sustainability potentials to support decision-making in evaluation and selection of conceptual designs. The proposed approach has been implemented in a sustainable design decision-support software prototype. Illustrative examples are discussed in the paper to demonstrate the use of the approach and the prototype in conceptual design selection of a consumer product.

Sensitivity Analysis of Relative Worth in Empirical and Simulation-Based QFD Matrices

Quality function deployment (QFD) is one of the most popular tools used in the product development process. It relates customer requirements to product requirements and enables engineers to determine which product requirement is more important than the others in satisfying customers. Some of the benefits of QFD are cost reduction, fewer design changes at the start of production, and improved communication among engineers. QFD applications use various approaches (i.e., worth calculation schemes and rating scales) to calculate the worth of requirements. The purpose of this paper is to study the change in the relative worth (normalized worth) of product requirements yielded by different rating scales and calculation schemes. We studied empirical and simulation-generated QFD matrices to determine how calculation schemes and rating scales influence the relative worth of requirements. Two representative scales and two calculation schemes are used to find the most and least sensitive cases, and the influence of the number of rows and columns in the relative worth of requirements. From the results, we identified the least sensitive and most sensitive combination of calculation scheme and rating scale. We also learned that QFD matrices become less sensitive to changes in rating scale and calculation scheme as the number of columns increases.

Conceptual Design of Identification Systems

This is a student design project to present the procedures and the results of conceptual design for identification systems. The sub-function structure of the identification system is created after recognizing the requirement and establishing the specification. The physical effects, physical principles and solution principles are found based on the sub-functions, and the alternatives or combined solution principles are generated. The Saaty method with the modified normalized values is used to determine the relative importance or weighting factors of the standard evaluation items by paired comparisons. The eigenvalues and eigenvectors of the evaluation items and alternatives are determined. The web method is then used to determine the most preferred design of the alternatives and the best alternative is recommended. It is learned that to determine the sub-functions, the physical effects, physical principles, solution principles and combined solution principles, surveys of evaluation items, matrices of evaluation items and alternatives are very difficult, tedious and time consuming.

A Method of Supporting Conflict Resolution for Service Design

Recently, the importance of service has been emphasized in various industries. However, few studies have focused on service design in spite of its great importance. This paper proposes a methodology for supporting service design by solving conflicts in service design solutions. The proposed methods enable service designers to discover existing conflicts in service design solutions and obtain the basic strategies to solve them using computers. The methods are verified by applying it to an existing service case.

The Decline of Design Across the Curriculum

Design across the curriculum has been a cornerstone of mechanical engineering education for well over a decade. The movement was an attempt to balance the tendency of most programs to over-emphasize engineering science. Over the course of that decade, many public universities have undergone a 7%–10% reduction in the number of credits required for graduation; usually in response to legislative pressure or competitive market conditions. In some instances, these reductions were not reflected in the general education content. Although the number of technical electives within the curriculum may have been reduced, seldom have they been completely omitted. Engineering science is considered the analytical foundation upon which new knowledge and engineering design are based. In addition, new frontiers in mechatronics, nanotechnology and alternative energy sources are becoming “must teach” subjects so that the discipline can evolve. The indication is that the “Design Across the Curriculum” concept either is, or will soon be in decline. This paper will present some historical perspective, a small sample of both common “solutions,” and a few unique approaches for maintaining design across the curriculum. The primary objective, however, is to initiate a dialog among engineering educators to begin to address the balance between engineering science and engineering design.

Examining Design Tool Use in Engineering Curriculum: A Case Study

This case study observes the effect of design tool use in engineering courses on subsequent uses of design tools. Students gain a familiarity with design tools as they use them in early engineering classes, and will traditionally implement similar methods to seek future design solutions. Problems arise because design tools are often used inappropriately, which may or may not lead to productive outcomes. Understanding how design tools are incorporated into engineering curriculum will reveal how that particular method was selected, the background information given to the student to facilitate tool use, and the benefit gained from using the specific tool in the given case. This information is valuable to the evaluation of the engineering curriculum of which few performance metrics exist. This case study utilizes a design team enrolled in a capstone design course to collect data on the use of design tools throughout their curriculum. Trends are revealed that relate how the tool use is implemented, how the instruction is delivered to the student, and the beneficial application of those to the given design project. These trends directly apply to the intellectual growth of the student as well as the topical coverage and implementation by the engineering department. Using this information, the engineering curriculum can improve its delivery of design instruction. It can be assumed that by improving the curriculum, the quality of the students will follow; yielding engineers who can study better and conduct design projects with intentional precision.

Experiences of a US-India Team in Developing a Case Study That Illustrates Technical and Global Issues in Weld Design

Understanding the real-world issues in the global industry is one of the ways of enhancing the learning experience of engineering students. This paper describes such an experience. This was a collaborative weld design project between Auburn University, Auburn, Alabama, Indian Institute of Technology (IIT), Madras, India and Bharat Heavy Electricals Limited (BHEL), Tiruchirappalli, India. The main problems BHEL faced were (1) Inspection time of the welds, (2) Inaccessibility of the welds, and (3) Detection of kissing bond or pasty weld. Three possible solutions to these problems were identified by the practitioners. In order to bring this real-world issue into engineering classrooms, the authors developed a case study. The authors also developed a multimedia CD-ROM which brings the problem live into class rooms using video, audio and pictures. This case study has been tested with mechanical engineering students. The majority of the students found the use of case studies to be beneficial, particularly because of the group work and applicability to real life situations. The details of the case study and its implementation in an engineering class room at Auburn University are discussed in the paper.

Enhancing the Efficiency and Accuracy in the Quotation Process of Turned Components

Many small and medium sized companies base their business strategy on their manufacturing processes. They are highly specialized in areas such as: die-casting, extrusion, machining, sintering, injection molding etc. The specialization is usually also focused on a limited number of material and alloys for the manufacturing process in question. These companies are commonly acting as subcontractors to other companies, original equipment manufacturers (OEMs). For the OEMs to be able to provide affordable products in a short time and to be at the competitive edge, every new design must be adapted to existing production facilities. In order to ensure this, collaboration between engineering design, at the OEM, and production engineering, at the subcontractors, has to be supported. With the dispersed organizations of today and the increasing amount of information that has to be shared and managed in the product realization process, this collaboration is a critical issue for many companies. A more intense collaboration is sought by many subcontractors as it will strengthen the business relation. To provide manufacturing knowledge and to be a partner in the product realization process is a means to outplay competitors. The purpose of this work is to investigate, explore, and develop a computerized method, i.e. an application system, to support the process planning and cost estimation in the quotation process. The main objective is to reveal concepts and principles to support application system development and utilization. The results are based on the experiences from a case study at a subcontractor of turned components.