| Summary: | This dissertation is concerned with the development of a systematic and quantitative method for evaluating designs. The method attempts to reduce the subjectivity of engineering design work. Heavy vehicle suspensions are used as the case study. A survey was sent to vehicle fleet operators in the UK, to acquire their perspectives and experience of suspension systems in operation. Chapter 2 provides detailed descriptions and analyses of the survey results. Chapter 3 specifies a baseline vehicle, standard conditions, and vehicle models for the use in the database analyses, performance simulations, and suspension evaluations which follow. Chapter 4 analyses a database of heavy vehicle suspensions, established by the University of Michigan Transportation Research Institute, to investigate the current performance levels and common design features of various suspensions. Chapter 5 gives details of vehicle modelling work, which includes the development of analytical procedures to simulate suspension performance and associated lifetime costing procedures. They constitute the basis for design evaluation. Sensitivity analyses are performed to reveal the effects of changes in suspension parameters on system performance. Chapter 6 investigates tools and methods for predicting fatigue damage of systems subjected to broad-band stress spectra, and the corresponding lifetime maintenance costs. A new cost-benefit approach for the evaluation of heavy vehicle suspensions is proposed in Chapter 7, on the basis of the frame-work provided in previous chapters. "Function structures" and a design specification for this type of suspension are presented. A comparison of the new evaluation approach with a traditional evaluation method is made. Four conventional suspensions are investigated using this new approach to reveal their relative benefits and costs.
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