# Chris Fox's Engineering Section

## Design and Materials Selection

When the desired functions of a finished product are known and the necessary information obtained, the product can be designed and its constituent material(s) selected.

The design process starts with a statement of the problem. Next comes the Problem Identification stage; this involves obtaining as much detail as possible about the problem, including the required functions of the finished product and any constraints on it. The engineer then needs to produce as many preliminary ideas as possible before selecting a short list of those ideas for further detailed analysis. When the analysis is complete, one idea is seen to be the best and is chosen as the final solution.

The materials selection process starts with a list of all materials. Apply the primary constraints (the most important ones) and performance maximising criteria to shorten this list to a subset of candidate materials. Then apply the secondary constraints and performance maximising criteria to produce a shortlist of materials. From this, a list of available materials is derived and one of those materials selected. Failure analysis is then performed on the material. If it passes, it can be used, otherwise the process is repeated until a suitable material is found.

These two processes are interrelated. The geometry of a design will be constrained by the properties of the available materials; and the choice of materials will be constrained by any limits that are placed on the geometry of the design.

[Specification] [Preliminary Ideas] [Decision Making] [Mathematical Modelling (in Design)] [Types of Engineering Drawings] [Welds] [Limits and Fits] [Geometrical Tolerancing] [Design for Machining and Assembly] [Strength of Mechanical Parts] [Fasteners] [Design Optimisation] [Materials Selection] [Performance Indices] [Quantitative Materials Selection] [Selection of Materials and Shape]

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