Designing for Function-

The first requirement of any design project is to deliver a product that measures up to the function specifications. If specifications of a combat aircraft call for a cruising speed of 2.5 Mach, a penetration of 1,000 km and a ceiling altitude of 15 km, the first task of the designer is to make sure that these characteristics are achived. The handling performance requirements, essential through they are, come over and above these functional requirements. If we are structural engineers and our task is to prepare a structural design for an 80-storey building, the first requirement is to produce a structure that can take up the load of 80 storeys, can withstand earthquakes and wind loads of reasonable magnitudes.

The path from design concept-

A final acceptable design is a long and winding one. The development phase of the design process consisits of putting the major elements of the concept togetherkeeping in mind that the resulting product should satisfactorily perform the expected functions. However, the acceptability of a product does not depend entirely on its functional utility or efficiency. A product needs installation, operation, maintenance and repair. The effort needed and the attention required for these functions are important determinants of the quality of the product as it appears to the user. To this end, therefore, the designer must build into the design, ease-of-use, installation, maintenance and repair. All these considerations constitute the preliminary design stage of the design cycle.

From Concept to product-

The abstract design concept consisting of the outline, an idea from here and a mechanism from there, expresses only a plausible relationship among elements thatpromises to fulfill the needs of the given problem. We then carry out a feasible study to estimate the chance of such plausible relationship being converted into a physical reality. However, unless we actually do produce the envisaged physical reality it is merely an intellectual exercise. The next step in the design process is the development of the design concept into a design that will work to the satisfaction of all concerned.

Using Utility for Design Selection-

To be able to use utility analysis for the selection of a design concept we need to further develop the concept of utility. It has been said that utility is a measure of the usefulness of a product, and that equal intervals on the utility scale of the different quality dimensions should be interchangeable, that is, substituting one unit of utility of say, realibility should not affect our performance. However, to construct such a utility scale is a tall order. To overcome this problem we use a slightly modified and simplified procedures, through the end result still remains the same.

The Concept of Utility-

The concept of utility has been developed as a common scale for evaluation of a product on a number of diverse dimensions such as cost, safety and ease-of-use. This scale is based on the personal preferences of the evaluator, and as such, is highly subjective. The utility of a product on a particular quality dimension measures the usefulness of that particular quality characteristics of the product in the opinion of the evaluator. Thus, the utility of a design on, say, the adaptability dimension is a measure of the contribution of the adaptability of the design to the overall usefulness of the product. The overall utility of a product is the sum of utilities of each of the quality dimensions

The Quality of Design-

Economic profitability is an important quality of a design, but only from the manufacturer’s or distributors point of view. The customer pays for the designed product, but except in the case of capital goods, does not create any monetary income from it and is, therefore, unable to calculate its profitability or economic worth.

Economic and Financial Feasibility-

All objects or systems by an engineer are directed towards some purpose. It is understood that for a design to be worthwhile the effort that goes into its realization should be substaintially less than the benefit obtained from it. One method of measuring the effort of designing and production is to measure the amount of money it costs in terms of wages and materials.

A Measure of Physical Realizability-

The physical realizibility of a design concept can be measured in terms of the confidence the designer has in his being able to transform the abstract concept into its physical embodiment. This confidence is expressed as a statement of subjective probability.

The place of Decision-making in Designing

When the search for solutions is carried out under such conditions, the outcome is a set of ideas, each of which is a rather rough outline of how the major elements of the design are to be connected. Each of these needs to be developed further, the details worked out and the procedures specified. The development of design costs and time and money are the important factors in designing.

Morphological Analysis-

This method serves to force the designer to increase the area her search for design concepts. It recognizes that the solution to a design problem consists of certain essential constituent parts and a good design is one, which selects the proper ‘ matching combination of component’. It is based on the premise that novel designs can be created by treating most designs.