**Types of Design Problem**

Although many design problems are complex, it is vital that a simple solution is not overlooked. There is a tendency to get involved with complex technical calculations and design when some thought would reveal that with the aid of a simple jig, manual operation might be totally satisfactory.

Design problems can be classified in a number of different ways, one grouping proposed by C Matthews splits them into four types:

1. Linear technical problems

2. Linear Procedural problems

3. Closed problems

4. Nested problems

1. Simple problems in mechanics often fall into this class (but not thermo - or fluid dynamics problems). These problems can be solved by applying well known engineering and physical laws by carrying out a sequence of calculations on plenty of 'given' data and information. The design is checkable and although large numbers of technical calculations may be carried out, often using sophisticated computer software, the problem has a low complexity.

2. A procedural problem has constraints which define the problem and its technical solution. A problem of poor interchangeability of components in a large scale manufacturing operation might fall into this class. Theoretically there might be a wide variety of approaches, but in practice there would be large numbers of restraints on what could be done.

3. These often relate to failure investigations or new product development and frequently have a very short description: eg. the service call outs on our mark x photocopier are excessive, we need to improve the reliability. Such problems are often highly complex and require carefully 'opening up' before any start can be made on a solution. The main problem will be likely to contain many sub - problems - all of which will have to be examined and probably solved. It will be necessary to think around the problem - brainstorming and group involvement will often be helpful.

4. These tend to be more complex problems - there may be nested technical levels with interacting procedural levels. Some problems in design and project management contain a great deal of procedural complexity - which must be satisfactorily solved - or set in place - before the technical content (layers or levels) can be efficiently solved. In many creative design problems there is a core technical problem with a number of linked problems - and these linked problems may have procedural constraints, which arise due to the way an industry operates.

Further Reading - 'Case Studies in Engineering Design', by C Matthews, chapter 2.

Return to Module Introduction.

David J Grieve, September 1998, revised 24th January 2003.