Gerhard Pahl and Wolfgang Beitz's
Theory of Systematic Engineering Design & Practice


The need for a systematic approach

The design of complex, complicated or a family of products is usually beyond the intuitive skills alone of a designer or design team. Gerhard Pahl and Wolfgang Beitz [1] have set out a strategy for the development of solutions which aims to increase the probability of technical and economic success of product design. This is done by creating a dependable approach which allows careful planning and systematic execution so that the whole design task reduces to a logical and comprehensible exercise and also allows recovery from inevitable errors. It also allocates a time schedule for the design stages which in turn leads to a predictable project timetable. Systematic design is general enough to be applied in any branch of engineering.

However they have not recommended that this method be automatically applied to all designs nor all aspects of a design. Work should never be done just for the sake of being systematic or for pedantic reasons. This is because tasks and problems will differ from product to product and also designers will have various backgrounds, experience, skill and preferences. Therefore a designer should assess the situation they are faced with and choose their own appropriate method for any particular design step. The authors also do not discount the role of inventiveness and intuition in developing solutions. Complex tasks are solved one step at a time and in each such step a designer has to find a balance between the systematic and the intuitive. Also intuitive inventiveness is one way technical or economic advantage can be introduced into products.

Wallace and Blessing [2] lend some perspective to systematic design by noting two contrasting ways in which design can be approached. The systematic generation of solutions set out by Pahl and Beitz is a problem-orientated approach and this is favoured in central Europe. In contrast, in the UK and the USA, a more product-oriented approach is evident in which an initial product idea is continually elaborated during the design process.

The steps which make up systematic design

Pahl and Beitz divided their method into a number of broad phases, each with a set of basic steps.

1. Start off with product planning and a clarification of the task

1.1 Clarify the task and build out the specification and requirements

The specification as presented to the designer may not be comprehensive and often will require clarification and additional information. The designer will also need to determine the clear aims which the solution needs to achieve. He or she also needs to be sure that there will be the requisite commercial motivation and intellectual stimulation to carry the design through to fruition. At the end of this phase the specification will be fully developed and requirements and constraints compiled.

2. Conceptual design phase

Before the conceptual design stage is started a decision is needed as to whether a conceptual elaboration is really needed or whether known solutions allow the designer to proceed directly to the embodiment and detail design phase. If not, then a conceptual design phase needs to be undertaken.

2.1 Abstract the task to identify the essential problem

Abstracting the task means describing it in the broadest way. This makes clear what the overall function should be. Too narrow a view of the task, or a quick prejudged one, may well lead the designer down a path to a non-optimum solution; one which would ultimately detract from the technical and economic success of the product.

2.2 Establish the functional structures

This is both an articulation of the boundaries of the solution (what is in and out of the design) and the functional way in which energy, material and signals (information) flow (are processed or converted) from input to output to meet the specification. It involves breaking down the overall function into sub-functions until the sub-function task becomes clear and simple. In essence, the development of functional structures aims to assist in discovering solutions.

2.3 Search for solution principles

There may be many means and ways in which a solution to a sub-function can be achieved and the designer seeking an optimum technical and economic solution will need to elaborate a wider rang of possible solutions in order to be able to assess the comparative merits of each possibility. Pahl and Beitz note that a successful solution is more likely to spring from the choice of the most appropriate principle than an exaggerated concentration on the finer points.

2.4 Combine the solution principles into concept variants

The larger product is built up from smaller solutions proving the sub-functions. As a result there is likely to be a number of product concepts or variants which can be derived in this way. This development of solution options is the strength of the systematic approach.

2.5 Evaluation of concept variants using technical and economic criteria

The designer needs to first draw up a set of evaluation criteria and then assess the relative merits of a solution using a bottom up approach starting from the sub-functions which make up each concept variant. In this way a comparative technical and economic evaluation can be built up for each concept variant and allows a decision to be made as to which particular solution should be manufactured.

An additional purpose of such an evaluation is to select one or two back-up solution which, while not as cost-effective, could nevertheless be deployed in place of the first choice should this turn out to be necessary.

3. Embodiment design

The authors realistically point out that in the embodiment design stage, many details and will need to be clarified, confirmed or optimised and as this is done it will become more obvious whether the right solution concept has been chosen. On a salutary note they comment that no embodiment design can hope to correct a poor solution concept. The final general observation is that the end of the embodiment design is the very latest to which assessment of financial viability of the project can be left.

3.1 Develop a definitive layout and check that the requirements are met

For each concept solution variant the designer will need to determine the layout which will end up being the technical product or system and check that function, strength and spatial compatibility requirements are met.

4. Carry out a detail design

4.1 Detail design

The exploration of options does not finish with a conceptual solution but extends to the physical realisation of the products. Again the principle of systematic design should be applied to make the choice of suitable components, materials, forms and finishes.

4.2 Documentation

Detail design also includes the production of final design drawings which can be used to manufacture the product. This firms up each possible product concept solution into a potentially manufacturable design. At this stage, a designer can say that they have explored all of the factors which potentially could significantly impact on the design, ending up with one or more potentially manufacturable designs.

Would all of this take too much time?

Pahl and Beitz note that the steps which they have described in any case will need to be examined at least implicitly as a designer prepares a design. It is therefore much better to be systematic about it rather than leave to chance whether or not some aspect of the design has been properly covered.

Later edition

The third English language edition updates and expands the material covered [3]. Also new chapters have been added on:

  • mechanical inter-connections,
  • mechatronics (integration of mechanics, electronics and information technology to create new and improved products and new ways to produce and assemble these),
  • adaptronics (adaptive structures with electronics so the structures continually fulfil their task by actively adapting to disturbances and to changes in loading or required functionality),
  • designing for quality, and
  • designing for minimum cost.


[1] G. Pahl and W. Beitz
      Engineering Design: A Systematic Approach
      Translated by Arnold Pomerans and Ken Wallace,
      Edited by Ken Wallace
      The Design Council London, 1988
      ISBN 0 85072 239x
      Original German Edition
      Konstruktionslehre: Handbuch für Stadium und Praxis
      Springer-Verlag, 1977

[2] Ken M. Wallace and Luciënne T. M. Blessing
      Observations on Some German Contributions to Engineering Design:
      In Memory of Professor Wolfgang Beitz
      Research in Engineering Design (2000)

[3] G. Pahl, W. Beitz, J. Feldhusen and K.H. Grote
      Engineering Design: A Systematic Approach, Third Edition
      Translators and Editors: Ken Wallace and Luciënne T. M. Blessing
      Springer-Verlag London Limited, 2007
      ISBN-10: 1846283183