Morphological chart

From WikID

This article is part of the Bachelor design guide; the original version can be found at page 138.

What is a morphological chart?

The morphological chart is a method to generate ideas in an analytical and systematic manner. Us­ing the morphological chart, the product’s purpose is splitted in a set of (sub-)functions. For each of the (sub-)functions ideas are generated and combined into an overall solution. In a morphological chart, possible components are listed based on their functions. Functions are listed in columns, and components are the means that realize the functions are listed in rows. The morphological method thus yields a matrix of functions and components that realize that function. Through careful selection and combination of a set of components, an idea comes about. This idea should be seen as a principle solution: a careful chosen combination of components that together form a conceptual solution.

Contents 1 What is a morphological chart? 2 When can you use a morphological chart? 3 How to use a morphological chart? 3.1 Starting points 3.2 Expected outcome 3.3 Possible procedure 4 Tips and concerns 5 Literature

A morphological chart consists of functions (listed in the columns) and components (listed in the rows). The parameters describe the functions (characteristics) which a product should have. The parameters indicate what the product should be; they are es­sential to the solution. The components are the means by which the functions (or characteristics) of the product may be realized. The components are thus the means by which the parameters are realized. The parameters are abstract, and indicate a category (with no reference to material features). The components are concrete and specific, specifying the elements that belong to a category (i.e. parameter). It is important that the parameters are independent of each other, meaning that the choice for a component in one parameter may not limit the options in the other parameters. For example, in a morphology of screws, the cost price may not appear as a parameter. Cost price depends on the decisions with regard to the length, diameter and sort of material of a screw.

The success of the morphological method depends on an intelligent choice of parameters. Usually, functions of the product are taken as a starting point. The various functions and sub-functions of a product can be established with a function analysis. Often a number of solutions to these (sub) functions are already known, others are thought up by yourself. These solutions will form the components in the morphological chart. However, functions and sub-functions consist on different levels of abstraction. Sometimes, functions are left out of morphological chart because they are found to be of no importance. Also, function analysis does not guarantee that all the relevant (sub)functions are identified.

Thus, the formulation of parameters and components are interrelated activities. Parameters are identified by focussing on the commonalities of components, and describing them as functions. These components are already known partially from existing solutions: analogous products. Also, new components are found by making the abstract parameters concrete through finding technical principles. In this way, the morphological method is an evolutionary method: parameters and components are evolved parallel until the final morphological chart is made.

In the end, solution principles are found by choosing one component from each parameter. In other words, each combination of components (with one component from each parameter) suggests a solution to the problem. The generation of solutions is thus a process of systematically combining components. However, the larger the morphological matrix, the larger the amount of possible solutions (theoretically, a 10 x 10 matrix yields 10.000.000.000 solutions), which takes much time to evaluate and choose from. Two evaluation strategies are helpful: analysis of the rows and grouping of parameters.

Analysis of the rows is based on rank ordering the components per parameter in a first and second preference. The rank order­ing is done against (a part of) the criteria or design requirements. Using only the first and second preference brings down the number of components and thus reduces the number of solutions. The second evaluation strategy is grouping the parameters in groups of decreasing importance. As a first step, only the most important group of parameters is evaluated. After one or more combinations of components have been chosen, only these are involved in the evaluation.

When can you use a morphological chart?

The morphological method is usually applied in the beginning of idea generation. Function analysis is used as a starting point. Not all design problems are suitable for using the morphological method. In particular for design problems in the field of engineering design, the morphological chart has been successful.

How to use a morphological chart?

Starting points

The starting point of a morphological chart is a well-defined design problem. A function analysis of the product that needs to be designed forms another starting point: the product should be described in terms of function and sub-functions.

Expected outcome

The expected outcome of the morphological method is a number of principle solutions (consisting of components) for the initial design problem.

Possible procedure

1. The problem to be solved must be formulated as accurately as possible.
2. Identify all parameters which might occur in the solution (i.e. functions and sub-functions).
3. Construct a morphological chart (a matrix), with parameters as the columns.
4. Fill the rows with the components that belong to that particular parameter. Components can be found by analysing similar products or thinking up new principles for the parameters (functions).
5. Use the evaluation strategies (analysis of rows and grouping of parameters) to limit the number of principle solutions.
6. Create principle solutions by combining at least one component from each parameter.
7. Carefully analyse and evaluate all solution with regard to (part of) the criteria (design requirements), and choose a limited number of principle solutions (at least 3).
8. The selected principle solutions can be developed in detail in the remaining of the design process.

Tips and concerns

• When a combination of components have yielded a principle solution, be sure to draw all the components when developing the solution principal in sketches.
• One is tempted to choose for the ‘safe’ combinations of components. Challenge yourself by making counter-intuitive combina­tions of components.
• Do not describe the components with words, but use pictograms or symbols to indicate them.

Literature

• N. Roozenburg and E. Eekels (1995) Product Design: Fundamentals and Methods, Lemma, Utrecht.
• N. Cross (1989) Engineering Design Methods, Wiley, Chichester.