funktionsstruktur

Funktionsstruktur, or function structure in English, is a representation of a system's intended functions and how these functions are realized. It decomposes the overall purpose into subfunctions and the means required to fulfil them. The result is typically a hierarchical diagram or matrix that links what the system must do (functions) with how it is done (means). The top-level function states the system's main purpose, while lower levels break that purpose into smaller, concrete tasks. Means are the components, processes, or actions that realize a function, and the connections show which means realize which functions.

Applications and use

Funktionsstruktur is used in early design stages to explore alternatives, improve modularization, and ensure coverage of requirements. It supports traceability from customer needs to design features and helps identify gaps or redundancies in the solution. By separating the “why” (needs) from the “how” (means), it enables systematic evaluation of different design options and facilitates collaboration across disciplines.

Elements and representation

A typical Funktionsstruktur includes functions, subfunctions, and means, often depicted as a tree or matrix. Functions are expressed as actions (often in verbs), subfunctions break down higher-level tasks, and means are the elements that perform the tasks. Relationships indicate which means realize which functions, sometimes including multiple means for a single function or shared means among several functions.

Relation to methodology

The concept is widely used in German-speaking engineering and product development and is closely related to function analysis and to methods such as FAST (Function Analysis System Technique) and the Function-Behavior-Structure (FBS) model. It supports structured ideation, requirement traceability, and value optimization.

Example

For a flashlight, the top function is "provide light." Subfunctions might include "generate light via energy conversion" and "focus the beam." Means include the battery, LED, reflector, lens, and switch.