Function Analysis System Technical

A Diagramme FAST (Functional Analysis System Technical) presents a rigorous translation of each function of service in function (S) technical (S), then materially in solution (S) constructive (S). Diagram FAST is built from left to right, in a logic of why with how. Thanks to its Technical culture and Scientific, the Engineer develops the functions of service of the product in technical functions. It chooses solutions to build the product finally. Diagram FAST constitutes then a whole of essential Données making it possible to have a good knowledge of a complex product and thus to be able to improve the solution suggested.

Two types of functions

Functions of service

The functions of service constitute a relation between the system and the external medium, they translate the action awaited or carried out by the product to answer an element of the need for a given user. One often needs several functions of service to meet a need. In a given study, their enumeration and their qualitative and quantitative formulation result from the analysis of the need to satisfy and describe it in a way necessary and sufficient.
There exist two types of functions of service:

  • principal functions, corresponding to the service rendered by the system to meet the needs.
  • forced functions, representing reactions, resistances or adaptations to elements of the external medium.

Technical functions

The technical functions are interns with the product, they are chosen by the manufacturer within the framework of a solution, to provide a function of service.

Schematization

Here the typical example of the diagram:

The method is based on an interrogative technique:

  • Why? why a function have does to be assured? Access to a technical function of a higher nature, one answers it by reading the diagram from right to left.
  • How? how this function have does to be assured? The function then is broken up, and one can from left to right read the answer to the question by traversing the diagram.
  • When? Quand this function have does to be assured? Seek simultaneities, which are then represented vertically.

The answer to each one of these questions is neither exclusive, nor single. Also there exist two types of junctions between the various columns, the junctions of the " type; et" , and junctions of the " types; ou".
One represents the connections or by two arrows (or more) on the basis of the same origin, whereas a connection " et" separates after the box representing the function origin. Here an illustration:

The functions must be described by a verb with the Infinitif.

One answers the questions in the following way:

In order to allow an easy comprehension of all, this type of representation is normalized. At the national level (French) it is controlled by the Norme NF INTO 1325-1 which describes the broad outlines of this method.

An example

One is interested in a autopilot of boat . One of its principal functions of service is: " To maintain the cap". Diagram FAST will be then:

Of course, it will be necessary to carry out a diagram FAST for each function of service, in particular of the forced functions. One of the functions forced here could be " to resist the humidité".

See too

References

  • R. PAPANICOLA, Diagram FAST , http://www.sciences-indus-cpge.apinc.org/Sys4-FAST?var_recherche=fast

  • Course of MPSI in Saint-Louis

External bonds

  • industrial Sciences in classes preparatory, diagram FAST

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