Research On Functional Safety-Critical Degree Of Mechanical&Electrical Products

Mechanical and electrical products has become necessities in our daily life, theirpresence greatly improves our life standard. However, due to the constraints of humanknowledge and technical capacity, mechanical and electrical products may bring about lots ofsafety related risk for the people, which is difficult to be fully taken into account in the designphase, especially new products. These risks may result in huge property losses and casualtiesin appropriate conditions. Therefore, improving the product safety has become one of themost important designers’ task.At present, the description of product safety is based on the components. This way maybring about lots of work and huge cost for designers when they are facing with large andcomplex systems. Therefore, this paper will be on the basis of the functional hazard analysisof MIL-STD-882and related research of product safety, and it will establish a new safetyanalysis mode in a functional perspective. Firstly, we use the function tree for decomposingthe products and use FMEA for analyzing the functional hazard in different grades. Secondly,we build some function fault trees and calculate the contribution degree of the failure modeThirdly,we will use AHP for the weight coefficient of the accident. Then the two values aresynthesized, and the result represents every failure mode contribution degree of the productsafety. Finally, for all failure modes which belong to a sub-function, the overall functioncontribution degrees of the product safety are synthesized. The final value is used to describethe functional safety-critical degree of the product. The way can be applied to large complexsystems to help designers and users to more clearly understand product safety in a newperspective so that they can re-design or choose another one.Finally, we take the automotive brake system for example to verify the application of thisstudy by getting the functional safety-critical degree, which are achieved through thefunctional decomposition, hazard analysis and functional tree analysis.