ROLE OF DESIGN IN ACHIEVING RELIABILITY

One of the most important methods for achieving high reliability is through design.  Use reliability cannot be higher than the design reliability of a device or equipment.  Selecting the type of components, derating, application of type of redundancy, improving  maintainability,  system simplification,  etc.  are  decided during the design stage of equipment. These concepts are discussed in detail.

Initially, an estimate of system reliability is predicted for a given design using parts count method.  Alternate designs are compared on this basis and the best one is accepted for detailed analysis using parts stress method. This is the most accurate method for reliability prediction of a design. Within the constraints of available resources, a best design can be selected in this way.

Once this is over, a detailed Failure Mode Effect Criticality Analysis is conducted to locate the weaker links of the system design, and these are eliminated by reducing stresses or use of more robust components, to further improve the design.