4. Failure Mechanics, Design and Reliability Testing

This chapter will deal with concepts of failure mechanism, design and reliability testing. Important design aspects of mechanical structures that implement the intended function and have its mechanism in the design process have a good quality—stiffness and strength for its own loading. Product requirements on stiffness, being the resistance against reversible deformation, may depend on their application. Strength, the resistance against irreversible deformation, is always required to be high through the design of product shape. If there is faulty design in the structure where the loads as an uncontrollable noise factor are applied, product will suddenly collapse in its lifetime. The failure mechanics of mechanical product is facture and fatigue—main Physics Of Failure (POF), which can be characterized by the stress (or loads) and materials on the structure. As modifying the shape and material in the structure, engineer would improve the faulty designs and increase its lifetime. These activities are called design. To improve the quality (or design) of product, (qualitative) method like FMEA, FEA, and Taguchi method will be established in the last century. On the other hand, quantitative method using reliability testing is still developing. The final goal of reliability testing is to discover the design problems and reveal if the reliability target for product is achieved.