INTRODUCTION

The design of equipment to withstand shock and vibration requires (1) a determination of the loads and resultant stresses acting on the equipment, and (2) the selection of a suitable material. The loads and stresses may be determined from an appropriate model of the equipment as described in Chap. 41. This chapter describes some of the considerations required to adapt the results from the model analysis to the selection of suitable materials, including such engineering properties as the stress-strain properties of metals and metal fatigue.

The selection of an appropriate material often involves an evaluation of the types of stress condition to which the equipment will be subjected. If a small number of severe stresses constitute the most critical situation, the most important consideration is to design the equipment for adequate strength. For equipment that will be subjected to sustained vibration or a large number of repeated applications of a load, fatigue strength is likely to be the critical design parameter. The relative importance of these types of loading must be determined for each application.

When strength is the primary design factor, an appropriate balance between stress and ductility is the most important consideration. Analytical models generally indicate the maximum stress based on linear properties of the material. If nonductile materials are used or if permanent deformation cannot be tolerated, the equipment must be designed in such a way that the stress does not exceed the elastic limit of the material. In some cases, permanent deformation...