为机器零件选材是设计者的基本任务之一。但是,选材涉及的问题很多,目前还没有制定出选材的统一原则。设计者总是根据自己的经验来选材的。由于选材不当而造成的失误也屡见不鲜。假定设计者已经确定了零件的最佳尺寸和作用在其上的力。这样,设计者可以相当精确地确定作用在危险截面上的应力。由于各种钢的弹性模量实际上是一样的 Material selection for machine parts is one of the basic tasks for designers. However, there are many problems involved in material selection. At present, there is no unified principle of material selection. Designers are always based on their own experience to material selection. Errors caused by improper material selection are also commonplace. Assume that the designer has determined the optimum size of the part and the force acting on it. In this way, the designer can fairly accurately determine the stress acting on the hazardous cross-section. Since the elastic modulus of all kinds of steel is actually the same