Basic properties of materials

Abstract

Goals After reading this chapter the student will understand the following. The mechanical properties and behavior of materials. Material failure under ductile or brittle conditions. The time-dependent mechanical behavior of materials. Corrosion and its various forms. Concepts related to the basic surface properties of materials. In everyday life, we often define materials using relative terms such as soft or hard, flexible or rigid, strong or weak, tough or brittle, and in a variety of other qualitative ways. What do these terms really mean in the world of engineering? Is such qualitative categorization sufficient for the design and manufacture of a product? The answer is definitely a no, especially when human health or lives may depend on the product. For example, you certainly would not want engineers who are building bridges to pick materials based on such relative and qualitative descriptions! Choices based on much more rigorous, scientific, and quantitative characterization would be expected. The same is true when selecting biomaterials. Material properties can be characterized quantitatively using standardized tests under defined conditions. Once characterized, these properties can be used in conjunction with engineering design techniques to predict the behavior of the engineered product under the expected operating conditions and to ensure that it would function safely. This is important because properties may change based on independent variables such as temperature or rate of application of force. Often a variety of material properties need to be considered for each product.