Chapter One Materials and Mechanical Elements Lesson 1Introduction for Materials Designers and engineers are usually more interested in the behavior of materials under load or when in amagnetic field in why they behave as they do.Yet the better one understands the nature of materials and the reasons for their physical and mechanical properties the more quickly and wisely will he/she be able to choose the proper material for agiven design.Generally,a material property is the measured magnitude of its response to astandard test performed according to astandard procedure in agiven environment.In engineering materials the loads are mechanical or physical in nature and the properties are recorded in handbooks or,for new materials,are made available by the supplier.Frequently such information is tabulated for room-temperature conditions only,so when the actual service conditions are at subfreezing or elevated temperatures,more information is needed.