Final answer:
When pressure is applied to a metal specimen causing it to stretch irreversibly, this indicates plastic deformation beyond its elastic limit. Understanding stress, strain, and tensile strength is crucial in designing applications subjected to load, such as metal structures and medical implants.
Step-by-step explanation:
When a metal specimen begins to stretch while pressure is gradually applied, this is known as plastic deformation. Initially, metals exhibit an elastic behavior—as outlined by Hooke's law—where they return to their original shape upon removal of the load. However, as the stress goes beyond the elastic limit, the material begins to deform irreversibly.
This is because metals start to behave plastically beyond the elastic limit; thus, they do not regain their original shape after the load is removed, indicating permanent deformation. Additionally, tensile strength is the maximum stress that a material can handle before it fails or fractures under tension.
Understanding the concepts of stress, strain, and tensile strength is crucial in various applications, such as the design of metal structures and medical implants, where knowing the material’s behavior under load is imperative for safety and functionality. For instance, in medical applications, metal implants must be designed to accommodate thermal stress and have similar expansion coefficients to prevent failure or discomfort.