CH 6 Materials Flashcards
Define Stress and Strain. How are they related to each other?
Stress is the force applied per unit area, Strain is the extension per unit length. They are related through Young’s Modulus (E = stress/strain).
What is Young’s Modulus and how is it calculated?
Young’s Modulus (E) is a measure of the stiffness of a material. It is calculated as the ratio of stress to strain (E = stress/strain).
Explain the difference between elastic and plastic deformation
Elastic deformation is reversible deformation, whereas plastic deformation is permanent.
Describe what is meant by the term “limit of proportionality”
The limit of proportionality is the point up to which the stress is directly proportional to strain
What is Hooke’s Law? Up to what point is Hooke’s Law applicable?
Hooke’s Law states that the extension of a stretched wire, x, is proportional to the load or force, F. (F = kx) up to the limit of proportionality
Draw and label a typical stress-strain graph for a ductile material. Identify key points such as the limit of proportionality, elastic limit, yield point, ultimate tensile strength, and breaking point
Typical stress-strain graph labels:
- Limit of proportionality: Linear region end.
- Elastic limit: End of elastic deformation.
- Yield point: Beginning of plastic deformation.
- Ultimate tensile strength: Maximum stress.
- Breaking point: Material fracture.
How does the stress-strain graph of a brittle material differ from that of a ductile material?
A brittle material shows little to no plastic deformation and breaks shortly after the elastic limit.
Define density and provide the formula for calculating the density of a material
Density (𝜌) is mass per unit volume
𝜌 = 𝑚/V
Explain Archimedes’ Principle and how it can be used to determine the density of an irregularly shaped object
What is the significance of the area under the stress-strain curve?
The area under the stress-strain curve represents the toughness of the material.
