ME Material Properties and Testing 2 — Questions and Answers
Question 1: Young's modulus (elastic modulus) is a measure of a material's:
- Resistance to plastic deformation
- Stiffness under elastic loading (Correct answer)
- Resistance to fracture
- Ductility
Correct answer: Stiffness under elastic loading
Young's modulus represents the ratio of stress to strain in the elastic region, quantifying a material's stiffness or resistance to elastic deformation.
Question 2: Poisson's ratio relates which two quantities in a material under uniaxial stress?
- Axial strain and lateral strain (Correct answer)
- Stress and hardness
- Thermal expansion and stress
- Yield stress and fracture stress
Correct answer: Axial strain and lateral strain
Poisson's ratio is the negative ratio of transverse (lateral) strain to axial strain when a material is stretched uniaxially.
Question 3: Which non-destructive testing (NDT) method is best suited for detecting internal cracks in a metal component?
- Liquid penetrant testing
- Magnetic particle testing
- Ultrasonic testing (Correct answer)
- Visual inspection
Correct answer: Ultrasonic testing
Ultrasonic testing uses high-frequency sound waves to detect internal flaws and discontinuities inside materials without causing damage.
Question 4: The 0.2% offset yield strength is used because many materials:
- Fracture at exactly 0.2% strain
- Show no proportional limit
- Have no clear yield point (Correct answer)
- Exhibit large Luders bands
Correct answer: Have no clear yield point
Many materials, especially non-ferrous alloys, do not have a distinct yield point, so the 0.2% offset method provides a standardized yield strength value.
Question 5: In materials testing, the term 'gauge length' refers to:
- The total length of the specimen
- The diameter of the specimen
- The measured portion of the specimen in a tensile test (Correct answer)
- The grip length
Correct answer: The measured portion of the specimen in a tensile test
Gauge length is the specific marked length of the specimen over which elongation is measured during a tensile test.
Question 6: Which property describes a material's ability to return to its original shape after the load is removed?
- Plasticity
- Elasticity (Correct answer)
- Toughness
- Creep resistance
Correct answer: Elasticity
Elasticity is the ability of a material to recover its original shape and dimensions after deformation when the applied load is removed.
ME Material Properties and Testing 2
Young's modulus (elastic modulus) is a measure of a material's: