CH 3: Mechanical Properties of Materials
Which of the following are the three basic types of static stresses to which a material can be subjected (three correct answers): (a) compression, (b) hardness, (c) reduction in area, (d) shear, (e) tensile, (f) true stress, and (g) yield?
Answer. (a), (d), and (e).
If strain measurements were made during a tensile test, which of the following would have the higher value: (a) engineering strain, or (b) true strain?
Answer. (a).
Most hardness tests involve pressing a hard object into the surface of a test specimen and measuring the indentation (or its effect) that results: (a) true or (b) false?
Answer. (a).
Which one of the following materials has the highest hardness: (a) alumina ceramic, (b) gray cast iron, (c) hardened tool steel, (d) high carbon steel, or (e) polystyrene?
Answer. (a).
Which one of the following types of stress strain relationship best describes the behavior of metals at temperatures above their respective recrystallization points: (a) elastic and perfectly plastic, (b) elastic and strain hardening, (c) perfectly elastic, or (d) none of the above?
Answer. (a).
If stress values were measured during a tensile test, which of the following would have the higher value: (a) engineering stress or (b) true stress?
Answer. (b).
The shear strength of a metal is usually (a) greater than or (b) less than its tensile strength?
Answer. (b).
Which one of the following materials has the highest modulus of elasticity: (a) aluminum, (b) diamond, (c) steel, (d) titanium, or (e) tungsten?
Answer. (b).
Which one of the following types of stress strain relationship best describes the behavior of most metals at room temperature: (a) elastic and perfectly plastic, (b) elastic and strain hardening, (c) perfectly elastic, or (d) none of the above?
Answer. (b).
The plastic region of the stress-strain curve for a metal is characterized by a proportional relationship between stress and strain: (a) true or (b) false?
Answer. (b). It is the elastic region that is characterized by a proportional relationship between stress and strain. The plastic region is characterized by a power function - the flow curve.
Viscosity can be defined as the ease with which a fluid flows: (a) true or (b) false?
Answer. (b). Viscosity is the resistance to flow.
Which one of the following is the correct definition of ultimate tensile strength, as derived from the results of a tensile test on a metal specimen: (a) the stress encountered when the stress-strain curve transforms from elastic to plastic behavior, (b) the maximum load divided by the final area of the specimen, (c) the maximum load divided by the original area of the specimen, or (d) the stress observed when the specimen finally fails?
Answer. (c).
Which one of the following types of stress strain relationship best describes the behavior of brittle materials such as ceramics and thermosetting plastics: (a) elastic and perfectly plastic, (b) elastic and strain hardening, (c) perfectly elastic, or (d) none of the above?
Answer. (c).