M5 Engineering mechanics stress and Strain

Toughness is best defined as the

• energy absorbed by a material without yielding.

• area underneath the stress-strain graph up to the yielding point

• energy absorbed by a material without fracturing

• ability of a material to resist deformation.

A material’s toughness is equal to the area under which part of the stress-strain curve.

• Elastic

• Plastic

• Both

• None

Hooke's law holds true up until the

• yield point

• proportional limit

• breaking point

• elastic limit

An applied load on a wire causes its radius to double. Determine the effect this will have on the Young’s modulus.

• Doubled

• Halved

• Quadrupled

• No effect

The tensile strength of a material is obtained by dividing the maximum load during the test by the

• minimum area after fracture

• area at the time of fracture

• original cross-sectional area

• average of (b) and (c)

If a part is heated and its movement is restricted, what stress will it experience as a result

• no stress

• tensile stress

• shear stress

• compressive stress

What can we deduce about a material if a test piece returns to its original shape after the load has been removed?

• It is plastic

• It is elastic

• It does not obey Hooke’s Law

• It has high stiffness

A material that does not give any indication of deformation when a stress is applied is known as a

• composite

• brittle material

• polymer

• ductile material

Factor of safety for a ductile material is the ratio of

• Ultimate stress to working stress

• Ultimate stress to yield stress

• Yield stress to working stress

• Breaking stress to working stress

For metals which have a progressive yield point, the proof stress is determined by drawing a line parallel to the elastic region at a strain of

• 0.2 %

• 0.5 %

• 1 %

• 2 %