ENG1008 Materials Tutorial Week 9

Upon the yielding in a tensile test, (choose all correct statements below)

• plastic deformation starts

• elastic deformation ceases

• material becomes weaker

• material fractures

What are the four main stages of deformation in a ductile material after the elastic deformation? Please put them in the correct order of occurance as _____, _____, _____, _____ (separately by a comma and a space)

The stress-strain curves below represent: red for ____ stress/strain; blue for _____ stress/strain.

• true, true

• engineering, true

• true, engineering

• engineering, engineering

In general, metals and alloys have relatively higher ____ than ceramics and polymers.

• yielding strength

• tensile (ultimate) strength

• ductility

• toughness

Resilience is the ability of a material to store strain energy during ______ deformation?

The toughness of a material can be determined by

• integrating the stress function over the full strain range

• the total area under stress-strain curve

• all energy of mechanical deformation per unit volume prior to fracture

• none of above

Modulus of Resilience can be calculated by the area under stress-strain curve up to

• necking

• ultimate strength

• yielding

• fracture

What is the ductility of the same material on the left and right sides of the transition temperature line?

• ductile, brittle

• brittle, ductile

• ductile, ductile

• brittle, brittle

An alloy has a yield strength of 805 MPa and an elastic modulus of 107 GPa. Calculate the modulus of resilience for this alloy (in J/m3, which is equivalent to Pa) given that it exhibits linear elastic stress-strain behavior.

• $6.6\times10^6$

• $3.3\times10^6$

• $2.2\times10^6$

• $1.1\times10^6$