(Model answers will be posted shortly after the due date.)

Question 6.3

A specimen of aluminium having a rectangular cross-section of 10 mm by 12.7 mm is pulled in tension with 35,500 N force, producing only elastic deformation. Calculate the resulting strain.

Question 6.8

A cylindrical rod of copper (E=110 GPa) having a yield strength of 240 Mpa, will be subjected to a load of 6660 N. If the rod is 380 mm long, what must its diameter be to allow an elongation of 0.5 mm?

Question 6.23

A cylindrical rod 120 mm long, diameter 15 mm, is to be deformed using a tensile load of 35 kN. It must experience neither plastic deformation nor a diameter reduction of greater than 0.012 mnm. Which of the materials listed below, if any, are possible candidates?

Material	E (GPa)	Yield Strength (MPa)	Poisson's Ratio
Aluminium	70	250	0.33
Titanium	105	850	0.360
Steel	205	550	0.27
Magnesium	45	170	0.2

Question 6.42

For a brass alloy, the following engineering stresses produce the corresponding plastic engineering strains prior to necking:

Engineering Stress (MPa)	Engineering Strain
315	0.105
340	0.220

On the basis of this information, calculate the engineering stress necessary to produce an engineering strain of 0.28.

Question 7.11

Consider a metal single crystal oriented with the normal to the slip plane and the slip direction at angles of 60 degrees and 35 degrees respectively to the tensile axis.

If the critical resolved shear stress is 5.7 MPa, will an applied stress of 12 MPa cause the crystal to yield? If not, what will?

Question 7.30

(i) What is the approximate ductility (%EL) of a brass that has a yield strength of 275 Mpa?

(ii)What is the approximate Brinell hardness of a 1040 steel having a yield strength of 690 Mpa?

Question 7.41

An uncold-worked brass specimen of average grain size 0.01 mm has a yield strength of 150 Mpa. Estimate the yield strength of this alloy after it has been heated to 500 degrees Celsius for 1000 seconds, if it is known that the value of sigma₀ is 25 Mpa.