343 Summer Midterm

Q1 Sketch the following planes and directions within a cubic unit cell (underlines used instead of bars): (a) [101] (b) [010] (c) [122] (d) [301] (e) [201] (f) [213] (g) (111) (h) (102) Q2 A 0.15% Carbon steel is carburized at 1100° C, giving 0.35% Carbon at a distance of 1mm beneath the surface. If the surface is kept at a 0.90% Carbon, what time is required. You may assume that the diffusion coefficient is 8.3 x 10-7 Q3 The following data were collected from a standard 0.505 in diameter test specimen of a copper alloy (initial length (lo=2.0 in); Load (lb) 0 3000 6000 7500 9000 10500 12000 12400 11400

Extension (in) 0 0.00167 0.00333 0.00417 0.0090 0.040 0.26 0.50 (max load) 1.02 (fracture)

after fracture the total length 3.014 in and the diameter was 0.374 in. Plot the data and calculate the 0.2% offset yield strength along with. (a) the tensile strength (b) the modulus of elasticity (c) the % elongation (d) the % reduction in area (e) the engineering stress at fracture (f) the true stress at fracture.

PROBLEM (4): A solid bracket of 3” diameter with dimensions AB=10” and BC”=10”

is shown in the diagram. If a load P is applied at C as shown what is the state of stress on the top of the bracket at the wall (see inset)? What are the principle stresses and maximum in-plane shear stress for this stress element. If the failure stress for the material is 50 psi what is the maximum load P that can be applied (use the maximum distortion energy criterion).

P