Answer Happy

a) Interpret the following properties of brittle fracture and ductile fracture in terms of: i. Fracture surface [4 marks] ii. Energy absorption [4 marks] iii. Crack propagation [4 marks] iv. Choose the preferred mode of fracture with ONE (1) reason [2 marks] b) i. A metal with an internal crack is loaded with a tensile stress of 20MPa. If the crack length and the radius of curvature are 3.6×10−2 mm and 1.8×10−4 mm, compute its maximum stress. [4 marks] ii. Given that the modulus of elasticity of the metal is 100GPa and the specific surface energy is 3.5 J/m2, compute its critical stress. [4 marks] c) An impact test was done on specimen M and R and the results are shown in Fig. Q2(c) and Table Q2(c). Based on the obtained results, choose whether specimen M or R is brittle or ductile in terms of: i. Impact strength [4 marks] ii. Fracture surface [4 marks]
Table Q2(c) \begin{tabular}{|c|c|c|} \hline Specimen & M & R \\ \hline Impact Strength (J/m2) & 4.35×105 & 1.21×106 \\ \hline \end{tabular}