Q4 (a) (c) Explain how Brittle fracture differs from that of Ductile fracture. In your answer include several (6 marks) materials and situations where these fractures may occur. (b) The following graph shows the influence of porosity on the flexural strength of aluminum oxide (8 marks) at room temperature. Explain how the volume fracture of porosity has such an influence on the strength of the alumina. DT022/3 DT023/3 Flexural strength (MPa) 250 200 150 100 50 May 2018 14984 MATR3111 16738 MATR3111 о 0.0 0.1 0.2 0.3 0.4 0.5 0.6 Volume fraction porosity 250 200 150 100 50 Flexural strength (MPa) Figure Q4. The influence of porosity on the flexural strength of aluminum oxide at room temperature. A wing of an aircraft is fabricated from an aluminum alloy with a plane strain fracture (5 marks) toughness of 40 MPa.m2, It has been determined that fracture occurs at a stress of 365 MPa when the maximum internal crack length is 2.5 mm. For this same component and alloy, compute the stress at which fracture will occur for a critical internal crack length of 4.0 mm. (d) Comment on your answer in section (c). (1 mark)