1- A metallic test piece of rectangular section with a width of 9 mm, thickness 2 mm and useful length of 30 mm was submitted to a uniaxial tensile test, resulting in the force-extension curve in the first moments of the test presented on the side. In the continuity of the test, the maximum force recorded was 1300 N and the final length of the useful region after rupture was 48 mm. Considering these data determine: a- Elasticity module; b- Flow limit; c- Limit of tensile strength; d- Ductility. e- Resilience module. 2- A sample of a brittle material that has a Young's modulus of 150 GPa is pulled in tension. Calculate what minimum stress (in Mpa) will be required for the specimen to fracture in a situation where its greatest defect is a surface crack with a length of 0.3 mm and a radius of curvature at the end of 5.10-4 mm. Assume a surface energy of 0.3 J/m2 .

900 800 70 600 SOO (N) 400 300 200 100 0,02 0,04 0,06 0,08 0,10 (mm) 0,12