Question

You can choose between fibres with critical fibre lengths of 0.4, 0.8, or 1.2 mm, all of which have the same strength and stiffness. Which fibre should you choose to achieve the strongest and stiffest composite? Explain your choice. (4 marks) 15.) designing a composite using short glass fibres and an epoxy resin. You are Page 4 of 11 Mid-year Examinations, 2018 PROD111-18S1 (C) 16.) Define specific heat and thermal conductivity. Why are those two properties important for the perception of the warmth of a material? (4 marks) 17.) Sketch a stress-strain curve expected of single diagram. Mark on it the tensile strength, Young's modulus and the strain to failure &r for both materials. No numerical values are required. (4 marks) typical ceramic and elastomer on a 18.) Examine the material property chart below. By what factor is polypropylene less stiff than titanium? Compare and rank bamboo, polypropylene and titanium by their specific Young's modulus. Approximate values are sufficient. (4 marks) Commercially pure titanium 1000 Bamboo 100 10 Polypropylene (PP) 0.1 0.01 Polyethylene (PE) 0.001 1e-4 100 1000 10 10000 Density (kg/m 3) (edo) sninpou s,6unoA

Answer 1

15. Better to select fibre with critical length of 1.2 mm because if the fibres are of optimum length then the matrix and fibre fails simultaneously. That means strength of matrix and fibre will be almost same so no one will be vulnerable to failure. No weak part .