Question

The true stress-true strain of several Al alloys that can be used in manufacturing a component in an aircraft is given by g = K €", where K is a constant and n the strain- hardening exponent. The manufacturing process involves sheet forming. During use, the component will be subjected to the following stress tensor: 10 20 0 20 -20 0 00-5 MPa The following information regarding available materials Alloy allowable Tallowable Cost/part Density (g/ce) (MPa tension (MPa) 3.05 0.22 SS 2,000 2,200 2.42 0.05 2.40 0.25 1,000 2.40 0.27 2,000 E 2.42 0.24 40 2,500 2.41 0.24 61 40 5,000 You were absent for two weeks. During your absence, your group recommended to the senior manager that material (C) be selected partly due to its low cost and partly due to its low density. What action should you take? (a) You accept the decision of your group. (b) You perform your calculations to check the selection of your group If the selection of your group is not correct, what should you do?

Answer 1

Givendata: 10 до о stress Tensor 20 -20 o rniPad, o o -5 (A No, I won't accept the decision the Mastm Max normal of shear strets struts tensor, are below the Fallow without checking for the given and Tallowble W @ material ' cis mot suitable. for the given the stress stresses Reason: principle tensor are 2. І с -4 = 0 І— Гаt Сут бъ 1, = a gr 6, - та-а-с. 1 - Та у 6+r 2 гау Туз Тә4 +4° - (т) = Г4 Tay (12) як у Ту- - - с. Г10 до о 20 - 20 | o o-s | І, = 0, + Our (2 = 10 - 20 -5 - - 15. х = 10(-20) + (-20)(-5)+(-5) 10 - (20) - = -2.00 + 100 -50 - 400 2 - 550

Iz = (10) (-20) (-5) -(20)(-5) 2 3000 allow 73+15= ? 5500-3000=0 solving the above equation 5,= 20 = -30 = -5 For material c all = 21MPa T = 26MPa one of the principle is dis very close to the o is also greater tham Follow Je> Tall. seat matrial will fails for the given su stressed. = max (10,- 62, 62-03h (ozoid subjected given the & man 5-20 20 + 30 = 50, 02-= -3075 = 25 =- 25 Tma. = 50 = 25 man ~ Tallow i imar is close to the Tallow Hence material & is not suitable sl material 'A' is suitable