Aerospace Materials Lab Final Exam - Spring 1996, Exams of Aerospace Engineering

Download Aerospace Materials Lab Final Exam - Spring 1996 and more Exams Aerospace Engineering in PDF only on Docsity! AEROSPACE MATERIALS LAB (ASE 224L) FINAL EXAM SPRING 1996 Monday, May 13, 9:00 – 11:00 a.m. Location: ENS 145 There are four questions in this exam. The number of points assigned to each question is shown in parenthesis. This is a closed exam, so you should not make any reference to notes, homeworks, books, etc. Name: __________________________________________ Section T W (Circle one) 1. a) Use a simple strength of materials approach to show that the moduli of a fiber reinforced polymer matrix composite are Ec o = ν f E f + vmEm parallel to the fibers and 1 Ec 90 = v f E f + vM EM perpendicular to the fibers. (5) b) Suppose you were given a sheet of unidirectional fiber reinforced composite, slicing saw, three-axis strain gage rosettes (measures two normal strains and the shear strain at a point) and a uniaxial testing machine. The fiber volume fraction of the sheet was 65%. The results of several tests are tabulated below. α ε x1 ε y1 γ x 1 y 1 σ x1 (%) (%) (%) (ksi) -60 0.1 0.024 -.005 15.4 -30 0.1 0.035 0.0 20.0 0 0.1 0.024 0.005 15.4 30 0.1 0.020 0.010 10.5 60 0.1 0.0024 0.0 1.4 Determine the tensile components of the compliance matrix and the fiber and matrix modulus. (6) c) The failure stains in tensile tests parallel and perpendicular to the fiber directions were 1.5% and 0.36%. Determine the tensile strengths of the material. (2) d) Explain how you would determine the shear modulus and strength of the material. (2) The compliance matrix of a plane orthotropic material is 1 E 1 −ν 21 E 2 0 −ν 12 E 1 1 E 2 0 0 0 1 G 12               x y x1 y1 α