Problem 2: External satellite panel (Ashby E3.28, 20 points) E3.28. An external panel of a satellite is made of the Grade 9 titanium alloy Ti-3Al-2V, with a yield strength o, of 550 MPa and Poisson's ratio v of 0.36. The panel heats up when the face of the satellite is directly exposed to the sun and cools when the sun is obscured by Earth. The panel is rigidly constrained around its edges by attachment to the frame of the satellite, which is maintained at a constant temperature in order to stabilize the electrics it contains. If the temperature of the panel can vary from -80"C to + 120"C. is there any risk that the resulting thermal stress might cause the panel to yield? Read the value of the thermal stress parameter o E for titanium alloys from Fig. 3.13 and use it to find out. (Here a is the thermal expansion coefficient and E is Young's modulus.) 1000 0.1 E -IMPak ummm Elastomers Polymers T-expansion - modulus PIPE 100 Metals Thermal expansion, a (ustrain/k() Foams 10 Natural materials Nontechnical ceramics Composites Technical ceramics CE - 001 MARK 0.01 0.1 10 100 1000 Young's modulus, E (GPa) FIGURE 3.13 The linear expansion coefficient, or, plotted against Young's modulus, E. The contours show the thermal stress created by a temperature change of 1"C if the sample is axielly constrained. A correction factor C is applied for biaxial or triaxial constraint (see text)