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Contours of equal moduli. For E x , Eq. (4.2.17) . Material properties of Graphite Epoxy from Ex. 4.2.1. Can you see what they are? What sanity checks can you apply?. 4.2.3 Optimization of stack thicknesses.
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Contours of equal moduli • For Ex , Eq. (4.2.17) Material properties of Graphite Epoxy from Ex. 4.2.1. Can you see what they are? What sanity checks can you apply?
4.2.3 Optimization of stack thicknesses • Usually, we do not maximize stiffness or strength for given thickness, but instead we minimize thickness for required stiffness or strength. Why? • Furthermore, often the ply orientations are given, and the only question is how much of each ply should we take. • We mentioned test data as a reason to use only certain ply angles (like 0,90,45), but continuity between panels in wing or fuselage structures is another reason.
Example 4.2.5 from another angle • In Example 4.1.1 we had graphite epoxy with • The limit on strains required h • Now we want the thinnest laminate of the form • We expect both constraints to be active or near active. Why? • Then we expect to change the ratio between and from 20:1 to 5:1.
Contours for different material, but… • Where should we be on Miki’s diagram? • Solution obtained in textbook is • Does it check by the figure?
Check on thickness with the other graphite/epoxy • For the graphite epoxy of Example 4.2.1/5 • The corresponding Tsai-Pagano properties • Converting stiffness requirements to SI units 1[lbf/in] = 175.126836986433 [N/m] • Ply thickness is 1.27e-4 m.
