Closed form approximation of effective elastic moduli of composites with cubic, octet and cubic + octet periodic microstructures

2019 ◽  
Vol 77 ◽  
pp. 103772 ◽  
Author(s):  
George Mejak
Author(s):  
Yu Cheng Liu ◽  
Jin Huang Huang

This paper mainly analyzes the wave dispersion relations and associated modal pattens in the inclusion-reinforced composite plates including the effect of inclusion shapes, inclusion contents, inclusion elastic constants, and plate thickness. The shape of inclusion is modeled as spheroid that enables the composite reinforcement geometrical configurations ranging from sphere to short and continuous fiber. Using the Mori-Tanaka mean-field theory, the effective elastic moduli which are able to elucidate the effect of inclusion’s shape, stiffness, and volume fraction on the composite’s anisotropic elastic behavior can be predicted explicitly. Then, the dispersion relations and the modal patterns of Lamb waves determined from the effective elastic moduli can be obtained by using the dynamic stiffness matrix method. Numerical simulations have been given for the various inclusion types and the resulting dispersions in various wave types on the composite plate. The types (symmetric or antisymmetric) of Lamb waves in an isotropic plate can be classified according to the wave motions about the midplane of the plate. For an orthotropic composite plate, it can also be classified as either symmetric or antisymmetric waves by analyzing the dispersion curves and inspecting the calculated modal patterns. It is also found that the inclusion contents, aspect ratios and plate thickness affect propagation velocities, higher-order mode cutoff frequencies, and modal patterns.


1988 ◽  
Vol 130 ◽  
Author(s):  
D. S. Stone ◽  
T. W. Wu ◽  
P.-S. Alexopoulos ◽  
W. R. Lafontaine

AbstractClosed-form elasticity solutions are introduced, that predict the average displacement beneath square and triangular, uniformly loaded areas at the surface of a bilayer. The solutions aid in the application of depth-sensing indentation techniques for measuring thin film elastic moduli. The elasticity solutions agree closely with experimental data of Al, Si, 1 μm Al on Si, and 2 μm Cr on Si. The case of poor adhesion between the film and substrate is briefly examined.


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