Department Seminar of Dan Davida - Anisotropic Disk Diametral Compression: Analytical and Experimental Study for Mechanical Characterization of Ceramic Matrix Composites
School of Mechanical Engineering Seminar
Wednesday, January 5th, 2021, at 14:00
Wolfson Building of Mechanical Engineering, Room 206
Advisor: Prof. Rami Haj-Ali
Anisotropic Disk Diametral Compression: Analytical and Experimental Study for Mechanical Characterization of Ceramic Matrix Composites
Composite materials are an integral part of many industries, such as aerospace, rocketry, automotive, sports, etc. One particular class of composites is the Ceramic Matrix Composites (CMC) which excel with their ability to withstand high-temperature conditions without mechanical properties degradation due to their specific strength-temperature ratio.
The CMC system investigated in this research was made from pyrolyzed 8-harness phenolic carbon-matrix composite followed by Liquid Silicon Infiltration (LSI) manufacturing process.
The main objective of the current study is to analytically and experimentally characterize the mechanical properties of an arbitrary CMC system. Analytical-computational models were proposed and examined using the Parametric High Fidelity Generalized Method of Cells (PHFGMC); a highly accurate and efficient nonlinear micromechanical model.
The first part of this study deals with the characterization of the mechanical properties of the materials through CT scans and the construction of a PHFGMC model in order to create a Repeating unit cell (RUC) that allows for micromechanical analysis, as well as developing a model reduction algorithm using two different methods.
Next, a fully analytical solution of an anisotropic diametrically compressed disk has been developed based on an adaptation of Lekhnitskii's anisotropic elasticity solution. The solution was verified and compared to finite element analysis. In addition, the analytical solution was used in inverse-type mechanics to extract elastic properties from experimental tests conducted on the CMC using the digital image correlation (DIC) method.
A dedicated setup for the diametrical compression disks setup was manufactured and used along with DIC, which provided the full-field strains needed to compare with the analytic solution and iterate to find the CMC's effective properties. The PHFGMC and the analytical and experimental methods are shown to be effective tools to simulate and characterize the linear elastic properties of CMCs. They can be extended to nonlinear and failure of CMCs.