SYMPOSIA PAPER Published: 01 January 1997

Measurement of Orthotropic Elastic Constants of Ceramic Matrix Composites from Impact Sound


The isotropic and/or orthotropic elastic constants of ceramic matrix composites are measured from the impact sound of a small rectangular bar specimen which is suspended by thin ceramic threads in a furnace. The natural frequencies at high temperatures of the flexural and torsional vibration modes are measured from the impact sound using a fast Fourier transform analyzer and elastic constants are computed from these frequencies using Timoshenko's beam theory and Saint-Venant's torsion theory. The natural frequencies of a rectangular silicon carbide/silicon carbide (SiC/SiC) plate are also measured at high temperatures and its elastic constants are determined using an iteration technique employing a finite element method. This technique is extended to measure the natural frequencies of a jet engine nozzle flap made of SiC/SiC composite panel from the impact sound before and after engine operation, and thus the damage of the flap is evaluated as the reduction of the Young's modulus of the material.

Author Information

Sakata, M
Takushoku University, Tokyo, Japan
Ohnabe, H
Composite Materials Center, Aero-Engine & Space Operations, Ishikawajima-Harima Heavy Industries Co., Ltd., Tokyo, Japan
Price: $25.00
Contact Sales
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Developed by Committee: C28
Pages: 219–233
DOI: 10.1520/STP11823S
ISBN-EB: 978-0-8031-5365-3
ISBN-13: 978-0-8031-2033-4