2003 Fiscal Year Final Research Report Summary
Measurements of Elastic Constants and Internal Friction of Fiber-Reinforced Metal-Matrix Composites and Evaluation of Their Damage : Development of a New Noncontacting Ultrasonic-Measurement Method
| Project/Area Number |
13450277
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Composite materials/Physical properties
|
|---|
| Research Institution | Osaka University |
|---|
Principal Investigator |
HIRAO Masahiko HIRAO,Masahiko, 大学院・基礎工学研究科, 教授 (80112027)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TARUMI Ryuichi TARUMI,Ryuichi, 大学院・基礎工学研究科, 助手 (30362643)
OGI Hirotsugu OGI,Hirotsugu, 大学院・基礎工学研究科, 助教授 (90252626)
|
|---|
| Project Period (FY) |
2001 – 2003
|
| Keywords | Fiber reinforced composites / Ultrasonic measurements / Elastic constants / Internal friction / Resonance / Laser measurement / Noncontact measurement / High-temperature measurement |
|---|
| Research Abstract |
We have determined all five independent elastic-stiffness coefficients C_ij of a silicon-carbide fiber with transverse isotropy from room temperature up to 873 K. First, we measured the C_ij of a Ti-alloy-matrix composite reinforced unidirectionally with the fibers and the matrix alloy alone. Electromagnetic acoustic resonance detected the free-vibration resonance frequencies of the specimens to determine their C_ij. Second, we applied a micromechanics calculation to deduce the fiber C_ij from the measured composite and matrix C_ij. The resulting fiber C_ij, show strong anisotropy in the temperature derivatives of the C_ij, the temperature derivatives for the fiber-axis-direction are much smaller than the others. Also, we developed a methodology to deduce exact elastic constants of an anisotropic solid material without using any advance information on the elastic constants by. incorporating a displacement-distribution. measurement into resonant ultrasound spectroscopy (RUS). The usual
… More
RUS method measures free vibration resonance frequencies of a solid and compares them with calculations to find the most suitable set of elastic constants by an inverse calculation. This comparison requires mode identification for the measured resonance frequencies, which has been difficult and never been free from ambiguity. This study then adopts a laser-Doppler interferometer to measure the displacement-distribution patterns on a surface of the vibrating specimen mounted on pinducers ; comparison of the measured displacement distributions with those computed permits us to correctly identify the measured resonance frequencies, leading to unmistakable determination of elastic constants. Because the displacement patterns are hardly affected by the elastic constants, an exact answer is surely obtained even when unreasonable elastic constants are used as initial guesses at the beginning of the inverse calculation. The usefulness of the present technique is demonstrated with an aluminum alloy and a langasite crystal. Less
|
