Detection of damage in carbon fiber woven composite using nondestructive vibration examination

• Main Authors: Hao-yuan Wu, 巫浩原
• Other Authors: Wei-pin Lee
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/51144549249585602043

碩士 === 逢甲大學 === 紡織工程學系 === 87 === The purpose of this study is to use a nondestructive vibration-based examination method to find the damage location and damage effect of a carbon fiber textile composite. First, we fabricate the carbon fiber textile by weaving process. Then, we make the textile composite. The composite specimen is fixed as a cantilever beam. The fundamental natural frequency is measured. The gapped smoothing damage detection method is used to find the damage index of every location. The damage index becomes larger when a damage is detected. The magnitude of damage index presents the strength reduction caused by the damage. The undamaged comparison specimen is not needed in this method. The finite element method is used to calculate the stiffness matrix K and mass matrix M. Substituting into the vibration equation, we derived the eigenvalue problem. The eigenvalues and eigenvectors are solved. The fundamental natural frequency and natural vibration mode can be found. The results will be compared to the experimental results. We will also use the traditional method of material mechanics to analyze the problem. The beam will be analyzed section by section using the force-displacement and moment-displacement relationship, we will derive a vibration equation to find the fundamental natural frequency. The results will also be compared to those by the finite element method and by the experiments. This nondestructive examination method does not need a comparison specimen. It can detect the damage effect and location. Verified by theoretical analysis, it provides the engineers whether the material is still in good condition. This method should have lots of applications in engineering.