Low-Velocity Impact Response of Metamaterial Units

• Main Authors: Meng-Jie Chen, 陳孟杰
• Other Authors: Hsin-Haou Huang
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/48210834852621887284

碩士 === 國立臺灣大學 === 工程科學及海洋工程學研究所 === 103 === This thesis extends the theoretical study of the mass-in-mass structure. Low-velocity impact response of mass-in-mass unit cell is investigated by two experimental methods. The mass-in-mass unit cell is manufactured by 3D printing technology. Modification is made by drilling holes on the shell for easiness of observation of the internal motion, and for decreasing the mass of the shell. In the first step of experiment, the bounce height of mass-in-mass ball and equivalent ball is recorded by high-speed camera for comparison. The result shows that the bounce height of mass-in-mass ball is lower than equivalent ball which means the mass-in-mass ball has impact-mitigation capability. Second, the relation between resonance frequency of mass-in-mass ball and bounce height is investigated. To predict the COR (coefficient of restitution) of mass-in-mass ball with different resonance frequency, trend line is built according to the experimental results. In addition, the impact response of two different specimens are observed. According to the research of cellular solids, structure with buckling property is fabricated by 3D printing technology. The self-designed drop impact tester is used to perform impact test, and the deformation of structure is recorded. Finally, a structure combining local resonance and buckling property is introduced. The experimental results show that the structure has a better impact-mitigation capacity.