The Measurement of the Mode II Fracture Toughness of Adhesive Gypsum Using Short Beam Compression Test

• Main Authors: jia-wei tsai, 蔡佳偉
• Other Authors: Chein-lee Wang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/16570537022408229597

碩士 === 國立成功大學 === 資源工程學系碩博士班 === 96 === This study attempts to measure the Mode II (sliding mode) fracture toughness of intact gypsum and adhesive gypsum under the short beam compression testing. The gypsum is simulated as the rock-like material and three adhesives including Epoxy(3:1), Epoxy(1:1), Unsaturated Polyester Resin(POLY), are evaluated for their availabilities in surfacial crack repairing. The resulting values of Mode II fracture toughness are analyzed. The effect of confining stress is also investigated in this study. The experimental setup is based on the configuration of the short beam compression with lateral confinement. This study examines the influence of the seperation of crack interval and the effect of confinement on the shear strength of the specimen. It is found that the testing condition is favorable for Mode II when the seperation ratio is between 0.1 and 0.25 for the unconfined test. When the seperation ratio exceeds above specified range, the fracture condition will result in an undesirable tensile failure. The increase in confining stress decreases tensile stress on the slot tip and hence obtains a favorable mode II condition. This study finds that the Unsaturated Polyester Resin(POLY) adhesive gypsum has the best response under confining condition. This study also uses a finite element package ANSYS to evaluate the correlation equation of critical stress intensity factor (fracture toughness) for the short beam compression test. The regression formula for fracture toughness is derived. The regression formula derived from this study is also compared with the results obtained from Wang(2007) and Ko & Kemeny(2006). The comparison is found to be consistent.