瓷砖胶粘结层剪切强度测试机理及方法改进研究

Research on the Testing Method for Shear Strength of Tile Adhesive Bonding Layer

准确测量瓷砖胶粘结层剪切强度对有效预防瓷砖脱落至关重要.本文首先改造常规拉力试验机,设计出一种基于单搭接接头的剪切测试装置,开展不同厚度瓷砖胶粘结层的剪切强度测试试验,结果表明:接头破坏模式均为粘结界面脱粘开裂破坏,无瓷砖胶内聚破坏;瓷砖胶层厚度越大,粘结层剪切强度越低.建立数值模型计算分析发现,单搭接接头剪切时会产生附加弯矩,导致纯剪变为拉剪,从而产生试验误差,且瓷砖胶厚度越大,剪切时因附加弯矩产生的误差越大.为消除附加弯矩对剪切测试结果的影响,本文改进剪切试验装置,通过双搭接接头对称加载的方式,有效避免因附加弯矩产生的试验误差,提高瓷砖胶粘接层剪切强度测试结果的准确性.

Accurate measurement of the shear strength of the tile adhesive bonding layer is crucial for effectively preventing tile detachment.Initially,a conventional tensile testing machine was modified to design a shear testing device based on a single lap joint,and shear strength tests were conducted on tile adhesive bonding layers with different thicknesses.The results show that the joint failure mode is adhesive interface debonding and cracking,with no cohesive failure in the tile adhesive.The thicker the tile adhesive layer,the lower the shear strength of the bonding layer.Further numerical simulations revealed that additional bending moments occur during the shearing of the single lap joint,transforming pure shear into tensile shear action,leading to experimental errors.The thicker the tile adhesive,the larger the error caused by the additional bending moment during shearing.To eliminate the influence of additional bending moments on shear test results,an improved shear testing device was proposed.By symmetrically loading through double lap joints,the experimental errors caused by additional bending moments were effectively avoided,enhancing the accuracy of shear strength test results of the tile adhesive bonding layer.