激光透射塑料焊接剪切强度测试方法分析研究

Study on tensile shear strength testing of plastic plaques jointed by laser transmission welding

选取透明有机玻璃(PMMA)板条和半透明聚苯乙烯(PS)板条试样搭接后进行了激光焊接,按照目前常用的两种塑料焊接强度测试方法在万能材料试验机上试验观测,对观测结果的测量和分析证明:第一种塑料焊接强度测试方法(两块板条搭接未做贴附补偿)会因为附加力矩的作用改变焊接面受力状态,第二种塑料焊接强度测试方法(两块板条搭接做贴附补偿)仍然会产生附加力矩,贴附补偿不能保证焊接面受力状态回归到纯剪切状态,最后讨论了附加力矩所带来偏转角Ф大小的主要影响因素。

Polymethyl methacrylate （PMMA） transparent plaque and polystyrene （PS） semitransparent plaque were jointed together by laser welding, and the tensile shear strength of the resultant samples were examined by two widely accepted testing methods, simple-lap method without additional joint and simple-lap method with additional joint. The comparative testing results show that simple-lap joint method without additional joint can not keep the stress at vertical definition to the plaque surface during testing, and the simple-lap method with additional joint also fails in shielding the specimens from tensile stress during testing, due to the existence of additional bending moments. It implies that the additional lap joint at the fixture block is not successful in providing pure shearing stress condition for the plaques. And the main factors of the deflection distortion angle （Ф） caused by additional bending moments are also discussed.