Investigation of Mechanical and Weld Appearance Properties of Polymer Based Composites in Ultrasonic Welding Process

In this paper, ultrasonic lap welding process has been used for welding of standard specimens of polypropylene composites reinforced with glass fiber with 4 mm thickness. The tensile-shear strength and appearance properties of welds under was used different conditions of time, pressure and vibration amplitude and glass fiber content were investigated. To investigation the relationship between input variables and appearance properties of welds and weld strength, the response surface method to decrease the number of experiments and costs considering four factors at three levels. Based on experimental observations, effects of input parameters on appearance of welds were clearly evaluated. The results indicated that amplitude and pressure had the most and the least significant effect on the tensile-shear strength of these composites respectively. Best appearance condition of welds (which has least weld defects) was resulted at an amplitude of 33 µm, welding time of 0.4s, pressure of 1.5 bar and glass fiber content of 10%. Increase of welding pressure, time and glass fiber content in composites has negative effects on welds appearance status and causes weld defects increase.