What are the requirements and effects of ultrasonic welding on materials
   The effect of ultrasonic welding is directly proportional to the modulus of elasticity, coefficient of friction, and thermal conductivity, and inversely proportional to its density, specific heat capacity, and melting point.

The effect of ultrasonic welding is mainly related to the melting point of the material and the surface friction coefficient. These parameters are different due to different materials and temperatures, and their changes during the ultrasonic welding process will affect the temperature, stress and deformation of the ultrasonic welding area, thereby affecting the quality of ultrasonic welding.
       However, the ultrasonic welding time is very short, and it is difficult to control the changes of parameters through experiments. Scholars at home and abroad use numerical simulation methods to solve this problem. Liu Chuan used the finite element method to analyze the influence of the physical parameters of polyvinyl chloride (PVC) during the ultrasonic ultrasonic welding process, and obtained that the temperature of the ultrasonic welding area is proportional to the thickness of the sample.
       Influence of welding material modification
       The modification of ultrasonic welding materials will affect the quality of ultrasonic welding. The addition of fillers such as fibers can increase the hardness of polymer materials and facilitate the transmission of ultrasonic waves. Adding fillers can increase the strength of ultrasonic welding joints under appropriate process conditions.
       The influence of material surface roughness
       Increasing the surface roughness of the material can reduce the acoustic impedance and increase the surface energy flow density, thereby improving the quality of ultrasonic welding. The use of film materials with rolling patterns on the surface can achieve higher ultrasonic welding quality, and the strength of ultrasonic welding joints is nearly doubled compared to that of PP film with a smooth surface.
       The influence of material overlap width
       The increase in the material overlap width reduces the strength of the ultrasonic welded joint. Because as the lap width increases, the stress concentration at the edge of the ultrasonic welded joint increases, the microcracks appearing at the edge increase, and the joint strength decreases. The strength of ultrasonic welded joints of glass fiber modified PP prepared by laminating method and dipping method for ultrasonic welding decreases as the width increases.
       The influence of the distance from the welding surface to the welding head
       When the distance from the ultrasonic welding surface of the material to the welding head reaches the half-wavelength value, the strength of the ultrasonic welding joint is maximum.
   Ultrasonic waves are mainly transmitted in plastics as longitudinal waves, and the maximum longitudinal wave peaks often appear at half wavelength. When the distance is close to half wavelength, the ultrasonic waves transmit the most heat energy to the ultrasonic welding interface, and a good ultrasonic welding joint can be obtained.
Ultrasonic ultrasonic welding was performed on HS1000 (aryl phosphate and clay modified polyphenylene ether, half-wavelength of 3.86 cm) of different thicknesses, and it was found that there is a critical thickness of 3.86 cm, which is less than the critical thickness of ultrasonic welding joint strength and elongation As the thickness increases, the strength of ultrasonic welded joints decreases rapidly when the thickness is greater than the critical thickness.