Forming mechanism of ultrasonic vibration assisted compression

To study the mechanism of ultrasonic vibration assisted forming, the static and vibration assisted compression tests of aluminum 1050 were carried out via a 25 kHz high-frequency ultrasonic vibration device. It is found that vibration reduces the flow resistance and improves the surface topography. The force reduction level is proportional to the ultrasonic vibration amplitude. By using numerical simulation of static and vibration assisted compression tests, the deformation characteristics of material were investigated. Throughout the vibration, the friction between the materials and tools reduces. The stress superposition and friction effects are found to be two major reasons for reducing the force. However, the force reduction because of stress superposition and friction effects is still less than the actual force reduction from the tests, which suggests that softening effect may be one of the other reasons to reduce the force.