：In the ultrasonic-assisted metal forming process, the dislocations within the material are easier to move due to the absorption of ultrasonic energy, which can effectively promote material flow and improve the formability of components, this phenomenon is called the ultrasonic softening effect. The ultrasonic softening effect is generally treated as homogeneous at the whole materials for simplicity, while the attenuation of the ultrasonic energy along the propagation direction will bring inhomogeneous distribution of softening degree. In addition, the absorption of the ultrasonic energy by material is also affected by the dislocation movements in the metal plastic processing procedure, resulting in the variation of the ultrasonic attenuation characteristics in the material with the plastic deformation, the current research has little concerned it. In this paper, the ultrasonic attenuation properties in 2219-O aluminum alloy with plastic strain were investigated. The influence of the dislocations and the dislocation movements caused by plastic deformation on the ultrasonic attenuation was characterized. The pre-strain specimen was designed to indicate the degree of plastic deformation of the material, and the specimen thickness direction was defined as the propagation direction of the ultrasonic energy. The experimental results and the microstructure observation showed that the absorption of ultrasonic energy by the material increases firstly and then decreases with the plastic strain increasing, which is related to the evolution of movable dislocations within the material. In order to accurately describe the ultrasonic energy attenuation characteristics in plastic deformation, the hardening equation of 2219-O aluminum alloy considering ultrasonic propagation distance and plastic strain was built and the model accuracy was verified based on the experimental data.

Current studies have shown that the application of composite energy fields in the plastic forming process can help reduce the forming load and promote material flow. In this paper, a new method of ultrasonic-assisted spinning integral forming for thin-walled cylindrical parts with outer ribs was proposed, which could not only improve the manufacturing efficiency of ribbed cylindrical parts, but also further improve the forming height of outer ribs. A simulation model of ultrasonic-assisted spinning for thin-walled cylindrical parts with longitudinal and transverse outer ribs was established, the influence of ultrasonic amplitude on the forming accuracy of longitudinal and transverse outer ribs was obtained, and the mechanism of ultrasonic vibration improving the forming accuracy of ribs was revealed. On this basis, ultrasonic-assisted spinning equipment was built to verify the feasibility of this process. The results showed that with the increase of ultrasonic amplitude, the forming height of longitudinal and transverse outer ribs gradually increases, and the effect of raising the forming height of transverse ribs is higher than that of longitudinal ribs. In addition, as the ultrasonic amplitude increases, the uniformity of the forming morphology of the outer rib is not obviously improved. The spinning of the outer rib is mainly realized by the material in the form of integral filling into the groove. The ultrasonic vibration improves the material flow properties, and promotes the filling of the material into the rib groove, thereby increasing the spinning forming height of the outer ribs. The forming height of the outer rib was measured with or without ultrasonic vibration. When the rolling reduction is 1 mm, the average forming height of the outer ribs is increased by 50% compared with that without ultrasound, which provides a new research idea for the integral forming of the spinning of thin-walled cylindrical parts with longitudinal and transverse ribs.

In the ultrasonic-assisted metal forming process, the dislocations within the material are easier to move due to the absorption of ultrasonic energy, which can effectively promote material flow and improve the formability of components, this phenomenon is called the ultrasonic softening effect. The ultrasonic softening effect is generally treated as homogeneous at the whole materials for simplicity, while the attenuation of the ultrasonic energy along the propagation direction will bring inhomogeneous distribution of softening degree. In addition, the absorption of the ultrasonic energy by material is also affected by the dislocation movements in the metal plastic processing procedure, resulting in the variation of the ultrasonic attenuation characteristics in the material with the plastic deformation, the current research has little concerned it. In this paper, the ultrasonic attenuation properties in 2219-O aluminum alloy with plastic strain were investigated. The influence of the dislocations and the dislocation movements caused by plastic deformation on the ultrasonic attenuation was characterized. The pre-strain specimen was designed to indicate the degree of plastic deformation of the material, and the specimen thickness direction was defined as the propagation direction of the ultrasonic energy. The experimental results and the microstructure observation showed that the absorption of ultrasonic energy by the material increases firstly and then decreases with the plastic strain increasing, which is related to the evolution of movable dislocations within the material. In order to accurately describe the ultrasonic energy attenuation characteristics in plastic deformation, the hardening equation of 2219-O aluminum alloy considering ultrasonic propagation distance and plastic strain was built and the model accuracy was verified based on the experimental data.