Effect of ultrasonic vibration on the deformation through indentation test and molecular dynamics simulation

An ultrasonic vibration-assisted indentation device is utilized to implement indentation tests, performed with a spherical indenter under static load and superimposed ultrasonic vibration excitation pressing into the sample to study the volume effect of ultrasonic vibration. The loading forces during the test are acquired by a Kistler force sensor. An indentation molecular dynamics model (IMDM) and an ultrasonic vibration-assisted indentation molecular dynamics model (UIMDM) are developed to study ultrasonic vibration on the microstructure evolution qualitatively. The test results show differences in the effects of ultrasonic vibration on materials with distinct microstructures, where a 17.2% reduction in loading force is observed for the aluminum sample and almost no change for resin. The molecular dynamics results indicate that ultrasonic vibrations do not affect the total potential energy of the model during the elastic deformation stage but increase the total potential energy of the model in the plastic deformation stage, attributed to the absorption of the ultrasonic vibration energy by the generation of dislocations. Simultaneously, ultrasonic vibration reduces the resistance to dislocation motion, the Peierls-Nabarro force, and increases the von Mises stress within the model, the driving force for dislocation motion, thus reducing the loading force required for plastic deformation.