Experimental study on influence of ultrasonic vibration on forming limit

Applying ultrasonic vibration in sheet metal forming can change its forming mechanism and improve its formability. The uniaxial tensile and bulging forming limit experimental setups were designed to study the ultrasonic vibration and forming limit relationship induced by ultrasonic excitation, and the results under different experimental conditions were analyzed. It was found that ultrasonic vibration has different effects on the left and right sides of forming limit diagram (FLD). Under the same ultrasonic vibration frequency, the maximum increment of left and right major limit strain is about 9.3% and 8.7%, respectively. The former is larger than the latter, and the strain increment increases with the increase of ultrasonic vibration frequency, but the basic shapes of FLD are unchanged.