超声疲劳试样动态应变测量及应力检定方法

Measurement Approach of Dynamic Strain and Stress Calibration for Ultrasonic Fatigue Specimen

超声疲劳试验技术是实现超高周疲劳测试的有效手段。然而,目前超声疲劳测试缺少应力检定方法,难以保证测试结果的可靠性与准确性。本文首先给出了超声疲劳测试中不同形状试样的设计方法和应力分布理论公式;然后,利用高速动态应变仪和高速相机对不同形状超声疲劳试样的动态应变进行测量,并将测试值和理论值进行了对比分析,证明了超声疲劳试样应变测量的可行性与准确性。在此基础上,提出了基于应变测量结果的超声疲劳试验检定方法,利用测得的应变值对应力值进行校核或修约,有效保证了超声疲劳测试的可靠性和准确性。

Ultrasonic fatigue technology offers an alternative and effective method for very high cycle fatigue testing.However,there is no stress calibration method for ultrasonic fatigue testing to assure the testing reliability and accuracy.Ultrasonic specimen design and stress distribution formula of different shapes are firstly introduced in this work.Then,high speed strain gauge and high speed camera based digital image correlation are utilized to measure the dynamic strain of ultrasonic fatigue specimen.The consistency of the measured results and the theoretical values confirms the feasibility of strain calibration for the ultrasonic fatigue specimen.As the linearity of the ultrasonic testing system,the stress can be calibrated according to the measured strain and the dynamic elastic modulus to ensure the reliability and accuracy of ultrasonic fatigue test results.