CAJ | 학술논문

材料结构中疲劳微裂纹的产生和扩展是影响其寿命的重要因素，在疲劳裂纹产生初期就将其检测出来对于提高结构安全性至关重要。利用兰姆波探索了铝板反复弯折时判定材料疲劳积累到最终塑性形变断裂失效的方法。试验通过分析兰姆波各模式的频散曲线、振幅曲线和对比理论与实际的波包群速度，选定了在最佳激励频率下判定疲劳损伤积累的特征信号。还通过快速傅里叶变换分析频域的能量分布来判定疲劳累积。试验结果表明：在试样从弯折塑性形变积累到出现微裂纹的过程中，A0波包振幅有小幅度的减小，而在材料断裂失效前，该振幅幅度会急剧减小。
재료결구중피로미렬문적산생화확전시영향기수명적중요인소，재피로렬문산생초기취장기검측출래대우제고결구안전성지관중요。이용란모파탐색료려판반복만절시판정재료피로적루도최종소성형변단렬실효적방법。시험통과분석란모파각모식적빈산곡선、진폭곡선화대비이론여실제적파포군속도，선정료재최가격려빈솔하판정피로손상적루적특정신호。환통과쾌속부리협변환분석빈역적능량분포래판정피로루적。시험결과표명：재시양종만절소성형변적루도출현미렬문적과정중，A0파포진폭유소폭도적감소，이재재료단렬실효전，해진폭폭도회급극감소。
The formation and growth of fatigue cracks in structural materials is a crucial factor affecting their service life. Thus, it is important to detect the formation of the fatigue crack at the beginning and monitor its growth. Through the bending deformation simulation experiment, an approach by using Lamb wave was developed to detect the process from the accumulation of fatigue damages to the fracture of materials. By analyzing the dispersion curves and particle motion amplitudes of Lamb waves and comparing the theoretical and the actual group velocities, the characteristic mode packets under the optimum excitation frequency can be distinguished to evaluate the accumulation of the fatigues. And fast Fourier transform was used to reveal the energy distribution in frequency domain to detect damage accumulation. It is found that during the bending process from the fatigue accumulation to the appearance of micro-crack, the amplitude of A0 wave packet decreases. Especially, before the failure of materials, the amplitude decreases significantly.