探讨起重机梁缺陷的声发射信号特征和发展规律。采用模拟梁加载试验，获得梁上人工裂纹萌发和扩展过程的声发射信号。通过经验模式分解方法分析出不同载荷和裂纹扩展过程的声发射频率特征。结果表明，起重机梁活性缺陷声发射信号为突发性信号，每一事件声发射所含频率成分复杂。一般裂纹萌发时的声发射信号频率较低；随着裂纹的发展，频率逐渐增高，缺陷频率范围约为25~160 kHz。该研究为起重机械活性缺陷的声发射检测技术提供了理论基础。

The acoustic emission(AE) signal feature and its developing rule for active defect in crane beam was discussed. Based on a testing rig of simulating beam with three artificial cracks, the AE signals were obtained. The signals were collected under different loadings and various moments of crack from beginning to extending. Because of the complexity of the signals, the method of empirical mode decomposition(EMD) was introduced to decompose them. The results demonstrated that the AE signals of active defect were burst type and contained many frequency components in a burst. Generally the frequency was lower in the beginning of crack, with the developing of crack, the frequency became higher. The total frequency range of crack development was 25~160 kHz. The research laid the theoretical fundament for AE examination in active defect in crane equipment.