基于非接触式麦克风冲击共振测试的钢-混组合结构界面脱空损伤识别方法研究

针对现有无损检测技术在钢-混组合结构界面混凝土脱空损伤识别问题上普遍存在的测试成本高、识别精度有限及操作过程复杂等不足之处,提出了一种基于麦克风冲击共振测试的非接触式检测方法。首先,基于四边约束矩形薄板振动理论,将钢-混凝土板局部脱空处钢板简化为四边固支约束的板壳模型进行分析。通过在ABAQUS中建立考虑流-固耦合的钢-混凝土板有限元模型,将模拟所得脱空处钢板自振频率值与理论解析结果进行对比,证明该经验公式可有效适用于脱空区域处局部钢板自振频率的估计当中。其次,依据相关声学理论研究成果,利用所建立的有限元模型进行了外部激励下钢-混组合结构声压场信号分布特征研究,结果表明设置及未设置脱空损伤的有限元模型所产生的声压响应存在明显不同,且未脱空模型中信号响应具有幅值大、周期长等特征;同时,针对一钢-混凝土板设置了8种不同类型的损伤工况,并利用麦克风传感器分别进行了基于冲击共振测试的脱空损伤识别。试验结果表明,麦克风摆放位置对测试所得声压信号频响函数基本特征的影响程度并不显著;且针对本试验所设置的损伤工况,该方法基本均能实现有效识别,但对平面尺寸在60 mm以下区域的测试效果并不明显。最后,在对一特定损伤区域进行栅格化处理的基础上,通过开展基于麦克风冲击共振法的损伤成像测试,对该脱空区域的平面轮廓进行了有效识别。除此之外,将试验测试效果分别与传统红外热像检测法、超声波探测法进行了对比分析,验证了该麦克风冲击共振法能够较好地适用于钢-混组合结构的脱空损伤识别问题当中,且具有非接触式、测试成本低、识别效果显著及操作便捷等优点。

Non-contact diagnosis for interface debonding of steel-concrete composited structure by using impact resonance test with microphone

To distinguish the debonding defects of steel-concrete composited structure( SCCS),the existed non-destructive test( NDT) is generally thought with the problems of high tested costs,limited measurement accuracy,complicated operation process and etc. Therefore,this paper has introduced a non-contact NDT method by utilizing the impact resonance test with microphones. Firstly,the steel plate at the debonding defect of SCCS was treated as the clamped thin plate model based on the vibration theory,and the analytic value was validated by the finite element( FE) SCCS model with coupledfluid-solid consideration in ABAQUS program,showing that the empirical formula can be employed into the natural frequency predictions of this problem. Secondly,based on the theory of acoustic analysis,the FE model was utilized to research the distribution feature of acoustic waves under external excitations,and it was revealed that both of the type and transmission path of acoustic waves were significantly different between the debonding/non-debonding areas of the SCCS model,where the debonding signals were observed with the larger vibration amplitude and natural period. Meanwhile,the impact resonance test with microphone sensors was conducted for the SCCS with eight types of debonding defects. It was noticed that the basic characteristics of acoustic frequency response function( FRF) was not significantly influenced by the arrangement position of microphones,and the debonding defects can be well distinguished by the method except for the debonding defect with dimension less than 60 mm. Finally,the acoustic imaging analysis with microphones was conducted for a certain meshed debonding defect,and the outline of region can be roughly distinguished according to the test result.However,the experimental accuracy was dropped at the edge of debonding region,which can be improved with a denser mesh grid. Simultaneously,the test result was compared with the traditional infrared thermography method and the ultrasound method,and it was showed that the debonding defect of SCCS can be well distinguished by the impact resonance test with microphones,which has additionally employed the advantages of non-contact,lower costs,significantly precision and conventional operate process.