基于超声平面波成像的钢轨螺孔裂纹检测方法研究

Research on the inspection method of railway bolt holes cracks using ultrasonic plane wave imaging

轨道交通在当今社会生产活动中发挥着重要作用。目前在役钢轨大量采用鱼尾板和螺栓联接的方式铺设。钢轨接头在服役过程中会频繁受到冲击载荷作用,容易诱发螺孔裂纹损伤。尽早发现螺孔裂纹,并对裂纹进行定量测量,是保障铁路运输安全,避免发生严重事故的关键。超声相控阵成像检测方法具有精度高、环境适应性强、实施方便的优点,在钢轨在役无损检测中得到了广泛的应用。然而,传统相控阵斜入射扇扫成像方法受裂纹倾斜角度的影响,在工业实践中依赖工人的主观判断和分析能力,难以实现检测的定量化与标准化。基于以上背景,本文提出了一种基于超声平面波全聚焦成像的钢轨螺孔裂纹检测方法。使用复合平面波成像方法对钢轨内部螺孔及附近区域进行高精度重建,获得裂纹伤损的初步检测图像。基于编码器信息,将多个扫查点上的初步检测图像融合,得到合成检测图像,从而覆盖不同倾斜角度的裂纹。基于主成分分析方法,对裂纹倾斜角度进行定量分析,进而借助方向最大强度投影方法,得到裂纹长度的定量检测结果。所述方法在钢轨螺孔裂纹试件检测试验中实现了对[-45°,45°]范围内裂纹的100%检出率;裂纹定位误差最大值为1.47 mm,接近1个波长;长度检测误差最大值1.17 mm,小于1个波长;裂纹角度检测误差最大5.01°。所述方法需要的设备结构简单,可集成于移动式钢轨巡检设备,具备自动化实施的能力。

Rail transportation plays a significant role in contemporary societal production activities.A large number of rails in service are built by using fishplate and bolt connections,leading to frequent impact loading on rail joints,which easily induces crack damage around bolt holes.The early detection and quantitative measurement of bolt hole cracks are crucial for ensuring railway transportation safety and preventing serious accidents.Phased array ultrasonic imaging technology,characterized by high precision,strong environmental adaptability,and convenient implementation,have been widely applied in non-destructive testing of rails.However,reconstructed images on cracks through traditional phased array sector scanning methods is influenced by the tilt angle of cracks,relying on operators′subjective judgment in industrial practice,making it difficult to achieve quantitative and standardized detection.Therefore,in this paper,a quantitative detection method towards rail bolt hole crack based on ultrasonic plane wave imaging is proposed.Compounded plane wave imaging method is utilized to achieve high-precision reconstruction of the region of interest.Reconstructed images from multiple positions are fused to generate final inspection image,ensuring cracks with different tilt angles are covered.Principle components analysis is deployed to quantitatively evaluate the tilt angle of the cracks.After that,directional maximum intensity projection is utilized to measure the length of the cracks.Experiments on a railway test block shows that the proposed method makes a 100%detection rate for cracks in the range of[-45°,45°].The maximal measurement error of the proposed method on the location of cracks is 1.47 mm,which is close to a wavelength.The maximal measurement error of the length is 1.17 mm which is less than a wavelength.The maximal error of tilt angle of cracks is 5.01°.The required equipment is simple and can be conveniently mounted on mobile rail inspection vehicles to achieve automatic inspection.