共查询到18条相似文献,搜索用时 187 毫秒
1.
2.
3.
超声表面波能有效检测出轧辊的表面裂纹,但由于其裂纹很浅且目前的超声波仪器无法对裂纹深度进行直接读数,因此轧辊表面裂纹深度的判定一直是困扰检测工作者的难题。通过计算得出了表面波检测中裂纹深度当量d与回波分贝差△的关系曲线,并将其应用于马钢各种型号的在役轧辊检测中,取得了良好效果。同时比对抛关系曲线并通过实践证明得出,GB/T23904--2009标准中的检测灵敏度调整方法不造用于磨削量最小为0.2mm的在役工作辊的表面波检测。该抛关系曲线使轧辊表面裂纹深度的判定更加简单准确,对在役工作辊的表面波检测具有一定的指导意义。 相似文献
4.
目的 提出一种光学玻璃机械加工亚表面损伤深度的检测方法,给光学玻璃超精密抛光的加工深度提供参考依据。方法 首先通过实验分析K9玻璃研磨试样在化学蚀刻过程中亚表面裂纹的结构变化,采用探针式粗糙度仪检测化学蚀刻表面的裂纹深度,并探讨探针半径和化学蚀刻时间对裂纹深度测量结果的影响,建立以蚀刻表面峰谷粗糙度(PV)表征亚表面裂纹深度的测量条件。然后利用激光共聚焦显微镜检测化学蚀刻表面PV粗糙度,确定光学玻璃的亚表面裂纹深度。最后采用截面抛光法直接检测光学玻璃的亚表面裂纹深度,验证上述两种检测方法的可靠性。结果 以蚀刻表面PV粗糙度表征亚表面裂纹深度的测量条件为,测量介质须在蚀刻表面裂纹开始融合之前有效探测至裂纹底部。针对W18和W40磨粒研磨的K9玻璃试样,采用激光共聚焦显微镜检测蚀刻表面PV粗糙度方法测得的两种试样裂纹深度为12.82 μm和20.45 μm,直接测量方法的测量结果为12.50 μm和19.34 μm。两种方法测量结果的偏差分别为2.56%和5.74%,一致性较好。结论 基于化学蚀刻和激光共聚焦显微镜检测光学玻璃亚表面损伤深度的方法不受表面裂纹宽度限制,满足以蚀刻表面PV粗糙度表征亚表面损伤深度的测量条件,且对试样损伤较小,提高了光学玻璃亚表面损伤深度的测量效率和结果可靠性。 相似文献
5.
采用激光离散处理对钢轨表面进行了强化,旨在提高钢轨的使用寿命。研究了3种不同分布形式的激光离散淬火工艺,利用滚动接触疲劳磨损试验机测定了钢轨的疲劳磨损性能,并对磨损表面形貌、截面形貌以及磨损机理进行了分析。结果表明:未处理钢轨试样表面发生塑性变形和疲劳剥落,产生严重的波磨,磨损量1.102 g;激光离散淬火强化后,波磨消失,磨损量显著降低,但是在试样边缘和淬火区界面有裂纹产生;当淬火区以间隔1 mm、倾斜60°分布时,试样中心的界面裂纹得到有效控制,磨损量最低,相比未处理试样减少了63%;通过缩小淬火区间隔,增大淬火区倾斜角度,可以有效提高激光离散淬火层的裂纹抗性和磨损性能。 相似文献
6.
7.
目的 设计一种钢轨表面缺陷检测方法,对钢轨表面存在的缺陷进行快速、准确地检测。方法 首先,利用图像的灰度均值构造灰度均衡模型,对钢轨表面图像中像素点的灰度值进行修正,以克服光照不均的影响。然后,利用图像的谱残差模型与相位谱增强钢轨表面图像中的缺陷部分,引入ostu阈值分割法对增强后的图像进行二值化,对图像中的缺陷区域进行准确地分割提取。最后,利用Gabor滤波器,将二值化图像中的噪声进行滤除,并保留缺陷区域的边缘等细节特征。结果 与对照组方法相比,所提方法的检测效果较好,精确率以及召回率都有所提高。直观测试结果显示,所提方法能够较为完整地检测出钢轨表面缺陷。客观测试实验结果显示,所提方法的精确率为90.11%,召回率为93.41%,且平均耗时为45.17 ms,相对对照组方法而言,耗时最少。结论 所提钢轨表面缺陷方法不仅能够准确地对钢轨表面缺陷进行检测,而且还具有较高的检测效率。 相似文献
8.
叙述了ZZC-1型转子中心孔超声检测装置的原理,性能及应用,该装置采用全油浸耦合,用聚束探头检测近表面缺陷,用表面波检测表面裂纹,用计算机化C扫描定量缺陷尺寸。 相似文献
9.
10.
11.
Stefano Coccia Ivan Bartoli Alessandro Marzani Francesco Lanza di Scalea Salvatore Salamone Mahmood Fateh 《NDT & E International》2011,44(1):93-100
This paper gives insight to the ultrasonic wave propagation in arbitrary cross-section waveguides such as rails, with application to ultrasonic inspection. Due to the geometrical complexity of the rail cross-section, the analytical solution to the wave propagation in the rail is not feasible. A Semi Analytical Finite Element method is described as an alternative yet still robust approach to get the solution of the problem. The free-vibration solution and the forced solution to a laser excitation of the rail head are shown up to a frequency of 500 kHz. The effects of different loading patterns are discussed, and experimental results are provided. The analysis allows for the identification of certain wave modes potentially sensitive to specific types of rail head defects. 相似文献
12.
Ultrasonic surface wave propagation and interaction with surface defects on rail track head 总被引:1,自引:0,他引:1
Electromagnetic acoustic transducers (EMATs) are non-contact ultrasonic transducers capable of generating wide band ultrasonic surface waves on metallic samples. A lab-based laser-EMAT system has been developed to observe the ultrasonic surface wave propagation and interaction with surface breaking defects on the sample rail head surface. A wide band EMAT generating surface waves with a frequency content between approximately 50 and 500 kHz is used to propagate ultrasonic waves on the surface of a rail head down the length of the sample. A stabilised Michelson interferometer is used to measure the out-of-plane displacement of the surface wave. A complete picture of the ultrasonic surface wave on the sample surface over time is reconstructed using this technique, with exceptionally high spatial and temporal resolution. Despite the curvature of the rail head, the ultrasonic surface wave propagating down the rail is found to have similar properties to Rayleigh waves by direct comparison to those observed on flat samples using the same technique. 相似文献
13.
Rail defects are responsible for many railroad accidents. Trains are derailed and serious consequences often occur. Traditional bulk wave testing wheel probes are often inadequate for finding all defects in a rail, especially under shelling. Shelling takes place as a result of wheel to rail Hertzian contact stresses that lead to surface and subsurface defects, as a result of high stresses below the surface of the rail. Guided waves can detect shelling, if so desired, by employing the proper mode and frequency. Guided waves can also detect transverse cracking under shelling by selecting a mode and frequency insensitive to the shelling, but sensitive to transverse cracking under the shelling. Special modes and frequencies can also be used to detect defects in the web or base of a rail. The guided wave methodology of using a hybrid analytical-FEM technique to accomplish the sensor design and subsequent scattering analysis is presented in this paper. Sensor design to generate rail boundary conditions via dispersion curve and wave structure analysis is illustrated along with a few static shots of animations of wave propagation and reflection from defects in a rail. 相似文献
14.
15.
《NDT & E International》1999,32(8):429-436
A method adopting the unsprung-mass acceleration signals is one of the essential techniques for the investigation of rail surface irregularities. This paper presents results of the spectral analysis of unsprung-mass acceleration signals for selected tracks of the Polish State Railways network. In particular, the following spectral characteristics of the rail surface irregularities have been determined: variance, spectral power in selected bands (in wave number or in wavelength domains), spectral moments of various orders and spectral width parameters. These characteristics have been determined for the track sections with various rolling surface conditions. The resulting standard deviations of vertical accelerations varied from 7.5 m/s2, for the track without corrugations, to 122.8 m/s2, for track section with corrugated rails, while the average wavelengths were in the range of 0.055–0.080 m. 相似文献
16.
17.
针对铁路用钢轨在钢铁企业生产后的长途运输(包括海运)、焊轨堆放和铺轨过程中的野外日晒雨淋和大气锈蚀,使钢轨表面发生锈蚀而发黄,并污染铁路道床和环境。本文着重介绍通过在钢轨表面采用自动喷涂透明的钢轨专用防锈油,涂装后的钢轨在野外大气环境条件下1年内钢轨踏面不完全锈蚀,轨腰和轨底无锈蚀、达到钢轨在生产出厂后至铺轨正式运营的时间内耐锈蚀的短期目标。 相似文献