带涂层在役压力容器的无损检测

“在用压力容器检验规程”中规定对检验的基本要求是:“内外部检验应以宏观检查、壁厚测定为主,必要时可采用表面探伤……”。宏观检查的方法有目视、锤击和灯光检查等。目视只能发现较大尺寸的容器表面最危险缺陷——裂纹,而对较小尺寸的裂纹则要借助于表面探伤(主要为磁粉探伤)方法。     

机器视觉在飞机结构损伤检测中的应用进展与展望

在无损检测领域,机器视觉凭借实时在线、非接触、检测精度高以及便于实现自动化等优点,正逐渐替代传统的目视检测,可用于裂纹、表面划伤、凹坑、断钉等结构表面损伤的检测和定量表征中。在梳理机器视觉技术发展脉络的基础上,重点介绍了近年来机器视觉在飞机结构损伤检测中的研究成果和应用进展,结合飞机结构损伤原位检测的工程需求,对机器视觉技术的发展趋势进行了探讨和展望。     

基于机器视觉的飞机故障检查系统

针对当前飞机维修检查工作以人工目视检查为主、效率低且存在人为因素影响的情况,设计一套基于图像识别与机器深度学习的飞机部件表面无损检测系统。收集并整理了某航空公司一线飞机维修员拍摄的飞机机身及发动机部件图片,对图片集进行预处理,包括通道提取、Sobel滤波处理及二值化;最后用Blob分析对处理后的图像进行特征提取与系统分析。系统运行速度快、准确率高且可连续自动识别图像。利用机器视觉技术对飞机部件表面进行无损检测不仅可以提高生产效率,同时可以去除人为因素对航空器飞行安全的影响,使得飞机的飞行安全得到进一步提升。实践证明,该系统性能稳定可靠,具有极高的推广应用价值。     

核电站蒸汽发生器二次侧远距离目视检查

核电站蒸汽发生器二次侧远距离目视检查已作为在役蒸汽发生器无损检测的一个重要方面 ,对检测传热管降质、评估结构完整性、制订维修计划、减少维修费用、保持电站热功率和减少非计划停堆方面起到了重要作用 ,越来越受到人们的重视。1　大亚湾核电站蒸汽发生器二次侧远距离目视检查1.1　管板表面的远距离目视检查[1,2 ]1.1.1　目视检查装置大亚湾核电站蒸汽发生器二次侧目视检查采用美国韦林公司ＶＰ3视频检查装置。它是一套观察小径管内壁及狭窄通道的专用设备 ,具有检查监控、一次成象、录象及图片说明等功能 ,自带光源 ,适用于无外光源区…     

工业内窥镜在全尺寸结构飞机疲劳试验中的应用

工业内窥镜在全尺寸结构飞机疲劳试验中,可用于检测飞机结构中人眼无法直接观察到的部位,通过物镜与液晶显示器的图像转换,达到间接目视检测的目的;检测人员可以在不需要拆卸或破坏构件的前提下,方便且迅速地观察及检测组装构件的内部表面结构或工作状态;并对裂纹长度进行测量等,从而有效地实施质量管理。     

基于激光三维扫描的裂纹可视化表征方法

疲劳裂纹是飞机服役过程中的常见损伤,激光三维扫描技术可通过获取点云数据实现结构参数的三维重构,但在用于裂纹识别和表征时,面临局部裂纹与结构尺寸之间存在跨尺度效应的问题。为此,基于目视检测难易程度,选取人工裂纹、易于目视可见裂纹、目视可见裂纹和目视勉强可见裂纹等4种典型裂纹特征作为研究对象,提取裂纹长度、裂纹宽度和裂纹两侧高度差作为重构参数来表征局部裂纹特征,并采用光学显微镜对裂纹特征参数进行定量。随后对4种裂纹特征开展激光三维扫描建模试验,分析重构参数对激光三维扫描裂纹特征识别和建模精度的影响。试验结果表明,激光三维扫描技术可以精确识别与表征裂纹特征,为飞机结构裂纹可视化表征提供了一种新的技术手段。     

利用时变温度场探测混凝土缺陷

根据有缺陷混凝土试件温度场差异，通过摄影采集混凝土结构洒水后温度和不同时刻含水量变化等参数的图像，并经图像处理对传统目视检查难以观察到的裂纹进行初步识别。试验验证该方法是可行的，但仍需进一步研究和完善。     

沿海飞机铝合金结构件腐蚀与防护

综合作者多年的飞机结构修理工作，分析、归纳了沿 海机场飞机典型腐蚀损伤，得出飞机结构腐蚀主要是环形间隙中未加保护的铝合金表面和间隙中的积水而形成的电化学腐蚀.提出缝隙密封等减少结构腐蚀的制造和使用维护过程中的防腐工艺措施.     

基于YoLov5的轴承端面表面缺陷检测方法

针对工业生产中轴承端面表面缺陷检测采用人工目视检测方法存在检测精度低、可靠性差等问题,提出一种基于YoLov5的轴承端面表面缺陷检测方法.首先,为了克服轴承端面表面缺陷样本数据不足问题,提出一种联合Mosaic与Copy-Pasting策略的数据增强方法对样本进行扩充,然后利用YoLov5具有较好的目标检测性能,基于Y...     

热超声技术在裂纹检测中的应用

材料表面和表面下浅层裂纹的检测对金属承力结构十分重要。热超声是一种新型的无损检测技术。该技术使用超声能量激励材料裂纹并用红外热像仪探测该裂纹。对飞机前起落架旋转臂试件进行的多次试验，证明此方法对金属裂纹的检测是有效的。     

Condition survey with embedded sensors regarding reinforcement corrosion

Besides visual inspections, taking cores or samples and measurements at the concrete surface, the use of embedded sensors can be an effective tool for the assessment of the condition of concrete structures. For new structures sensors can be placed in positions without the possibility of access during use and for existing structures sensors can be used to follow the condition of the structure at relevant selected points. Actually different types of sensor systems are available based on different electrochemical or other methods.     

Use of gamma rays in the inspection of steel wire ropes in suspension bridges

Regularity visual inspections are performed on steel wire ropes of suspension bridges. However, because the steel wire ropes were coated with plastic materials, inspectors could not visually detect the deterioration conditions of the ropes. In this paper, radiation tests and electromagnetic testing were compared. The gamma rays used in the radiation tests were employed to develop two assessment techniques, namely the exposure time formula and sensitivity assessment of steel wire ropes. Actual tests showed that such techniques can be adopted to evaluate the defects of steel wire ropes and help engineers improve the safety of suspension bridges.     

Design for inspection of concrete bridges

In order to achieve durable concrete bridges, adequate measures need to be considered already in the design phase. An evaluation of common deteriorations in concrete structures leads to the conclusion that visual inspection is and will remain the method to be applied first. More refined and complementing methods will result in similar requirements for design. Therefore, the role of inspections in bridge management has to be identified and future methods of inspection and condition survey have to be anticipated. The main focus is a safe and convenient access to all concrete surfaces, hollow boxes, and decisive structural parts like bearings and expansion joints. Some of those measures are even worth to be considered for existing bridges when these are significantly modified due to bad conditions or new requirements.     

Experimental study to differentiate between top and bottom defects for MFL tank floor inspections

Defects due to corrosion can occur on top and bottom surfaces of a tank floor. The current magnetic flux leakage (MFL) tank inspection machines can detect and locate defects on both the top and bottom of a plate, but generally they are unable to differentiate between top and bottom. Further cleaning for visual inspections is needed to identify those defect that are on the top side and are thus more readily repaired. To avoid this additional inspection ideally the machine should be able to distinguish automatically between top and bottom surface corrosion. This paper presents experimental work specifically designed to asses the capability of current MFL based machines to distinguish defects located on the top and those on the bottom of the tank floor. Although some open literature suggests that such top or bottom classification might be possible, purpose designed experimental results presented here show that there is a very high similarity between signals belonging to top and bottom defects which suggests such discrimination is not viable using standard MFL based techniques.     

Local detailed inspection methods regarding reinforcement corrosion of concrete structures

Full surface surveys which are likely to include e.g. a deterioration and potential mapping as well as a cover depth survey, should be the base to identify critical areas which are suspect to be suffering from reinforcement corrosion 1 . Localised assessment in these areas should give further information about the type and extent of deterioration. It should include the determination of the chloride profile beyond the cover depth, the depth of carbonation and a direct visual assessment of the steel reinforcement by breaking away the cover concrete at selected locations. Further valuable information may be collected by determining the water content of the concrete or performing corrosion rate measurements. Within this publication the essential methods for local detailed inspections are discussed regarding the application and interpretation of the results. An overview of the survey procedure is given in ref. 2 .     

Imaging-based detection of AAR induced map-crack damage in concrete structure

Imaging-based inspection methods are increasingly being employed for crack detection in concrete structures, because they provide quantitative information compared to inspections based solely on conventional visual approaches. However, efficient image analysis methods are needed. This study proposes the application of the grey level co-occurrence matrix (GLCM) texture analysis approach and an artificial neural network (ANN) classifier to obtain surface damage information, such as the total amount of superficial cracking, as well as the total length, and range of crack widths. These methods were applied to thermographic, visual colour and greyscale images of concrete blocks from CANMET that were exposed outdoors for ten years, as well as slabs from GRAI that were kept indoors, all specimens exhibiting various levels of alkali-aggregate reaction (AAR) damage. Results of the classifications show that the greyscale imagery performed fairly well, with an overall classification accuracy range of 72.3–76.5% for the CANMET blocks, and 68.7–75.3% for the GRAI slabs. Classifications using the colour imagery were slightly better than the greyscale imagery, with accuracies ranging from 71.4% to 75.2% for CANMET blocks and 70.9–72.0% for the GRAI slabs. The thermographic imagery, however, produced the highest overall classification accuracies, which range from 73.1% to 76.3% for the CANMET blocks and 74.2–76.9% for the GRAI slabs. The results show that all three types of imagery are relatively effective in characterizing and quantifying crack damage; however, the infrared thermography produced more accurate results compared to the visual colour, and greyscale images.     

Prediction of solid state structure based on eutectic and eutectoid transformation parameters in spheroidal graphite irons

Abstract

The aim of the present work is to predict experimentally the structural trend of liquid iron based on its solidification features and the subsequent solid state transition. Both transformation processes in SG iron samples are simultaneously studied by means of industrial thermal analysis techniques. Experimental parameters are established in both cases in order to quantify the main metallurgical facts and correlate them with the structural properties of different alloys used in real manufacturing processes. A computer aided program has been designed for the treatment of the cooling curves.

A large number of experimental tests using different chemical compositions were made. After curves treatment, several studies have been conducted to correlate the thermal parameters obtained and the structural properties detected via metallographic inspections. The influence of the solidification parameters on carbon diffusion process and the resulting structures is discussed. A new structural model was developed in order to predict the ferrite content on the basis of thermal evolution of SG iron. Nucleation potential (inoculation grade), carbide formation tendency and solid state evolution of metal are evaluated and final structure distribution is accurately estimated.     

On the role of inspections and interventions in infrastructure management

In this article, a view of the role of inspections and interventions in the management of infrastructure is presented. The paper is to serve as a reminder, in a time when there is ever increasing discussion over the durability/sustainability of structures, that infrastructure exists to provide an adequate level of service over a specified time period and that the goal of management is to ensure that this level of service is provided while incurring the least total negative impacts; impacts that can be incurred through normal use, and the execution of inspections and interventions. The significance of this view in determining the inspections and interventions to be included in optimal management strategies is demonstrated through an example where the optimal management strategies for a reinforced concrete bridge deck are determined under different assumptions of the value of negative impacts. It is shown that it is impossible to determine the inspections and interventions to be included in an optimal management strategy without first developing all management strategies to be investigated and determining the one that results in the least negative impacts. It is also shown that many rules of thumb used to select inspections and interventions, such as inspections which provide more accurate information are better than those that provide less accurate information, are not always true.     

Korrosionsinspektion im Flugzeugbau

Corrosion inspection in aircraft construction The inspections required on an aircraft during its operational phase are determined largely by the materials and constructions used. Practical experience has shown that corrosion can generally not be prevented on metallic aircraft structures, even if the surface protection systems have been chosen with great care. Constructions and materials used on aircraft and the result types of corrosion are described and the inspection concept is explained on the basis of this. Finally, typical inspection tasks are presented and the measurement results obtained with different NDT methods are presented and discussed.     

Modal analysis for masonry arch bridge spandrell wall separation identification

The arch bridge forms an important part of our infrastructure, and maintenance of the bridge stock is becoming increasingly expensive. This paper presents the results of a nondestructive investigation of large scale model brickwork arches. Experiments were undertaken on brickwork arches using modal testing. The key features detected were: the effect of load on the backfill's surface, and the effect of spandrel wall separation from the arch itself. Mode shapes, fundamental frequencies, and damping ratios are presented for both qualitative and quantitative analysis of arch behaviour. Changes in these parameters were used to detect defects in the structures; as such the method may prove useful as a tool to assist civil engineers currently undertaking major bridge inspections.