聚乙烯管道电熔接头缺陷超声相控阵成像模拟和实验研究

为了快速获得电熔接头超声成像图以便研究聚乙烯管道电熔接头无损评估算法研究,运用了多物理场耦合有限元分析软件COMSOL Multiphysics对聚乙烯管道电熔接头金属电热丝的超声响应特性进行了有限元分析,并对聚乙烯管材内壁钻孔缺陷及含孔洞缺陷聚乙烯管道电熔接头进行了超声相控阵检测成像实验,验证了超声相控阵检测成像有限元模拟分析结果的正确性。采用Richardson-Lucy反卷积算法对聚乙烯管材内壁钻孔缺陷超声相控阵成像图进行了图像复原处理。实验结果表明:基于超声傅里叶成像的相控阵成像仿真方法具有可行性,有限元模型为聚乙烯管道电熔接头缺陷超声相控阵成像提供了数值模型。     

聚乙烯电熔接头表面不规则对超声相控阵检测的影响分析

超声相控阵技术及B扫描实时成像技术,可以实现对表面平整的聚乙烯电熔接头缺陷的检测。然而针对表面不规则的聚乙烯电熔接头进行检测,由于耦合剂与聚乙烯两者声速与声阻抗的差异,会造成检测盲区的增大、检测图像的畸变和灵敏度的降低。对聚乙烯电熔接头表面不规则对超声相控阵检测的影响进行系统地分析和研究,并探索出一种实用的方法可以消除表面不规则对超声相控阵检测的影响,使超声相控阵技术能够用于表面不规则的聚乙烯电熔接头的质量检测。     

聚乙烯(PE)管道焊接接头超声相控阵检测试验研究

针对聚乙烯管道电熔焊接无损检测技术匮乏的特点,开展了一系列的试验。通过超声波相控阵检测技术,对聚乙烯电熔焊接常见的缺陷进行检测验证分析,证实了相控阵检测方法对聚乙烯电熔焊接缺陷的检测具有较高的精度及可靠性,可以用于工程实践。     

基于DR检测的非金属压力管道检验分析及应用

通过研究提出了一种非金属压力管道检验方法。聚乙烯管在燃气行业已得到广泛的应用,但燃气用聚乙烯管道的焊接接头的无损检测仍未有一个得到公认的、成熟的技术规范,其接头的内部质量无法通过可行有效的无损检测手段进行检测,现有的手段仍以外观检查和压力试验作为检测手段。通过对燃气用聚乙烯材质及焊缝的研究,提出了采用X射线数字成像检测技术(DR)对聚乙烯焊接接头进行检测,实验结果表明,DR检测能够作为一种可靠检验手段对聚乙烯焊接接头进行内部缺陷探伤。     

应用超声相控阵检测技术对钢制对接焊接接头的检测实例与分析研究

介绍了利用超声相控阵检测钢制对接焊接接头的技术,该检测技术可使缺陷的检出与定量更为精确、有效。在检测结果的自动记录图上,除A型显示外,还有B型、C型及5型显示,并提供了缺陷的三向视图。     

奥氏体不锈钢小径管焊缝缺陷多模式超声复合全聚焦成像研究

奥氏体不锈钢广泛应用于重大装备的关键部件中,而焊缝是整个装备的薄弱部位。在考虑超声波的多路径和易发生波型转换的特性情况下,进行奥氏体不锈钢小径管焊缝多模式超声相控阵检测方法研究。通过数值仿真,对比分析4种不同直达波检测模式和8种不同底面一次反射波检测模式对小径管焊缝中典型缺陷的检出能力。基于优选出的一种直达波检测模式和一种底面一次反射波检测模式,发展了一种多模式复合全聚焦成像方法。在此基础上,进行奥氏体不锈钢小径管焊缝缺陷检测试验。结果表明,多模式复合全聚焦成像方法可以很好实现小径管中多种缺陷检测,与单一模式全聚焦成像相比,多模式复合全聚焦成像方法不仅可以提高成像的信噪比,且可以大大减小伪像的产生。项目研究工作为奥氏体不锈钢小径管焊缝检测提供了可行的技术方案。     

接管焊缝超声相控阵多模全聚焦检测技术

接管角焊缝是承压设备的关键部位,也是易于出现危害性缺陷的薄弱环节,因此,针对该薄弱区域的定期检测非常重要。相对于传统超声无损检测,超声相控阵全聚焦对焊缝内部缺陷的定位和定量具有优势。提出了一种针对焊缝内部缺陷的超声相控阵全聚焦方法,将多模成像方法应用于小口径接管焊缝的缺陷检测,实现对焊缝内部缺陷的有效检出。同时,根据检测对象的实际尺寸,通过智能算法计算声束入射参数,选择最佳成像区域,获得了一种有效区域多模融合成像方法。试验结果表明,本方法可检出直径为0.53 mm的角焊缝内部气孔缺陷,相对于单视图成像和普通超声能够有效提高缺陷定量和定位的准确性。     

微波扫描法检测聚乙烯管道热熔接头缺陷初探

以聚乙烯管道热熔接头为检测对象,使用微波扫描的方法检测热熔接头中不同类型的缺陷.首先对无缺陷的热熔接头进行微波扫描检测,得到的扫描图像作为参考图像.然后对含有裂纹、冷焊等不同缺陷的聚乙烯管道热熔接头进行微波扫描检测,得到具有不同特征的扫描图像.对这些扫描图像进行分析可以判别缺陷的类型.最后,利用拉伸力学测试的结果,初步验证了微波扫描方法对聚乙烯管道热熔接头缺陷检测的有效性.     

聚乙烯燃气管道电熔接头熔区应力分析

电熔焊接是聚乙烯管道最常用的连接方法之一,电熔接头的设计对管道系统安全至关重要。电熔接头焊接界面应力分布的准确分析是电熔接头设计的基础。采用理论公式推导和有限元分析相结合的方法,研究电熔接头在内压、轴向力和温度变化作用下的应力分布情况,发现接头焊接界面应力分布呈现中间小、两边大的规律。定义端部应力集中系数为界面峰值应力与平均应力的比值,分析得到应力集中系数随熔区长度的关系,结果可为基于内压与轴向力的电熔接头熔区设计提供理论参考。     

碳钢惯性摩擦焊接头的组织和强度

对Ｑ２３５钢惯性摩擦焊接头进行了超声检测,观察了典型接头包括含缺陷和无缺陷接头的微观组织,并做了拉伸试验和冲击试验。试验证明,碳钢惯性摩擦焊接头的接合面晶粒细小,静强度很高,接合面的缺陷对静强度影响不大,但使接头的冲击韧性大大下降;超声检测用于碳钢惯性摩擦焊接头,能有效地检出缺陷。     

金属材料超声探伤缺陷分类辅助系统的研究

针对在目前工业生产的超声检测中缺陷难以定性的问题,在现有缺陷信号处理和人工神经网络分类研究工作的基础上,基于虚拟仪器的设计思想及功能模块化的设计方法,采用PC机和数据采集卡作为硬件系统,在L abV IEW平台上建立了能对缺陷进行智能识别的系统——金属材料超声探伤缺陷分类辅助系统。系统具有采集金属材料中缺陷回波数据、降噪、特征提取和智能识别缺陷等主要功能。实验结果表明,该系统基本上能自动识别出各类缺陷。     

Infrared Thermographic Testing of Hybrid Materials Using High-Power Ultrasonic Stimulation

Ultrasonic infrared thermography is a rapid and informative method of nondestructive testing, used to inspect materials and products in aviation and rocket and space industries. High-power piezoelectric emitters stimulate various materials by ultrasound and help revealing hidden flaws by local temperature changes, which can amount to tens of degrees. The possibility of optimizing the procedure of ultrasonic infrared thermography by choosing the frequency of acoustic waves so as to match the frequencies of local resonances of defects of different sizes has been investigated.     

Ultrasonic Multichannel Flaw Detector for Testing Rails with Signal Recording

Although automated testing instruments have been introduced intensely on the railways of Russia, up to 95% of hazardous flaws in rails are detected by ultrasonic two-line (removable) flaw detectors. The paper describes the functional diagram and basic functions of an ultrasonic detector of the new generation, AVIKON-01, with continuous recording of data. The instrument is supplied with the software package for analysis of testing results, and it has advantages of both hand-held removable flaw detectors and high-performance instruments for nondestructive testing of rails.     

基于支持向量机和特征选择的超声缺陷识别方法研究

缺陷的自动识别在管道缺陷超声无损检测和评估中具有重要意义。提出了一个新的超声缺陷自动识别系统。该系统采用小波包分解提取超声信号的特征，采用混沌遗传算法来消除冗余和不相关的特征，并采用支持向量机（SVM）来对缺陷进行识别。为了验证系统的有效性，在实验室内作了大量的超声检测实验。实验结果表明，系统对管道缺陷具有较高的分类性能。     

Peculiarities of ultrasonic pulsed immersion testing of blanks of railway axles

Research has been conducted and methods have been developed for revealing small-sized flaws in blanks of railway axles by ultrasonic immersion testing technique. It has been established that the use of probing pulse packets significantly improves the sensitivity of testing.     

棒料锯切在线自动超声波检测技术

文章研究开发了一套集棒料锯切与在线自动超声探伤于一体的综合系统,采用数字化超声探伤仪,实现了探伤与锯切的同步进行,大大提高了检测效率,有利于及时发现、剔除缺陷,对后续精密成形的实现具有重要意义。     

Determining the probability of detecting flaws in weld joints by phased-array ultrasonic testing

The article is devoted to ultrasonic testing of weld joints in aerospace industry with an acoustic phased array. Testing planar flaws of lack-of-fusion and joint-root-crack types by sector scanning is considered. A technique is suggested for calculating the probability of detecting flaws (POD) by means of numerical modeling of the ultrasonic-testing procedure with allowance for interferences. A finite-element model has been developed, and 40 cracks with randomly generated geometry have been modeled. Using the modeling results, a conditional crack height at a level of 10% of the echosignal amplitude from a reference reflector has been determined. POD curves have been calculated using the results of numerical experiments.     

A nonlinear effect-based ultrasonic flaw detector for detecting cracks

The operation of an ultrasonic flaw detector using a nonlinear modulation method of crack detection that is suitable for effectively testing cracks in wafers is considered. It differs from analogues in the technique of modulation of elastic characteristics of flaws, namely, a sequence of phase-inverted pulses of Lamb waves. The results of testing of an ultrasonic flaw detector intended for detecting model flaws (single cracks and cavities) in wafers are presented.     

Specific features of ultrasonic flaw detection in studies of the distribution of structural fragments in strongly inhomogeneous media

Results of ultrasonic testing of a building’s multilayer reinforced-concrete foundation that is encased in metallic fixed shutters are analyzed. Testing is conducted according to the impact-echo method in the frequency range 0.02–1.0 MHz to experimentally determine the average velocity of longitudinal ultrasonic waves. The results obtained were used subsequently to determine the distances to structural inhomogeneities (flaws) within the volume of the structure and to assess their dimensions.     

Study on flaw identification of ultrasonic signal for large shafts based on optimal support vector machine

Automatic identification of flaws is very important for ultrasonic nondestructive testing and evaluation of large shaft. A novel automatic defect identification system is presented. Wavelet packet analysis (WPA) was applied to feature extraction of ultrasonic signal, and optimal Support vector machine (SVM) was used to perform the identification task. Meanwhile, comparative study on convergent velocity and classified effect was done among SVM and several improved BP network models. To validate the method, some experiments were performed and the results show that the proposed system has very high identification performance for large shafts and the optimal SVM processes better classification performance and spreading potential than BP manual neural network under small study sample condition.