Reliability of ultrasonic inspection of welded joints with incomplete structural fusion

A correlation is established between the depths of incomplete-fusion areas along the surfaces of welded flanges in T-joints and incomplete structural fusion. A rejection level is chosen for the echo-signal amplitude that makes it possible to decrease errors in ultrasonic testing.Translated from Defektoskopiya, Vol. 40, No. 9, 2004, pp. 38–41. Original Russian Text Copyright © 2004 by Konovalov.     

Choosing the parameters of transducers during ultrasonic testing of welded joints by the tandem technique

Formulas for acoustic channels of ultrasonic testing of products by the tandem method have been obtained and numerically studied for strip-and flat-bottom-type flaws. The choice of optimal parameters for a root-tandem transducer for inspecting the unit of welding of a collector to a ПГВ-1000 steam generator of the ВВЭР-1000 reactor is substantiated.     

基于遗传神经网络的GH4169高温合金摩擦焊超声检测缺陷识别

摩擦焊接过程中,由于焊接参数波动或一些非正常因素的介入,接头中容易产生未焊合及伪结合缺陷,而传统BP网络在进行缺陷识别过程中存在收敛速度慢和容易陷入局部极值点的问题,将遗传算法引入BP网络优化初始权值,提出了改进后的缺陷识别BP网络.通过验证超声C扫描成像法检测到的某GH4169高温合金的缺陷信号,表明该方法使缺陷的定性分类获得了更高的准确率,可大大降低人为主观因素对缺陷识别的影响.     

Impact of pinless stirring tools with different shoulder profile designs on friction stir spot welded joints

Journal of Mechanical Science and Technology - Friction stir welding is commonly used to join metals because it is environmentally friendly and provides higher fatigue strength than electric...     

Some aspects of using piezoelectric probes for ultrasonic inspection of thin welded joints

The choice of parameters of dedicated piezoelectric probes is considered with allowance for a surface wave arising at probe angles close to the second critical angle. Recommendations are given for the choice of optimal probe angles and probe x-values. Examples are given to show the application of the dedicated probes, the choice of their type, and the parameters (frequency, probe angle, x-value) for the inspection of butt-welded joints of tubes on the heating surfaces of boilers at thermoelectric power stations.     

基于分形理论的摩擦焊超声检测缺陷信号识别

采用超声波探伤仪U1traPAC系统对GH4169高温合金摩擦焊件进行检测,针对缺陷信号特点,提出基于分形理论的摩擦焊超声检测缺陷信号的识别方法.运用一种新的分形维数计算方法一归一化尺度计盒维数法对试件超声回波缺陷信号盒维数进行计算,统计分析出三种缺陷信号盒维数范围.并对结果进行方差分析.分析结果表明,有缺陷信号与无缺陷信号有着各自分形维数区间,且不交叠,据此可用来判断缺陷的有无.该方法对摩擦焊件缺陷信号的分类识别有较好的统计特性.     

Aluminum 6060-T6 friction stir welded butt joints: fatigue resistance with different tools and feed rates

The fatigue behavior of AA6060-T6 friction stir welded butt joints was investigated. The joints were produced by using both a standard and a threaded tri-flute cylindrical-tool with flat shoulder. The friction stir welding process was carried out using different feed rates. Preliminary tensile tests, micrograph analyses and hardness profile measurements across the welds were carried out. Welded and unwelded fatigue samples were tested under axial loading (R = 0.1) with upper limits of 10⁴ and 10⁵ cycles, using threaded and unthreaded (standard) tools at different feed rates. The best tensile and fatigue performance was obtained using the standard tool at low feed rate.     

旋转超声电解复合加工小孔的仿真加工

为研究旋转超声电解复合加工小孔的成型过程,进行了旋转超声电解复合加工小孔试验,得到了不同加工时间孔的截面,并根据试验参数,进行了基于ANSYS的二维仿真加工和三维仿真加工。对小孔的入口直径、底面直径和加工深度进行了对比分析,结果表明由于三维仿真加工中采用了管电极,并考虑了电解加工中阴极超声高频振动对电解液电导率的影响,故其仿真结果更加接近试验值,间接证明了旋转超声电解复合加工小孔三维仿真加工的可靠性,展示了不同时刻的三维加工型腔,为旋转超声电解复合加工的成型过程和成型规律的研究提供了参考。     

On the problem of the simulation of the acoustic path of an angle transducer during ultrasonic testing of thin welded joints

The results of theoretical and experimental studies of signals from high-frequency angle transducers during ultrasonic testing of thin-welded joints are presented. The effect of the quasi-bending of an acoustic beam of a piezoelectric transducer at high frequencies is confirmed. The appropriate testing parameters for such welded joints are recommended.     

Some special features of using DGS (AVG) diagrams during ultrasonic testing of welded joints

The results of development of a method and piezoelectric probes with DGS (AVG) diagrams for ultrasonic testing devices are considered. The technique is compatible with European standards for ultrasonic testing of welded joints as regards the parameters of piezoelectric probes and sensitivity tuning taking into account damping of elastic waves. The succession of operations in tuning of devices, ultrasonic testing, and evaluation of the results with DGS (AVG) diagrams is considered.     

Evaluation of machining performance of STAVAX with PCBN tools

A study was undertaken to investigate the wear characteristics of polycrystalline cubic boron nitride (PCBN) cutting tools and surface integrity during machining of STAVAX (specialised stainless steel) with and without coolant. Plastic deformation and formation of overtempered martensite and white layer (untempered martensite) were the dominant subsurface and surface defects. It was found that decreasing the hardness of the STAVAX from 55 HRC to 40 HRC could result in fracture on the flank face, leading to a deterioration of the surface finish. It was observed that low CBN content tools (60%CBN/40%TiN) exhibited greater fracture resistance than high CBN content tools (85%CBN/15%TiN, 90%CBN/10%Co). Although coolant could not bring about a reduction in the flank wear, it was effective in reducing the subsurface and surface defects, and in preventing chipping of the tool edge, leading to an improved surface finish. A superior surface finish (Ra<0.3 m) was obtained with cutting fluid using a tool with a radius of 0.8 mm, depth of cut of 0.05 mm and feed rate of 0.05 mm/rev.     

小波包分析在摩擦焊超声检测信号消噪中的应用

在摩擦焊接过程中,由于焊接参数的波动或一些非正常因素的介入,接头中容易产生未焊合及伪结合等缺陷。对于伪结合缺陷,其超声检测信号信噪比很低,一般条件下很难检测出来。本文采用小波包对该类缺陷超声检测信号进行消噪,结果表明,该方法不仅能有效抑制噪声,而且能明显提高信噪比。     

硅镜超声加工声学系统设计

近年来,超声加工方法已经越来越多地应用于脆硬材料的加工,超声声学系统是功率超声设备的核心和关键所在,其设计的好坏直接影响到其应用的效果.在分析超声声学系统工作原理的基础上,给出了该声学系统的具体设计方案,并且专门针对硅镜超声加工声学系统进行了设计及实验.实验结果表明,所设计的声学系统性能比较稳定,换能器发热较少,效率较高.     

全焊接阀体管线球阀焊接接头安全评估

介绍了一种评价焊接接头安全性的方法,根据焊接接头断裂韧度CTOD试验值,对埋弧焊焊接接头免焊后热处理的可能性进行安全评定。为大型全焊接阀体管线球阀制造提供科学依据。     

Residual stress evaluation in dissimilar welded joints using finite element simulation and the L CR ultrasonic wave

Subsurface stresses in welded structures increase the likelihood of fatigue cracks and environmental induced material degradation. The ability to evaluate stresses at the surface as well as in the interior of welded structural members would substantially increase the accuracy of structure life estimation. The longitudinal critically refracted (L _CR) wave is a bulk longitudinal mode that travels within an effective depth underneath the surface. It may be used to detect in-plane subsurface stresses in the structures. This paper presents a three dimensional thermo-mechanical analysis to evaluate welding residual stresses in dissimilar plate-plate joint of AISI stainless steel 304 and Carbon Steel A106-B type. After finite element simulation, the residual stresses were evaluated by L _CR ultrasonic waves. Finally the results of two methods were compared and verified by hole-drilling method. This paper introduces a combination of ??Finite Element Welding Simulation?? and ??Ultrasonic Stress Measurement using the L _CR Wave?? which is called as ??FEL _CR??. The capabilities of FEL _CR??. The capabilities of FEL _CR in residual stress measurement are confirmed here. And also this paper evaluates residual stresses of dissimilar welded joints by LCR ultrasonic waves. It has been shown that predicted residual stress from three dimensional FE analyses is in reasonable agreement with measured residual stress from LCR method and also the results of both are verified with hole-drilling experimental measurements.     

棱体成形车刀加工圆锥面工件时的形状误差分析

用棱体成形车刀加工圆锥面工件时,是否因车刀有前角就必然会产生双曲线误差,目前存在两种不同的观点。第一种观点认为,由于车刀有前角,切削刃为直线型,加工结果必然产生形状误差;第二种观点则认为,只要采取相应的工艺措施,便不会产生上述形状误差。本文就这两种观...     

Fabrication of stepped hole on zirconia bioceramics by ultrasonic machining

Zirconia (ZrO₂) is a highly biocompatible ceramic material providing fracture strength properties that allow application as dental implants in biomedical engineering. In this present research, experimental analysis has been made for generating stepped hole on zirconia bioceramics with desired quality using ultrasonic machining (USM) process. Four independent controllable input process parameters are abrasive grain diameter, power rating, concentration of abrasive slurry, and tool feed rate. Material removal rate (MRR), overcut of larger diameter (OLD) hole, and overcut of smaller diameter (OSD) hole of stepped hole are considered as the responses. Response surface methodology (RSM) is used for modeling the performance of USM process. Multiobjective optimization has been performed to maximize the MRR and minimize the OLD hole and OSD hole of stepped holes. All the responses are improved at the optimal parametric condition and verified by confirmation test. The present research opens up the application feasibility of USM process for stepped hole generation on bioceramics and its utilization in biomedical field.     

Effect of ultrasonic impact treatment on the ultra high cycle fatigue properties of SMA490BW steel welded joints

This paper presents bi-criteria formulation of a tolerance allocation model for an interchangeable assembly to simultaneously evolve suitable combination of manufacturing facility in multiple facility shaft-hole production environments of medium- and large-scale industries and tolerances to complement the need of customers. An Exhaustive Search Procedure is used to obtain the optimal solution for small and medium size problems and simulated annealing algorithm is used for large size problems. The usefulness of the Pareto front in manufacturing tolerance allocation decisions is demonstrated with three case study problems. The effect of process capability of shaft-hole assembly manufactured from alternative manufacturing machines and the optimality is analyzed in three cases to understand their criticality in decision-making. The models discussed in this paper could be useful for medium- and large-scale manufacturing industries, where there will be a variety of manufacturing facilities (specifications, capabilities, models, and types) for making both shaft-hole assembly and play a key role to meet the tolerance and cost requirements of different customers. This paper further discusses how this formulation and methodologies can be used for two hole and two shaft assemblies and multiple shaft-hole assemblies. Finally, the paper ends with highlighting directions of future research avenues in the shaft-hole assembly.     

Vibration suppression in ultrasonic machining described by non-linear differential equations

Vibrations are usually undesired phenomena as they may cause damage or destruction of the system. However, sometimes they are desirable, as in ultrasonic machining (USM). In such case, the problem is a complicated one, as it is required to reduce the vibration of the machine head and have reasonable amplitude for the tool. In the present work, the coupling of two non-linear oscillators of the tool holder and tool representing ultrasonic cutting process is investigated. This leads to a two-degree-of-freedom system subjected to multi-external excitation force. The aim of this work is to control the tool holder behavior at simultaneous primary and internal resonance condition and have high amplitude for the tool. Multiple scale perturbation method is applied to obtain a solution up to the second order approximations. Other different resonance cases are reported and studied numerically. The stability of the system is investigated applying both phase-plane and frequency response techniques. The effects of the different parameters of the tool on the system behavior are studied numerically. Comparison with the available published work is reported. This paper was recommended for publication in revised form by Associate Editor Eung-Soo Shin M. M. Kamel received his B.S. degree in Mathematics from Ain Shams University, EGYPT, in 1979. He then received his M.S.c degrees from Ain Shams University, in 1986 and Ph.D. degrees from Menofia University, in 1994. Dr. M. M. Kamel is currently an Associate Professor of Mathematics at the Department of Engineering Mathematics, Faculty of Electronic Engineering Menofia University, Egypt. Dr. M. M. Kamel research interests include Differential equations, Numerical Analysis, and Vibration control. W. A. A. El-Ganini received her B.S. degree in Mathematics from Ain Shams University, EGYPT, in 1980. She then received her M.S.c and Ph.D. degrees from Suez Canal University, in 1984 and 1989, respectively. Dr. W. A. A. El-Ganini is currently an Assistant Professor of Mathematics at the Department of Engineering Mathematics, Faculty of Electronic Engineering Menofia University, Egypt. Dr. W. A. A. El-Ganaini research interests include Differential equations, Numerical Analysis, and Vibration control. Y. S. Hamed received his B.S. degree in Mathematics from Menofia University, EGYPT, in 1998. He then received his M.S.c and Ph.D. degrees from Menofia University, in 2005 and 2009, respectively. Dr. Y. S. Hamed is currently an Assistant Professor of Pure Mathematics at the Department of Engineering Mathematics, Faculty of Electronic Engineering Menofia University, Egypt. Dr. Y. S. Hamed research interests include Differential equations, Numerical Analysis, and Vibration control.