Using Ultrasonic Testing Research Articles

Analysis of the Suitability of Ultrasonic Testing for Verification of Nonuniform Welded Joints of Austenitic-Ferritic Sheets.

The purpose of the presented research was to determine the suitability of using ultrasonic testing (UT) to inspect heterogeneous, from a material point of view, welded joints on the example of the joints of a ferritic steel element with elements made of an austenitic steel. The echo technique with transverse (SEK) and longitudinal wave heads (SEL) addressed this issue. Due to the widespread use of 13CrMo4-5 and X2CrNiMo17-12-2 steel grades in the energy industry, they were selected as the test materials for the study. The objects of the presented research were welded joint specimens with thicknesses of 8, 12, and 16 mm and dimensions of 300 × 300 mm, made using the 135 metal active gas (MAG) process with the use of the Lincoln 309LSi wire-a ferritic-austenitic filler material. The stages of the research task were (1) making distance-amplitude curve (DAC) patterns from the test materials; (2) preparation of specimens of welded joints with artificial discontinuities in the form of through-holes; (3) performing UT tests on welded joints with artificial discontinuities using heads with 60° and 70° angles for the transverse wave and angle heads for longitudinal waves with similar beam insertion angles; (4) selection, by radiographic testing (RT), of welded joint specimens with natural discontinuities in the form of a lack of sidewall fusion; (5) performing UT tests on welded joints with natural discontinuities, using heads as welded joints with artificial discontinuities. It was found that (1) the highest sensitivity of discontinuity detection was obtained by performing tests on the ferritic steel side, which is due to the lower attenuation of the ultrasonic wave propagating in ferritic steel compared to austenitic steel; (2) the best detection of discontinuities could be obtained using a longitudinal ultrasonic wave; (3) there is a relationship between the thickness of the welded elements, the angle of the ultrasonic beam introduction, and the effectiveness of discontinuity detection.

Anisotropic polymer components with desired elastic properties manufactured through fused filament fabrication additive manufacturing

AbstractFused filament fabrication (FFF) is a popular additive manufacturing (AM) process, primarily used for fabricating polymer components. Optimizing the mechanical properties of FFF components, such as their elastic moduli, is crucial in many applications. This study focuses on adjusting the elastic properties of polymer components manufactured through FFF process by selecting appropriate process parameters. The elastic constants of the anisotropic FFF components are measured by using ultrasonic testing (UT). Response surface methodology (RSM) is employed to determine the optimal settings for these parameters to achieve the desired elastic properties. The effects of layer thickness, printing speed, and raster angle on Young's modulus are explored. Analysis of variance (ANOVA) is used to identify the contributions of each process factor on the output responses. According to ANOVA results, the optimal conditions identified are: a printing speed of 2040 mm/min, a layer thickness of 0.2 mm, and a raster angle of 29°. These conditions collectively achieved the maximum Young's modulus. The differences between the predicted and measured moduli for all responses are less than 5%. The structural factors influencing the results are examined by analyzing the fracture surfaces of the tensile testing (TT) specimens with field emission scanning electron microscopy. Additional measurements of other properties, including ultrasound velocity and wave attenuation, are conducted on the samples. The findings indicate that optimizing the parameters by setting them to their minimum values does not only improve the maximum elastic modulus in specific directions but also reduces attenuation. It is concluded that the desired elastic modulus for a component can be achieved by properly adjusting the process parameters.Highlights Optimizing AM parameters to achieve the desired elastic properties of FFF samples. Examining the effects of each AM parameter by utilizing ANOVA and RSM methods. Measuring the anisotropic elastic properties of AM samples by UT. Verifying UT results through TT and measuring attenuation.

Nondestructive Evaluation and Residual Property Assessment of Impacted Nylon/carbon-Fiber Additively Manufactured FFF Components Using Four-Point Bend and Ultrasonic Testing

ABSTRACT Fusion-based material extrusion additive manufacturing, commonly known as fused filament fabrication (FFF), is a layer-by-layer manufacturing process known for creating custom components, specializing in complex geometries, with applications in the aerospace, automotive, medical, as well as many other industries. Due to the critical nature of these industries, it is imperative to understand the relationship between the AM material in question, the nature of the resultant damage, and the impact of these two parameters on the future performance of the component. The purpose of this study is to investigate the relationship between low-velocity impact and the resultant damage in common functional FFF materials and to develop methods of visualizing that damage using ultrasonic nondestructive evaluation. Coupons of a nylon feedstock infused with and without 10% chopped carbon fiber were fabricated using an Essentium HSE printer and impacted at various energies. The extent of the damage was visualized using ultrasonic testing (UT), in which significant internal cracking was observed. Four-point bend testing was utilized to compare behavior of the material prior to impact at a lower impact energy (3J), and a higher impact energy causing visual fracture (7J). X-ray CT was also performed on two samples to validate UT findings.

Auto Sizing of CANDU Nuclear Reactor Fuel Channel Flaws from UT Scans.

The inspection of nuclear power plants is an essential process that occurs during plant outages. During this process, various systems are inspected, including the reactor's fuel channels to ensure that they are safe and reliable for the plant's operation. The inspection of Canada Deuterium Uranium (CANDU®) reactor pressure tubes, which are the core component of the fuel channels and house the reactor fuel bundles, is performed using Ultrasonic Testing (UT). Based on the current process that is followed by Canadian nuclear operators, the UT scans are manually examined by analysts to locate, measure, and characterize pressure tube flaws. This paper proposes solutions for the auto-detection and sizing of pressure tube flaws using two deterministic algorithms, the first uses segmented linear regression, while the second uses the average time of flight (ToF) within ±σ of µ. When compared against a manual analysis stream, the linear regression algorithm and the average ToF achieved an average depth difference of 0.0180 mm and 0.0206 mm, respectively. These results are very close to the depth difference of 0.0156 mm when comparing two manual streams. Therefore, the proposed algorithms can be adopted in production, which can lead to significant cost savings in terms of time and labor.

Finite element analysis and experimental investigation of ultrasonic testing of internal defects in SiCp/Al composites

Revealing the interactions of sound waves with both SiC particles and internal defects is crucial for facilitating the detectability of internal defect features in SiCp/Al by using ultrasonic testing (UT). In the present work, we demonstrate the feasibility of UT of internal flat-bottom holes with diameters ranging from 0.2 mm to 2 mm in SiCp/Al composites through the combination of finite element (FE) simulations and experiments. Specially, a 2D FE model of UT of SiCp/Al with consistent geometrical features of SiC particles with experimental one is established, the accuracy of which is validated by theoretical and experimental characterizations of P-wave velocity and ultrasonic attenuation coefficient of SiCp/Al. Subsequently, the propagation behavior of sound waves in the SiCp/Al specimen with pre-existing defects under UT, in particular the impact of defect boundary on the scattering behavior of sound waves, is revealed in detail by FE simulations and also validated by corresponding experiments. Furthermore, the UT limit of detectable size of the internal defects is revealed jointly by FE simulations and experiments, based on which a correlation map between defect size and echo signal amplitude is established. Current study provides theoretical and practical guidance for the UT of internal defects in SiCp/Al composites.

Experimentation for Sag and Dimension Measurement of Thin-Walled Tubes and Pipes Using Multi-Channel Ultrasonic Imaging System

Thin-walled tubes and pipes are employed in industries to work under the conditions of high temperature, high pressure, high flow rates and radiation. Due to such stresses and harsh working conditions, tubes lead to sag during operation because of its low Wall Thickness and smaller diameters. There is a requirement to accurately measure sag and dimensions and assess the health and remaining life of tubes and pipes, as per the relevant safety and reliability standards. Sag measurement is a complex task as it has to be performed in-situ. Other than that there is an important requirement to accurately measure Inner Diameter (ID), Outer Diameter (OD) and Wall Thickness (WT) of tubes and pipes. In this paper, a novel type of linear array-based sag and dimension measurement scheme has been proposed for the thin-walled tubes and pipes using Ultrasonic Testing (UT). UT technique has also been employed to accurately measure the sag and dimensions of the thin-walled tubes and pipes. The operating principle of UT is majorly based on Water-Immersion mode for the measurement of sag and dimensions by acquiring Time of Flight (TOF). In this paper, experimentation has been carried out using an in-house developed 4-Channel Ultrasonic Imaging System and using water-immersion mode. The 4-Channel Ultrasonic Imaging System along with an inspection head carrying a novel arrangement of ultrasonic transducers for measurement of sag and dimensions have been utilized. This paper provides details of the sag and dimension measurement of the sample tube and pipe, using the 4-Channel Ultrasonic Imaging System.

Internal Cracks and Non-Metallic Inclusions as Root Causes of Casting Failure in Sugar Mill Roller Shafts.

The sugar mill roller shaft is one of the critical parts of the sugar industry. It requires careful manufacturing and testing in order to meet the stringent specification when it is used for applications under continuous fatigue and wear environments. For heavy industry, the manufacturing of such heavy parts (>600 mm diameter) is a challenge, owing to ease of occurrence of surface/subsurface cracks and inclusions that lead to the rejection of the final product. Therefore, the identification and continuous reduction of defects are inevitable tasks. If the defect activity is controlled, this offers the possibility to extend the component (sugar mill roller) life cycle and resistance to failure. The current study aims to explore the benefits of using ultrasonic testing (UT) to avoid the rejection of the shaft in heavy industry. This study performed a rigorous evaluation of defects through destructive and nondestructive quality checks in order to detect the causes and effects of rejection. The results gathered in this study depict macro-surface cracks and sub-surface microcracks. The results also found alumina and oxide type non-metallic inclusions, which led to surface/subsurface cracks and ultimately the rejection of the mill roller shaft. A root cause analysis (RCA) approach highlighted the refractory lining, the hot-top of the furnace and the ladle as significant causes of inclusions. The low-quality flux and refractory lining material of the furnace and the hot-top, which were possible causes of rejection, were replaced by standard materials with better quality, applied by their standardized procedure, to prevent this problem in future production. The feedback statistics, evaluated over more than one year, indicated that the rejection rate was reduced for defective production by up to 7.6%.

An integrated framework for solid modeling and structural analysis of layered composites with defects

Laminated fiber-reinforced polymer (FRP) composites are widely used in aerospace and automotive industries due to their combined properties of high strength and low weight. However, owing to their complex structure, it is difficult to assess the impact of manufacturing defects and service damage on their residual life. Non-destructive evaluation (NDE) of composites using ultrasonic testing (UT) can identify the presence of defects. However, manually incorporating the damage in a CAD model of a multi-layered composite structure and evaluating its structural integrity is a tedious process. We have developed an automated framework to create a layered 3D CAD model of a composite structure and automatically preprocess it for structural finite element (FE) analysis. In addition, we can incorporate flaws and known composite damage automatically into this CAD model. The framework generates a layer-by-layer 3D structural CAD model of the composite laminate, replicating its manufacturing process. The framework can create non-trivial composite structures such as those that include stiffeners. Outlines of structural defects, such as delaminations detected using UT of the laminate, are incorporated into the CAD model between the appropriate layers. The framework is also capable of incorporating fiber/matrix cracking, another common defect observed in fiber-reinforced composites. Finally, the framework can preprocess the resulting 3D CAD models with defects for direct structural analysis by automatically applying the appropriate boundary conditions. In this paper, we show a working proof-of-concept of the framework with capabilities of creating composite structures with stiffeners, incorporating delaminations between the composite layers, and automatically preprocessing the CAD model for finite element structural analysis. The framework will ultimately aid in accurately assessing the residual life of the composite and making informed decisions regarding repairs.

Artificial intelligence based defect classification for weld joints

This paper mainly deals with the development of a defect classification system that uses Artificial Neural Network (ANN) to classify weld defects based on ultrasonic test data. The system enables real-time identification of weld defects which finds application in testing of critical welding applications and also reduces dependency on skilled workforce for the function. The study mainly consists of three parts- (i) Weld defect detection using Ultrasonic Testing (UT) (ii) Implementation of ANN (iii) Defect classification. An ultrasonic test performed on welded samples shows different results for welds with and without defects and further between defects as well. The ultrasonic test data is fed into the ANN algorithm to train it to identify the various weld defects. An Artificial Neural Network (ANN) is an information processing paradigm that uses a large number of highly interconnected processing elements called neurons, working in unison to solve the specific problems. There are two types of neural network architectures that are used for classification - a back propagation network (BPN) and a probabilistic neural network (PNN). Back propagation network has been used for the purpose of this study. In order to test the performance of the back propagation neural network, four classes of defect namely porosity, lack of side wall fusion, lack of penetration and slag inclusion are considered.

Effect of induction heating on flaw generation and expansion

During acceptance tests phase of plasma facing components, main performance requirements are checked. For divertor application, it is important to achieve an adequate heat exhaust capability. For ITER divertor, defects localized at tungsten to compliant layer interface are defects impacting such capability. For this reason, acceptance tests, of ITER divertor components, mainly consist in using ultrasonic testing (US) and high heat flux (HHF) tests. If a defect is detected by US tests, it is mandatory to validate that detected defect as no detrimental impact on component heat exhaust capability. At present, HHF tests can assess this performance. In this paper, we describe a test, called STING (thermomechanical STamping by Induction heatiNG), which aims to evaluate, before HHF tests, the heat exhaust evolution of plasma facing components after a moderate thermal solicitation. This paper is focused on the effect of STING solicitation on flaw generation and expansion.

Online Eccentricity Monitoring of Seamless Tubes in Cross-Roll Piercing Mill

Wall-thickness eccentricity is a major dimensional deviation problem in seamless steel tube production. Although eccentricity is mainly caused by abnormal process conditions in the cross-roll piercing mill, most seamless tube plants lack the monitoring at the hot piercing stage but only inspect the quality of finished tubes using ultrasonic testing (UT) at the end of all manufacturing processes. This paper develops an online monitoring technique to detect abnormal conditions in the cross-roll piercing mill. Based on an image-sensing technique, process operation condition can be extracted from the vibration signals. Optimal frequency features that are sensitive to tube wall-thickness variation are then selected through the formulation and solution of a set-covering optimization problem. Hotelling T2 control charts are constructed using the selected features for online monitoring. The developed monitoring technique enables early detection of eccentricity problems at the hot piercing stage, which can facilitate timely adjustment and defect prevention. The monitoring technique developed in this paper is generic and can be widely applied to the hot piercing process of various products. This paper also provides a general framework for effectively analyzing image-based sensing data and establishing the linkage between product quality information and process information.

On-power detection of wall-thinned defects using lock-in infrared thermography

Recently, nuclear power plants (NPPs) have been using ultrasonic testing (UT) to inspect the pipes of secondary piping systems. However, UT is not suitable for measuring wall-thinned defects in small-diameter pipes and requires a long period of time to acquire analysis results. In addition, it is less reliable when inspecting small-diameter piping, and it is almost impossible to inspect defects during NPP normal operation. Therefore, UT is not reliable for detecting wall-thinned defects in the small-diameter pipes of NPPs during normal operation. In this study, we developed a lock-in infrared (IR) thermography technique to detect wall-thinned defects in the small diameter pipes of a NPP's secondary systems during normal operation. For experiments, a mock-up loop was constructed that contained artificially generated defects. The fluid inside the loop was maintained at a temperature similar to the operating conditions of a NPP. Based on the results of experiments where lock-in IR thermography was applied, it is expected to be possible to detect wall-thinned defects in piping during normal operation, shorten the maintenance time of NPPs, and improve the work efficiency of the inspector.

ESTIMATION OF THE CRITICAL DETECTABLE SIZE OF NATURAL FLAWS IN DUCTILE CAST IRON USING ULTRASONIC TESTING

Abstract To evaluate the critical size of detectable flaws in ductile cast iron (DCI) for storage casks of spent nuclear fuels using ultrasonic testing (UT), round robin tests have been conducted. One test was to detect artificial defects using the normal and angle beam UT and a second test was to detect natural defects using UT. This paper describes the results of the second test and discussions including the previous test results. The main results are: (1) The detected echo level of natural defects was lower than the artificial defects of a 6 mm diameter by about 10 dB or more. (2) The detectability increased with the defect size. (3) The estimated size of detected defects was larger than that of actual natural defects. (4) The statistical critical detectable size of natural flaws was estimated once again to be 16.9 mm, which was the same as the previous paper concerning artificial defects. (5) This size has the safety factor of 2 or more for the allowable flaw size of DCI casks.