Ultrasonic Testing Method Research Articles

Low sidelobe level and high time resolution for metallic ultrasonic testing with linear-chirp-Golay coded excitation

Linear-chirp-Golay (LCG)-coded excitation combined with pulse compression is proposed in this paper to improve the time resolution and suppress sidelobe in ultrasonic testing. The LCG-coded excitation is binary complementary pair Golay signal with linear-chirp signal applied on every sub pulse. Compared with conventional excitation which is a common ultrasonic testing method using a brief narrow pulse as exciting signal, the performances of LCG-coded excitation, in terms of time resolution improvement and sidelobe suppression, are studied via numerical and experimental investigations. The numerical simulations are implemented using Matlab K-wave toolbox. It is seen from the simulation results that time resolution of LCG excitation is 35.5% higher and peak sidelobe level (PSL) is 57.6 dB lower than linear-chirp excitation with 2.4 MHz chirp bandwidth and 3 μs time duration. In the B-scan experiment, time resolution of LCG excitation is higher and PSL is lower than conventional brief pulse excitation and chirp excitation. In terms of time resolution, LCG-coded signal has better performance than chirp signal. Moreover, the impact of chirp bandwidth on LCG-coded signal is less than that on chirp signal. In addition, the sidelobe of LCG-coded signal is lower than that of chirp signal with pulse compression.

Novel Method for the Detection of Onset of Delamination in Reinforced Concrete Bridge Decks

AbstractThis paper presents a discussion and the experimental proof-of-concept results of a novel ultrasonic testing (UT) method to identify the onset of delamination in reinforced concrete bridge ...

Development, optimization and validation of ultrasonic testing for NDE of ELM coils

Institute for Plasma Research (IPR) has been developing technologies appropriate towards realizing fusion relevant Edge Localized Mode (ELM) magnets in Tokamaks such as Joint European Torus (JET) and Steady State Superconducting Tokamak (SST-1). The winding pack of ELM coils have been encased inside the Inconel 625 casing using customized double groove and single bevel weld joints. It is critical to ensure soundness of these weld joints. With this motivation, Non-Destructive Evaluation (NDE) method using ultrasonic technique has been developed and established for inspection of weld joints in ELM control coils. The development of ultrasonic test procedure, test parameters, test validation and optimization using simulation as well as experimental approach has been discussed in this paper. The selection and locations probes along with beams parameters for weld joints have been optimized with commercially available software CIVA- versatile simulation tool developed by CEA (French Atomic Energy Commission), France. Further, the developed ultrasonic test method has been established and validated on mockup box sample of casing for ELM coils. It has been again successfully demonstrated for its performance on 1:1 demo coil equivalent to small ELM coil.

Austenitic Biomaterial Cracks Evaluation by Advanced Nondestructive Techniques

The article deals with Non-Destructive Evaluation (NDE) of austenitic stainless steels. Eddy current, ultrasonic testing and non-contact magnetic field mapping methods are used for this purpose. ECA (Eddy Current Array) and TOFD (Time of Flight Diffraction) are methods that have become widely-used in the field of NDE and this is the reason for their utilization. Magnetic field mapping is nowadays an effective method of evaluation of surface-breaking defects mainly in ferromagnetic materials. The fluxgate sensor-based measurement is presented and discussed. The artificial fatigue and stress-corrosion material’s cracks are inspected. Experimental results are presented and discussed in this paper.

PAUT-based defect detection method for submarine pressure hulls

A submarine has a pressure hull that can withstand high hydraulic pressure and therefore, requires the use of highly advanced shipbuilding technology. When producing a pressure hull, periodic inspection, repair, and maintenance are conducted to maintain its soundness. Of the maintenance methods, Non-Destructive Testing (NDT) is the most effective, because it does not damage the target but sustains its original form and function while inspecting internal and external defects. The NDT process to detect defects in the welded parts of the submarine is applied through Magnetic particle Testing (MT) to detect surface defects and Ultrasonic Testing (UT) and Radiography Testing (RT) to detect internal defects. In comparison with RT, UT encounters difficulties in distinguishing the types of defects, can yield different results depending on the skills of the inspector, and stores no inspection record. At the same time, the use of RT gives rise to issues related to worker safety due to radiation exposure. RT is also difficult to apply from the perspectives of the manufacturing of the submarine and economic feasibility. Therefore, in this study, the Phased Array Ultrasonic Testing (PAUT) method was applied to propose an inspection method that can address the above disadvantages by designing a probe to enhance the precision of detection of hull defects and the reliability of calculations of defect size.

Experimental and Simulation Analysis of the Successful Production of Heavy-Gauge Steel Plate by the Clad Rolling Process

Abstract Heavy-gauge Q235 steel plate was successfully roll bonded, and this process was simulated using MARC software. The test results revealed that the chosen ultrasonic testing method satisfies Ⅰ level requirements and the mechanical properties of the materials fully meet the necessary standards. There were uniform ferrite+pearlite microstructures and sound bond areas at the bond interface. Simultaneously, fracture analysis revealed ductile fracture. Using EDS analysis, oxide+MnS inclusions were detected in sample indentations. The MARC simulation showed that after the first rolling pass, little equivalent strain occurred at the center of slab. At the third hot rolling pass, the equivalent strain of the center increased to 0.5. When rolling the last pass, the equivalent strain tended to be uniform in the roll gap region.

MULTI-WAVE ULTRASONIC CONTROL OF CONCRETE

The existing non-destructive testing system of structure concrete is actually orientated on the usage of longitudinal acoustical waves. This is due to simplicity of technical realization for measuring velocity (time) of acoustical pulse propagation in bulk concrete. But a reverse side of simple measuring procedure is a loss of additional information on concrete which is contained in the accepted acoustical signal. Therefore usage of an ultrasonic concrete testing method is limited by assessment of its strength. Joint usage of several wave types, so-called multi-wave testing, allows to refine metrology parameters of the ultrasonic method and to gain more information while determining physical and mechanical properties of concrete in laboratory and in situ conditions. The paper considers testing of elongated concrete elements and structures by an ultrasonic pulsing method on the basis of longitudinal subsurface and Rayleigh waves. It has been proposed to use methodology for time selection of wave components according to amplitude parameter and it has been applied for standard acoustical transformers with considerable reverberation time and not possessing spatial selectivity Basic principle of the proposed methodology is visual (according to oscillogram of the received signal) determination of characteristic time moments which are used for calculation of differential value of a propagation velocity in the Rayleigh wave impulse. The paper presents results pertaining to simulation of acoustical pulse propagation on the basis of 0.15 m and data of concrete ultrasonic in situ testing on measuring bases from 0.25 to 1.75 m. Advantage of large baseline for sonic test is a possibility for execution of a hundred percent inspection for surface of large-sized elements and structures, and so there is no need to make a selective inspection in some control areas as it is stipulated by provided by existing regulations. Responsivity of the Rayleigh wave parameters to near surface concrete defects permits quickly and efficiently to detect crack areas in a reinforced structure. Energy localization of a surface wave in a layer having width λ/2–λ provides a possibility to ignore reinforcement availability under appropriate selection of oscillation frequency. In addition to this, large measuring baseline makes it possible to lower effect of concrete structural inhomogeneity on statistical stability for pulse velocity assessment that ultimately reveals a possibility to register an appearance of concrete acoustical elasticity effect under in situ conditions.

Effect of test frequency on fatigue strength of AZ31 alloy

Investigation of fatigue strength of extruded AZ31 magnesium alloy was performed by ultrasonic fatigue tests (test frequency about 19500Hz) and taken to compare with conventional tension-compression fatigue tests (20Hz). The fatigue life under ultrasonic loading exhibits longer than the conventional one. Effects of ultrasonic frequency on the S-N curve, crack initiation and growth behaviour of AZ31 alloy is discussed. This work would be useful for improving the ultrasonic fatigue test method to observe the fatigue behaviour in very high cycle regime.

Very high cycle fatigue testing of concrete using ultrasonic cycling

Abstract The ultrasonic fatigue testing method has been further developed to perform cyclic compression tests with concrete. Cylindrical specimens vibrate in resonance at a frequency of approximately 20 kHz with superimposed compressive static loads. The high testing frequency allows time-saving investigations in the very high cycle fatigue regime. Fatigue tests were carried out on “Concrete 1” (compressive strength fc = 80 MPa) and “Concrete 2” (fc = 107 MPa) under purely compressive loading conditions. Experiments at maximum compressive stresses of 0.44 fc (Concrete 1) and 0.38 fc (Concrete 2) delivered specimen failures above 109 cycles, indicating that no fatigue limit exists for concrete below one billion load cycles. Resonance frequency, power required to resonate the specimen and second order harmonics of the vibration are used to monitor fatigue damage in situ. Specimens were scanned by X-ray computed tomography prior to and after testing. Fatigue cracks were produced by ultrasonic cycling in the very high cycle fatigue regime at interfaces of grains as well as in cement. The possibilities as well as limitations of ultrasonic fatigue testing of concrete are discussed.

Characterization of Weldments Defects through Non Destructive Evaluation Techniques

Background/Object: Non-destructive Testing (NDT) methods are valuable tools in quality assurance of weldments in engineering and technology. The objective of this paper is to evaluate the structural health monitoring of the weldments through NDT methods. Methods/Analysis: The samples taken for these studies are extensively used in Aerospace and industrial applications. The dimensions of fabricated samples of stainless steel and mild steel is 300 mm × 180 mm × 10 mm, D3 tool steel is 180 mm × 150 mm × 25 mm, Aluminum is 150 mm × 120 mm × 10 mm and Titanium is 160 mm × 60 mm × 2 mm. These samples are subjected to Gas Tungsten Arc welding (GTAW) during welding artificial defects are incorporation by altering the weld parameters. The profile of weld defects is studied by using basic Non-Destructive Testing techniques. Findings: Defects which are open to surface and subsurface defects up to 6mm depth are detected by Visual Inspection (VI), Liquid Penetrant Test (LP) and Magnetic Particle Inspection (MPI) techniques. Ultrasonic - B scan NDT technique is adapted for study of thickness profile of weld region of weldments found distinct result in aluminum weldments. Orientation and Internal of defects of the weldments were detected by Gamma ray Radiography and Ultrasonic Testing methods found forging material inclusion in SS material, Aluminum weldments. Application/Improvements: These evaluation studies through Nondestructive Testing techniques are much useful for structural health monitoring of the weldments.

Principles and Applications of Ultrasonic-Based Nondestructive Methods for Self-Healing in Cementitious Materials.

Recently, self-healing technologies have emerged as a promising approach to extend the service life of social infrastructure in the field of concrete construction. However, current evaluations of the self-healing technologies developed for cementitious materials are mostly limited to lab-scale experiments to inspect changes in surface crack width (by optical microscopy) and permeability. Furthermore, there is a universal lack of unified test methods to assess the effectiveness of self-healing technologies. Particularly, with respect to the self-healing of concrete applied in actual construction, nondestructive test methods are required to avoid interrupting the use of the structures under evaluation. This paper presents a review of all existing research on the principles of ultrasonic test methods and case studies pertaining to self-healing concrete. The main objective of the study is to examine the applicability and limitation of various ultrasonic test methods in assessing the self-healing performance. Finally, future directions on the development of reliable assessment methods for self-healing cementitious materials are suggested.

Fatigue testing of thin CoNiCr wire up to 1010 cycles

The CoNiCr alloy MP35N in the form of thin wires is commonly used as conductor in cardiac leads. The application requires high fatigue strength, in particular in the very high cycle fatigue (VHCF) regime. High frequency fatigue testing techniques are of great interest for material characterization and development since existing techniques require very long testing times.In this study, adapting the ultrasonic fatigue testing method to sub-millimeter wires has been accomplished for the first time. Fatigue tests of as-drawn low-Ti MP35N wire with 100μm diameter have been performed with a novel technique at 20kHz cycling frequency at load ratio R=0.3. Measured lifetimes show good agreement with conventional servo-hydraulic tension-tension fatigue data of the same material at 30Hz. Ultrasonic tests were run up to 2×1010cycles, and no fatigue limit was observed.Crack initiation occurs at Al2O3-inclusions at the surface, where the interfaces between particles and matrix fail. Sizes of the crack initiating inclusions, areainc. are between 1.9μm and 3.5μm. Fatigue lifetimes can be approximated with a single S-N curve between 104 and 1010 cycles. No change of crack-initiation mode into the interior is observed when lifetimes extend into the VHCF regime. Inclusions can be considered as initial cracks, and a fracture mechanics concept is used to describe fatigue lifetimes. On average a stress intensity range as low as 1.0MPam can propagate the crack to fracture at lifetimes above 108cycles.

Experimental assessment of the influence of multiple cyclic loading on the dynamic modulus of elasticity of concrete

The goal of the experiment was to determine the influence that cyclic loading has on concrete dynamic modulus of elasticity and compressive strength. Each test specimen was subjected to cyclic loading with the loading force equivalent to one third of the expected compressive strength value similarly to the static modulus of elasticity test with the difference that the total number of loading cycles was 3000. The dynamic modulus of elasticity was determined on every specimen before and after loading by means of the ultrasonic pulse velocity test and resonance method. The result of the experiment is the degree to which the dynamic modulus of elasticity decreased after multiple cyclic loading. A decrease was observed in all specimens.

Signal processing methods to improve the Signal-to-noise ratio (SNR) in ultrasonic non-destructive testing of wind turbine blade

Ultrasonic non-destructive testing (NDT) methods are being used quite effectively nowadays, but the multilayered structure of composite materials results in the serious problem in the detection of defects/flaws. The resulting ultrasonic signal is often noisy and denoising of this signal is necessary in order to extract useful information so that faults can be detected, located and sized. Currently, there is a high demand for automatic ultrasonic signal processing techniques to not only remove the need for manual flaw detection and assessment, but also increase the accuracy, reliability and repeatability of the non-destructive evaluation. There are various signal processing techniques which can be used in ultrasonic measurements and selection of appropriate method is one of the major key factors in the field of ultrasonic testing of composite materials. In the presented work, the sample of wind turbine blade (WTB) manufactured using glass fiber reinforced plastic (GFRP) was investigated using ultrasonic NDT in order to estimate the artificially made disbond type defects of 15 mm and 25 mm diameter on the trailing edge. The transmitting and receiving transducers were fixed on movable panel at distance of 50 mm and guided waves (GW) were received at each one millimeter step along the scanning distance of 500 mm. The measurement is performed using low-frequency (LF) ultrasonic system which was developed by Ultrasound Institute of Kaunas University of Technology. Various signal processing techniques were applied to overcome the structural noise and/or extract the information about the defects. The three most promising signal processing techniques: cross-correlation methods, wavelet transform (WT) and Hilbert-Huang (HHT) transform were discussed and compared in the process of defects estimation.

Study to detect bond degradation in reinforced concrete beams using ultrasonic pulse velocity test method

Concrete technologists have used ultrasonic pulse velocity test for decades to evaluate the properties of concrete. However, the presented research work focuses on the use of ultrasonic pulse velocity test to study the degradation in steelconcrete bond subjected to increasing loading. A detailed experimental investigation was conducted by testing five identical beam specimens under increasing loading. The loading was increased from zero till failure in equal increments. From the experimentation, it was found that as the reinforced concrete beams were stressed from control unloaded condition till complete failure, the propagating ultrasonic wave velocity reduced. This reduction in wave velocity is attributed to the initiation, development, and propagation of internal cracking in the concrete surrounding the steel reinforcement. Using both direct and semidirect methods of testing, results of reduction in wave velocity with evidence of internal cracking at steel-concrete interface are presented. From the presented results and discussion, it can be concluded that the UPV test method can be successfully employed to identify zones of poor bonding along the length of reinforced concrete beam. The information gathered by such testing can be used by engineers for localizing repairs thereby leading to saving of time, labor and cost of repairs. Furthermore, the implementation strategy along with real-world challenges associated with the application of the proposed technique and area of future development have also been presented.

Research on Ultrasonic Testing Methods for Adhesion Quality of Ceramic Coatings

Ceramic coatings are widely used in aerospace field as thermal barrier materials for their high-temperature performance. The adhesion quality of ceramic coatings on metallic substrate is an important index for coating performance. The uniformity of coating thickness is also important since it determines the thermal stresses in the coatings, which means the coating performance is closely related with the uniformity. The reflection characteristic of the coating-substrate interface is an essential factor for evaluating the adhesion quality. Since the acoustic impedance of ceramic coatings is very close to that of substrate, it is not easy to distinguish their reflection wave in the received waves. In this paper, the propagation characteristics of ultrasonic wave in coatings with different thicknesses on the substrate were researched using immersion ultrasonic testing with pulse-echo method. An algorithm based on the amplitude and phase of reflection waves was proposed for the evaluation of adhesive quality. The results show that, pulse-echo method is highly reliable for the measurement of coating thickness and that the algorithm is effective for the evaluation of adhesion quality of ceramic coatings.

Evaluation of Very High Cycle Fatigue Properties of β-Titanium Alloy by Using an Ultrasonic Tensile-Compressive Fatigue Testing Machine

β-titanium alloy has been developed recently because β-titanium alloy has better cold workability, proof stress, and tensile strength. In order to use β-titanium alloy for automobile parts subject to cyclic loading, very high cycle fatigue properties of β-titanium alloy should be investigated. In this study, very high cycle fatigue properties of β-titanium alloy Ti-22V-4Al were evaluated by using an ultrasonic fatigue testing method, which allows us to reduce a fatigue testing period to 1/100 − 1/1000 of that by using conventional testing methods. An S-N diagram and fracture morphology of Ti-22V-4Al in the very high cycle region were investigated. Fatigue failure was observed and subsurface fracture occurred in the very high cycle region.

Nondestructive testing of pitting corrosion cracks in rivet of multilayer structures

This research proposes an ultrasonic testing method for inspecting pitting corrosion cracks in a rivet of multilayer structures. The system is a combination of a magnetic sensor array and an ultrasonic sensor. The magnetic sensor array is used to automatically measure the presence of a rivet and its center position. Then, the ultrasonic sensor is guided to the rivet center in order to inspect pitting corrosion cracks in the rivet. The magnetic sensor uses a 64-Hall sensor elements array with a 0.52-mm interval that can measure the rivet center position at a standard deviation of 0.27 mm and 0.42 mm in the scan and sensor directions, respectively. The ultrasonic signal is analyzed in the frequency domain using the short-time Fourier transform that helps better observe the presence of cracks compared with the conventional signal analysis in A-scan present.

Moisture-dependent elastic characteristics of walnut and cherry wood by means of mechanical and ultrasonic test incorporating three different ultrasound data evaluation techniques

Ultrasonic testing is a non-destructive testing method of choice for estimating the anisotropic elastic properties of wood materials. This method is reliable for estimating the Young’s and shear moduli. However, its applicability to Poisson’s ratios remains uncertain. On the other hand, despite their destructive nature, mechanical tests allow a direct measurement of all elastic properties including the Poisson’s ratios. In some cases (e.g. when assessing cultural heritage objects), destructive testing may not be an option. In this work, two types of hardwood walnut (Juglans regia L.) and cherry (Prunus avium L.), which often appear on cultural heritage objects, were tested using both ultrasonic and mechanical testing methods under four different moisture conditions below fibre saturation point. The results show that a higher moisture condition leads to a decrease in material elasticity. For walnut wood, their longitudinal Young’s modulus (\(E_{\rm L}\)) was reduced by 679 MPa under the compression load for a one per cent increase in moisture content. Moreover, three ultrasound data evaluation techniques, which differ in the way they incorporate the Poisson’s ratios (full stiffness inversion, simplified uncorrected, and simplified corrected), were used to estimate the Young’s moduli (E). The main goal is to obtain reliable material parameters using the ultrasound test. As a result, it is concluded that the chosen data evaluation method influences the accuracy of the calculated E. In a certain case, the simplified-corrected method, which requires only one specimen type, gave a closer agreement to mechanical tests (e.g. \(\Delta E_{\rm T}=6\,\%\) deviation on mechanical results). In another case, the full-stiffness-inversion method, which requires four specimen types, gave the best estimation (e.g. \(\Delta E_{\rm L}=2\,\%\)). In this corresponding direction, the simplified-corrected method can only partially reduce the overestimation of the simplified uncorrected from \(\Delta E_{\rm L}=47\) to 32 %. The variation of E produced by different evaluation procedures is due to the different correction factor values, which is a consequence of the variation in \(\nu\).

Destructive and non-destructive evaluation of copper diffusion bonds

The current study reports diffusion bonding phenomena of copper to copper (Cu/Cu). The bonding was conducted in the temperature range varying between 700°C and 850°C at varying soaking time (30–120min) under uniaxial pressure of 5–15MPa in vacuum atmosphere. The bonded regions were characterised, using light and scanning electron microscopic (SEM) studies. The bonded strength was evaluated through destructive testing using micro tensile and microhardness tests. In addition, the bond quality was also assessed by nondestructive testing (ultrasonic C-scan test) method. The grain growth equation was used to understand the bonding mechanism. The investigational results were compared with the model developed by Pilling, observing void closure by creep flow and diffusion mass transfer. The superior bond strength ratio of 91% was observed at bonding temperature of 750°C for the applied pressure of 15MPa of 60min soaking period. The correlation between destructive and non-destructive tests was studied.