Destructive Testing Techniques Research Articles

Characterization of Aging Behavior of AA6061 Aluminum Alloy Through Destructive and Ultrasonic Non-destructive Testing Techniques

An experiment was conducted to characterize microstructural and mechanical behavior of AA6061 alloy during an artificial aging treatment through destructive and ultrasonic nondestructive techniques. Identical aluminum plates of AA6061-T6 aluminum alloy were solutionized at ≈800 K, followed by quenching and artificial aging at 493 K up to 8 h. The microstructural evolution was analyzed using scanning electron microscopy. The variations in hardness, yield stress, and ultimate tensile strength with respect to aging time were discussed. Besides, ultrasonic parameters velocity and attenuation were measured and correlated with the microstructural evolution as well as certain mechanical properties. The ultrasonic measurements showed a good correlation with the microstructural features and mechanical properties of the alloy during aging, whereby an excellent correlation was found between the longitudinal wave velocity and strength properties of the aged specimens. The longitudinal wave velocity was found to be directly related to the hardness with a correlation coefficient of 0.99.

A PHM Approach to Additive Manufacturing Equipment Health Monitoring, Fault Diagnosis, and Quality Control


 
 
 Fabrication of three-dimensional (3D) objects through direct deposition of functional materials using 3D printing equipment is called additive manufacturing (AM). Benefits of AM include producing goods quickly and on-demand, with greater customization and complexity and less material waste. While the use of AM has been growing, a number of challenges continue to impede its more widespread adoption, particularly in the areas of non-destructive evaluation/non- destructive testing (NDE/NDT) techniques for AM equipment health monitoring and measurement. In this paper, a prognostics and health management (PHM) approach to AM equipment health monitoring, fault diagnosis and quality control is presented and illustrated with a case study. The presented PHM approach is developed using two types of NDE/NDT sensors: acoustic emission (AE) sensor and piezoelectric strain sensor. A seeded driving belt fault on a fused filament fabrication desktop 3D printer is used to validate the feasibility of the PHM approach in the case study. The case study results have shown the effectiveness of the presented method for AM equipment fault diagnosis and quality control.
 
 

Non–destructive Material Testing (Ndt) Techniques Applied for the Life Extension Program of the Aircraft in the Hungarian Defence Forces

Most aircraft in the Hungarian Defence Forces (HDF) were planned back in the 1960s and 70s. Accordingly, strategies of operating and maintaining these aircraft reflect the level of engineering, technology and diagnostics of that era. However, since the mid 1990s until today a new generation of modern aircraft (JAS–39 EBS HU Gripen, MiG–29 tactical fighter aircraft) have been used in the Hungarian Defence Forces. By using these third and fourth generation fighters, new, modern operating and maintenance environment and systems have also been introduced. This publication is aimed at providing a short overview of Non–Destructive Material Testing; a very special segment of the many diagnostic testing methods used during life extension programs.

Flash Thermography to Evaluate Porosity in Carbon Fiber Reinforced Polymer (CFRPs).

It is a fact that the presence of porosity in composites has detrimental effects on their mechanical properties. Then, due to the high probability of void formation during manufacturing processes, it is necessary to have the availability of non-destructive evaluation techniques, which may be able to discover the presence and the distribution of porosity in the final parts. In recent years, flash thermography has emerged as the most valuable method, but it is still not adequately enclosed in the industrial enterprise. The main reason of this is the lack of sufficient quantitative data for a full validation of such a technique. The intention of the present work is to supply an overview on the current state-of-the-art regarding the use of flash thermography to evaluate the porosity percentage in fiber reinforced composite materials and to present the latest results, which are gathered by the authors, on porous carbon fiber reinforced polymer laminates. To this end, several coupons of two different stacking sequences and including a different amount of porosity are fabricated and inspected with both non-destructive and destructive testing techniques. Data coming from non-destructive testing with either flash thermography or ultrasonics are plotted against the porosity percentage, which was previously estimated with the volumetric method. The new obtained results are a witness to the efficacy of flash thermography. Some key points that need further consideration are also highlighted.

Comparison of Hot Extrusion and Hot Piercing Processes for Manufacturing Stainless Steel Hot Finished Pipes/Tubes

In this work, a comparison study has been performed on the two hot finished manufacturing processes i.e. hot extrusion and hot piercing which are used for manufacturing stainless steel hot finished pipes/tubes. Study is based on different parameters which include raw material, temperature, extrusion ratios, manufacturing process, compressive stresses, shear stresses, friction forces, tooling, etc. The aim of the study is to determine the qualitative difference in the output product which is manufactured through these two processes for hot finished pipes manufactured in austenitic, duplex, super-duplex stainless steels and nickel alloys. The study includes the testing of the hot finished product with non-destructive testing techniques of water immersion ultrasonic testing, Inside Diameter eddy current testing and dye penetrant testing and destructive testing techniques of mechanical testing, microstructure analysis and corrosion testing methods for confirming the qualitative difference in the outputs of both the processes. The products manufactured by hot extrusion are much more superior in terms of defects observed on the inside of the hot finished pipe apart from material soundness, metallurgy and corrosion properties.

Porosity and Inclusion Detection in CFRP by Infrared Thermography

The ever wide use of composite materials in the aeronautical industry has evidenced the need for development of ever more effective nondestructive evaluation methodologies in order to reduce rejected parts and to optimize production costs. Infrared thermography has been recently enclosed amongst the standardized non destructive testing techniques, but its usefulness needs still complete assessment since it can be employed in several different arrangements and for many purposes. In this work, the possibility to detect slag inclusions and porosity is analyzed with both lock-in themography and pulse thermography in the transmission mode. To this end, carbon-fiber-peinforced polymers different specimens are specifically fabricated of several different stacking sequences and with embedded slag inclusions and porosity percentages. As main results, both of the techniques are found definitely able to reveal the presence of the defects above mentioned. Moreover, these techniques could be considered complementary in order to better characterize the nature of the detected defects.

Non destructive testing techniques for risk based inspection

Ensuring the safety of offshore structures is of vital importance for the reliability of oil and gas drilling rigs.Risk based inspection (RBI) is becoming an industry standard for management of equipment integrity. Theobjective of risk based inspection is to determine the likelihood of equipment failure (probability) and theconsequences of such an event. Combining the probability of an event with its possible consequencesallows determining the risk of an operation. Risk based inspection enables to optimize the frequency ofinspection, by moving from periodic inspection (based on arbitrary calendar dates) to an informedinspection program (based on equipment condition).One of the most important tools to determine the condition of the equipment, and to calculate its reliability,is the use of non destructive testing (NDT) techniques to detect cracks, flaws and defects. The probability ofdetection and the probability of sizing depend on the type of NDT method used. Combining NDTinformation on crack size and depth with fracture mechanics based damage models, allows predicting theremaining life time of a component.In this paper, the philosophy of risk based inspection is introduced and recent advances in non destructivetesting (in particular ultrasonic and electromagnetic techniques) are reviewed. Then, the use of fracturemechanics based damage models is demonstrated to predict fatigue failure for offshore structures.

Ultrasonic field profile evaluation in acoustically inhomogeneous anisotropic materials using 2D ray tracing model: Numerical and experimental comparison

Ultrasound propagation in inhomogeneous anisotropic materials is difficult to examine because of the directional dependency of elastic properties. Simulation tools play an important role in developing advanced reliable ultrasonic non destructive testing techniques for the inspection of anisotropic materials particularly austenitic cladded materials, austenitic welds and dissimilar welds. In this contribution we present an adapted 2D ray tracing model for evaluating ultrasonic wave fields quantitatively in inhomogeneous anisotropic materials. Inhomogeneity in the anisotropic material is represented by discretizing into several homogeneous layers. According to ray tracing model, ultrasonic ray paths are traced during its energy propagation through various discretized layers of the material and at each interface the problem of reflection and transmission is solved. The presented algorithm evaluates the transducer excited ultrasonic fields accurately by taking into account the directivity of the transducer, divergence of the ray bundle, density of rays and phase relations as well as transmission coefficients. The ray tracing model is able to calculate the ultrasonic wave fields generated by a point source as well as a finite dimension transducer. The ray tracing model results are validated quantitatively with the results obtained from 2D Elastodynamic Finite Integration Technique (EFIT) on several configurations generally occurring in the ultrasonic non destructive testing of anisotropic materials. Finally, the quantitative comparison of ray tracing model results with experiments on 32mm thick austenitic weld material and 62mm thick austenitic cladded material is discussed.

Study of the weld ability of aluminum alloy 5083 H116 with pulsed arc GMAW (GMAW-P)

This research was based on the analysis of the weldability of aluminum joints, Alloy GL AW 5083 H116, with filler AWS 5.10 ER 5183 by GMAW-P process to determine the conditions of the heat-affected zone in the base material, depending on the heat input for the GMAW-P process with different pulsed technologies available in Colombia. The variables considered within this study were: welding positions (horizontal, vertical up, and overhead), type of welded joints (butt and fillet), and parameters for welding equipment (voltage, current, speed, power supply, speed development), and protective gas used (Argon, 100%). Non-destructive and destructive testing techniques were used to characterize the discontinuities found and the criteria to accept or reject the AWS D1.2 code (STRUCTURAL WELDING CODE - ALUMINUM by the AMERICAN WELDING SOCIETY). As a result, the investigation yielded the conditions for the application of filler material (ER 5183) on base material (alloy AW5083 GL H116), supported by Welding Procedure Specifications Documents (WPS) and Procedure Qualification Record (PQR) to implement in aluminum welding at the COTECMAR shipyard.

Ultrasonic non destructive testing based on sparse deconvolution

The acoustic modality yields non destructive testing techniques of choice for in-depth investigation. Given a precise model of acoustic wave propagation in materials of possibly complex structures, acoustical imaging amounts to the so-called acoustic wave inversion. A less ambitious approach consists in processing pulse-echo data (typically, A- or B-scans) to detect localised echoes with the maximum temporal (and lateral) precision. This is a resolution enhancement problem, and more precisely a sparse deconvolution problem which is naturally addressed in the inversion framework. The paper focuses on the main sparse deconvolution methods and algorithms, with a view to apply them to ultrasonic non-destructive testing.

Physics and Modeling of Magnetic Non Destructive Testing Techniques

Magnetic Non Destructive Testing (MNDT) methods are a tool not limited in the detection of cracks and defects, like traditional NDT methods for ferrous structures, but they have shown a potential for the monitoring of the structure and crack prevention. MNDT techniques include surface Magnetic Barkhausen Noise measurements (MBN) yielding localized information about the surface stresses and magnetization processes in the vicinity of the measurement; the use of Magnetostrictive Delay Lines (MDL) for the measurement of surface stresses; the Magneto Acoustic Emission (MAE), revealing information about the magnetic domain wall propagation and indirectly about the underlying structure’s role in the magnetization process of the material; magnetic major and minor loop (B-H) bulk measurements which yield information on the macroscopic magnetic properties of the material such as, the coercivity, Hc, the remanence, Br, or the permeability, µ. Results show that changes in these properties are definite signs of non-uniformly distributed stresses along the material and reveal a definitive dependence of the various magnetization reversal mechanisms such as domain wall propagation and domain rotation on the microstructure of the material,eg, the domain wall structure, the effect of dislocations, the grain size, built-in stresses. However, the quantitative mapping of the MNDT results to the microstructure and from there to the possibility of crack generation and propagation is still a very attractive but open question. Modeling at the atomic level involving Ising Models, at the microscopic level using micromagnetic calculations and at the macroscopic level employing the Preisach formalism, has so far provided useful insight. The use of modeling in order to not only explain experimental results but in forecasting is expected to greatly enhance the position of the MNDT techniques in industrial NDT.

Simulation and prediction for the effect of natural and steel fibers on the performance of concrete using experimental analyses and artificial neural networks numerical modeling

Utilization of fibers as concrete reinforcement is one method of preserving environment through the recycling of agriculture and industrial wastes. However, the optimum and efficient application of these fibers requires a measurable evaluation of their effect on properties and performance of concrete. In this study, the application of metallic steel fibers and natural (Linen) fibers in concrete industry is investigated, experimentally. Twenty one mixes are made with different mix proportions and with different types of fibers. The parameters are concrete characteristic strength, age and type of reinforcing fibers. Compressive, tensile and impact strength were measured for all mixes in addition to the residual compressive strength after exposure to elevated temperature. Measurements were also made using two Non Destructive Testing (NDT) techniques. Experimental results were compared and showed the enhancement level obtained by including steel and natural fibers. Following this experimental effort, one of the artificial intelligence techniques (Artificial Neural Network) was applied for simulating and predicting the performance of concrete with different mix proportions. The current paper introduced the Artificial Neural Network (ANN) technique to investigate the effect of natural and steel fibers on the performance of concrete. The results of this study showed that the ANN method with less effort was very efficiently capable of simulating and predicting the performance of concrete with different mix proportions and different types of fibers.

Characterization of Material Properties of 2xxx Series Al-Alloys by Non Destructive Testing Techniques

2xxx series Al-alloys are widely employed in structural applications due to their good mechanical properties. During heat treatment of these alloys, solution treated parts sometimes mixed with age hardened parts during handling. This result in difficulty in distinguishing between solution treated and aged parts of various grades. Moreover, it is also necessary to separate improper aged parts from properly treated parts. The traditional methods of characterization of different heat treated parts are hardness, tension testing and microscopy, however these are destructive in nature and sometimes not desired particularly for finished products. The main purpose of this paper is characterization of material properties of 2xxx series Al-alloys by eddy current and ultrasonic NDE techniques so that the inspection can be carried out effectively in the shortest possible time. Three wrought Al-alloys of 2xxx series (AA 2014, AA 2024 and AA 2219) were homogenized followed by solution heat treatment and age hardening treatments at specific temperatures for 1–16 h. The changes in hardness and microstructure during heat treatments were determined by traditional material characterization methods and then correlated with electrical conductivity, sound velocity and attenuation coefficient obtained through Nondestructive Evaluation (NDE) techniques. Results demonstrated an excellent correlation between hardness and sound velocity, whereas extend of aging can be easily predicted by electrical conductivity, and attenuation coefficient measurement. Investigation suggested a way towards the non-destructive detection and characterization of material properties when conventional testing methods are not applicable.

Advanced materials and structures response prediction and monitoring

Advanced materials and structures response prediction and monitoring

Experimental study for non-destructive mechanical evaluation of ancient chestnut timber

The paper deals with an experimental study for in situ mechanical characterization of ancient timber members using combined Non Destructive Testing (NDT) techniques. An experimental campaign, including non-destructive and destructive tests, was developed on timber structural elements and defect-free specimens, made of old chestnut wood (Castanea sativa Mill.). The following NDT methods were employed in the research activity: hygrometric tests to estimate wood moisture content; ultrasonic investigations to determine stress wave properties; sclerometric tests to assess material hardness and superficial consistence; resistographic measurements to detect internal defects and density variations. Destructive tests in compression parallel to grain and in bending were performed to assess stiffness and strength properties, post-elastic behaviour and collapse mechanisms of the timber elements. Experimental results are discussed and statistically analyzed. Correlations between non-destructive and destructive parameters are provided, based on linear regression models, for the prediction of the wood density, strength and modulus of elasticity of the tested old chestnut timber. The analysis shows that the use of NDT techniques is a useful supplement to the traditional visual grading, allowing a reliable mechanical identification of timber members in practical applications, leading to the appraisal of the timber structures safety and integrity.

Electromagnetic characterization of the CFRPs anisotropic conductivity: modeling and measurements

This work deals with the characterization of the conductivity tensor of a carbon fiber reinforced polymer composite (CFRP) thin plate. We propose a contactless method based on the eddy current non destructive testing technique. The used eddy current sensor consists of a ferrite torus on which a winding is wound. The torus is of a rectangular section and contains a thin air-gap in which the thin CFRP plate is inserted. We developed analytical relations giving the longitudinal and transversal conductivities of the CFRP plate as functions of the impedances variations of the eddy current sensor, corresponding to the orientations of the carbon fibers parallel and transverse to the direction of the torus width which is much greater than its thickness. The analytical relations are developed by inverting interpolation functions of curves giving the variations of the sensor impedances as functions of the longitudinal and transversal conductivities of the CFRP plate. These curves are obtained by a numerical model based on a simplified integro-differential formulation in terms of the electric vector potential in the CFRP plate, coupled to the magnetic circuit equations in the ferrite torus. The modeling results are supported by measurements.

Optical Measurement of Deformations in Drying Lumber

None of the destructive or nondestructive testing techniques for monitoring wood behavior during drying allow continuous quantitative measurements of the deformation and strain distribution in a section undergoing nonuniform moisture content changes in a kiln drying regime. In this study, a noncontact optical measurement technique based on digital image correlation (DIC) principles was used to visualize and measure the progressive deformation of wood subjected to simulated kiln drying conditions. A test apparatus was designed to simulate kiln drying conditions in such a way that a section of the specimen was accessible for optical measurements, and a hardwood and a softwood were dried at several temperatures. Full-field maps of principal strains were developed to illustrate the progress of the deformation gradients. The principal observations are that (1) the deformation of wood starts in the beginning of drying when the average moisture contents are well above the fiber saturation point, (2) the difference between the average deformations in the tangential and radial directions is much larger than expected, and (3) the samples swell a little in the radial direction early in drying.

Comparing infrared thermography and ESPI for NDE of aircraft composites

Infrared Thermography is gaining acceptance by industry as a suitable non destructive testing and evaluation (NDT/E) technique. Likewise Electronic Speckle Pattern Interferometry (ESPI) has also been shown to be suited for similar purposes, particularly for the inspection of composite materials. This paper presents the theory of the two inspection methods. Selected composite samples containing defects are subjected to identical inspection procedures using both techniques. The results are presented and compared with each other. From the results it is clear that both techniques are suited for the detection of the defects in the composite sample. The results also indicate that ESPI is a more sensitive inspection technique than IRT. Comparisons are drawn and the benefits of each technique discussed.

Modelling and Validating Ferrite-core Probes for GMR-eddy Current Testing in Metallic Plates

Non Destructive Testing techniques are more and more exploited in order to quickly and cheaply recognize ∞aws into the inspected materials. Within this framework, modelling is a powerful tool for inspection improvements. It helps probe-coil designers to optimize sensors for each examination requirement, providing better understanding of the involved physics, supporting operator training and increasing defect analysis reliability. The efiect of the ferrite core is analyzed in order to optimize the design of probe-coils and study various conflgurations of inspection. Particularly, Finite Element based analyzes will be carried out into this path. Direct problem will be assessed, and direct model will be formulated, dependent by difierent parameters, e.g., coil shape, working frequencies and so forth. The model will be subsequently validated by in-lab experimentations. 1. INTRODUCTION Non Destructive Testing and Evaluation (NDT/E) of metallic materials ofiers an exciting and interesting challenge to both researchers and applied technologists. For this kind of materials, the major problem of interest is the detection, location, orienting and sizing of single cracks, nondestructive evaluation of homogenous materials is presently in a state of detecting a variety of damage modes. In plane words, the present state of knowledge concerning what damage mode in metallic materials is responsible for the flnal failure process is still unclear. Hence, it is still not possible to suggest to NDT/E personnel exactly what type of damage, size, orientation, etc. needs to be found in an inspection process. Hence, the challenge. The excitement for researchers in the area of NDT/E of metallic plates is in the fact that NDT/E is presently playing an important role in helping to identify damage mechanisms in homogenous materials and to characterize the role played by these damage mechanisms in the flnal failure process. A variety of NDT/E techniques has been applied extensively to the investigation and characterization of metallic materials. Generally, one flnds that a combination of complementary NDT/E techniques are appropriate, and often required, to obtain as complete information as possible on the damage state of the specimen. Eddy-current (EC) methods are commonly applied because of their relative ease of their use, and the relative amount of information that can be obtained from them. As far as metals are concerned, the EC techniques has been used for quite some time for varied applications such as the detection of cracks, porosities and inclusions; metal sorting, evaluation of plate or tubing thickness, measurement of coating thickness and the thickness of non-conducting fllms on metallic bases and so forth 1 When a coil carrying alternating current is brought near an electrically conducting material, eddy-currents are induced in the materials by electromagnetic induction. The magnitude of the induced eddy currents depends upon the magnitude and frequency of alternating current; the distance between the current-carrying coil and the material under test; the presence of defects or inhomogeneities in the material and the physical properties of the material. The induced eddy-currents modulate the impedance of the exciting coil or any secondary coil situated in the vicinity of the test material. The difierence between the original coil impedance and the modulated coil impedance (due to the presence of eddy currents) is monitored to obtain meaningful information regarding the presence of defects or changes in physical, chemical or microstructural properties. Typical testing conflgurations may consist of ferrite core coil probes, placed above a planar (or at least locally planar) conductive specimen and operating in the time-harmonic domain, at frequency depending on the problem (typically between a few (Hz) to a few (MHz)) (2). The aim of ferrite core is to focus the magnetic flelds into the specimen, in order to increase the probe sensitivity to the defect. For each application, the coil model as well as the operating frequencies are set according to the task. This work proposes an integrated approach starting from the design and implementation of a novel probe in order to optimize the sensor efiect and the drop-in suppression, the operating parameters of the frequency

EC MODELLING AND ENHANCEMENT SIGNALS IN CFRP INSPECTION

Non Destructive Testing techniques are more and more exploited in order to quickly and cheaply recognize ∞aws into the inspected materials, specially for carbon flber reinforced polymers in recent years. Their production which are widely used both in civil and military applications, is an elaborate process un-free from faults and problems. Problems during the manufacturing, such as plies' overlapping, can cause ∞aws in the resulting material, this way compromising its integrity. Within this framework, this work aims to propose a design of ferrite core probe for eddy current non destructive evaluation, in order to investigate the presence of defects in carbon flber epoxy composite materials. In this context, modelling is a powerful tool for inspection improvements. It helps probe-coil designers to optimize sensors for each examination requirement, providing better understanding of the involved physics, supporting operator training and increasing defect analysis reliability. Particularly, Finite Element based analyzes will be carried out into this path. After this step, in order to improve the quality of simulated measurement, a flltering technique has been exploited in order to improve the accuracy and performance of the ∞aw detection.