Destructive Testing Techniques Research Articles

Innovative magnetic flux leakage applications in non destructive testing of metallic ropes

The Magnetic Flux Leakage (MFL) principle applied to metallic ropes, also called Magneto-inductive (MI), is not a new non destructive testing (NDT) technique and has been applied from several tens of years in ropeway plants according standards as or CEI EN 12927. The recent evolution of international standards, regarding the discard criteria of metallic ropes in other sectors, as in ISO4309, start to introduce the MFL beside visual inspection in lifting applications. Even if the component under control is always one or more ropes, the discard criteria, the rope conformation and the fault typologies can be influenced by the application sector. Different magnetic detectors have been developed by the Authors in order to satisfy the several technical constraints and practical requirements of the different field of applications. Several new application in industrial and civil sector as hoisting and elevators are starting to use this kind of non destructive methodology and new sensor with peculiar characteristics have been developed and implemented. In this paper recent development on magnetic flux leakage applied on metallic ropes is then presented. Different theoretical and practical experiences in the magnetic design, material characterization of metallic ropes and in the signal filtering system is presented and discussed.

A Review: Non - Destructive Testing (NDT) Techniques, Applications and FutureProspects

A Review: Non - Destructive Testing (NDT) Techniques, Applications and FutureProspects

Laboratory and in-situ mechanical characterisation of masonry components by comparing destructive and minor destructive testing techniques

The safeguard of existing masonry buildings requires a meticulous characterisation of the component materials (units and mortar) by using in-situ minimally intrusive techniques. This need is especially prominent in the case of heritage buildings in order to minimize their damage and alteration. This paper presents a research on some minor destructive techniques (MDT) for the in-situ evaluation of the mechanical properties of masonry components. In the research, the results derived from MDT were empirically correlated with the compressive strength obtained by using well-known destructive testing (DT) techniques executed in the laboratory. The experimental campaign focused on two different MDT techniques, namely the Pin Penetration Test (PPT) and the Helix screw Pull-out Test (HPT). The PPT is based on the measurement of the depth of penetration of a steel pin. The HPT is based on the measurement of the pull-out load necessary to extract a steel tie inserted into a hole drilled in a brick or in a mortar joint. The experimental campaign also included an evaluation of the Double Punch Test (DPT) by comparison with strength values obtained from mortar specimens prepared and tested following the standard EN 1015–11. The experimental results show a satisfactory agreement between the MDT measurements and the compressive strength obtained with DT. Although both the PPT and HPT are useful for the evaluation of the compressive strength of masonry components, the former exhibits a lower scattering in the experimental measurements.

Investigation of fracture source mechanisms through full-field imaging and acoustic emission

The identification and understanding of fracture processes is a vital component in securing engineering structures. By collecting data through experiments or simulations, the identification of material parameters and the understanding of failure mechanisms can be investigated. In the context of in-laboratory experiments, this is done by provoking fracture process through destructive testing (TD) techniques, while collecting data by non-destructive testing (NDT) techniques and postmortem analysis. While NDT techniques are often used individually, increasing interest is given to collective investigations of source activities. Like this, limitations of one method can be compensated by the next. A multi-modal experimental setup is proposed for holistic understanding of source mechanisms. Combined time resolved AE, DIC and in-volume measurements with post-mortem fracture surface analysis are applied on PMMA tensile cracking experiments for the purpose of AE localization, crack tip detection and determination of crack front complexities and kinematics, respectively. Both high and lower amplitude AE signals were captured and respectively associated to localized dynamic instabilities and stable crack advance. Signals are analyzed individually using localization, waveform analysis, and AE descriptor classification. Crack front velocity heterogeneities are identified as valuable quantity to correlate with fracture induced AE responses. For dynamic instabilities, a linear relationship between AE absolute energy and crack propagation area was found. While identification and analyses of local and global dynamic instabilities has shown to be rather trivial, difficulties arose with respect to quasi-static related AE events.

Implementation of Non Destructive Testing and in-line monitoring techniques on extra-large structures printed with WAAM technology

Grade2XL is a European project funded by the H2020 program that gathers 21 academic and industrial partners. Started in March 2020 for 4 years, the principal objective is to print extra-large structures using the WAAM (Wire Arc Additive Manufacturing) method with a complete control of the fabrication process. Since WAAM is a relatively new technology for printing large specimens, it is important to develop quality assurance methods that can be used during the fabrication and once the structure has been built, which is the focus of CEA List in the project. Regarding methods applied built structures, CEA List has investigated Resonant Ultrasound Spectroscopy (RUS) for the material characterization and more specifically the evaluation of the elastic constants or more conventional ones for the inspection with phased-array ultrasonic techniques (PAUT) or eddy current (EC) for the detection of indications are implemented and optimised them for the inspection of the final structures. Concerning the development of in-line monitoring methods, CEA List has been working on laser Doppler vibrometry (LDV) and X-ray fluorescence (XRF) spectrometry, in order to get structural information during the printing but also detect the appearance of abnormal events and correlate them to the appearance of defects generated during the WAAM process. This proceeding presents the advantages of those methods for the inspection of extra-large structures made by WAAM and discusses the first results obtained in the framework of the project. Keywords: Additive Manufacturing, NDT, Imaging techniques, Eddy current, In-line monitoring, laser vibrometry, X-ray fluorescence spectrometry, Resonant Ultrasound Spectroscopy.

Wear Analysis of 3D-Printed Spur and Herringbone Gears Used in Automated Retail Kiosks Based on Computer Vision and Statistical Methods.

This paper focuses on a wear evaluation conducted for prototype spur and herringbone gears made from PET-G filament using additive manufacturing. The main objective of this study is to verify if 3D-printed gears can be considered a reliable choice for long-term exploitation in selected mechanical systems, specifically automated retail kiosks. For this reason, two methods were applied, utilizing: (1) vision-based inspection of the gears' cross-sectional geometry and (2) the statistical characterization of the selected kinematic parameters and torques generated by drives. The former method involves destructive testing and allows for identification of the gears' operation-induced geometric shape evolution, whereas the latter method focuses on searching for nondestructive kinematic and torque-based indicators, which allow tracking of the wear. The novel contribution presented in this paper is the conceptual and experimental application of the identification of the changes of 3D-printed parts' geometric properties resulting from wear. The inspected exploited and non-exploited 3D-printed parts underwent encasing in resin and a curing process, followed by cutting in a specific plane to reveal the desired shapes, before finally being subjected to a vision-based geometric characterization. The authors have experimentally demonstrated, in real industrial conditions, on batch production parts, the usefulness of the presented destructive testing technique providing valid indices for wear identification.

Development of Non-Destructive Dynamic Characterization Technique for MMCs: Predictions of Mechanical Properties for Al@Al2O3 Composites

In the past several decades, many destructive and non-destructive testing techniques have been developed to evaluate the characteristics of metal matrix composites (MMCs). This research aims to calculate the mechanical properties of the Al@Al2O3 composites by varying alumina nanoparticles (Al2O3 NPs) content using a non-invasive, position sensing detector (PSD) unit-based optical method. The composite was prepared by a powder metallurgy technique, and its characterization was conducted using SEM and XRD to understand its surface morphology and microstructure. The natural frequency and Young’s modulus of the composite were estimated experimentally. Young’s modulus was calculated using this natural frequency. The proposed study shows that Young’s modulus of the composite increases with an increase in Al2O3 NPs content in the composition, irrespective of the testing method. Along with this, natural frequency also increases with the increase in the Al2O3 NPs content. Evaluated properties were compared with the numerical modeling using COMSOL Multiphysics. The experimental and numerical results are equivalent and within the margin of error. This study illustrates the development of an experimental approach for evaluating the mechanical properties of a composite material. This experimental approach can be used whenever sample dimension and space are constrained to evaluate the mechanical behavior of nanomaterials and nanocomposites.

Predicting the performance of existing pre-cast concrete pipes using destructive and non-destructive testing techniques

One of the most significant and critical urban assets for a sustainable community is the sewer pipeline network and water distribution system. Water sewer networks and distribution systems have a definite service life span to provide continuous facilities to end users. Therefore, it is pertinent to continuously evaluate the condition of water and sewer concrete pipelines to ensure the reliable, sustainable, and cost-efficient transport of water and sewerage for the safety of society. The condition assessment is commonly carried out by visual observations followed by some non-destructive testing methods. However, it is the need of the hour to shift assessment methods to advance assessment techniques to save time and money for our community. Currently, in this project, the condition assessment of pre-cast concrete pipes was carried out by destructive and non-destructive methods. Different test trials i.e., ultra-sonic pulse velocity, Schmidt hammer also known as rebound hammer test, visual inspection, three edge bearing test, and core cutting test on the old buried and new concrete pipes were performed. It was observed that concrete used for the construction of existing precast concrete pipes still has better quality indices after 20 years as compared to that of concrete of new pipes. However, steel has deteriorated with time and clear corrosion of steel was identified in existing pre-cast concrete pipes. At the same time, it was observed that there should be an automated mechanism to continuously asses the condition of pre-cast existing pipes which will address the sustainable development goals (SDG 6, 9, 11). Consequently, it can be said that condition assessment of pre-cast concrete pipes will lead to sustainable societies and infrastructure.

A comprehensive experimental review of strain rate, size effect, creep and confinement in concrete: Part III

A comprehensive review of destructive testing techniques to understand concrete behavior is presented in this work. The main objective of this article is to summarize the literature from the last three decades related to the following topics: 1) the size effect in plain and reinforced concrete, 2) the crack estimation and propagation in concrete under various loading conditions, 3) the determination of material properties of concrete using triaxial testing techniques, 4) the behavior of concrete under creep and early age shrinkage which eventually affect the properties of concrete and lastly 5) the strain rate effect in concrete using various experimental techniques such as Split Hopkinson pressure bar, impact loading, drop hammer and the literature related to cyclic loading on concrete. The scope of the presented work is limited to destructive testing related to the topics defined above. To completely understand the behavior of material, at least three aspects must be required: the material’s theoretical basics, experimental validation, and numerical implementation. The authors presented the review articles related to theoretical basics and numerical implementation in parts I and II of this article. The presented work is part III, which is related to experimental work. In the upcoming section, the research related to specific topics is presented, and a summary is provided at the end of each section. Finally, the future works and the research directions are shown in the conclusion section.

Influence of coarse aggregate size and content on the properties of recycled aggregate concrete using non-destructive testing methods

Recycled concrete aggregates (RCA) are obtained by concrete recycling processes. When adopted with specially graded aggregate, long-established inexpensive and unobtrusive non-destructive techniques have the potential to revolutionize the construction sector. The combined influences of RCA size and content are commonly proprietary information or incompletely reported in available literature by means of non-destructive tests (NDTs). Hence, this paper represents the experimental investigation of the recycled aggregate concrete (RAC) properties prepared with varying sizes and replacement levels of coarse aggregate using destructive and non-destructive testing techniques. In this work, several NDTs were performed on cylindrical samples of 100 mm dia. x 200 mm and compared to destructive testing (DT) to determine the properties of 5-12 mm and 12–20 mm coarse aggregate concrete mixes having 15%, 30%, and 45% replacement of natural coarse aggregate (NCA) by RCA. For this purpose, 0%, 15%, 30%, and 45% RAC contents were utilized with the corresponding replacement of NCA for 5–12 mm and 12–20 mm coarse aggregate to determine their effects on the slump, compressive strength, digital rebound hammer, ultrasonic pulse velocity (UPV), electrical resistivity, water permeability, and modulus of elasticity (MOE) tests. It was revealed that RAC achieved lower compressive strength, rebound number, MOE, electrical resistivity, and UPV values with the increment of RCA replacement level at 7, 28, and 56 days, especially inferior values observed for 45% RCA replacement concrete mixes. On the other hand, the concrete with 5-12 mm aggregate size showed higher surface hardness, compressive strength, water permeability, UPV, and electrical resistance than the concrete with 12-20 mm aggregate size. Furthermore, several empirical relationships have been established between DT and NDT on the concrete properties and compared with other research findings. Therefore, these relationships demonstrated that NDT could efficiently predict RAC properties by increasing the pace of testing as well as reducing the cost of determining those parameters.

An aggregated non-destructive testing (NDT) framework for the assessment of mechanical properties of unreinforced masonry Italian medieval churches

Medieval churches constructed of unreinforced masonry (URM) represent critical assets of Italian architectural heritage. In order to preserve these churches against earthquakes, obtaining robust information regarding their material mechanical characteristics is necessary as part of a reliable structural analysis and strengthening intervention program. Given the drawbacks of semi-destructive or destructive testing of heritage material, non-destructive testing (NDT) is the most viable approach to obtain data regarding the mechanical characteristics of the material composing the structure of the churches. However, there are several uncertainties inherent within NDT techniques based on the current state of the art. Thus, two different NDT techniques (i.e., rebound hammer testing, and pulse velocity testing) and two expert judgment-based investigation techniques (i.e., masonry quality index, and mechanical properties ranges based on the Commentary to the Italian building code) were applied to 170 specimens belonging to the walls of 72 URM Italian medieval churches to assess the quality of the URM and its components. The surveyed churches walls, although highly variable in geometry, materials, and conditions, can be classified into four URM types: a) irregular stone masonry with pebbles, erratic and irregular stone units; b) roughly cut stone with good bond; c) ashlar masonry with regular squared blocks and mortar joints; and d) solid fired clay bricks with lime mortar. Subsequently, using the SonReb technique, predictive equations that aggregate the two NDT techniques and the correlation coefficient specific for each URM type were developed to define some of the critical mechanical properties of the URM (i.e., compressive strength, Young’s modulus, and shear modulus). The mechanical properties determined via predictive equations were then plotted and compared with the predictions of the two well-established expert judgment-based investigation techniques to evaluate the accuracy of the approach. Finally, a partial validation based on NDT and destructive testing techniques of six URM prisms was performed to evaluate the accuracy of the proposed predictive equations. Ultimately, three equations to determine the compressive strength, the Young’s modulus, and the shear modulus were developed. The developed equations offer to engineering practitioners a rapid NDT technique to assess URM properties that do not solely rely on the judgment and expertise of the practitioner.

Material characterization of GFRP by ultrasonics

In general, material selection for an application depends on its mechanical properties such as the young’s modulus, shear modulus and bulk modulus. There is no material science without material characterization. The conventional mechanical testing involves breaking of the test piece while determining the mechanical properties, thus rendering the sample piece useless after testing. Moreover, conventional testing machines are bulky and costly. Non–destructive testing techniques were most commonly used for the detection and characterization of flaws. But in the past few decades many researchers are conducting experiments to even calculate material properties using NDT methods. In the present work an attempt has been made to use a NDT technique, namely Ultrasonic testing, to determine the mechanical properties of three Glass fiber reinforced polymer (GFRP) plates (Unidirectional, Bidirectional & cross directional).

Linear and non-linear FEM analyses to assess a shear flat-jack test for masonries

The shear properties are key characteristics for evaluating masonry elements under in-plane horizontal actions. Historical structures may need the evaluation of these properties in order to perform safety evaluations, diagnoses, retrofitting, etc. These properties are often difficult to estimate and may be measured using Destructive Testing ( DT ) methods, which are not always compatible with the structure under test, either because of the cultural value, the high cost or the excessive damage introduced. Therefore, this paper addresses a Minor Destructive Testing ( MDT ) technique with the purpose of measuring masonry shear properties. This represents a first contribution to a universally adopted and accepted MDT technique, which is not currently available. The present paper aims to study in detail the experimental results of four shear Flat Jack ( FJ ) tests from literature, by means of linear and non-linear analyses performed using micro and macro Finite Element models. These analyses are meant to study the ability of the shear FJ test for evaluating the shear modulus and the diagonal tensile strength of unreinforced brick masonry . The numerical results highlight the potential for the shear FJ test to become a suitable MDT method for evaluating the shear modulus and strength of brick masonry and evidence some aspects where further investigation is advisable. • Numerical study of in-situ performed shear Flat Jack tests on existing masonry. • Linear analyses of FE micro-models for studying measured shear moduli. • Non-linear analyses of FE macro-models for studying measured shear strengths.

Waste from stone industry as a cement replacement towards a reduced carbon footprint of concrete

Self-Compacting Concrete (SCC) is a unique kind of concrete that tends to consolidate in terms of its weight. In this study, the prime target is to investigate the durability properties of SCC developed using eco-friendly economical waste binding materials as partial replacement to costly cement. This circular economy concept will not only help in the development of green concrete but will also help to improve the climatic condition by reducing the use and production of cement. An economical design methodology has been applied to produce environmentally friendly construction material. This research focuses on the application of Alum Sludge (AS) and Brick Dust (BD) in Self-Compacting Concrete (SCC). Both materials are waste materials containing binding properties. Performance of SCC developed using these two materials was tested considering mechanical properties of concrete using the destructive testing technique. Results showed that BD and AS can be utilized for up to 12% and 9% of ...

Utilization of Self-Consolidated Green Material for Sustainable Development: An Environment Friendly Waste Materials Application for Circular Economy.

Self-Compacting Concrete (SCC) is a unique kind of concrete that tends to consolidate in terms of its weight. In this study, the prime target is to investigate the durability properties of SCC developed using eco-friendly economical waste binding materials as partial replacement to costly cement. This circular economy concept will not only help in the development of green concrete but will also help to improve the climatic condition by reducing the use and production of cement. An economical design methodology has been applied to produce environmentally friendly construction material. This research focuses on the application of Alum Sludge (AS) and Brick Dust (BD) in Self-Compacting Concrete (SCC). Both materials are waste materials containing binding properties. Performance of SCC developed using these two materials was tested considering mechanical properties of concrete using the destructive testing technique. Results showed that BD and AS can be utilized for up to 12% and 9% of replacement of cement, respectively, to achieve equal or higher compressive, tensile, and flexural strength. The application of BD and AS has demonstrated a subsequent improvement of SCC’s mechanical properties, i.e., compressive, tensile, and flexural strength. This study will help the production of composite green materials with the help of eco-friendly and economical waste materials for sustainable infrastructure development.

Characterization and analysis of TIG welded stainless steel 304 alloy plates using radiography and destructive testing techniques

Welding is one of the join processes of any materials with usage of filler metal along with addition of heat, pressure on the surface parts. Gas Tungsten Arc welding (GTAW) is one type of joint method in which electric-arc formed and preserved amid non-consumable electrodes. the aim of this particular paper is to comparing the defects instigated of welded-Joint and mechanical behaviors such as tensile testing, bending, hardness, and impact test under various loads and conditions performing on work specimen in destructive testing. The effort of butt joints is made on stainless steels 304(SS304) plates via TIG welding apparatus the inner defects of specimens found from radiography testing in Nondestructive testing. Finally, explore the performance and conditions of TIG welded- plates after completing the work to compare radiography testing defects and mechanical properties.

HIGH RISE FRAME BUILDING CONSTRUCTION WITH REGARD TO DEFECTS IN MONOLITHIC BASE SLAB

The paper analyzes the influence of defects detected in a monolithic base slab on the possibility of its further application in the construction of a 25-storey high-rise frame building. Non destructive testing and vertical core sampling techniques are used for the detailed analysis of the monolithic base slab. It is found that irregularities in the procedure during winter concreting of the base slab decreases the strength properties of concrete and provides the defect formation in the slab structure, namely delamination of the lower protective concrete layer and uncovering of working reinforcement. For the safe use of the 25-storey high-rise building, the base slab is proposed to be strengthened by adding in-situ reinforced concrete layer 100 cm thick.

Shear Flat Jack Test for Evaluating Shear Characteristics on Unreinforced Masonry Structures

ABSTRACT The shear properties of unreinforced masonry are key parameters used in order to understand the behaviour of these structures under horizontal actions. These characteristics are usually determined using Destructive Testing (DT) methods. However, this typology of tests is not always suitable due to both their high impact and cost. The present work aims to design, analyze and apply an innovative Minor Destructive Testing (MDT) technique for the determination of the shear mechanical properties. To limit the impact on the structure, the Flat Jack (FJ) technique was adopted. The geometrical configuration, chosen among six different layouts, was studied in order to comprehend the role-played by different parameters and to have then a mathematical model representative of the stresses inside of the sample. Finally, four in situ tests were executed and are analyzed and discussed.

The fast computation of eddy current distribution and probe response in homogenized composite material based on semi-analytical approach

Due to the excessive use of composites in the industrial field, many numerical modeling approaches dedicated to the characterization of such complex material by means of Non Destructive Testing Techniques were developed. In this paper, we present a numerical model dedicated to simulate the inspection of unidirectional Carbon Fiber Reinforced Polymer using Eddy Current technique for detecting fiber disorientation. A semi-analytical model based on a modal approach is developed for the fast computation of quasi-static field induced by an arbitrary 3D Eddy Current probe in the material. Because of the high anisotropy and strong heterogeneity of such material, a prior phase of homogenization is assumed and the material is then considered as homogeneously anisotropic. The modal approach consists in resolving Maxwell’s equations in the Fourier domain. Therefore, the electromagnetic field is expressed as a sum of eigen-modes. To take into account the wave propagation through the multilayered structure and boundary conditions at each separating interface, a stable and recursive scattering matrix algorithm has been implemented. The impedance of the probe is computed analytically using Auld’s formula in orders to identify the main orientation of the fibers in the inspected zone. For numerical validation, simulated data provided by the model are compared to finite element data.

Magnetic hysteresis loop behaviour of welded ferritic stainless steel 409L with the variation of magnetic field intensity

Hysteresis loop analysis technique, being a non-destructive testing technique is more beneficial than the destructive testing techniques to characterise the welded plate. In this study, the ferritic stainless steel AISI 409L plate was butt welded by gas metal arc welding process. Hysteresis loop analysis technique was used to study the microstructures and microhardness of the base metal region, heat affected zone and weldmetal zone. This study has been carried out at four different values of magnetic field intensity 250, 500, 750 and 1000 Oe. The effect of variation of magnetic field intensity on the hysteresis loop characteristics (average maximum flux density and core loss) has been investigated for base metal, heat affected zone and weldmetal zone. It was found that for each region, the average maximum flux density as well as core loss increases on increasing magnetic field intensity. Also, the variation of average maximum flux density is inversely proportional to the microhardness of the region at each value of magnetic field intensity.