Destructive Testing Methods Research Articles

Fuzzy logic based quality monitoring in short-circuit gas metal arc welding

Conventional methods, e.g. destructive and non-destructive testing methods, are expensive and time-consuming; therefore, possibilities of online and automated quality control of a welding process during welding as such are investigated. The paper deals with the possibilities of application of fuzzy logic to the analysis of weld quality, particularly assessment of the weld surface condition by means of measurable electric signals emitted during welding. A simple fuzzy inference system was realised which could relatively efficiently assess the weld quality on the basis of time variations of the welding voltage and short-circuit time in a certain time window.

Application of a micromechanical model of three phases to estimating the porosity of mortar by ultrasound

Among the factors that affect the durability of cement-based materials, porosity is important due to its role in transporting substances inside the material. Porosity can be determined using destructive testing methods, but the civil construction industry needs a nondestructive method for the estimation of the volume of pores in cement-based materials to evaluate the deterioration process. In this investigation, a micromechanical model of three phases developed in a previous paper is used to estimate the porosity of a series of mortar samples. The proposed model takes into account the microstructural characteristics and elastic properties of the constituent phases. In a first stage, the model is used to predict the influence of both the volume fraction of sand and pores and the elastic constants of the matrix and the sand on the ultrasonic velocity. Next, experimental measurements are made on a series of mortar samples of varying water/cement ratio, cement type and sand concentration, with the results used to demonstrate that porosity can be estimated using the proposed nondestructive method.

Investigation of gas composition on discharge lamps fractured during operation by means of mass spectrometry

Recently, metal-halide lamps were also used as automotive light sources because of their major advantages over tungsten halogen lamps (longer lifetime, improved efficacy). However, the lifetime of the lamps is strongly deteriorated by impurities present in the lamp. The impurities can be investigated by a destructive test method when the discharge vessel is fractured in high vacuum conditions, and the resultant residual gas is subject to analysis. Impurity tests have been carried out on inoperative lamps at room temperature so far. However, both the filling components and some of impurities of the lamp are in gaseous phase close to the steady-state lamp operating temperature only. At room temperature most of the dose constituents, including some of the impurities, are in condensed phase, i.e. solid or liquid. Thus they hardly show up in the mass spectrum. Consequently, the result of mass spectrometry analysis on the gas composition of an operating lamp can be substantially different from that of an inoperative lamp. In order to perform gas impurity analysis on operating lamps, a mass spectrometer based in situ fracture stage has been built, which operates at an elevated temperature. The term ‘elevated temperature’ means a temperature value that is significantly higher than room temperature but cannot be defined accurately in degrees because of its rapid change at fracturing. A microphonic noise impulse is used to synchronize the spectrum recording with the fracturing, so that we could analyse the spectrum right after fracturing. This spectrum is the most informative since it is recorded before major condensation happens. Some test results are also presented along with the details on the method of measurement.

High heat flux actively cooled plasma facing components development, realisation and first results in Tore Supra

The development, design, manufacture and testing of actively cooled high heat flux (HHF) plasma facing components (PFCs) has been an essential part of the Tore Supra programme towards long powerful tokamak operation. The Tore Supra PFC programme has culminated in the installation and operation of a toroidal pump limiter, since 2002, which already allowed to reach new world records in steady state operation (1 GJ injected in a 6 min discharge). The HHF PFCs development and manufacturing was achieved through a long lead development and industrialisation programme (about 10 years) marked out with a number of challenges. The major technical topics cope with bonding technology analysis involving an adequate material selection and procurement, repair processes development and implementation, development of destructive and non-destructive testing methods, and more generally industrialisation assessment. All these lessons are relevant to the ITER divertor PFCs manufacturing, although the technical solution adopted for Tore Supra (flat tiles concept) is different from the one proposed for the ITER divertor (monoblock concept). The routine operation of the actively cooled toroidal pumped limiter (TPL), capable to sustain up to 10 MW m −2 of nominal convected heat flux, is described. Up to now, the limiter fulfills its objectives in terms of heat exhaust. However, the thermographic monitoring exhibits unexpected behavior of the surface temperature. Particle exhaust control displays a complex pattern, due to the high fraction of the injected deuterium, which remains in the wall. The first experimental results with a full actively cooled wall gives access to ITER relevant information on wall conditioning, hydrogen plasma density and vacuum vessel inventory control, carbon erosion and redeposition and capability of in situ monitoring in a completely actively cooled environment.

Mechanical properties of old concrete using destructive and ultrasonic non-destructive testing methods

Mechanical properties of old concrete using destructive and ultrasonic non-destructive testing methods

Discussion: Mechanical properties of old concrete using destructive and ultrasonic non-destructive testing methods

Discussion: Mechanical properties of old concrete using destructive and ultrasonic non-destructive testing methods

DIELECTRIC SPECTROSCOPY IN CRUSTAL ROCKS: PRELIMINARY RESULTS FROM NORTHEASTERN SICILY (ITALY) AND THE GULF OF CORINTH (GREECE)

Dielectric response was studied on two samples of manganese- and iron bearing rock materials of two different geological origins, one from Northeastern Sicily (Italy) and one from the Southern Gulf of Corinth (Greece). The study of the dielectric properties is a flexible non destructive testing method. The technique is based on the application of a single- frequency AC electric field to the sample and the measurement of the amplitude and phase of its response. In the present work the broadband dielectric relaxation spectroscopy technique was applied in the frequency range from 1kHz to 1MHz. The hydrated samples, of the above rock materials, that give rise to high values of both the real and imaginary part of the complex dielectric permittivity function are due to interfacial polarization mechanisms attributed to pore water. The two dry samples exhibit much lower values with respect to the hydrated ones while they have a big differentiation between their own permittivityvalues as well as between the shapes of their dielectric responses. This can be attributed to different origins of geotectonic deformation of the samples.

Restfestigkeit von impactgeschädigten Glasfaserverbundproben

The lamb wave analysis is a non destructive test method (NDT) which is used to examine GFRP specimens damaged by impact. The reported test series aims to correlate NDT results and residual strength by means of samples being damaged on different energy levels. Applying such a correlation function to a part damaged by an impact of unknown energy, the loss of strength and safety can be estimated. The NDT method introduced here is based on ultrasonically induced Lamb waves and their distortion in damaged areas. Wave deflections in thin GFRP plates are recorded along a line parallel to the direction of the wave propagation. The wave fields around a series of damages with different sizes are each analysed and the change in wave amplitudes results in a single characteristic damage parameter. This parameter is plotted versus the damaging energy and provide a diagram which can be used to estimate the residual strength of a part with an impact of unknown energy.

Mechanical properties of old concrete using destructive and ultrasonic non-destructive testing methods

This paper examines the variation in properties of a specific type of 28-year-old concrete, the characteristics of which were known at 7, 28, 36 and 90 days. Beyond the destructive tests (compression, splitting tension and bending), the concrete was studied with non-destructive ultrasound testing. Moreover, the relationship between the compressive strength of this concrete and the ultrasonic longitudinal wave velocity, as well as the dynamic modulus of elasticity were determined. The objective was to control changes in the quality of concrete over a long period of time and to contribute to the development of a non-destructive method for the determination of concrete strength in structures. The presented approach, that seems promising for such development, uses the velocity of ultrasonic waves in concrete.

Mechanical properties of old concrete using destructive and ultrasonic non-destructive testing methods

This paper examines the variation in properties of a specific type of 28-year-old concrete, the characteristics of which were known at 7, 28, 36 and 90 days. Beyond the destructive tests (compression, splitting tension and bending), the concrete was studied with non-destructive ultrasound testing. Moreover, the relationship between the compressive strength of this concrete and the ultrasonic longitudinal wave velocity, as well as the dynamic modulus of elasticity were determined. The objective was to control changes in the quality of concrete over a long period of time and to contribute to the development of a non-destructive method for the determination of concrete strength in structures. The presented approach, that seems promising for such development, uses the velocity of ultrasonic waves in concrete.

Characterization of silane coated hollow sphere alumina-reinforced ultra high molecular weight polyethylene composite as a possible bone substitute material

Silane coated hollow sphere alumina ceramic particles were moulded with ultra high molecular weight polyethylene (UHMWPE) to form a series of composites with alumina weight percent in the range from 15 to 50. The composites were prepared in a cylindrical mould using powder-processing technique. The composites were characterized for mechanical properties using destructive and non-destructive ultrasonic testing methods. The physical properties of the composite were determined and compared with those of cortical bone.

Monitoring corrosion rate for ordinary portland concrete (OPC) and high-performance concrete (HPC) specimens subjected to chloride attack

This paper presents the results and the applicability of an electrochemical technique, the Tafel plot method, for determining the corrosion rate of reinforcing steel embedded in laboratory ordinary portland concrete (OPC) and high-performance concrete (HPC) specimens. Fifty-two OPC and 52 HPC concrete cylinders, each with a single embedded reinforcing steel rod, have been subjected to various laboratory conditions, and the corrosion rate of each specimen has been monitored. Results indicate that HPC specimens performed much better than OPC specimens in terms of resisting corrosion, as the corrosion rates were far lower for the HPC specimens than for the OPC specimens. Sodium chloride concentration played an important role in the propagation of corrosion: the higher the NaCl concentration, the higher the corrosion rate. In addition, different cycles of wetting and drying of concrete specimens had different impacts on corrosion rates. Results for the chloride concentration based on the American Society for Testing and Materials (ASTM) destructive testing method C1218 were in agreement with the corrosion rate results from the Tafel plot method used in the study.Key words: corrosion, electrochemical, reinforced concrete, Tafel method, high-performance concrete.

Möossbauer Spectroscopy Used for Testing of Reactor Steels

The main goal in the area of nuclear industry is to increase nuclear safety and reliability of nuclear power plants (NPP). Previous material study was based mainly on experimental data from different destructive testing methods. Modern approach is based more on the non-destructive methods. The present investigation is focused on the application of Mossbauer spectroscopy in the evaluation of the microstructure parameters of materials used in nuclear industry. Usefulness of this method is documented on the evaluation of degradation processes going on in the NPP reactor pressure vessel steels. Experimental results of original irradiated reactor pressure vessel surveillance specimens are presented and discussed in the paper. Systematic changes in the relative areas of Mossbauer spectra components were observed mainly during the first period (1-year stay in irradiation containers in operating conditions by "speed factor" of about 10). They could be explained by changes caused by precipitation of elements like Cu or Cr mainly in carbides to the surface. These results confirm that the close environment of Fe atoms in b.c.c. lattice of reactor pressure vessel steels stay after initial changes almost stable and could be perhaps correlated with the ductile-brittle transition temperature curve from mechanical tests.

Microstructural modelling of electrical conductivity and mechanical properties of sintered ferrous materials

The role of microstructure on mechanical properties of sintered ferrous materials was studied using a method based on electrical conductivity measurement. The method was accompanied by quantitative fractography to evaluate the dewaxing and sintering process in iron compacts. The effects of manufacturing parameters, such as compacting pressure in the range of 150–800 MPa, sintering temperature from 400 to 1300°C, sintering time up to 8 h, and lubrication mode were investigated. Several mathematical models were checked to obtain the best one for prediction of electrical conductivity changes as a function of manufacturing parameters. The mechanical properties of the sintered compacts were also evaluated to establish a relationship between conductivity, total porosity, pore morphology, and mechanical behaviour. The results show that the electrical conductivity/resistivity of sintered materials is closely related to its microstructure, so that measuring these properties can replace destructive test methods for prediction of mechanical strength of sintered materials with homogeneous matrix microstructure. The application of the method is shown for sintered Fe, Fe–0·8%C, and Fe–1·5%Mo–0·7%C compacts.

Neutron radiography in Indian space programme

Pyrotechnic devices are indispensable in any space programme to perform such critical operations as ignition, stage separation, solar panel deployment, etc. The nature of design and configuration of different types of pyrotechnic devices, and the type of materials that are put in their construction make the inspection of them with thermal neutrons more favourable than any other non destructive testing methods. Although many types of neutron sources are available for use, generally the radiographic quality/exposure duration and cost of source run in opposite directions even after four decades of research and development. But in the area of space activity, by suitably combining the X-ray and neutron radiographic requirements, the inspection of the components can be made economically viable. This is demonstrated in the Indian space programme by establishing a 15 MeV linear accelerator based neutron generator facility to inspect medium to giant solid propellant boosters by X-ray inspection and all types of critical pyro and some electronic components by neutron radiography. Since the beam contains unacceptable gamma, transfer imaging technique has been evolved and the various parameters have been optimised to get a good quality image.

Das Schädigungsverhalten von C/C-SiC

Damage state and development in Carbon fibre reinforced silicon carbide (C/C-SiC) has been investigated by means of destructive and non destructive testing methods. This type of material shows a defect pattern already after manufacturing which is mainly caused by the thermal mismatch of fibres and matrix. SEM investigations showed that at these inherent cracks crack opening occurs after tension loading. Light microscopy using digital image processing has been performed in order to determine if the number of cracks ranging in meso- and macroscale is influenced by tension loading. No significant change was observed. The DC potential drop method was used to detect damage mainly in the conductive fibre bundle area. A relationship between nominal stress, true stress, total strain and remnant plastic strain respectively, and the measured potential was found. This relations could be used to quantify damage in tension-loaded C/C-SiC specimens.

Prüfung der Plattierung mit Impuls-Wirbelstromund Ultraschallverfahren

The application of non destructive testing methods like ultrasonic- or pulsed-eddy-current techniques at stainless steel welds, austenitic clads or in general at anisotropic materials are difficult due to the interaction of the fields with the material. Therefore safety statements for a component can not only be based on the results of one ndt-technique. That is one of the reasons for the combination of redundant techniques e. g. pulsed-eddy-current- and ultrasonic techniques. In the present contribution examples for clad inspection using the above mentioned techniques are presented.

Reliability of Destructive Leakage Detection Methods for Semirigid Retort Packages

Three different destructive testing methods for package integrity (biotesting, dye penetration and electrical conductance) were compared with each other using intact and leaking retort packages. In biotesting, both vegetative cells of Enterobacter aerogenes and spores of Bacillus subtilis were used as test microbes. The biotest results did not significantly differ from each other, most packages with a 50 pm channel leak through the seal area were contaminated. Biotesting with E. aerogenes was regarded as a more favourable method than testing with spores of B. subtilis since it was easier to perform and gas formation in the packages was a simple indicator for product contamination. The electrolytic test was able to discover most of the leaking packages more reliably than the biotests and the dye penetration test. The dye test had similar sensitivity in identifying leaks to that of the biotests. In conclusion, the microbial integrity of packages should not be estimated only by biotests, even if they are generally regarded as the most severe package integrity test methods.

Detection of weld defects by computer aided X-ray radiography image processing : Suga, Y.; Kojima, K.; Tominaga, T. Proceedings of the 4th (1994) International Offshore and Polar Engineering Conference, Osaka (Japan), 10–15 Apr. 1994. Vol. IV, pp. 431–440. Edited by Y. Ueda, J.F. Dos Santos, I. Langen, Y. Tomita and K. Waagaard. ISOPE (1994) ISBN 1-880653-14-1.

The X-ray radiographic testing method is often used as a non- destructive testing method to detect weld defects, although it is difficult to detect small defects from the X-ray film. However, a computer visual image processing system can give an objective assessment, and has a high speed judgement. An image processing system to abstract weld defects from the X-ray radiography film including noises was constructed. This paper describes the image processing methods for detecting defects such as pores, slag inclusions and cracks, and displaying the defects using computer graphics.

若材齢時のコンクリート強度測定法に関する研究

The strength testing methods for the quality control of shotcrete being used as a main tunnel support of the NATM are all performed at present with destructive testing methods by obtaining specimens. In actual construction work, however, more rational and simpler testing method than the pull-out testing method for testing young-age strength of shotcrete has been sought for.The authors estimated in this paper that the PARO tester used in printing factories for testing the hardness of paperrolls might be suitable to measure the range of young-age strength of shotcrete and that it would suit the purpose more effectively because it would not create much difference by the different impact directions. It was on these grounds that the authors verified the possibility of using the PARO tester for the purpose by carrying out some indoor tests.In addition, other tests were carried out to compare it with the testing method using Schmidt Hammers, which was formerly tried in the past, and to see if the difference in measurement values will occur due to the different impact directions of the PARO tester used on the hexagonal specimens.As the results of the subject tests, it has been confirmed that the proposed new testing method has good applicability for the estimation of concrete strength in range of 20-100 kgf/cm2, and therefore, has good possibility of being used for the eatimation of young age strength of shotcrete.