Nondestructive testing

Structural information on soil organic matter (SOM) at the molecular level can be obtained on diverse structural units that are amenable to degradation techniques. Chemolytic techniques in combination with colorimetric analyses or GC MS are used to determine amino acids (proteins), sugars (polysaccharides), lipids, or aromatic oxidation products from lignin or charred organic matter. Microbial markers (amino sugars, muramic acid) are analyzed after hydrolysis and gas chromatographic separation. Macromolecular structures can also be subjected to thermochemolytic degradation or pyrolysis and subsequent analysis of the fragments by GC MS. Alternative techniques for the examination of organic matter in heterogeneous macromolecular mixtures are non-destructive spectroscopic methods, such as nuclear magnetic resonance (NMR) spectroscopy. Although this technique can give good results concerning the gross chemical composition, speci®c compounds are hardly identi®ed. The combination of spectroscopic techniques with thermolytic and chemolytic methods will add substantially to the understanding of the nature of refractory soil organic matter. Physical fractionation prior to analysis provides a means to dierentiate between distinct SOM pools that can be further characterized by the methods described above. Studies on SOM structural characteristics have focused mainly on the A horizons of soils under agriculture and litter biodegradation in forest soils and need to be extended to a wider variety of soil types and the subsoil. #

J Nondestruct Eval (2010) 29: 38–42 DOI 10.1007/s10921-010-0063-7 Acoustic Properties of Selected Tropical Wood Species Yahya Sedik · Sinin Hamdan · Ismail Jusoh · Mahbub Hasan Published online: 12 February 2010 © Springer Science+Business Media, LLC 2010 ...

There is currently no method for detecting corrosion under Shuttle tiles except for the expensive process of tile removal and replacement; hence NASA is investigating new NDE methods for detecting hidden corrosion. Time domain terahertz radiation has been applied to corrosion detection under tiles in samples ranging from small lab samples to a Shuttle with positive results. Terahertz imaging methods have been able to detect corrosion at thicknesses of 5 mils or greater under 1" thick Shuttle tiles and 7-12 mils or greater under 2" thick Shuttle tiles.

We investigated the time-course changes in the elasticity index (EI) and the texture index (TI) 2 of pears (Pyrus communis L.), namely, 'La France' during the postharvest period. EI was 3 determined using a formula EI = f 2 2 ·m 2/3 , where f 2 is the pear sample's second resonance 4 frequency and m is the sample mass. A nondestructive vibrational method using a laser Doppler 5 vibrometer (LDV) was used for measuring the pear samples' second resonance frequency (f 2 ).

The properties of concrete containing fine recycled aggregate are investigated. Recycled aggregate consisted of crushed concrete (CC) or crushed brick (CB) with particles less than 5 mm in diameter. The free water/cement ratio was kept constant for all mixes. The fine aggregate in concrete was replaced with 0%, 25%, 50% and 100% CC or CB. Generally, there is strength reduction of 15 -30% for concrete containing CC. However, concrete incorporating up to 50% CB exhibits similar long-term strength to that of the control. Even at 100% replacement of fine aggregate with CB, the reduction in strength is only 10%. Beyond 28 days of curing, the rate of strength development in concrete containing either CC or CB is higher than that of the control indicating further cementing action in the presence of fine recycled aggregate. More shrinkage and expansion occur in concrete containing CC or CB. D

The characterization and accurate determination of the chloride content in cement=concrete is very important for the assessment of the durability and safety of a concrete structure. The available analytical techniques are relatively expensive and time consuming. In this study, a laserinduced breakdown spectroscopy (LIBS) system was used for determination of elemental composition in three different types of cement samples. The plasma was generated by focusing a pulsed Nd: YAG laser at 1064 nm on the cement samples. The concentrations of different elements of significance for structural stability in cement samples were determined. The evaluation of the potential and the capabilities of LIBS as a rapid tool for characterization of cement samples is discussed. The optimum LIBS setup and experimental conditions to detect and measure chloride in building materials are reported. The LIBS results were compared with the results obtained using a standard analytical technique such as inductively coupled plasma emission spectroscopy (ICP-ES). The limits of detection were determined, and calibration curves were measured. The results of this investigation indicate the reliability of LIBS to characterize different cement samples and to assess the chloride content in these cements.

A field mapping system based on external electrooptic sampling has been developed in order to determine the vectorial components of the electric near-field distribution within microwave integrated circuits. The capabilities of the setup are demonstrated by two-dimensional measurements of normal and tangential fields in a coplanar microwave distribution network at frequencies up to 15 GHz. Results obtained on a functioning power-distribution network, as well as on two nonfunctioning networks, show the ability of the technique to interrogate internal circuit operation and to isolate faults through investigation of the field distributions.

X-ray-computed tomography (CT) successfully underwent a transition from slice-by-slice imaging to volume imaging in the decade after 1990 due to the introduction of spiral scan modes. Later, the transition from single-slice to multislice scanning followed. With the advent of new detector technologies we are now looking forward to circular and spiral scanning using area detectors and the respective reconstruction approaches.

An improvement has to be made in the inspection speed and the crack detection ability needed to inspect cracks in express train wheels. In this paper a linearly integrated Hall sensor array (LIHaS) is proposed in order to improve the ability for crack detection. In addition, the exclusive parallel signal conditioning circuits, the analog-to-digital convertors, and the interface were developed to reduce the measurement time. The permanent magnet, which applies the vertical magnetic field to the wheel, and the differential-type LIHaS, which measures the distribution of the magnetic field around a crack, is designed to be buried in the rail. An experiment was performed in order to verify the proposed method.

The aim of this paper was to predict the static bending modulus of elasticity (MOE S ) and modulus of rupture (MOR) of Scots pine (Pinus sylvestris L.) wood using three nondestructive techniques. The mean values of the dynamic modulus of elasticity based on flexural vibration (MOE F ), longitudinal vibration (MOE LV ), and indirect ultrasonic (MOE US ) were 13.8, 22.3, and 30.9 % higher than the static modulus of elasticity (MOE S ), respectively. The reduction of this difference, taking into account the shear deflection effect in the output values for static bending modulus of elasticity, was also discussed in this study. The three dynamic moduli of elasticity correlated well with the static MOE S and MOR; correlation coefficients ranged between 0.68 and 0.96. The correlation coefficients between the dynamic moduli and MOE S were higher than those between the dynamic moduli and MOR. The highest correlation between the dynamic moduli and static bending properties was obtained by the flexural vibration technique in comparison with longitudinal vibration and indirect ultrasonic techniques. Results showed that there was no obvious relationship between the density and the acoustic wave velocity that was obtained from the longitudinal vibration and ultrasonic techniques.

J Nondestruct Eval (2010) 29: 38–42 DOI 10.1007/s10921-010-0063-7 Acoustic Properties of Selected Tropical Wood Species Yahya Sedik · Sinin Hamdan · Ismail Jusoh · Mahbub Hasan Published online: 12 February 2010 © Springer Science+Business Media, LLC 2010 ...

The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.

Aircraft structural components such as wings and fuselages are constantly exposed to harsh environments, which make them susceptible to corrosion initiation and growth. To complicate matters, corrosion is normally hidden under paint and primer and cannot be visually detected until significant corrosion has occurred, causing the paint to blister. Corrosion of this type is usually preceded by the presence of corrosion precursor pitting. Hence, early detection of pitting is a critical issue in the maintenance of an aircraft and its structural components. Near-field microwave nondestructive testing techniques have been successfully used for detection of corrosion under paint, including very small laser machined pits. However, it is desirable to improve the spatial resolution associated with these techniques so that pits with dimensions in the range of a few hundreds of micrometers can be effectively detected.

The world’s wind resource is abundant, and has great development potential. In the traditional low rated wind generator, the mechanical friction
resistance between the bearings is too large, due to low wind speed in the city, usually it can’t start up when the wind speed is not big enough, whereas the
high rated ones produce lot of noise. In both cases the AMBs can be used to overcome their problems. Magnetic bearing is a mechanical and electrical
integration bearing which suspends and stabilizes the rotor with the electromagnetic force, compared with the general bearings, for no mechanical friction,
the damping of small wind generator with AMB can be minimized; power consumption is about 1/10 of ordinary bearings, which makes the wind generator
start up with low-speed wind. Active Magnetic Bearings (AMB) have many advantages such as no friction loss, no abrasion, lubrication free quality, and
used for high rotational speed applications. A complete AMB system consists of an actuator, power amplifier, a rotor position sensor and a control system. In
this paper, a closed loop decentralized Fuzzy Logic controller for Active magnetic Bearings is designed. For the numerical evaluation of control algorithm a
MIMO (multiple input multiple output) mathematical model of the controlled plant is determined. The AMB system which is open-loop unstable and highly
coupled due to nonlinearities inherited in the system such as gyroscopic effect and mass imbalance requires dynamic controller that can stabilize the system.
The majority of industrial applications of active magnetic bearings were still based on conventional PID control system. The proposed control design is based
on rule based procedure. It has been shown, that the presented FL control guarantees satisfactory high damping, low parameter variations and measurement
noise of the overall system. The designed FL controller is able to maintain the rotor in centre position in the final steady state. Simulations are provided to
illustrate the performance of the controller. This Paper deals with developing a model of an Active Magnetic Bearing (AMB), and its 1-DOF, 2-DOF, 4-DOF
model using a Fuzzy controller. The effectiveness of the proposed controller is compared with the conventional PID controller.

Over the last 30 years, there has been a large amount of research attempting to develop an automatic (or semiautomatic) system for the detection and classification of weld defects in continuous welds examined by radiography. There are basically two large types of research areas in this field: image processing, which consists in improving the quality of radiographic images and segmenting regions of interest in the images, and pattern recognition, which aims at detecting and classifying the defects segmented in the images. Because of the complexity of the problem of detecting weld defects, a large number of techniques have been investigated in these areas. This paper represents a state-of-the-art report on weld inspection and is divided into the two parts mentioned above: image processing and pattern recognition. The techniques presented are compared at each basic step of the development of the system for the identification of defects in continuous welds. This paper deals with the first part.

In this paper the pulsed eddy current (PEC) response of a range of heat treatable and non-heat treatable aluminium alloys (AA-1050, 2024, 5083 and 7075) to applied stress well below the elastic limit is studied. The effect of prior heat treatment and prior plastic deformation on the stress dependency of the pulsed eddy current response is quantified using the peak value of the PEC difference signal. In certain cases non-linear stress responses are measured. Because it is well known that the effect of stress on conductivity is anisotropic both isotropic (circular) probes and directional (rectangular) probes are compared. It is found that both prior plastic work and heat treatment condition can have a strong effect on the stress coefficients, even changing the sign of the stress dependence. The implications of these effects for the future characterisation of residual stress state by PEC are discussed. 44 0 191 222 563; fax: + 44 0 191 222 8180. E-mail addresses: Maxim.Morozov@ncl.ac.uk (M. Morozov), Philip.Withers@manchester.ac.uk (P.J. Withers). NDT&E International 43 (2010) 493-500

One of the important overall surprises of the Northridge earthquake of 17 January 1994, was the widespread and unanticipated brittle fractures in welded steel beam-column connections. The economy, versatility and presupposed high plastic deformation capacity of welded steel moment-resisting frame (WSMF) buildings led to their common usage in Los Angeles and elsewhere in the US. No casualties or complete collapses occurred during the Northridge earthquake as a result of these connection failures, and WSMF buildings in areas of moderate shaking were not damaged at all. However, a wide spectrum of brittle connection damage did occur, ranging from minor cracking observable only by nondestructive testing to completely severed columns. This paper reviews the performance of steel buildings during the Northridge earthquake, and examines some of the results of studies undertaken as part of a project initiated by US Federal Emergency Management Agency (FEMA) to reduce the earthquake hazards posed by steel momentresisting frame buildings. The objective of this project is to develop and verify reliable and cost-effective methods for the inspection, evaluation, repair, and rehabilitation of existing steel frame buildings and the construction of new ones. The project is conducted by the SAC Joint Venture, consisting of the Structural Engineers Association of California, the Applied Technology Council and the California Universities for Research in Earthquake Engineering.

Abstract: The paper reviews the background and methodology of the primary calibration of Acoustic Emission (AE) sensors. Two practically realised basic calibration methods are described and explained. The method of reciprocity calibration is based on the reciprocity theorem. The ...

Radiographic testing is a well-established non-destructive testing method to detect subsurface welding defects. In this paper, an automatic computer-aided identification system was implemented to recognize different types of welding defects in radiographic images. Imageprocessing techniques such as background subtraction and histogram thresholding were implemented to separate defects from the background. Twelve numeric features were extracted to represent each defect instance. The extracted feature values are subsequently used to classify welding flaws into different types by using two well-known classifiers: fuzzy k-nearest neighbor and multi-layer perceptron neural networks classifiers. Their performances are tested and compared using the bootstrap method. q

Real-time vibration monitoring and diagnostics system is developed and supplied for the 5 stand 4-h tandem cold rolling mill 2030 NLMC. Mechanism of chatter regeneration due to high frequency strip thickness variation and stands synchronization in the tandem rolling mills are considered. Methods for chatter passive damping and active suppression are considered. Work rolls hydraulic bending system influence on bearings vibration and chatter is discussed. The new methods are used for the 3rd octave chatter early diagnostics and model based mill control.

The optimization of crashworthiness in aerospace and automotive industries is one of the key  research  targets  of  the  leading  respective  industries.  In  the  past  few  decades;  the  use  of composites  in  structural  applications  has  been  increasingly  used  in  aerospace  and  advanced transportation industries because of their excellent mechanical properties and better strength-to-weight ratio than metal. In this paper composite materials constituent and their application in  aerospace  industry  and  their  failure  modes  has  been  presented.  The  effects  of  the  impact damage  on  the  carbon  fiber  composites  as  the  one  of  the  most  common  materials  in  the aerospace  industry  has  been  investigated  and  evaluated  by  using  non-destructive  testing methods.  This  review  considered  the  capabilities  of  the  most  common  methods  of  NDT  in composite  materials.  Damage  modes  interaction,  types  of  velocity,  and  influence  of  various factors on impact behavior was investigated and must be considered to predict any failure in composite materials.

The monitoring systems presently available for vibration observation of civil engineering struc-tures are normally based on networks of accelerometers and strain gages distributed along the structure connected to one or more central computer. 1, 2 This computer launches the acquisition and stores and transmits the collected data. Depending on the dimensions of the structure and the extensiveness of the monitoring system, one common issue with most widely used monitoring systems is the use of electrical cables to power sensors and ...

Water ingress inside honeycomb sandwich panels during service has been linked to in-flight failure in some aircraft. There is an ongoing effort to develop nondestructive testing methods to detect the presence of water within the panels. Magnetic resonance (MR) represents an attractive approach in that it is sensitive to moisture. Using a unilateral MR sensor, testing can be applied directly to the surface of the panel.

Infrared thermography in nondestructive testing provides images (thermograms) in which zones of interest (defects) appear sometimes as subtle signatures. In this context, raw images are not often appropriate since most will be missed. In some other cases, what is needed is a quantitative analysis such as for defect detection and characterization. In this paper, presentation is made of various methods of data analysis required either at preprocessing and/or processing images. References from literature are provided for briefly discussed known methods while novelties are elaborated in more details within the text which include also experimental results.

This paper presents the design and performances of a partially filled dielectric-loaded waveguide resonator for sensing application, in particular, for evaluating very small flaws on a metal surface. The resonator consists of a rectangular waveguide loaded with a transversally and longitudinally finite dielectric insert that concentrates the electromagnetic field within it and effectively creates a quarter-wavelength resonator. The quarterwavelength resonator is short-circuited at one end, whereas the other end is formed by tapering the dielectric insert. It is shown that the coupling between the resonator and the feeding waveguide can be widely varied by changing the geometrical and dielectric properties of the insert. Simulations are performed to demonstrate the characteristics of this resonator using a standard K-band (18-26.5 GHz) rectangular waveguide. To demonstrate the potential practical usefulness of such a resonator as a sensor, small perturbations, such as shallow pits or notches (representing damage or flaws), in the surface of the shorting plate of the resonator were used to evaluate the change in the resonator characteristics. These changes can be used for sensing and sizing such surface flaws in nondestructive testing applications (i.e., inspection of aircraft fuselage panels). Measurements are conducted to verify the potential of this sensor for shallow-pit-depth evaluation.

The numerical simulation using Finite Element (FE) method is a main activity in the design - validation process of mechanical products. Using this method and CAD tools can give an efficient advantage in the CAD - Analysis loop. The geometric model (mesh) used in the FE method is mainly obtained from the CAD model (CSG, B-Rep). In order to reduce the analysis time without bringing precision on computation results, we propose to integrate a new link in the design and analysis interoperability process. This link is named Idealization or simplification of CAD model. So, the automation of the idealization task is important in the CAD-Analysis integration process. In this paper, we propose an idealization approach which mainly depends on the geometry, the solicitations and the behavior of material. According to the analysis goal, the designer can have several alternatives of analysis models which depend on the level of eliminated details and the abstraction level (1D, 2D or 3D). The non manifold models should not be a barrier to the considered analysis model. We start with a positioning of several geometry simplification methods for CAD models in order to generate analysis models adapted with the considered analysis point of view. Based on this state of the art, we present the idealization approach in an integrated design context. Then, we propose our general method of the CAD geometry idealization. This one is based on an original algorithm witch integrate tow alternatives approach (selective approach and automatic approach). In order to emphasize our contribution, we present some examples of idealized form features (parallelepiped, cylinder, and wedge) implemented with OpenCacade code. Finally, an example of mechanical part using implemented form features is developed. The output of the algorithm is some proposed analysis models based on the CAD model of the part.

http://www.designsociety.org/publication/25383/idealization_of_cad_geometry_using_design_and_analysis_integration_features_models

In this comprehensive review, a general introduction, an explanation of the technique physics, several specific examples of applications on polymers and sample preparation requirements of Raman spectroscopy are included.  In addition, the local availability of Raman facilities at N.C. State as well as availability in the current market was investigated.
Raman spectroscopy is a structural characterization technique that relies on inelastic scattering of monochromatic light, which is known as Raman scattering.  The wave number position indicates the vibrational states in the material while the width describes the molecular structure.  Also, the intensities can be compared in the polarized and perpendicular directions to determine the orientation and symmetry of a material.  In order to understand how Raman spectroscopy works, the physics of technique are discussed.  Analysis methods were discussed with examples in the corresponding sections.  A commercial analysis of Raman instrument features and price, as well as operating costs at local and regional labs were also discussed.      Finally, a comparison of Raman spectroscopy to infrared spectroscopy and x-ray fluorescence spectroscopy are discussed.

The two broad categories of fiber-reinforced composite liner repair and deposited weld metal repair technologies were reviewed and evaluated for potential application for internal repair of gas transmission pipelines. Both are used to some extent for other applications and could be further developed for internal, local, structural repair of gas transmission pipelines. Principal conclusions from a survey of natural gas transmission industry pipeline operators can be summarized in terms of the following performance requirements for internal repair: • Use of internal repair is most attractive for river crossings, under other bodies of water, in difficult soil conditions, under highways, under congested intersections, and under railway crossings. • Internal pipe repair offers a strong potential advantage to the high cost of horizontal direct drilling when a new bore must be created to solve a leak or other problem. • Typical travel distances can be divided into three distinct groups: up to 305 m (1,000 ft.); between 305 m and 610 m (1,000 ft. and 2,000 ft.); and beyond 914 m (3,000 ft.). All three groups require pig-based systems. A despooled umbilical system would suffice for the first two groups which represents 81% of survey respondents. The third group would require an onboard self-contained power unit for propulsion and welding/liner repair energy needs. • The most common size range for 80% to 90% of operators surveyed is 508 mm (20 in.) to 762 mm (30 in.), with 95% using 558.8 mm (22 in.) pipe. Evaluation trials were conducted on pipe sections with simulated corrosion damage repaired with glass fiber-reinforced composite liners, carbon fiber-reinforced composite liners, and weld deposition. Additional un-repaired pipe sections were evaluated in the virgin condition and with simulated damage. Hydrostatic failure pressures for pipe sections repaired with glass fiberreinforced composite liner were only marginally greater than that of pipe sections without liners, indicating that this type of liner is only marginally effective at restoring the pressure containing capabilities of pipelines. Failure pressures for larger diameter pipe repaired with a semi-circular patch of carbon fiber-reinforced composite lines were also marginally greater than that of a pipe section with un-repaired simulated damage without a liner. These results indicate that fiber reinforced composite liners have the potential to increase the burst pressure of pipe sections with external damage Carbon fiber based liners are viewed as more promising than glass fiber based liners because of the potential for more closely matching the mechanical properties of steel. Pipe repaired with weld deposition failed at pressures lower than that of un-repaired pipe in both the virgin and damaged conditions, indicating that this repair technology is less effective at restoring the pressure containing capability of pipe than a carbon fiber-reinforced liner repair. Physical testing indicates that carbon fiber-reinforced liner repair is the most promising technology evaluated to-date. Development of a comprehensive test plan for this process is recommended for use in the field trial portion of this program.

Dans le but de concevoir un système de diagnostic des défauts d'un moteur diesel 4 temps à combustion interne, l'incidence d'un défaut de distribution sur la vibration du moteur a été étudié. Ce défaut a été simulé en modifiant les jeux entre les cames et les poussoirs en contact avec les queues des soupapes.

The relentless competition among automotive companies and increased demands from customers for driver assistance functions, dynamically-controlled safety systems, driving comfort and infotainment services in vehicles are creating mounting time-to-market pressures and, consequently, shortened development times. With the shortened development times and increased vehicle complexity, guaranteeing hardware-software integrity and, hence, vehicle performance has become a salient issue. This is because poor vehicle performance increases maintenance costs to customers and warranty costs to automotive manufacturers; which, in turn, result in customer dissatisfaction and reduced competitiveness of US automotive industry. The development of methods for enhancing the reliability of embedded systems of heterogeneous components that are designed and implemented by different suppliers, and vehicle diagnostics and prognostics are of vital interest to US automotive industry.

A breakdown of the electrical insulation system causes catastrophic failure of the electrical machine and brings large process downtime losses. Preventive maintenance and online monitoring are some of the methods to improve the reliability and to reduce unscheduled downtime. One of the main reasons for the failure of the machine is the breakdown of the stator turn insulation. The offline surge test is the most commonly used offline test to assess the condition of the turn insulation. There is no online monitoring method that is applicable to low-voltage machines and has the same capabilities as the surge test. This paper introduces new concepts to implement an online surge test. The possibilities and limitations of the online surge test are presented, as well as the simulation and experimental results, to validate the concepts.

In this paper, we present a failure analysis methodology of a structural component using a conventional 14step failure analysis approach. This failure analysis methodology focused on observation, information gathering, preliminary visual examination and record keeping, nondestructive testing, mechanical testing, selecting/preservation of fracture surfaces, macroscopic examinations, microscopic examinations, metallography, failure mechanism determination, chemical analysis, mechanical failure analysis, testing under simulated service conditions, and final analysis and report. The application of this methodology is demonstrated in the failure analysis of a mixer unit shaft made of AISI 304 stainless steel. Using this failure analysis approach, we pinpointed the primary mode of failure and developed a means of circumventing this type of failure in the future. The results show that the steel shaft failed due to intergranular stress cracking (sensitization during welding) at the heat effected zones (weld plugs).

The author's experience in the estimation of concrete strength by combined methods of nondestructive testing is summarized in this paper. Both the traditional well-known rebound hammer and ultrasonic pulse velocity tests were used in the study. Various charts showing the results are presented. All charts show the 95% prediction intervals, thus enabling professionals to predict concrete strength simply and reliably. Unlike other work, the research ended with one simple chart that requires no previous knowledge of the constituents of the tested concrete. The method presented is simple, quick, reliable, and covers wide ranges of concrete strengths. The method can be easily applied to concrete specimens as well as existing concrete structures. The final results were compared with previous ones from literature and also with actual results obtained from samples extracted from existing structures. D

A fost descoperit de A.Volts în 1778 în malul balţilor şi a fost numit prima oară gaz de baltă. Metanul este cel mai simplu alcan, o hidrocarbură saturată aciclică, primul termen al seriei de hidrocarburi parafinice. Se gaseşte sub formă de zăcaminte naturale în stare destul de pură. Ţara noastră posedă zăcăminte de metan cu puritate ridicată ( 98%-99% ) , cele mai importante fiind cele de la Sărmăşel , Copşa Mică , Bazna , Nadeş , Şincai , Deleni etc..

Quality control during fabrication and failure monitoring during service have gained importance in the field of metal matrix composites because of their growing uses, especially for structural applications. This review aims to provide a survey of quality control and nondestructive testing relevant to metal matrix composites. The first part presents the determination of the reinforcement parameters which play a very important role in controlling the performance of metal matrix composites. The second part describes the main relevant nondestructive techniques used to identify the defects produced during fabrication or in service. It also shows that the validation of nondestructive techniques and the relationship between their results and component performance should be particularly emphasized in future research work on metal matrix composites. ; Fax: ϩ32 16 32 1992.