Computed tomography (CT) data has the ability to provide qualitative and quantitative data on composite materials. The focus of this paper will be on the specification and development of qualitative and quantitative analysis tools for he evaluation of engineering components made from metal- matrix composite materials. Qualitative tools include 2D and 3D visualization tools. Quantitative tools include segmentation methods that can output to commercial finite element, micromechanical, and/or continuum damage model software for evaluation of composite materials and components. The linkage of CT data with engineering analysis methods provides the engineering community the ability to do a complete structural analysis on an as-manufactured component rather than solely on an as-designed component. With this capability, extensive effect of defect studies can be performed to determine the effect of manufacturing anomalies on part performance. This will provide a truly nondestructive evaluation capability for engineering structures.

X-ray microfocus radioscopy and computed tomography (CT) offer detailed information on the internal assembly and material condition of objects under failure analysis investigation. Using advanced systems for the acquisition of radioscopic and CT images, failure analysis investigations are improved in technical accuracy at a reduced schedule and cost over alternative approaches. A versatile microfocus radioscopic system with CT capability has been successfully implemented as a standard tool in the Boeing Defense and Space Group Failure Analysis Laboratory. Using this tool, studies of electronic, electromechanical and composite material items have been performed. Such a system can pay for itself within two years through higher productivity of the laboratory, increased laboratory value to the company and resolution of critical problems whose worth far exceeds the value of the equipment. The microfocus x-ray source provides projection magnification images that exceed the sensitivity to fine detail that can be obtained with conventional film radiography. Radioscopy, which provides real-time images on a video monitor, allows objects to be readily manipulated and oriented for optimum x-ray evaluation, or monitored during dynamic processes to check performance. Combined with an accurate manipulating stage and data acquisition system x-ray measurements can be used for CT image reconstruction. The CT image provides a cross sectional view of the interior of an object without the interference of superposition of features found in conventional radiography. Accurate dimensional measurements and material constituent identification are possible from the CT images. By taking multiple, contiguous CT slices entire 3D data files can be generated of objects.

Aging of adhesives is usually characterized by preparing standard bonded samples and destructively measuring shear, tensile or peel adhesion strength. Similarly the integrity of bonded devices is ascertained by destructive testing of duplicate samples, manufactured under identical conditions. The method requires a great number of samples in order to monitor the aging process. A new non-destructive testing method is suggested based on many experimentally determined correlations between the internal friction properties of materials and their strength, as a tool of characterizing the aging status of adhesives in bonded devices. Damping measurements we performed on simple flat and cylindrical joints made out of metallic adherents and various adhesives. The joints were aged in natural environments as well as through thermal accelerated treatments. Vibrations were introduced into the samples by a brief impact with an electromagnetic shaker and detected with a microphone. Special care was devoted to the fastening of the samples to insure reliable results. The NDT measurement results were corroborated by destructive shear tests of new and aged bonded joints. The results show that aging of adhesives can indeed be non-destructively characterized. Very good correlation was found between the specific damping capacity of the samples and the shear strength of the joints.

In this paper, after having established a mathematical modeling of detecting micro bulk defects by Mie scattering theory, a novel way called near infrared laser scanning tomography (LST) technique is developed that can detect micro bulk defects in Si-based materials and has the advantages of high resolution and high contrast. Simulating experiments on micro bulk defects in glass are implemented and scattered graphs collected in the direction vertical to the incident light are processed in order to prove the rightness of the modeling. Satisfactory results are achieved which demonstrates that the scattering modeling is correct and that the LST non-destructive detection of micro bulk defects technique is feasible.

Microwave and millimeter wave nondestructive testing and evaluation methods are increasingly gaining recognition as viable inspection techniques. This paper briefly describes the reasons for using these techniques as well as applications in which they may be considered useful. Several practical examples of the utility of these techniques for different applications are also provided.

The amplitude and phase spacing distributions of electromagnetic fields are imaged and measured using microwaves interferometry revealed by photothermal films and lock-in infrared thermography. Such EM fields imaging is a powerful tool for NDE of dielectric and radar absorbing materials.

We compare results of ultrasonic, microwave, and thermal imaging of graphite-epoxy composite panels with artificial defect structures.

This article describes a single transducer ultrasonic imaging method based on ultrasonic velocity measurement that eliminates the effect of plate thickness variation in the image, i.e. the method is thickness-independent. The method, currently being commercialized under a cooperative agreement between NASA Lewis Research Center and Sonix, Inc., thus isolates ultrasonic variations due to material microstructure. Its use can result in significant cost savings because the ultrasonic image can be interpreted correctly without the need for precision thickness machining during nondestructive evaluation stages of material development. Images obtained using the thickness-independent methodology are compared with apparent velocity maps and c- scan echo peak amplitude images for monolithic ceramic and metal matrix composite materials having thickness and microstructural variations. It was found that he thickness- independent ultrasonic images reveal and quantify correctly areas of global microstructural variation due to the elimination of thickness effects.

Lamb waves are increasingly attractive for nondestructive testing of adhesively bonded structures due to their unique properties. Larger areas can be inspected using single pulse excitation compared to localized point-by-point standard bulk wave ultrasonic testing with only two modes, longitudinal or shear waves. Lamb waves offer an infinite number of guided wave modes to design wave structure and/or field distributions having specific sensitivity to certain defects, material properties and geometry of the component. The objective of this work was to study the sensitivity and efficiency of adhesive bond inspection using Lamb waves and to facilitate the interpretation through imaging.

Adhesive bonding has been used for many years to mechanically connect components to various structures. The quality of the adhesive bond is primarily dependent upon the strength of the adhesive and of the interface between the adhesive and the adherent. Further, the strength of the interface is dependent upon a number of parameters, such as the area of adherence, cleanliness of the interface, and cure of the adhesive. There is difficulty in evaluating these parameters and the associated quality of the adhesive bond because the adhesive layer is sandwiched between two adhesively bonded layers and is not accessible for visual inspection. A number of nondestructive evaluation (NDE) techniques have been developed to prove the adhesive bond to determine the status of these physical parameters Ultrasonics is one of the most often in the form of liquid. Many manufacturers of adhesively bonded joints would like to avoid the use of liquid in the presence of the bondline. This is especially true when the bonded materials are hygroscopic.

High precision manufacturing is dependent on the accurate positioning of the part prior to each processing step. The part is typically held in a transfer fixture which may be used either simply as a part holder or as an alignment reference. A typical application is explored in this work, grinding of slots in a thick ceramic wafer mounted on a part fixture. A 1 micron slot is located with a position tolerance of 10 microns in the nickel-zinc-ferrite wafer. Part location is determined by means of a 50.8 by 1 micron target deposited onto the ceramic during an earlier process. In the current process, the target is magnified by a 250X vision system and the machine operator manually aligns the part using a set of cross hairs overlaid on the image. A high precision x-y stage is used to adjust the pat location. However, the use of a fixed focal distance camera combined with part mounting variation results in an unfocused image for the operator. Manual alignment of the unfocused image leads to target location error during centering of the target in the cross hairs. The misalignment, in turn, results in process variation. The location of the slots varies based on alignment and reduces the process capability. To reduce process variation, an automated target location algorithm has been applied. The algorithm uses template matching to detect the target. This simple algorithm has been shown to locate the target within the required tolerance in spite of image blur. Using low cost processing, the system is able to determine the target location in real-time. For real-time control, the algorithm must determine the x-y coordinate of the target in 10 seconds or less. This effort shows the potential for a simple location algorithm to be implemented in a manner which can significantly decrease process variation in a precision fabrication process.

Acoustography provides an alternative to the conventional point-by-point scanning approach employed for ultrasonic inspection of composites. In acoustography, an acousto-optic area detector is employed for direct ultrasonic imaging of composites in near real time. In this work, we will report on the application of this approach for inspecting composites where the point-by-point approach may not be practical and/or cost-effective.

Ultrasonic testing techniques are currently used as an alternative to radiography for detecting, classifying,and sizing weld defects, and for evaluating weld quality. Typically, ultrasonic weld inspections are performed manually, which require significant operator expertise and time. Thus, in recent years, the emphasis is to develop automated methods to aid or replace operators in critical weld inspections where inspection time, reliability, and operator safety are major issues. During this period, significant advances wee made in the areas of weld defect classification and sizing. Very few of these methods, however have found their way into the market, largely due to the lack of an integrated approach enabling real-time implementation. Also, not much research effort was directed in improving weld acceptance criteria. This paper presents an integrated system utilizing state-of-the-art techniques for a complete automation of the weld inspection procedure. The modules discussed include transducer tracking, classification, sizing, and weld acceptance criteria. Transducer tracking was studied by experimentally evaluating sonic and optical position tracking techniques. Details for this evaluation are presented. Classification is obtained using a multi-layer perceptron. Results from different feature extraction schemes, including a new method based on a combination of time and frequency-domain signal representations are given. Algorithms developed to automate defect registration and sizing are discussed. A fuzzy-logic acceptance criteria for weld acceptance is presented describing how this scheme provides improved robustness compared to the traditional flow-diagram standards.

Advanced waveform based acoustic emission (AE) techniques have been previously used to evaluate damage progression in laboratory tests of composite coupons.In these tests, broad band, high fidelity acoustic sensors were used to detect signals which were then digitized and stored for analysis. Analysis techniques were based on plate model wave propagation characteristics. This approach, more recently referred to as Modal AE, provides an enhanced capability to discriminate and eliminate noise signals from those generated by damage mechanism. This technique also allows much more precise source location than conventional, threshold crossing arrival time determination techniques. To apply Modal AE concepts to the interpretation of AE on larger composite structures, the effects of wave propagation over large distances and through structural complexities must be well characterized and understood. In this research, measurements were made of the attenuation of the extensional and flexural plate mode components of broad band simulated AE signals in large composite panels. As these materials have applications in a cryogenic environment, the effects of cryogenic insulation on the attenuation of plate mode AE signals were also documented.

Advanced ceramic composites with complex architecture have stimulated interest in innovative embedded fiber optic sensors for in-situ real-time characterization of the structure. Careful selection of a compatible optical fiber material and an inexpensive signal detection technique are most critical factors for successful incorporation of these embedded sensors. The focus of this paper is two-fold. The first reports on the development of a novel optical waveguide consisting of sapphire fiber core and polycrystalline alumina cladding, and how can these fibers be embedded into ceramic composites. The second aspect of this paper is devoted to the application of a novel inexpensive and sensitive signal detection technique, namely, the spatial intensity modulation technique to sapphire optical fibers. This technique is applicable to multimode fibers. It is based on modal power distribution modulation under external perturbations. A theoretical model has been developed to correlate variations in the modal power within multimode optical fibers to the changes induced in the state of the hosting material. Numerical results obtained from the model are shown to be in agreement with experimental observations. This paper provides a novel means to characterize high temperature composites using multimode sapphire optical waveguides.

Fiber-reinforced composite materials are beginning to be employed in applications related to retrofit and repair of large-scale civil structures. This paper discusses the utilization of a passive, pea, strain monitoring technology to the damage and health assessment of composite structures. Applications considered include epoxy-matrix composite materials reinforced with chopped glass, continuous glass fibers, carbon-fiber mat as well as continuous carbon-fiber. The advantages of the various material applications are discussed as they apply to large civil structures with peak strain monitoring data presented to illustrate how the systems can be field monitored. Full-scale structural component testing as well as subscale laboratory testing results will be presented and discussed. Recommendations are provided to guide the engineering community in such composite applications and to provide a design framework for the inclusion of simple and reliable sensor systems to detect both short-term and long-term damage.

The main problems of optical time and frequency domain reflectometry systems using for nondestructive evaluation of fibers, optical transparent and untransparent materials and composites structural integrity are analyzed in present paper. Their common and special solutions are given. The results of elaboration and utilization of perspective units for optical reflectometry systems based on fiber sensors are represented.

A new sensor called the Meandering Winding Magnetometer (MWM) and associated grid measurement algorithms is described. The MWM can be used to determine property profiles for ferrous and nonferrous components, to provide repeatable and reproducible measurements on curved surfaces or inspection of difficult to access locations, and to detect and characterize cracks. This paper describes the application of the MWM to detection and characterization of early stage fatigue damage in aluminum and stainless steel. Other potential applications include coating characterization, case depth measurement, crack detection, and embedded sensing. The MWM is a thin and conformable sensor that incorporates both eddy current type sensing and magnetic induction sensing methods to measure conducting and magnetic properties of nonferrous and ferrous metals. The grid measurement approach is a model-based technique used to measure two properties independently, at a single frequency. This grid method also provides a convenient framework for MWM system calibration and processing of multiple frequency data. For example, this permits measurement over a wide frequency range using a single MWM sensor geometry. This paper provides a general introduction to the MWM technology and specific capability demonstrations on ferrous and nonferrous alloys.

Eddy current sensors provide non-contact monitoring of advanced materials during industrial manufacturing. Inducing an alternating electromagnetic field which surrounds and penetrates the material being measured, the eddy current sensor performs highly accurate monitoring of the process. An eddy current sensor is capable of measuring the electrical conductivity and magnetic permeability of a material which can then be correlated to changes in shape and density as well as other properties critical to meet final product design requirements. The proliferation of eddy current technology in the non-destructive evaluation field has been limited to temperatures that are well below those encountered during consolidation of powdered metal and metal matrix composite materials. The drive for net shape forming and cost effective manufacturing, especially with advanced materials, has led to the recent development of a high temperature eddy current monitoring system. The system has been successfully demonstrated at industrial hot isostatic pressing sites. This paper describes the latest high temperature eddy current probe sensor design and how the sensor can be used to monitor and control consolidation of titanium matrix composites.

The analysis of eddy current data collected form nuclear steam generator tubes is both very important and very labor intensive. To aid the analysis team we have been developing an automatic data analysis package. It is directed towards multispectral data collected with differential bobbin coil probes. The analysis package calibrates the data against a standard tube, and flags all candidate flaws with a bipolar signature similar to the impulse response of the probe. Three stages of analysis are: preprocessing, wavelet analysis, and fuzzy inference. The wavelet transform is the basis for minimizing the number of false positive s caused by noise while the fuzzy inference system further prunes the false positives. Results from tests thus far indicate that the analyzer generally detects the flaws found by humans, but has difficulty distinguishing between very weak flaw signals from cracks near tube support plates. Further development is underway creating better procedures for support plate regions.

Signals that are obtained in a variety of nondestructive evaluation (NDE) processes capture information not only about the characteristics of the flaw, but also reflect variations in the specimen's material properties. Such signal changes may be viewed as anomalies that could obscure defect related information. An example of this situation occurs during in-line inspection of gas transmission pipelines. The magnetic flux leakage (MFL) method is used to conduct noninvasive measurements of the integrity of the pipe-wall. The MFL signals contain information both about the permeability of the pipe-wall and the dimensions of the flaw. Similar operational effects can be found in other NDE processes. This paper presents algorithms to render NDE signals invariant to selected test parameters, while retaining defect related information. Wavelet transform based neural network techniques are employed to develop the invariance algorithms. The invariance transformation is shown to be a necessary pre-processing step for subsequent defect characterization and visualization schemes. Results demonstrating the successful application of the method are presented.

While magneto-optic/eddy current imagers (MOIs) are widely used for the nondestructive inspection (NDI) of aging aluminum airframes, they are not currently used to inspect aerospace composites for two reasons. First, most composites are essentially electrical insulators, which makes it difficult for the MOI to induce sufficient eddy currents in these materials for imaging. Second, unlike steel, which can be easily magnetized and inspected using the MOI, most composites are not appreciably magnetic. Exceptions to these two stated limitations are composites containing electrically conducting 'screens' of aluminum or copper for lighting-protection, 'stealthy' military composites containing iron particles for radar absorption, and some commercial composites containing nickel-coated carbon fibers for lighting protection and/or electromagnetic shielding. These existing composites can be inspected, to one degree or another,with the MOI. Moreover, by 'tagging' the matrix component of newly-manufactured composites with magnetic oxides, excellent MOI images of cracks, voids, potential disbonds and defects in fiber-weave are possible. Experimental results presented here demonstrate these facts. It is anticipated that when this new technology is perfected, and when magnetic 'tagging' at the time of manufacture becomes an accepted practice, the MOI will be widely used for the NDI of composites during their manufacture, in-service inspection or repair.

We describe the application of IR thermal wave imaging for the nondestructive evaluation of composites and coatings. The technique uses pulsed surface heating and fast, synchronous IR imaging of the surface temperature to form images of subsurface defects in materials. In the case of composites and coatings, we present examples of the detection of defects such as delaminations, disbonds, subsurface impact damage, fluid infiltration, etc. The technique can be used to measure the depths of defects, and also the thicknesses of various coatings.

A method utilizing the advantages of TV- holography/shearography and ultrasonic C-scan for nondestructive evaluation of materials is described. Experimental results using this method to detect defects in fiber reinforced plastics are presented. This approach is cost-effective, and it should be equally applicable to other materials. Some practical issues involved in the experiment are discussed.

Recently, a method to remove the effect of the shear distance from shearographic recordings by reconstruction of the displacement field was presented. Conventional phase- shifting shearography is used to obtain a phase map which represents an approximation to the displacement derivative. To calculate the displacement information of r a point in the final image, the phase values of certain image points of the shearogram are added. Applying this summation top all image points results in a phase map representing the displacement field with the effect of image-doubling removed. This manuscript concentrates on the experimental verification of the effect and shows the application to the measurement of out-of-plane as well as in-plane deformation. The method combines the advantages of conventional shearography and electronic speckle pattern interferometry displacement measurement. It uses the same optical set-up as shearography, which has proved its applicability in industrial environments, and delivers the displacement field with the effect of image-doubling removed. This displacement field is easier to interpret than the approximated displacement derivative of conventional shearography.

A quantitative assessment has been made of the performance of the transient thermography NDE method in the evaluation of defects in carbon-epoxy composite panels. Images have been obtained of artificial defects and their sizes are compared with the modeling predictions. Images have also been obtained of impact damage defects, impact energies up to 5 joules, and these results have been compared with defect images produced by ultrasonic c-scan.

The USS Constitution is the oldest flowing commissioned ship in the US Navy. Recently, the USDA Forest Service, Forest Products Laboratory, was involved in developing an inspection methodology for the use of Navy personnel responsible for maintaining the ship. Several NDE techniques were used to assess the condition of fasteners in the ship and the general condition of the wood comprising it. Radiography and ultrasonic techniques were used to assess the condition of the copper pins used as fasteners. Stress wave NDE techniques were used to locate areas of degradation in the wood. This paper describes the stress wave techniques employed and results obtained form their use.

A study was recently conducted to assess the technical feasibility of using stress wave nondestructive evaluation methods to locate decayed members in timber bridges. Stress wave nondestructive evaluation techniques were used to locate decayed components in several timber bridges in eastern Oregon. Various stress wave techniques were used to conduct an in-situ evaluation of stringers, decking, and compression members. Components suspected as having decay were identified and evaluated in a laboratory after dismantling. Both visual evaluation of the members and subsequent laboratory testing indicated that the stress wave techniques were able to locate decayed components with a high degree of accuracy.

Millions of wooden pallets are discarded annually due to damage or because their low cost makes them readily disposable. Higher quality wooden pallets, however, can be built from high quality deckboards and stringers, and have a much longer life cycle and a lower cost per trip. The long- term goal of this project is to develop an automated pallet part inspection system to sort pallet parts according to grade. Ultrasonic time of flight (TOF) measurements in a pitch-catch arrangement are being used to distinguish types of defects, including knots, decay, cross grain, and voids, from clear wood. Rolling transducers of 3 different frequencies have been used to collect measurements on four oak deckboards of 1/2 inch thickness. Ultrasonic C-scans taken on a 1/2 inch by 1/2 inch grid indicate that TOF with 84 KHz transducers can be used to partially distinguish between several deckboard features and clear wood. Nevertheless, future application of these results to defect detection must not be limited to single, pixel value classification, but must include pixel neighborhoods with textural information.

The potential of using stress wave nondestructive evaluation techniques to sort green southern yellow pine and DOuglas fir veneer into stress grades was evaluated. Stress wave nondestructive evaluation was used to separate green veneer into several grades for use in manufacturing engineered wood composites, most notably laminated veneer lumber. The effect of moisture content and preservative treatment on stress wave determined properties of green (wet) southern yellow pine and Douglas fir veneer was investigated during the preliminary stages of the project. A digital oscilloscope and a commercial stress wave timer were used to measure the transit time it took for an induced stress wave to travel the longitudinal length of each veneer. Stress wave transit times were measured in each piece in the wet condition, during drying, and at a dry equilibrated moisture content of approximately 10 percent. Strong correlative relationships exist between stress wave velocity measured in untreated and preservative treated green (wet) and dry veneer.

Neglect of residual stresses created during welding and forming processes can lead to stress corrosion cracking, distortion, fatigue cracking and premature failures in components. Accurate characterization of residual stresses in welds has been difficult and often impractical since most residual stress measurement techniques are destructive or lack the resolution to accurately characterize the steep stress gradients that exist in weld heat affected zones. The nondestructive nature of the x-ray diffraction technique and its ability to characterize severe stress gradients provided the inducement to develop an extremely portable stress analysis system. The Defense Research Establishment Atlantic and Proto Mfg. Ltd. embarked on a joint project to develop a truly portable stress analysis system which was suitable for use in the marine environment. This paper describes why x- ray diffraction was selected as the means of determining residual stress and provides a brief description of the technique, summarizes the result of the mXRD development and provides illustrations and performance results of some of its recent applications on marine structures.

Classical log-decrement techniques have been used to evaluate the damping property of materials. However, the consistency and repeatability of the method when applied to wood and wood-based materials has been found lacking. A different way to view the free vibration of a single-degree- of-freedom system in the (chi) -(chi) (DOT) plane is presented. When (chi) and (chi) (DOT)/(omega) _d are used to describe the free vibration, it will plot as a spiral curve asymptotically approaching the origin. The radius R of the spiral curve, when plotted in the time domain,is the same as the decay profile curve of the free vibration. Since every sample point has its associated radius, all points of the free vibration can be used to calculate the damping property. This method does not require a knowledge of the initial conditions and is easy to use. Preliminary results show that the new method is more consistent and repeatable in measuring damping than the classical method for wood- based materials.

We have designed a radiation-based system for density measurement of wood composites during pressing. During pressing, heat and mass transfer, consolidation speed and mat characteristics interact to produce a density distribution in the mat that is typified by high surface density and low core density. Measuring density of the wood mat during consolidation is a key parameter for understanding subsequent product performance. The system provides for density measurement at three horizontal planes in the wood mat, at positions of 25 percent, 50 percent, and 75 percent of the mat thickness at any time during the press cycle. The system incorporates three cesium sources and electronic detection equipment, collimated to move in concert with the up-acting press platen. Radiation count data taken at eight counts per second is converted to density. Press position and time are simultaneously recorded with the count data. Experimentation with the system has included radiation measurements in aspen and pine wood mats, incorporating different rates of press closure and furnish moisture content; both variables known to influence formation of the density distribution in the mat. Results are presented that depict density changes in the mat during pressing.

Application of the fast-acting digital computers and the technical means of signals treatment allowed to spread the possibilities and the resolution of activation autoradiography. Analysis of autoradiographic features is connected with the elucidation of the optical distribution of the exposed and treated photoemulsion used as of detector of the secondary beta irradiation. In this report the possibilities of the digital image processing by the autoradiographic investigations of impurity and component distributions in the granat crystal are shown. Identification of radionuclides and the qualitative evaluation of their contents wee conducted by gamma-spectrum of specimens irradiated by neutrons. The treatment of autoradiograms was conducted with the help of the dialogue system having matrix in 512 by 512 elements. For the interpretation of the experimental data clustering analysis methodology was used. Classification of zones on the minimum of the square mistake was conducted according to the data of histograms of the optical densities of the studying autoradiograms. It was proposed algorithm of digital treatment for reconstruction of autoradiographic features. At a minimal contrast the resolution of the method has been enhanced on degree by adaptation of methods of digital image processing to suppress background activity.

The dynamic elastic moduli of the porous alpha-two titanium aluminide compacts are measured using an ultrasonic technique. BOth shear and longitudinal velocities are measured for compacts of different densities, making computation of all the four elastic constants, viz., the Young's modulus, shear modulus, bulk modulus and Poisson's ratio. Ultrasonic techniques have been successfully used to measure the dynamic elastic moduli of porous compacts of a model material. It is seen that the elastic modulus, the shear modulus follow a power law relation as a function of relative density. WIth the choice of an appropriate form density function the relation can be presented with a linear model. The correlations of elastic and shear moduli with the relative density are found similar to the correlations of relative microhardness to density, indicating a possibility of mapping the elastic moduli, if the stress intensification factor of the material is known. The Poisson's ratio is seen to obey a linear correlation and the bulk modulus measured an exponential correlation with the relative density. The results obtained in this study are compared with some of the earlier models. Some of the uncertainties in the earlier models are discussed and the possibility of using ultrasonic nondestructive methods for the measurement of density gradients as well as of anisotropy in the compacts is investigated.