Results Of Ultrasonic Testing Research Articles

Mechanical properties soil stabilized with nano calcium carbonate and reinforced with carpet waste fibers

Abstract One of the geotechnical engineering strategies for dealing with weak soils in a construction site is to alter their mechanical properties with the assistance of soil improvement techniques. The present study examined the effect of the addition of nano calcium carbonate (0, 0.4, 0.8 and 1.2% by weight of the soil) as a stabilizing nanoparticle and carpet waste fibers (0, 0.2, 0.4, and 0.6% by weight of the soil) as a reinforcement agent on the soil behavior. A total of 52 unconfined compressive strength tests, 52 ultrasonic pulse velocity tests, 12 unconsolidated undrained (UU) triaxial tests, and 8 Atterberg limit tests were performed to investigate the effect of fiber and nanoparticle contents and treatment time on the geotechnical properties of the clayey soil. The results showed that the addition of nanoparticles to the clayey soil reduces its liquid limit and increases its plastic limit. The best improvement in the soil strength, which was about 100%, was observed in the 42 days old sample with 1.2% nano calcium carbonate content. The combined use of fibers and nanoparticles also led to significant strength improvement. The addition of carpet waste fiber was found to increase the soil stiffness. Increasing the carpet waste fiber content above the 0.2% did not have much impact on the maximum strength, but significantly improved the residual strength. The addition of carpet waste fibers up to 0.2% increased the velocity of ultrasonic waves, but further increase in the fiber content resulted in reduced velocity. The paper provides a number of equations that express the relationship between the unconfined compressive strength and the ultrasonic pulse velocity for the clayey soils with different additive contents. The provided equations can be used to estimate the success of stabilization and strength improvement efforts based on the results of non-destructive ultrasonic pulse velocity test. The results of unconsolidated undrained triaxial tests showed that the used fibers alter the sample behavior in high strains. Also, the use of nano calcium carbonate and carpet waste fibers together almost doubled the undrained cohesion.

Concrete sulfate corrosion coupled with hydraulic pressure

A type of sealed steel box was designed to simulate sulfate attack and hydraulic pressure on concrete. Cup-shaped concrete specimens with water/cement (w/c) ratios of 0.4, 0.5, and 0.6 were fabricated. During the 270 days corrosion time, corrosion behavior on concrete surfaces was observed every 30 days. The extent of damage on concrete was calculated on the basis of the results of periodic ultrasonic testing. After the completion of experiments, X-ray fluorescence analysis was conducted on the element contents at different depth locations of partial specimens. Experimental results showed that hydraulic pressure accelerated the sulfate attack on concrete, and high pressure yielded serious damage. In comparison with zero pressure, the accelerating coefficients of 0.1, 0.2, and 0.3 MPa hydraulic pressures were 1.48, 1.75, and 2.35, respectively. Hydraulic sulfate corrosion can bring additional sulfate ions into concrete and cause chemical and physical sulfate corrosions on concrete simultaneously, thereby resulting in serious damage on concrete. The reduction of w/c ratio and incorporation of fly ash are beneficial for concrete to resist hydraulic sulfate attack.

Ultrasonic evaluation regarding the effects of biological corrosion of historical roof trusses

For many years work has been performed to obtain sufficiently accurate correlation between the results of ultrasonic tests and the results of strength tests for evaluation of the strength parameters of wood in a structure. It is also important to ensure the development of methods which will facilitate the work of construction mycologists; that is, non-invasive methods of determining the volume of missing materials caused by biological corrosion. The study presents the idea of the objective examination of the thickness of a corroded layer by measuring the velocity of ultrasonic pulse along the fibre length using for this spot heads with thin waveguides. Another testing method presented in the study is controlling the velocity of ultrasonic wave in the direction tangential to annual growth rings by conducting tests on the corner of the corroded beam.

Ultrasonic Quality Assessment of Polymer-Cement Concrete with Pet Waste as the Aggregate

AbstractElaborating composites containing waste materials requires study of basic mechanical properties and assessment of their structure quality. The subject of investigation was PPC concrete where aggregate was substituted with PET remaining after beverages bottles grinding. Substitution was done up to 25% (by volume). Waste material was fractioned and applied in various granulations. The main goal was to indicate the influence of such modification on the composite mechanical properties and to examine composite structure quality at macro level. Since PET and quartz differ greatly in density, to perform such examination it was possible to apply the nondestructive ultrasonic method, one of the most common NDT techniques used in material science and industry. The paper presents the effects of substitution of quartz with PET on ultrasonic wave propagation in PCC. The ultrasonic test results (measurements of wave velocity) compared with results of destructive tests (flexural and compressive strength) showed great correlation.

Improving the quality of forgings based on upsetting the workpieces with concave facets

We propose a forging method for forgings, which implies the upsetting of workpieces with concave facets. A procedure for the theoretical research has been devised aimed at studying the mechanism of closure of artificial axial defects in workpieces. The study was performed based on a finite element method. The key examined parameter was the depth of the concave facets in a workpiece. This parameter varied in the range 0.75; 0.85; and 0.80. The angle of the concave facets was 120°. The results of the theoretical study are the following distributions: deformations, temperatures, and stresses in the body of a workpiece in the process of upsetting the workpieces with concave facets. Based on these parameters, we established an indicator of the stressed state in the axial zone of the workpiece.In order to verify the theoretical results obtained, a procedure for experimental research has been developed. The study was performed using the lead and steel workpieces. The results of the theoretical study allowed us to establish that the effective depth of the concave facets is the ratio of diameters of protrusions and ledges equal to 0.85. At this ratio there occurs the intensive closure of an axial defect. This is due to the high level of compressive stresses when upsetting the workpieces with concave facets. We have established the effective degree of deformation at which the intensive closure of defects takes place. Also established are the distributions of deformations for the cross-section and height of the workpiece, as well as a change in the indicator of the stressed state in the process of upsetting workpieces with concave facets. The closure of axial defects has been confirmed by experimental study using lead and steel samples.The new technique for upsetting workpieces with concave facets has been implemented. The results of ultrasonic testing have allowed us to establish that the obtained parts do not have internal defects, which exceed the requirements of the European standard SEP 1921. Our research has led to the conclusion of the high efficiency of the proposed new method for upsetting workpieces with concave facets, which implies the improvement of quality of the axial zone of large forgings when using a given technique.

Materials and Manufacturing of Container and Stem Forgings for the Extrusion Industry

Extrusion tools, such as containers and stems, are expensive components, and it is important to use the most suitable materials to gain a long service life. It has to be pointed out, however, that not only the applied materials determine the life time of these tools, but also melting and forging techniques as well as heat treatment have an essential impact. For many years, Bohler Special Steel Open Die Forge has been a supplier of forged high-quality components for the extrusion industry, e. g. mantels, liner, liner holder, stems, and accessories for containers. This paper reports on the experiences and research activities in the fabrication of forged components for containers and stems for the extrusion industry and covers material selection up to achieved mechanical properties and ultrasonic test results. Moreover, heating and Finite Element Method (FEM) modelling of stress distributions in the container during the extrusion process in order to optimize and predict the lifetime of these components are discussed. From the material side, the focus is set on the classical 5% chromium steel class, up to the high-alloyed and sophisticated Maraging steels for stem application, mainly in indirect extrusion processes, with the highest compressive stresses required.

Modeling of Ultrasonic Waves in Fractured Rails with an Explicit Approach

Ultrasonic wave propagation in steel rails with explicit identification of flaws is numerically simulated. The problem is to detect a vertical crack in a railhead by applying ultrasonic nondestructive testing techniques. The propagation of elastic waves in the rail profile is simulated for various sizes and positions of the crack. It is shown that the finite-difference grid-characteristic method in the time domain and full-wave simulation can be used to analyze the effectiveness of rail flaw detection by applying ultrasonic nondestructive testing techniques. Full-wave simulation is also used to demonstrate the failure of the widely used echo-mirror method to detect flaws of certain types. It is shown that techniques for practical application of the ultrasonic delta method can be developed using full-wave supercomputer simulation. The study demonstrates a promising potential of geophysical methods as adapted to the analysis of ultrasonic nondestructive testing results.

Quantitative analysis of QSI and LVI damage in GFRP unidirectional composite laminates by a new ultrasonic approach

Abstract Our work is focused on a new experimental approach for the comparison between Quasi Static Indentation (QSI) damage and Low-Velocity Impact (LVI) damage in polymer composites starting from the results of ultrasonic goniometric immersion tests. In particular, the comparison is performed through the analysis of the additional anisotropy induced by the damage in unidirectional Glass Fiber-Reinforced Polymer (GFRP) composites due to QSI and LVI damage tests performed with a low level of the employed energy. To this aim, we ultrasonically reconstruct the acoustic curves (velocity curves and slowness curves) before and after the damage. Ultrasonic experiments are performed by using a goniometric ultrasonic immersion device designed and built at our laboratory, aimed at the mechanical characterization of anisotropic materials. We highlight differences and similarities between QSI and LVI damage starting from the analysis of the variations of the acoustic behavior and by using a suitable anisotropic damage model developed in the framework of the Continuum Damage Mechanics theory. The proposed experimental approach can be suitably developed for in situ investigations on low-velocity impact damage in polymer composite components.

Investigation on the Sensitivity of Ultrasonic Test Applied to Reinforced Concrete Beams Using Neural Network

An experiment on reinforced concrete beams using four-point bending test during an ultrasonic test was conducted. Three beam specimens were considered for each water/cement ratio (WC) of 40% and 60%, with three reinforcement schedules named design A (comprising two top bars and two bottom bars), design B (with two bottom bars), and design C (with one bottom bar). The concrete beam had a size of 100 mm × 100 mm × 400 mm in length with a plain reinforcement bar of 9 mm in diameter. An ultrasonic test with pitch–catch configuration was conducted at each loading with the transducers oriented in direct transmission across the beams' length with recordings of 68 datasets per beam specimen. Recordings of ultrasonic test results and strains at the top and bottom surfaces subjected to multiple step loads in the experiment were done. After the collection of the data, feed-forward backpropagation artificial neural network (ANN) was used to investigate the sensitivity of the ultrasonic parameters to the mechanical load applied. Five input parameters were examined, as follows: neutral axis (NA), fundamental harmonic amplitude (A1), second harmonic amplitude (A2), third harmonic amplitude (A3), and peak-to-peak amplitude (PPA), while the output parameter was the percentage of ultimate load. Optimum models were chosen after training, validating, and testing 60 ANN models. The optimum model was chosen on the basis of the highest Pearson’s Correlation Coefficient (R) and soundness, confirming that it exhibited good behavior in agreement with theories. A classification of sensitivity was performed using simulations based on the developed optimum models. It was found that A2 and NA were sensitive to all WC and reinforcements used in the ANN simulation. In addition, the range of sensitivity of A2 and NA was inversely and directly proportional to the reinforcing bars, respectively. This study can be used as a guide in the selection of ultrasonic parameters to assess damage in concrete with low or high WC and varying reinforcement content.

Abstract PD2-05: Evaluation of sentinel lymph nodes with high-frequency ultrasound: Correlations to histopathology

Abstract Purpose: The sentinel lymph node (SLN) is biopsied during breast conservation surgery (BCS) since it is the first site of metastasis for breast cancer. If malignant, axillary lymph node dissection (ALND) may be performed to remove additional nodes in and around the affected breast, limiting the spread of the malignancy. Often, ALND results in hardship for the patient in the form of further surgeries, having nodes removed that may not be malignant, and in debilitating side effects. Developing a method to analyze SLNs intraoperatively would eliminate additional surgeries and the patient's associated suffering. This research aims to develop the use of high-frequency (HF) ultrasound (20-80 MHz) as a real-time analysis method to determine SLN status during BCS. Background: HF ultrasonic data from BCS tissue specimens were gathered from 73 patients at the Huntsman Cancer Institute, Salt Lake City, UT, immediately following surgery. In addition to 349 margin specimens, data were collected from 78 SLNs, with initial results displaying high statistical measures. A limitation of the SLN analyses, however, was that pathology results were provided only on a per sample basis, whereas the ultrasonic method often tested multiple positions on a node (max = 4, avg = 1.26). Because of the mismatch between the ultrasonic measurements (per position basis) and pathology results (per specimen basis), an ambiguity existed in how to best analyze the data. The aim of this study was to examine the scope of this ambiguity by determining the differences in statistical measures obtained by analyzing the SLN data on a per position basis versus a per specimen basis given the current data available. Method: HF ultrasound parameters extracted from the data were peak density (the number of peaks in the ultrasonic spectra) and attenuation. Both parameters correlate to tissue malignancy, and were used in a multivariate analysis to provide the final results. The statistical measures for the ultrasonic test results were calculated as follows: (1) per position basis: the pathology of each position was determined by the pathology results for the entire specimen; (2) per specimen basis: only one measurement position on each node was selected, based on the highest peak density value, to correlate to the specimen pathology. Results: The analyses revealed that the HF ultrasonic data yielded an accuracy, sensitivity, and specificity of 79.6%, 76.9%, and 80.0%, respectively, for the per position basis, and 84.6%, 87.5%, and 84.3%, respectively, for the per specimen basis. The results indicate that HF ultrasound provides intraoperative detection capabilities competitive with many SLN evaluation methods currently in use, including imprint cytology, frozen-section analysis, and qRT-PCR. Detailed analyses of the SLN pathology slides from the 73-patient study are currently being conducted to improve the correlations between the ultrasound results and histopathology. Image analysis methods are being used to quantify the extent of the malignant tissue in each SLN. This will provide pathology results on a per position basis, and thus more accurate, one-to-one correlations. These correlations would significantly further the development of HF ultrasound for real-time SLN evaluation. Citation Format: Khelfa S, Factor RE, Sanjinez DA, Zambrana AF, Doyle TE. Evaluation of sentinel lymph nodes with high-frequency ultrasound: Correlations to histopathology [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD2-05.

PECULIARITY OF ULTRASONIC METHODS CONTROL OF EQUIPMENT FILLED WITH TRANSPORTING OR STORING FLUIDS

The paper considers the issue of the difference in the results of ultrasonic testing of newly installed equipment and equipment in the process of operation. In most defects located directly in the cavity of the metal, there is a vacuum, the acoustic properties of which are significantly different from the acoustic properties of the base metal. Therefore, defects in the weld cavity or in metal are well reflected, and are easy to be identified and make it possible to estimate their equivalent area by amplitude. All existing ultrasonic testing methods provide device setup taking into account the absence of technological fluid in defect. This is true only for new equipment that is not in practice yet. In practice, it is often necessary to control equipment that is under operation already. It is often not adequately prepared for the survey, because of presence of transporting or storing fluids in it. If in the weld or in the base metal there is a defect with opening into the inner cavity, then it can be filled with the technological fluid under the action of capillary forces. Thus, under standard setting of the flaw detector the fluid will mask the defect, influencing the magnitude of the amplitude of the reflected signal. So not all defects are fully rejected, especially flat ones, which are the most dangerous from the point of view of equipment operation. The simulation of the studied equipment diagnostics issue using two different models of flaw detectors and the filling of the cavity of a bulk defect by various substances is performed in the work. The authors obtained the results of the influence of chemical and physical properties of fluids on indications of a defect detection.

The influential factors on very high cycle fatigue testing results

When the fatigue cycle is extended from high cycle (105~107) to very high cycle (107~109), the fatigue testing results will be more sensitive to the influential factors such as specimen size, specimen surface roughness and the inclusion size. The influential factors on the very high cycle fatigue testing results are investigated in the present paper. Firstly, the design and control method for ultrasonic fatigue test were introduced for several specimen shapes. The effect of the shape, size and the surface roughness of specimen on the ultrasonic fatigue test results are investigated. Meanwhile, the effect of test frequency and the size of the inclusion on the fatigue test results are also investigated. It is concluded that: 1. the test results of specimen with different shape and size differ with each other, due to the risk volume is different. 2. There is a critical roughness for the specimen, depending on the hardness of tested metallic material. A larger roughness than the critical one will lead to a premature fracture. 3. The frequency effect is obvious for the low strength steel, however, is prone to vanish for the very high strength steel. 4. The very high cycle fatigue will be more sensitive to the inclusion size as the strength increases and the S/N curve character is strongly related to the size of the inclusion.

The permeability of SO42− and Cl− in concrete under the effect of seepage flow and stress fields

The ultrasonic velocity in concrete and the concentrations of ions at different depths along the directional flow of ion erosion were measured under the joint effect of seepage flow and stress fields. The permeability of sulfuric acid and chloride ions in concrete under different pressure head and load were analyzed (pressure head and load are perpendicular to each other). The results show that the concentrations of chloride ion and sulfate ion in different depths of concrete were increased to a certain extent either under the water head pressure or load effect. The differences in water head can induce the variation of ions concentration in the surface layer of concrete and the influenced depth can reach up to 60 mm. The load imposed a similar effect on the ions concentration of different layers and the directions of ion erosion, respectively. The ultrasonic testing results of corroded concrete are consistent with the results of ions concentration measured by spectrometry.

Ultrasonic Testing of Butt Weld Joint by TOFD Technique

The aim of the article was to check the internal defects in the butt welded joints by non-destructive TOFD (Time of Flight Diffraction) technique. Subsequently, the macrostructure from the defect indication site was evaluated and assigned to the TOFD ultrasound indication. Basic knowledge of ultrasonic TOFD testing are described in the theoretical part of a submitted paper. Ultrasound technique TOFD is non-destructive method that can detect internal defects inside test material without damaging it. It is a reliable method for detecting mainly flat internal defects such as incomplete root penetration, lack of fusion, etc. Ultrasonic test procedures and test results obtained in non-destructive testing of butt weld are shown in experimental part. Evaluation of the ultrasonic TOFD testing results, its advantages and disadvantages are described at the end of this article.

THE ABRASION RESISTANCE AND ADHESION OF HFCVD BORON AND SILICON-DOPED DIAMOND FILMS ON WC–Co DRAWING DIES

Diamond films have been deposited on the interior hole surface of cobalt-cemented tungsten carbide (WC–Co) drawing dies from acetone, trimethyl borate (C3H9BO3), tetraethoxysilane (C8H[Formula: see text]O4Si, TEOS) and hydrogen mixture by hot-filament chemical vapor deposition (HFCVD) method. The structures and quality of as-deposited diamond films are characterized with field-emission scanning electron microscopy (FESEM) and Raman spectroscopy. The abrasion ratio and the adhesive strength of as-deposited diamond films are evaluated by copper wire drawing tests and ultrasonic lapping tests, respectively. The results suggest that diamond films with small grain size and high growth rate can be obtained due to the mutual effects of boron and silicon impurities in the gas phases. The results of ultrasonic lapping tests show that diamond films doped with boron and/or silicon can bear the severe erosion of the large diamond powder. Diamond films peeling off within the reduction zone of the drawing dies cannot be observed after testing of 2[Formula: see text]h. The abrasion ratio of boron and silicon-added diamond films is five times that of diamond films without any addition. Adding boron and/or silicon in the diamond films is proved to be an efficient way to obtain high-adhesive-strength and high-abrasion-resistance diamond-coated drawing dies.

Crosshole seismic CT data field experiments and interpretation for karst caves in deep foundations

Foundations at karstic terrains often cause instability problems for the supporting piles of upper buildings, resulting in uneven settlement and/or rock failure. Borehole investigation of the study site showed that the limestone cavities existed from 77.0m to 100.1m below the surface with the mean dimension of 1.52m and maximum of 8.0m. However, it is difficult to characterize these deeply buried karst caves accurately and completely. In this study, we used crosshole seismic CT techniques to image the P-wave velocities of the limestone stratum. Field experiments were designed to acquire seismic data from 44 boreholes and 113 survey lines at depths of >75m. The inverted P-wave velocities were iterated by combining the shortest path raytracing method and the damped least-square QR decomposition (LSQR) method on the basis of the initial model. Issues including the inverted velocities, uncertainty, stability and resolution of the results, and ray coverage were evaluated from the synthetic model. As bases for the interpretation of cavities, fractures and fillings, the quantitative relationship between P-wave velocities and geological anomalies was consequently obtained through correlating the results of field tomography and ultrasonic tests to the borehole data and limestone samples from karst foundations, respectively. Representative P-wave velocity maps were shown and the interpreted cavities were projected onto horizontal planes. Two sampling boreholes and in-situ water injection/pumping tests verified the interpretations. Regarding the number and scale of cavities, each area was divided into three engineering geological zones providing references for the grouting proposals of different zones.

Friction stir weld-bonding defect inspection using phased array ultrasonic testing

Weight reduction is an important driver of the aerospace industry, which encourages the development of lightweight joining techniques to substitute rivet joints. Friction stir welding (FSW) is a solid-state process that enables the production of lighter joints with a small performance reduction compared to the base material properties. Increasing the FSW lap joint performance is an important concern. Friction stir weld bonding is a hybrid joining technology that combines FSW and adhesive bonding in order to increase the mechanical properties of FSW lap joints. FSW and hybrid lap joints were produced, using 2-mm-thick AA6082-T6 plates and a 0.2-mm-thick adhesive layer. Defect detection using the non-destructive test, phased array ultrasonic testing (PAUT), has been made. Microscopic observations were performed in order to validate the phased array ultrasonic testing results. Lap shear strength tests were carried out to quantify the joint’s quality. PAUT inspection successfully detected non-welded specimens but was not able to distinguish specimens with major hook defects from specimens correctly weld bonded with small hook defects.

Study on the coating of nano-particle and 3DOM LaCoO3 perovskite-type complex oxide on cordierite monolith and the catalytic performances for soot oxidation: The effect of washcoat materials of alumina, silica and titania

The novel catalysts of LaCoO3/ɤ-Al2O3/cordierite monolith, LaCoO3/SiO2/cordierite monolith, LaCoO3/TiO2/cordierite monolith were prepared by using aluminum oxide, silicon dioxide and titanium dioxide nanoparticles as washcoat and monolithic cordierite as the monolithic ceramic substrate.The obtained samples were characterized by means of XRD, SEM, EDS, BET, and ultrasonic vibration test (Medi II Pselecta). The surface area of the cordierite monolith-supported LaCoO3/ɤ-Al2O3 is larger than those of LaCoO3/SiO2 and LaCoO3/TiO2. The coating of alumina, silica oxide and titania nanoparticles could increase the surface area of monolithic cordierite and also endue the coated layer with engineered structure. The results of thermal treatment experiment indicate that the good thermal stability of the ɤ-Al2O3 coating on the cordierite. The ultrasonic vibration test results showed that the washcoat was adhered to the substrate strongly. The weight loss for the samples LaCoO3/ɤ-Al2O3/cordierite (the most desired preparation protocol in this study) eventually reached about 3%, which was considered as a low weight loss.The LaCoO3/ɤ-Al2O3/cordierite monolith catalysts were successfully prepared by coating ready-made 3DOM LaCoO3 (perovskite-type oxides) catalysts onmonolithic cordierite substrate with a dip-coating method by employing aluminasol for the first time. The catalytic activities of a series of monolithic catalystsLaCoO3/ɤ-Al2O3/cordierite, LaCoO3/ɤ-Al2O3/cordierite (3DOM-catalysts), LaCoO3/SiO2/cordierite, LaCoO3/TiO2/cordierite were evaluated for soot combustion. Thenano LaCoO3/ɤ-Al2O3/cordierite catalysts gave the highest catalytic activity for soot combustion among the studied catalysts. The T10, T50, T90 over the LaCoO3/ɤ-Al2O3/cordierite catalyst were 199.4°C, 340.5°C, 405.3°C, respectively, and sco2m was 99.9%.

Ultrasonic control of welded joints in a Du800-type pipeline. Part II: Improving image quality and comparison with X-ray testing results

It has been shown in the first part of the article that the DFA method in its version intended for ultrasound propagating in a homogeneous isotropic medium does not suffice for reconstructing high-quality images of reflectors in the welded joint of a Du800-type pipeline. To improve the image quality further while using the DFA method, it is necessary to determine the elastic properties of a Du800 pipeline buildup and allow for its anisotropy with respect to the propagation of ultrasound as well as the surface profile. The DFA-Y and maximum-entropy (ME) methods have been applied to increase the resolving ability and reduce the noise level. Comparing the results of ultrasonic and X-ray testing has made it possible to draw a conclusion that the former is more informative for revealing crack-like reflectors.

Some advancements in the ultrasonic evaluation of initial stress states by the analysis of the acoustoelastic effect

The acoustoelastic effect – that is the correlation between the acoustic properties and the stress state for a solid body – can be profitably employed for experimental measurements of applied and/or residual stress, for example starting from the results of ultrasonic tests. Usually, the interpretation of the results of acoustoelastic experiments is performed in the theoretical framework of the so-called third-order elasticity. In the recent past, more general theoretical models aimed at overcoming some limitations of the third-order elasticity for acoustoelastic stress measurements have been developed. In particular, here we refer to a model developed within the linearized finite elasticity theory and describing the propagation of small amplitude waves in prestressed elastic materials. In this model, no assumption on the origin of initial stress neither on the initial anisotropy of the material is made, but the only hypothesis is that ultrasonic waves superimposed on the stressed reference configuration behaves elastically; then, this theoretical approach is also applicable for the experimental stress analysis of plastically deformed bodies and of anisotropic materials. Moreover, this model leads to “universal relations” relating ultrasonic velocities to the stress in a prestressed configuration of a body. Ultrasonic acoustoelastic tests on specimens under known stress states allows us for showing that the application of the above mentioned theoretical model, together with the use of a suitable experimental setup developed at our laboratory, may lead to stress measurements with an high level of accuracy.