Longitudinal Ultrasonic Wave Propagation Research Articles

Исследование случаев «аномального» затухания ультразвуковых колебаний в заготовках из никелевых жаропрочных сплавов

An ultrasonic non-destructive testing has found out a new phenomenon in several stamped forgings made from heat-resistant nickel alloys (Ni-superalloys) of two grades: local attenuation of the bottom echo signal amplitude, when the workpiece surface had large (over 20 mm) randomly located zones with significant (up to 1.5%) fluctuations of the longitudinal ultrasonic wave propagation velocity. On top of that, there were no various grain sizes or coarse-grained structures that usually lead to a an increase of a rate of ultrasonic attenuation in such alloys, and which triggers off a bottom echo signal amplitude attenuation. The Article states the studies carried out to explain the tangible reasons of the detected macroinhomogeneity of the velocity, and how it associated with a bottom signal amplitude attenuation.

Biological and Physicochemical Assessment of Middle Ear Prosthesis.

Polymers modified with bioactive nanoparticles are a promising solution for patients who need a tissue replacement. Modern implants, thanks to bioactive and bactericidal functions, facilitate the healing and regeneration process of the replaced tissue. The aim of this study was to assess whether silver nanoparticles (AgNPs) could support antibacterial function without cytotoxic effect and deterioration of biostability. This article describes biological and physiochemical aspects concerning a new polymeric middle ear implant (Otoimplant) enriched with silver nanoparticles. This kind of prosthesis is a promising implant for the reconstruction of ossicles in ossiculoplasty. We found that incorporation of silver nanoparticles into a polymeric matrix resulted in bactericidal efficacy against Gram-positive and Gram-negative bacteria, both resistant to antibiotics and basic strains. Our prostheses do not show cytotoxic effect and are a suitable biomaterial platform for effective culture of Saos2 and NHOst osteoblastic cells. The in vitro incubation of the samples in distilled water revealed that surface parameters, such as roughness, may slightly increase as a result of unveiling nanoparticles. However, the prolonged immersion does not change mechanical parameters. During one-year incubation, the prosthesis proved to retain stable values of Young’s modulus, tensile strength, propagation of longitudinal ultrasonic waves, pH, and conductivity.

Changes of Physical Properties of Silesian Granite Due to Heat Loading

Temperature affects both the physical and structural properties of rocks and there may even cause chemical changes of minerals. Rocks are more or less inhomogeneous material, so that during testing the same rock samples taken from one location the measured values of physical properties can vary on large scattering between test specimens. To eliminate the influence of inhomogeneity of rock, we analyzed the effect of heat loading (up to 700˚ C) on the same specimens. For this reason we have used in our research particularly non-destructive testing methods – determination of bulk density, measuring of longitudinal ultrasonic wave propagation velocity, thermal conductivity and volumetric heat capacity. Besides the physical characteristics determined in the same specimen before and after tempering gas permeability and thermal expansion untempered and tempered test specimens was determined. Hg porosity and total porosity of untempered and tempered specimens were found, too. As model material was chosen so-called Silesian granite from Nový lom quarry (Žulová pluton, Czech Republic), which has been previously tested, and over macroscopically homogeneous character the variances in the measured parameters were found. Hg and total porosity and gas permeability increase with increasing temperature. The bulk density, the ultrasonic wave propagation velocity and thermal conductivity decrease with increasing temperature. The most sensitive parameters are ultrasonic wave velocity, thermal conductivity and permeability.

Elastic loss and dispersion in ceramic-matrix piezocomposites

Ceramic-matrix composites of different types have been comprehensively studied using three-dimensional numerical simulation, resonance analysis of impedance spectra, and pulse-echo ultrasonic measurements. The results of finite-difference simulation of longitudinal ultrasonic wave propagation in different viscoelastic ceramic-matrix composites (porous ceramics and ceramics/crystal) have been presented. The experimental studies have revealed regions of elastic dispersion characterized by anomalies of the frequency dependences of the imaginary and real parts of the elastic moduli. The simulation results have been compared with experimental data.

Acoustic studies of gradient glasses

The results of investigation of the propagation of longitudinal ultrasonic waves in glasses with a regular volume distribution of elastic properties resulting in the narrowing of a beam of ultrasonic waves at the output of the sample are presented. Such glasses have not been used in acoustics previously. They were used by us for the creation of the first samples of inhomogeneous acoustic lenses. The results obtained in the investigation of inhomogeneous acoustic lenses based on specially developed inhomogeneous glasses and methods for their production are discussed. It is shown that the noticeable effect of focusing ultrasonic waves in the range 2–14 MHz is observed already for glass samples with dimensions 10–20 mm. Other possible applications of inhomogeneous acoustic lenses, for example, as a medium for ultrasonic delay lines and acousto-optical cells, are discussed.

Issues on the pulse-width dependence and the shape of acoustic radiation induced static displacement pulses in solids

Recent experimental results showing the pulse width independence and the flat topped shape of static displacement generated during finite amplitude sinusoidal ultrasonic tone burst propagation in solids and the contradicting previous results reported in the literature are considered. The pulse width independence is analytically confirmed and the flat topped shape is explained by considering the progressive spatial and time domain shapes of the static strain and displacement pulses. A numerical simulation of the finite amplitude longitudinal ultrasonic wave propagation in solids has been performed to further verify the pulse width independence of the static displacement pulse.

Characterisation of IC packaging interfaces and loading effects

In IC packaging, the quality of the interfaces such as that between mold compound and silicon is a critical issue in the reliability testing during the manufacturing process and in-service. Weak interfaces have often gone undetected and may become potentially defective at a later stage. Furthermore, the stress due to mechanical or thermal loading may further deteriorate the interface quality, making the interface unreliable. There is a desire to study the interface quality quantitatively, so potential defects can be evaluated and identified early. In this paper, finite element analysis using multilayer interface model is used to study the reflection coefficient from the interface of varying quality. Different conditioning techniques were used to degrade the interface quality. Characterisation of the interface quality of the MC/Si interface was conducted using longitudinal ultrasonic wave propagation with contact transducers. A combined test that measures the reflection coefficient of the interface under stress load was also conducted to quantify the effect of the load. A nondestructive evaluation methodology is proposed that measures the available strength of the interface by using ultrasonic reflection coefficients, and it shows the correlation between the reflection coefficient and available strength of the interface can be developed and used as a quantitative indicator.

Ultrasonic Control of Fastener Tightening Using Varying Wave Speed

A high precision ultrasonic technique and a test apparatus are developed for the real time control of the fastener elongation during the tightening process of bolted joints. This is accomplished by monitoring the propagation of longitudinal ultrasonic waves through the fastener material and the reflection of these waves at the end of the fastener. The round trip time of the longitudinal waves is continuously measured and monitored in real time. Using the wave speed in the fastener material, the change in the round trip time determines the fastener elongation, which creates fastener tension and joint clamp load. The wave speed through the bolt material is stress dependent; hence, it continuously changes as the fastener is being elongated during the tightening process. A varying wave speed algorithm is developed and utilized in order to compensate for wave speed variations. Because the torque-tension relationship in threaded fasteners is highly sensitive to friction variations, the scatter in such relationship is often unacceptable, especially in critical applications. By contrast, the automatic control of the fastener elongation during the tightening process would eliminate the dependence on the torque value as a predictor for the bolt tension. Hence, the new ultrasonic technique for the real-control of the fastener tension, by monitoring its elongation, would significantly enhance the reliability of bolted assemblies.

Non-destructive evaluation of the interface between silicon dies and copper leadframes in integrated circuit packaging

The silicon die and copper leadframe in integrated circuit (IC) packaging are bonded together by die attach adhesive, and the quality of the interface is a critical issue in the reliability of IC packaging. Common defects such as cracks and delaminations can be detected using the C-scan ultrasonic microscopy method with sufficient confidence. However, weak interfaces due to weak adhesion and poor cohesion have often gone undetected, to subsequently become potential defective areas. In this paper we present experimental work to evaluate the quality of the interfaces that typically exist in IC packages using longitudinal ultrasonic wave propagation with contact transducers. Three different conditioning processes, varying curing, moisture exposure and pre-curing moisture contamination, are used to degrade the interface bonding the silicon die and copper leadframe. Ultrasonic reflection coefficients from the interface are then measured. The results show that the reflection coefficient depends strongly on the interface quality, and can be used as a quantitative indicator to characterize the bond quality.

Ultrasonic evaluation of the silicon/copper interfaces in IC packaging

The silicon die and copper lead-frame in integrated circuit (IC) packaging are bonded using a die attach adhesive, and the quality of the adhesive interface is a critical issue in the reliability testing of IC packaging and during the manufacturing process. Common defects such as cracks and delamination can be detected using the C-mode ultrasonic microscopic method with sufficient confidence. However, a weak interface due to weak adhesion and poor cohesion has often gone undetected and may become a potential defect at a later stage. There is a desire to study the interface quality quantitatively, so that any potentially defective area can be evaluated and identified early. This paper describes work in evaluating the quality of the interfaces that typically exist in IC packages by using longitudinal ultrasonic wave propagation with contact transducers. An interface spring model is used to predict the ultrasonic reflection coefficient relationship with varying interfacial spring constants. Experimental results of normal incidence reflection coefficients are obtained from the two-layered specimen bonded with die attach adhesive under varying conditioning process that simulates the degrading of the interface. Good qualitative agreement between the measurement and the prediction is obtained, and shows that the reflection coefficient depends strongly on the interface quality. The study demonstrates that the quantification of the interface quality is possible, using the reflection coefficient as a criterion.

Ultrasonic evidence of a spin-Peierls transition inα′-NaV2O5

We report the anomalous behavior of the ${C}_{22}$ elastic constant in ${\ensuremath{\alpha}}^{\ensuremath{'}}$-NaV${}_{2}$O${}_{5}$ by studying the propagation of longitudinal ultrasonic waves along the chain direction. A stiffening anomaly is clearly seen at 35 K, which could be the signature of a spin-Peierls transition. The results are discussed and compared with the temperature dependence of the analogous elastic constant ${(C}_{33})$ in the ${\mathrm{CuGeO}}_{3}$ system. Magnetic-field effects have also been investigated. Anomalously small shifts of the transition temperature are observed.

Ultrasonic Study of Magnetoelastic Effects in the Spin-Peierls State of CuGeO3

The quasi-one-dimensional CuGeO3 compound is the first inorganic material to exhibit a spin-Peierls transition driven by the magnetoelastic interaction between antiferromagnetic chains and the phonon field which opens a finite energy gap in the spin excitation spectrum by the dimerization of the lattice. The anomalous elastic character of the spin-Peierls system is established by studying in a high magnetic field the propagation of longitudinal ultrasonic waves along the three crystalline axes. We have measured the longitudinal elastic constants C 11 , C 22 and C 33 of CuGeO 3 in magnetic fields up to 20 Teslas. The phase boundaries between the uniform (U), modulated (M) and dimerized (D) phases are associated to large anisotropic variations of the elastic constants. The temperature dependence of the three elastic constants exhibits a minimum at the U-D and U -M phase boundaries. The field dependences of C22 and C33 are reported.

Ultrasonically determined elasticity and cortical density in canine femora after hip arthroplasty

Effects of canine hip replacement (with a porous-coated femoral component) on the material properties of surrounding cortical bone were evaluated. The hypotheses were: (1) after four months of implantation, mechanical properties of the cortex would change, and (2) a collared implant would be associated with smaller changes than a collarless design. Unilateral total hip arthroplasty was performed in 15 mixed-breed dogs. Nine received a collared and six received a collarless femoral component. Four months after implantation, longitudinal ultrasonic wave propagation velocities and bone mineral densities (from dual energy X-ray absorptiometry) were measured in harvested femora and used to calculate the axial elastic constitutive coefficients for the cortex surrounding the implants. Results showed no difference in bone elasticity or bone density between collared and collarless designs. Significant velocity decreases from control values ( p<0.0001) were noted in all implanted femora at four months. Bone mineral densities also displayed decreased values after four months of implantation ( p<0.0145). Elastic coefficients were consistently less after four months of implantation when compared to control values ( p<0.0001). This alteration in material properties would affect load transfer into the implanted femur via the increased disparity between implant and bone stiffnesses regardless of the component design. Significant differences in the elastic coefficients between implanted and control femora support hypothesis 1. However, no group differences were found between collared and collarless implantations; thus, the study does not support hypothesis 2.

Temperature dependences of longitudinal ultrasonic wave propagation velocity in gallium arsenide and indium phosphide single crystals

Results are considered for experimental studies of the longitudinal ultrasonic wave propagation velocity in gallium arsenide and indium phosphide single crystals in the temperature range 200–355 K with measurements made through each 0.5–1 K. Measurements were made by the ultrasonic echo-pulse procedure using calibration marks of time. The frequency of the sounding signal is 10 MHz.

Ambiguity of temperature dependences for the elastic characteristics of materials with nickel and germanium as examples

Experimental data are presented for precise measurements of longitudinal ultrasonic wave propagation rate in single-crystal germanium and polycrystalline nickel. With these materials as examples the existence of ambiguity is demonstrated in values of elastic characteristics in successive cycles of thermal exposure, i.e., temperature ranges in which the material does not undergo phase transformation.

Oscillatory behaviour of ultrasonic attenuation in KH 2PO 4 near the phase transition temperature

Oscillations in ultrasonic attenuation have been observed in KH 2PO 4 near the ferroelectric phase transition temperature for longitudinal ultrasonic wave propagation along the polarization axis. Oscillations are present both above and below the transition temperature; the periods of oscillations are different in the two phases for the same ultrasonic frequency and the same ∣ T − T c ∣. The temperature dependence of the oscillations shows that they are due to the phase transition.

Longitudinal ultrasonic wave propagation along X-axis in KDP near it's ferroelectric phase transition temperature

Abstract We have examined the propagation behaviour of longitudinal ultrasonic wave along the X-axis near the ferroelectric phase transition temperature of KDP. We find the propagation behaviour is similar in nature to that along the Z-axis (polarization axis).

Relationship between solid nonlinearity parameters and thermodynamic Grüneisen parameters

The relationship between the ultrasonic nonlinearity parameter for solids and the acoustic Grüneisen number has been derived for longitudinal ultrasonic wave propagation in the pure mode directions of cubic crystals and isotropic solids. Agreement between the acoustic Grüneisen number and the thermodynamic Grüneisen parameter is best for ultrasonic harmonic generation measurements along the [100] direction of a cubic crystal. Comparison of the temperature curves of the acoustic Grüneisen number of copper shows that the acoustic Grüneisen number generally follows the temperature dependence of the lattice contribution to the thermodynamic Grüneisen parameter.

Propagation of longitudinal ultrasonic waves in RbH2PO4 near its ferroelectric phase transition temperature

Ferroelectric phase transition in RbH2PO4 has been investigated using propagation of longitudinal acoustic waves along the polar axis near the transition temperature. The velocity of this mode is continuous across the transition temperature. Velocity data in the ferroelectric phase are analyzed in terms of coupled soft modeacoustic mode model of Pytte to obtain the temperature dependence of the soft mode frequency. The attenuation data in the ferroelectric phase show power law dependence. It follows scaling behaviour of the type predicted by Kawasaki from the mode-mode coupling theory and the dynamical scaling.

Ultrasonic propagation near the ferroelectric phase transition temperature in RbH 2PO 4

Ferroelectric phase transition in RbH 2PO 4 is studied by the propagation of longitudinal ultrasonic waves along the polar axis. The velocity data are analyzed to obtain the temperature dependence of the soft mode frequency in the ferroelectric phase. Unlike KH 2PO 4 and KD 2PO 4, the attenuation in RbH 2PO 4 does not exhibit a relaxation type behaviour.