Relationships of wood density and compressive strength to within-stem variation of ultrasonic velocity in Pinus massoniana trees

Radial and axial variations in the longitudinal ultrasonic wave velocity within stem of 17–19-year-old Melia azedarach planted in two different sites in northern Vietnam were experimentally investigated. Wood samples were collected from 10, 50, and 90% of the radial length from pith at 0.3, 1.3, 3.3, 5.3, and 7.3 m heights above the ground to measure ultrasonic velocity (Vu), fiber length (FL), air-dry density (AD), and compressive strength (CS) at moisture content approximately 12%. The average wave velocity for two sites exhibited minimum value near the pith about 3700 m/s. It kept increasing to 4200 m/s at the middle position before remaining constant value forward to outside. In axial direction, the variation of Vu with height was very small and without statistical significance. Vu had a strong positive linear relationship with both FL (r = 0.69, p < 0.001) and AD (r = 0.67, p < 0.001). These findings reveal that the FL and AD greatly influence the within-tree variations in the ultrasonic wave velocity in M. azedarach. Besides, the significant positive linear correlation between CS and Vu suggests that Vu was a useful predictor of the CS for M. azedarach planted in northern Vietnam.

Primeval TC4 titanium alloy was subjected to solution treatment at 1150°C for 1h, followed by water quenching, oil quenching, air cooling and furnace cooling, respectively. The pulse-echo method was carried out to measure ultrasonic longitudinal wave velocities (ν) and attenuation coefficients (α) of these heat-treated samples. The relationship between microstructures of different cooling rates and ultrasonic parameters such as ultrasonic longitudinal wave velocities (ν) and attenuation coefficients (α) was investigated. The results show that the microstructures of heat-treated TC4 alloy were α phase and β boundaries, and the ultrasonic longitudinal velocities and attenuation coefficients of these heat-treated samples, in turn, increased with reducing the cooling rate from water quenching to furnace cooling.

Improvements in the national standard for the unit of the propagation velocity of longitudinal ultrasonic waves in solids are examined. The measurement techniques and standard measures for velocity are described. The composition and metrological characteristics of the new standard are discussed. In accordance with the scientific and technical program "Standards of Russia" and the steps planned for the intro- duction of the national primary standard for the unit of the propagation velocity of longitudinal ultrasonic waves in solids, GET 189-2010 (1), work has been under way at the Far Eastern Branch of the All-Russia Research Institute of Physicotech- nical and Radio Measurements (VNIIFTRI) during 2010-2012 to improve the standard, including the development and intro- duction of two new standards facilities as part of the standard for measuring the propagation velocities of shear and surface ultrasonic waves in solids. Thus, the new national primary standard GET 189-2012 ensures the uniformity of measurements of the propagation velocities of the main types of acoustic waves in solids. This standard is at the top of the national verifi- cation scheme for means of measuring the propagation velocity of ultrasonic waves in solids, which establishes the order of transfer of reproduced units to working standards and means of measurement. The need for measurements of the propagation parameters of ultrasonic waves in solids arises from fundamental, as well as applied research. The propagation parameters of ultrasonic waves are used in fundamental research for calculating the elastic constants and moduli of elasticity - the most important characteristics of solids (2). These parameters are also need- ed for determining the physical and mechanical characteristics, as well as the endurance properties of solids, and are of the greatest importance for creating new materials, and in developing techniques for producing and using these in technology and industry. However, the demand for measurements of the propagation velocity of ultrasonic waves is primarily related to the need to ensure the uniformity of measurements in the area of nondestructive testing of the quality of materials and work pieces using acoustic methods and means of measurement. An analysis of Russian and foreign literature in this area shows that the most promising approach for the develop- ment of original standard means of measurement in solid-state acoustics is the use of contactless methods for generating and receiving ultrasonic waves: optical and capacitive (3-8). Optical methods form the basis of the standard GET 189-2012. The standard laser-interference system for measuring the propagation velocity of longitudinal ultrasonic waves in the standard GET 189-2010 (1) serves as the basis for creating the unified standard facility for reproduction of the units of the prop-

Currently, ultrasonic measurement is a widely used nondestructive approach to determine wood elastic properties, including the dynamic modulus of elasticity (DMOE). DMOE is determined based on wood density and ultrasonic wave velocity measurement. The use of wood average density to estimate DMOE introduces significant imprecision: Density varies due to intra-tree and intra-ring differences and differing silvicultural treatments. To ensure accurate DMOE assessment, we developed a prototype device to measure ultrasonic wave velocity with the same resolution as that provided by the X-ray densitometer for measuring wood density. A nondestructive method based on X-ray densitometry and the developed prototype was applied to determine radial and intra-ring wood DMOE profiles. This method provides accurate information on wood mechanical properties and their sources of variation. High-order polynomials were used to model intra-ring wood density and DMOE profiles in black spruce and jack pine wood. The transition from earlywood to latewood was defined as the inflection point. High and highly significant correlations were obtained between predicted and measured wood density and DMOE. An examination of the correlations between wood radial growth, density, and DMOE revealed close correlations between density and DMOE in rings, earlywood, and latewood

In tire industry, it is very crucial to evaluate physical and mechanical properties of rubbers which are used for production of tires, to ensure the quality of the final product. Resilience is an important property of a rubber, which cannot be evaluated through direct measurement in production cycle in this industry. Therefore, non-destructive ultrasonic testing, which has been used in many applications for examination of various material properties, can be used as an alternative approach for this purposes. In this study, the non-destructive ultrasonic testing method has been employed to investigate the resilience of nanoclay reinforced rubber compounds. By changing physical and mechanical properties of materials, ultrasonic wave velocities are changed. For this purpose, sixteen different samples of nanoclay reinforced rubber compounds with different formulations were prepared and both their resilience and the longitudinal ultrasonic wave velocity through them were measured. In the next step, using the relevance vector machine regression analysis, a mathematical expression for the rubber resilience based on the longitudinal ultrasonic wave velocity was developed, which was proven to be qualified with acceptable accuracy and generalization capability. The results of this research can be used for online evaluation of the rubber resilience in tire production cycle.

The performances of different ultrasonic detection applications on the longitudinal wave propagation in Japanese cedar (Cryptomeria japonica) and China fir (Cunninghamia lanceolata var. lanceolata) lumber were evaluated in the study. Results showed that insignificant differences among longitudinal ultrasonic wave velocities measured by transducers from 40 to 1000 kHz were found using the direct transmission method. The average wave velocities were 5074 and 6003 m s^(-1) for Japanese cedar and China fir, respectively. The longitudinal ultrasonic wave velocity obviously decreased with both the surface transmission method and semi-direct transmission method under 500-and 1000-kHz conditions. Good correlations, i.e., R^2 values of between 0.92 and 0.94, among the measured longitudinal ultrasonic wave velocities in the 3 detection methods with a 40-kHz transducer were obtained. Longitudinal ultrasonic wave velocities of wood measured with the different-shaped transducers and coupling methods also had good correlations, with R^2 values of between 0.95 and 0.99. The velocity measured with the flat transducer was 8.8~11.1% higher than that with the tapered transducer. The modulus of elasticity of wood can be estimated using longitudinal ultrasonic wave velocities measured by the 3 different detection methods with R^2 values of between 0.79 and 0.85 for Japanese cedar and China fir. It is expected that ultrasonic detection can be applied to the derivation of allowable strengths of structural lumber from Taiwanese plantations and for field inspections.

In the metallurgical industry, ultrasonic inspection is routinely used for the detection of defects. For the non-destructive inspection of small high strength steel parts, the material can be considered isotropic. However, when the size of the parts under inspection is large, the isotropic material hypothesis does not necessarily hold. The aim of this study is to investigate the effect of the variation in mechanical properties such as grain size, Young’s modulus, Poissons ratio, chemical composition on longitudinal and transversal ultrasonic wave velocities. A 2 cm thick slice cut from a 40-ton bainitic steel ingot that was forged and heat treated was divided into 875 parallelepiped samples of 2x4x7 cm3. A metallurgical study has been performed to identify the phase and measure the grain size. Ultrasonic velocity measurements at 2.25 MHz for longitudinal and transversal waves were performed. The original location of the parallelepiped samples in the large forged ingot, and the measured velocities were used to produce an ultrasonic velocity map. Using a local isotropy assumption as well as the local density of the parallelepiped samples calculated from the chemical composition of the ingot provided by a previously published study, Youngs modulus and Poissons ratio were calculated from the longitudinal and transversal wave velocities. Micro-tensile test was used to validate Youngs modulus obtained by the ultrasonic wave velocity and an excellent agreement was observed.

This paper discusses the ability of ultrasonic wave velocity to evaluate some physical parameters within mortar. The behavior of ultrasonic pulse velocity within mortar subjected to incremetal stress was also studied. For experimentation, we carried out ultrasonic measurements on mortar samples before and during uniaxial compressive strength, perpendicularly to the stress direction. The water/cement ratios were varied in order to contribute certain specific characteristics. A set of expressions was obtained linking the initial velocities of longitudinal ultrasonic waves with compressive strength, density, porosity and load at elastic limit.The evolution of ultrasonic velocity through mortar samples under continuous incremental uniaxial stress were also investigated. The results illustrated the behavior of ultrasonic pulse velocity as a function of the applied stress. It was observed that velocity did not decrease under initial loading and until about 70% of the ultimate stress, where sudden decrease occurred, followed by the failure of the material.

Partial replacement of quartz flour microfiller in polymer composites with biocarbon is one of the potential ways to utilize this waste. The article discusses the possibility of using biocarbon as a component of vinyl ester mortars, in the context of their chemical resistance. The tests were carried out for mortars with different quantitative compositions, and therefore with different biocarbon contents. They were subjected to 12-month exposure to a chemically aggressive environment. Solutions of 0.5% sulfuric acid(VI) and 5% sodium hydroxide were used. Measures of resistance were changes in weight, compressive strength, longitudinal ultrasonic wave velocities and quantitative changes in microstructure compared to chemically unstressed samples. The results show that vinyl ester mortars with biocarbon are more resistant to chemical aggression with sulfuric(VI) acid solution. A significant decrease in compressive strength, ultrasonic wave velocity and an increase in the values of stereological parameters were observed after exposure of the composites in sodium base solution. This is in contrast to the chemical aggression in the acid solution, after which the changes in the properties and microstructural parameters of the mortars were not so clear

Combined ultrasound methods of concrete testing : 48109 Galan, A. Elsevier, 350 pp. (1990)

Ultrasonic Characterization of Microstructural Changes in Ti-10V-4.5Fe-1.5Al β-Titanium Alloy

A method for estimation of the elastic moduli of porous ceramics solely based on ultrasonic longitudinal wave velocities is proposed. The method is based on a polynomial correlation between ultrasonic shear wave and longitudinal wave velocities of a given porous material. It is also shown that variations of Poisson's ratios for porous material with longitudinal wave velocities agree with the predictions of Mori‐Tanaka mean field approach. The method provides a simplified route to quantitative non‐destructive evaluation of the elastic moduli of porous material.

Addressing the shortcomings of currently available concrete reinforcement techniques, a new method using sprayed Glass Fibre Epoxy Mortar (GFEM) reinforcement is proposed. To investigate the effect of this method on the frost durability of concrete, a total of 156 specimens in four groups were designed, and related freezing and thawing cycle tests were conducted. The apparent morphology, mass loss rate, ultrasonic velocity, freeze–thaw damage, and strength loss rate of each group of specimens after different freeze–thaw cycles were analysed comparatively. The test results show that the concrete specimens reinforced with GFEM have a better mass loss rate after freeze–thaw cycles and ultrasonic wave velocity than the unreinforced concrete specimens. The compressive strength of specimens in group A is 24.04 MPa, and the compressive strengths of specimens in groups B, C, and D are 35.28 MPa, 35.73 MPa, and 36.37 MPa, respectively, which is higher than that of group A by 46.76%, 48.63%, and 51.29%, respectively, and 46.76%, 48.63%, and 51.29% higher than group A, respectively. It can be seen that the concrete specimens reinforced with sprayed Glass Fibre Epoxy Mortar can effectively improve the frost durability of concrete; the reinforcing effect is obvious, and in a certain range of fibre mixing, the larger the better the frost resistance. The integration of GFEM is cost-effective and improves viscosity, and the best glass fibre mix percentage is about 0.8%. A freeze–thaw damage model for GFEM-reinforced concrete was developed using the Weibull distribution theory, and an improved strength attenuation model under freeze–thaw cycles was established. By correlating the strength attenuation model with the freeze–thaw damage model, a damage evolution equation for the reinforced specimens was formulated, allowing for the prediction of freeze–thaw damage based on the number of cycles and the relative compressive strength.

The mineral component of bone is mainly composed of calcium phosphate, constituting 70% of total bone mass almost entirely in the form of hydroxyapatite (HAp) crystals. HAp crystals have a hexagonal system and uniaxial elastic anisotropy. The objective of this study was to investigate the effect of HAp crystallite preference on macroscopic elasticity. Ultrasonic longitudinal wave velocity and the orientation of HAp crystallites in bovine cortical bone are discussed, considering microstructure, density, and bone mineral density (BMD). Eighty cube samples of cortical bone were made from two bovine femurs. The orientation of HAp crystallites was evaluated by integrated intensity ratio of (0002) peak using an X-ray diffractometer. Ultrasonic longitudinal wave velocity was investigated with a conventional pulse system. The intensity ratio of HAp crystallites and velocity were measured in three orthogonal directions; most HAp crystallites aligned in the axial direction of the femurs. Our results demonstrate a linear correlation between velocity and intensity ratio in the axial direction. Significant correlation between velocity and BMD values was observed; however, the correlation disappeared if we focused on the identical type of microstructure. In conclusion, differences in microstructure type have an impact on density and BMD, which clearly affects the velocity. In addition, at the nanoscopic level, HAp crystallites aligned in the axial direction also affected the velocity and anisotropy.

A suspended dense graded broken stone road foundation stabilized by cement is a commonly employed material in roadworks, which is vulnerable to harm caused by freezing and thawing processes. This investigation intends to evaluate the laboratory behavior and the characteristics of freezing and thawing process-induced deterioration in a broken stone road foundation stabilized by cement with suspended dense grading, employing mechanical examinations and acoustical methods. The rate of mass loss in the broken stone road foundation stabilized by cement progressively rises, and the rate of decline in the compressive strength could potentially intensify as freezing and thawing processes augment. The modulus of resilience diminishes as freezing and thawing processes progress, and ultrasonic wave velocity also decreases. The patterns of mass loss, compressive strength decline, resilience modulus reduction, and ultrasonic wave velocity alteration adhere to a parabolic fitting relationship with freeze–thaw cycles, with an R2 above 0.95. The curves depicting the relationship of mass, compressive strength, resilience modulus, and ultrasonic wave velocity exhibit a steeper trend significantly after 10–15 cycles, which can be ascribed to the emergence of microcracks and the progression of flaws within the material. The evolution of damage in the broken stone road foundation stabilized by cement is monitored to progress through three distinct stages based on acoustic emission: initial, stationary, and failure. As freezing and thawing processes accumulate to 20 cycles, the length of initial phase correspondingly rises to three times, the length of failure stage diminishes to about one fifth.