FEM Model for Non-Invasive Temperature Changes Estimation using Ultrasonic Echo Shifts Based on Mean Scattering Space Study

Thermal expansion is an important design parameter of materials, which should be taken into account when developing, producing and using products. To control this significant characteristic of new materials, it is necessary to develop equipment, methods and measurement procedures that take into account the novelty of the specific behavior of these materials. The production of specially shaped samples is the main limitation in thermal expansion measurements. This primarily applies to new materials (heterogeneous, composite, poorly processed) developed for special tasks. These factors necessitated the development of a method for measuring the temperature coefficient of linear expansion of products and materials with arbitrary sample shapes, which was not available in previous implementations of interferometric methods. An interference speckle dilatometer SD was developed for measuring samples with irregular shape in the temperature range from 200 to 400 K. When creating the speckle dilatometer SD, the speckle interferometry method was implemented to measure the elongation of samples with an irregular surface with nanometer sensitivity. Since this device has no analogues, a study was conducted on the uncertainty components arising when measuring the thermal coefficient of linear expansion of materials on this device. The analysis of the uncertainty components of the measurement of the thermal coefficient of linear expansion of materials on the speckle dilatometer SD was carried out. An experimental determination of the measurement uncertainty of the thermal coefficient of linear expansion of TCLE measures of arbitrary shaped samples was obtained using the SD speckle dilatometer. After research and initial certification, the developed measurement instrument was approved and included in the State Secondary Standard of the unit of thermal coefficient of linear expansion of solids in the range of values from 0.05 · 10–6 to 100.0 · 10–6 K–1 in the range of temperature values from 90 to 1,900 K.

The corrugated layer structure bismuth has been successfully tailored into negative thermal expansion along c axis by size effect. Pair distribution function and extended X-ray absorption fine structure are combined to reveal the local structural distortion for nanosized bismuth. The comprehensive method to identify the local structure of nanomaterials can benefit the regulating and controlling of thermal expansion in nanodivices.

Relevance. Coatings based on bioactive glass are widely used in maxillofacial and orthopedic implantology due to their ability to osseointegration, degradation control and bone compatibility. At the same time, when implants are operated in loaded areas, glass coatings experience mechanical loads, thermal fluctuations and the effects of an aggressive biological environment, which places high demands on their crack resistance, adhesion and thermo-mechanical stability. Objective. To carry out a comparative evaluation of the performance characteristics of the new bioactive coating for the dental implant FAR-5X and its analogue, aimed at identifying potential advantages in mechanical stability and compatibility with the titanium base. Materials and methods. This study presents a comparative analysis of the mechanical properties of two glass–ceramic composite coatings, FAR-5X and FAR-5.3/E, designed for application on titanium implants. The analysis focused on key mechanical parameters, including the coefficient of thermal linear expansion, Vickers microhardness, fracture toughness, Young’s modulus, and adhesion strength. All measurements were performed on seven samples of each coating type using standard micro-mechanical testing methods. Statistical processing was conducted using one-way ANOVA and Tukey's post-hoc test. Results. The developed glass composite coating FAR-5X demonstrates a set of high-performance characteristics due to its nanostructured morphology obtained through optimized thermal treatment. This approach promotes a homogeneous distribution of the crystalline phase within the amorphous matrix, enhancing the material’s mechanical integrity. The results revealed a statistically significant higher coefficient of thermal linear expansion value in the FAR-5X coating compared to FAR-5.3/E (p < 0.05), indicating improved thermomechanical compatibility with the titanium substrate. A statistically significant difference between the coatings was found only in the coefficient of linear thermal expansion, indicating better thermal compatibility of FAR-5X with the titanium base. No significant differences were observed in microhardness, fracture resistance, elastic modulus, or adhesion strength, confirming comparable mechanical integrity between the coatings. Conclusion. The findings suggest that the newly developed FAR-5X coating offers advantageous thermal expansion behavior while maintaining the necessary mechanical robustness, supporting its potential application as a bioactive coating in orthopedic and dental implant systems.

The mean coefficient of linear thermal expansion is used to define a new “instantaneous coefficient of linear thermal expansion” (ILTE) which is proved to be independent of reference temperatures required to define mean values. Hence it can be considered a true material property. The new ILTE provides a common reference to compare thermal expansion data of different materials. This instantaneous coefficient is different from the instantaneous value defined by ASTM standards. Values of the new coefficient are compared with the widely used mean coefficient values. Accuracy of calculations using the new ILTE is demonstrated using the mean coefficient data of two materials.

Noninvasive therapies such as focused ultrasound were developed to be used for cancer therapies, vessel bleeding, and drug delivery. The main purpose of focused ultrasound therapy is to affect regions of interest (ROI) of tissues without any injuries to surrounding tissues. In this regard, an appropriate monitoring method is required to control the treatment. This study is aimed to develop a noninvasive monitoring technique of focused ultrasound (US) treatment using sparse representation of US radio frequency (RF) echo signals. To this end, reasonable results in temperature change estimation in the tissue under focused US radiation were obtained by utilizing algorithms related to sparse optimization as orthogonal matching pursuit (OMP) and accompanying Shannon's entropy. Consequently, ex vivo tissue experimental tests yielded two datasets, including low-intensity focused US (LIFU) and high-intensity focused US (HIFU) data. The proposed processing method analyzed the ultrasonic RF echo signal and expressed it as a sparse signal and calculated the entropy of each frame. The results indicated that the suggested approach could noninvasively estimate temperature changes between 37°C and 47°C during LIFU therapy. In addition, it represented temperature changes during HIFU ablation at various powers, ranging from 10 to 130 W. The normalized mean square error of the proposed method is 0.28, approximately 2.15 on previous related methods. These results demonstrated that this novel proposed approach, including the combination of sparsity and Shanoon's entropy, is more feasible and effective in temperature change estimation than its predecessors.

Effective thermal expansion of heterogeneous materials with application to low temperature environments

Because of the lack of data on the thermal expansion of natural solid wood and many wood products, such as plywood, impreg, compreg, and many others, studies were conducted at the Forest Products Laboratory in an effort to obtain such data. The coefficients of linear thermal expansion, called α were measured on a wide variety of wood materials in three structural directions. General formulas were developed which permit calculation of the coefficients of linear thermal expansion in any grain direction of the specimen from the original and final specific gravities, the percentage by weight of resin and glue present, the percentage of cross-banding, and the slope of grain relative to any three axes of reference.

High temperature thermal expansion of BaAl2Si2O8, CaAl2Si2O8, and Ca2Al2SiO7 studied by high-temperature X-ray diffraction (HT-XRD)

Anisotropic thermal expansion of bio-based rigid low-density closed-cell polyurethane foams

A new technique for measuring Young's modulus of an ultra-thin film, with a thickness in the range of about 10 nm, was developed by combining an optical lever technique for measuring the residual stress and X-ray diffraction for measuring the strain in the film. The new technique was applied to analyze the mechanical properties of Ga-doped ZnO (GZO) films, that have become the focus of significant attention as a substitute material for indium-tin-oxide transparent electrodes. Young's modulus of the as-deposited GZO films decreased with thickness; the values for 30 nm and 500 nm thick films were 205 GPa and 117 GPa, respectively. The coefficient of linear thermal expansion of the GZO films was measured using the new technique in combination within-situresidual stress measurement during heat-cycle testing. GZO films with 30–100 nm thickness had a coefficient of linear thermal expansion in the range of 4.3 × 10−6– 5.6 × 10−6 °C−1.

The linear coefficient of thermal expansion and the Debye temperature of PbTe in the high-temperature range have been investigated using X-ray diffractometry. The studies were carried out on samples of two types: single crystal and PbTe powder, synthesized separately. Both types of samples showed fairly similar results in all measurements. It has been established that in the temperature range 293-773 K the linear thermal expansion coefficient is constant and for powder: α=20.1· 10-6± 0.9· 10-6 K-1 and for single crystal: α=19.7· 10-6± 0.8· 10-6 K-1. The Debye temperature measured in the temperature range 293-573 K equal to 105±3 K Keywords: lead telluride, linear thermal expansion coefficient, Debye temperature.

Temperature-influenced dimensional change of different molar anatomical areas

Rubber as additives to lower thermal expansion coefficient of plastics: 1. Morphology and properties

Influence of the structural state and crystallographic texture of Zr-2.5% Nb alloy samples on the anisotropy of their thermal expansion

Thermal expansion of Cr 2xFe 2−2xMo 3O 12, Al 2xFe 2−2xMo 3O 12 and Al 2xCr 2−2xMo 3O 12 solid solutions