Thermal Elastic Deformation Research Articles

Effect of Cattaneo–Christov heat flux model and elastic deformation on Walters'B viscoelastic fluid flow with porosity

In the current work, flow of 2-D MHD Walters'B viscoelastic fluid is discussed in the existence of elastic deformation, Cattaneo–Christov Heat Flux Model (CCHFM), heat source, Newtonian heating, viscous dissipation and porous medium. Dimensionless equations that are in charge of the problem's analysis are produced by using the suitable similarity transformation, and Optimal Auxiliary Functions Method (OAFM) is employed to solve them. In the ongoing investigation, the main results are decreasing behavior of temperature profile for the thermal relaxation parameter and elastic deformation parameter, while the reverse effect is noticed while increasing the Weissenberg number and porosity parameter. Our findings reveal significant insights into the fluid dynamics and heat transfer characteristics. Integrating the Cattaneo–Christov heat flux model and elastic deformation analysis in Walters'B viscoelastic fluid flow having its importance in polymer processing, aerospace engineering and waste treatment systems.

First-principles approach to x-ray active optics: design and verification.

This paper presents the first-principles design approach for x-ray active optics. The feature of deterministic modulation enables the simulation-modulation cycle in place of the measurement-modulation feedback loops used in traditional active optics. We apply an x-ray mirror with localized thermal elastic deformation to validate the idea. Our experiments have demonstrated that the new active optics have the potential to outperform the accuracy of surface shape metrology instruments.

Influence of Alloying Elements Content on High Temperature Properties of Ti-V-Cr and Ti-Al-V Series Titanium Alloys: A JMatPro Program Calculation Study

For the issues of high temperature performance affected by the alloying elements content in Ti-V-Cr and Ti-V-Cr alloys, the thermodynamic calculation method based on JMatPro program was applied in this study. The research is mainly focused on the analysis of phase composition, thermodynamic parameters and mechanical properties of Ti-Al-V and Ti-V-Cr series alloys with different element proportions under high temperature environment. Those obtained results show that the proportion of Al in Ti-Al-V alloys has a great influence on the high temperature properties. Increasing the content of Al not only increases the transformation temperature of β single-phase structure and delays the transformation process of α/β microstructure to β single-phase structure, but also helps to improve the high temperature thermal conductivity and elastic deformation resistance of the alloy. In Ti-V-Cr alloys, the influence of V element on high temperature properties is mainly focused on the improvement of thermal conductivity and high temperature deformation properties, while the influence of Cr element is relatively weak. Besides, adding a small amount of Al element to Ti-V-Cr alloy can further improve the thermal conductivity of the alloy. The Young’s modulus of the Ti-V-Cr alloy increases when 0.3%-1% of C element is added. Finally, the effect of Si element on the high temperature elastic deformation of the alloy is relatively weak.

Robust crystal structure identification at extreme conditions using a density-independent spectral descriptor and supervised learning

The increased time- and length-scale of classical molecular dynamics simulations have led to raw data flows surpassing storage capacities, necessitating on-the-fly integration of structural analysis algorithms. As a result, algorithms must be computationally efficient, accurate, and stable at finite temperature to reliably extract the relevant features of the data at simulation time. In this work, we leverage spectral descriptors to encode local atomic environments and build crystal structure classification models. In addition to the classical way spectral descriptors are computed, i.e. over a fixed radius neighborhood sphere around a central atom, we propose an extension to make them independent from the material’s density. Models are trained on defect-free crystal structures with moderate thermal noise and elastic deformation, using the linear discriminant analysis (LDA) method for dimensionality reduction and logistic regression (LR) for subsequent classification. The proposed classification model is intentionally designed to be simple, incorporating only a limited number of parameters. This deliberate simplicity enables the model to be trained effectively even when working with small databases. Despite the limited training data, the model still demonstrates inherent transferability, making it applicable to a broader range of scenarios and datasets. The accuracy of our models in extreme conditions (high temperature, high density, large deformation) is compared to traditional algorithms from the literature, namely adaptive common neighbor analysis (a-CNA), polyhedral template matching (PTM) and diamond structure identification (IDS). Finally, we showcase two applications of our method: tracking a solid–solid BCC-to-HCP phase transformation in Zirconium at high pressure up to high temperature, and visualizing stress-induced dislocation loop expansion in single crystal FCC Aluminum containing a Frank–Read source, at high temperature.

The effect of thermal-elastic deformation on the sealing performance of supercritical CO2 dry gas seal

PurposeThe purpose of this study is to investigate the sealing performance of S-CO2 dry gas seals (DGSs) by considering the effects of pressure-induced deformation, thermal deformation and coupling deformation.Design/methodology/approachA hydrodynamic lubrication flow model of S-CO2 DGS was established, and the model was solved using the finite difference and finite element methods. The pressure-induced deformation and thermal deformation of the sealing ring, as well as the sealing performance under the effects of pressure-induced deformation, thermal deformation and coupling deformation, were obtained.FindingsThe deformation of the sealing ring is mainly thermal deformation. The influence of pressure-induced deformation on leakage and gas film stiffness is greater than that of thermal deformation and coupling deformation. However, thermal deformation has a greater impact on friction torque and minimum film thickness than pressure-induced deformation and coupling deformation. The influence of deformations on sealing performance is important.Originality/valueThe sealing performance of S-CO2 DGSs was analyzed considering the effect of pressure-induced deformation, thermal deformation and coupling deformation, which can provide a theoretical basis for S-CO2 DGS optimization design.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2023-0120/

A hybrid interferometer sensor for simultaneous measurement of temperature and gas pressure based on tapered seven-core fiber and PDMS

A novel hybrid interferometer sensor composed of a tapered seven-core fiber (TSCF) and a polydimethylsiloxane (PDMS) cap at the end face of a TSCF is proposed for simultaneous measurement of temperature and gas pressure. TSCF forms a Michelson interferometer (MI), and the PDMS cap on the end surface of TSCF forms a Fabry–Pérot interferometer (FPI). The sensing head consisted of a cascade of MI and FPI. When the external temperature or gas pressure changes, owing to the thermal effect or elastic deformation of PDMS, the interference spectrum of the FPI shifts significantly, so the FPI is very sensitive to temperature and gas pressure. MI, which is made of quartz optical fiber, is sensitive only to temperature and is not to gas pressure. The experimental results show that FPI has a temperature sensitivity of −0.22 nm °C−1 in the temperature range of 40 °C–80 °C, and a gas pressure sensitivity of −2.27 nm MPa−1 in the gas pressure range of 0–0.3 MPa. MI has a temperature sensitivity of 0.05 nm °C−1 in the temperature range of 40 °C–80 °C, and a gas pressure sensitivity of zero in the gas pressure range of 0–0.3 MPa. Using the temperature and gas pressure sensitivities of FPI and MI to construct a measurement matrix, it is possible to simultaneously measure temperature and gas pressure, eliminating their cross-sensitivity. This sensor has the comprehensive advantages of compact structure, small size, easy manufacturing, low cost, high reliability, and high sensitivity, and is expected to be applied in industrial practice.

Study of the Effect of Axial Grooves on the Thermal Behavior and Pressure Distribution in a Hydrodynamic Bearing Under the Influence of Thermal Elastic Deformation

Study of the Effect of Axial Grooves on the Thermal Behavior and Pressure Distribution in a Hydrodynamic Bearing Under the Influence of Thermal Elastic Deformation

Determination of thermal, stiffness and electrical effective tensors in composite media

The paper considers the problem of calculating effective anisotropic thermal, electric and mechanical properties of composite media. We propose numerical algorithms for the homogenization of heterogeneous media based on the upscaling technique and effective medium theory. The algorithms rely on the direct mathematical modelling of thermal conductivity, elastic deformation, and electromagnetic field. We discretize mathematical models using multiscale non-conforming finite element methods. We investigate the effect of the physical properties and the arrangement of the microinclusions on the effective tensors for various types of field excitation.

Experimental Study on Percolation Rate Characteristics of Gas-Filled Coal Bodies Based on True Triaxial Condition

To research the percolation rate of gas-filled coal based on true triaxial condition, this paper uses the three-phase coupling true triaxial servo test device to carry out the seepage test of coal, and the percolation rate of coal under different conditions of three factors such as gas pressure was measured by Darcy’s law, and the variation of percolation rate of coal was studied based on the comprehensive consideration of thermal elastic swelling deformation, expansion deformation of adsorbed gas, and compression deformation of interstitial pressure. The results are as follows: (1) When the main stress and temperature maintain unchanged, the percolation rate presents the trend which first decreases and then becomes gentle with the gas pressure; when the gas pressure and main stress maintain unchanged, the percolation rate increases with the decrease of temperature; when the pressure and temperature maintain unchanged, the changes of percolation rate present a shape of “V” with the main stress. (2) The strain curve of gas-filled coal decreases at first and then increases; that is, the percolation rate decreases gradually when the strain increases at the compression phase and elastic phase, while the percolation rate increases with the increase of strain at the yield phase and failure phase. (3) In the process of increasing volume stress, the percolation rate decreases gradually in the pore compaction stage, the percolation rate increases gradually from crack propagation to peak failure stage, and then, the percolation rate increases significantly after the peak damage. According to the test results, the percolation rate and volume strain show an inverse proportion.

Optimal analysis of gear modification fitting in alternating time domain aiming at minimizing meshing-in impact of teeth-pair contact interface

In a pair of actual gears alternating meshing process, the transmission system errors and thermal elastic deformation of the gear teeth can cause gears in the meshing zone to form high contact pairs inconsistently mesh-in and mesh-out points to deviate from the theoretical line, which will lead to sudden changes in meshing velocity and an instantaneous meshing effect. Offline meshing impact generates large additional loads, and it increases the vibration and noise of gear transmission system. Further, the gear teeth mesh-in impact is significantly greater than that of gear teeth mesh out. Therefore, to analyze the impact with the minimum value of gear teeth mesh in, the initial mesh-in points need to be determined, and the meshing impact velocity and impact force of teeth meshing-out need to be calculated. The optimized meshing tooth-pair contact interface (CI) anti-impact numerical calculation mode is validated using the loaded teeth contact analysis method.

Thermally conductive, self-healing, and elastic Polyimide@Vertically aligned carbon nanotubes composite as smart thermal interface material

Smart thermal interface materials must exhibit self-healability and high thermal conductivity (k) and elastic deformation as they can experience repeated compression and undergo sudden damage. However, it remains challenging to ensure high phonon mobility/efficient phonon transfer, self-healing, and good elasticity by optimizing its molecular orientation or cross-links. Herein, a self-healing and elastic polyimide copolymer (EMPI) cross-linked by flexible and rigid segments is uniformly filled into the gaps of a forest of vertically aligned carbon nanotubes (VACNTs). The EMPI@VACNTs composite exhibits a high k value at 10.83 ± 0.22 W m−1 K−1, low interfacial thermal resistance at 6.83 ± 0.15 K mm2 W−1, high elastic compressive deformation (30% at 2.5 MPa), and strong surface adhesion (0.3 MPa). Further, it could recover 90.8% of its elastic modulus and 92% of its thermal resistance after self-healing at 80 °C for 80 h. An EMPI@VACNTs-Cu device exhibits efficient heat conduction not only by recovering after gradient compressive strains of up to 30% but also by self-healing its damage or reforming the interface with Cu. Thus, the thermally conductive, self-healing, and elastic EMPI@VACNTs composite opens new avenues for smart thermal management in various high-power/intelligent devices.

Optimal design of gears contact interface modification for an objective as minimum impact resistance of initial meshing-in time domain

In gear pair actual alternating meshing process, the comprehensive errors of the transmission system and the thermal elastic deformation of the teeth body cause the gears in the meshing state to high pair contact nodes inconsistently, especially the transient process of meshing-in and meshing-out points will deviate from the theoretical line, which will cause a sudden change in the meshing velocity and cause instantaneous impact of meshing. Off line meshing impact will generate large additional loads, which has attracted many attentions. The gear transmission system vibration and noise are increased, and the impact of gear teeth meshing-in is significantly greater than that of meshing-out. Therefore, optimal analysis of the impact with the minimum value of gear teeth meshing-in includes determining the initial meshing points, calculating of meshing impact velocity and the impact force of teeth meshing-out. The optimized calculation model using loaded teeth contact analysis method is validated.

Shape optimization analysis for thermal elastic deformation problems in three dimensions based on the adjoint variable and the finite element methods

Shape optimization analysis for thermal elastic deformation problems in three dimensions based on the adjoint variable and the finite element methods

Thermally induced vibrations in an inhomogeneous fiber-reinforced thermoelastic medium with gravity

PurposeThe present investigation is concerned with the two-dimensional deformations in an inhomogeneous fiber-reinforced thermoelastic medium under the influence of gravity in the context of Green–Lindsay theory.Design/methodology/approachMaterial properties are supposed to be graded in x-direction, and normal mode technique is adopted to obtain the exact expressions for the temperature field, displacement components and stresses.FindingsNumerical computations have been carried out with the help of MATLAB software, and the results are depicted graphically to observe the disturbances induced in the considered medium. Comparisons made within the theory of the physical quantities are shown in figures to highlight the effects of fiber reinforcement, inhomogeneity parameter, gravity and time.Originality/valueIn the present work, we have investigated the effects of fiber reinforcement, inhomogeneity parameter, gravity and time in an inhomogeneous, fiber-reinforced thermoelastic medium under the influence of gravity. Although various investigations do exist to observe the disturbances in a thermoelastic medium under the effects of different parameters, the work in its present form i.e. thermally induced vibrations in an inhomogeneous fiber-reinforced thermoelastic material with gravity has not been studied till now. The present work is useful and valuable for analysis of problems involving thermal shock, gravity parameter, fiber reinforcement, inhomogeneous and elastic deformation.

A two-dimensional half-space problem in an initially stressed rotating medium with microtemperatures

PurposeThe purpose of this paper is to establish a model of two-dimensional half-space problem of linear, isotropic, homogeneous, initially stressed, rotating thermoelastic medium with microtemperatures. The expressions for different physical variables such as displacement distribution, stress distribution, temperature field and microtemperatures are obtained in the physical domain.Design/methodology/approachNormal mode analysis technique is adopted to procure the exact solution of the problem.FindingsNumerical computations have been carried out with the help of MATLAB programming, and the results are illustrated graphically. Comparisons are made to show the effects of rotation, time and microtemperatures on the resulting quantities. The graphical results indicate that the effects of rotation, microtemperatures and time are very pronounced on the field variables.Originality/valueIn the present work, we have investigated the effects of rotation, time and microtemperature in an initially stressed thermoelastic medium. Although various investigations do exist to observe the disturbances in a thermoelastic medium under the effects of different parameters, the work in its present form, i.e. the disturbances in a thermoelastic medium in the presence of angular velocity, initial stress and microtemperature have not been studied till now. The present work is useful and valuable for analysis of problems involving coupled thermal shock, rotation parameter, microtemperatures and elastic deformation.

Performance of Tilting Pad Journal Bearings with the Same Sommerfeld Number

This paper presents the change of non-dimensional characteristics and thermal behavior of different sized tilting pad journal bearings (TPJBs) with the same Sommerfeld number. A three-dimensional (3D) TPJB numerical model is provided considering the thermo-elastic hydro-dynamic (TEHD) lubrication model with pad thermal-elastic deformation. The pivot stiffness is assumed to be the combination of linear and cubic stiffness based on the Hertzian contact theory. The TPJBs in a configuration of load between pad (LBP) with the same Sommerfeld number having seven different sizes are simulated, and their non-dimensional dynamic and static characteristics and thermal behavior are compared. Pad thermal and elastic deformation are both taken into account. If the changes in lubricant viscosity, thermal deformation, and elastic deformation of journal/pads due to viscous shearing are ignored, the bearings with identical Sommerfeld numbers should show the same performance characteristics. However, the heat generation at the bearing clearance during operation (a) induces a decrease in viscosity and heat transfer to journal/pads and (b) results in a thermal deformation. Furthermore, the elastic deformation of the tilting pads and pivots also affects the bearing dynamic performance. For the same Sommerfeld number, the numerical analyses provide how the viscous shearing and elastic deformation lead to a change in bearing performance. For the small bearings with the same Sommerfeld number, the non-dimensional characteristics did not change significantly, where the heat generation was small being compared to the large sized bearing. The largest change in non-dimensional characteristics occurred when the maximum temperature of the oil film increased by 30 °C or more compared to the lubricant supply temperature. The root cause of the change in the non-dimensional characteristics is the viscous shearing in the oil film, and the thermal deformation of the structures surrounding the oil film acts in combination. These results provide insight into the Sommerfeld number, which can be used for the early stage of bearing design.

Design optimization of mesh antennas for on-orbit thermal effects

Cable network antennas are widely used in space missions, and high requirements on the reflector surface accuracy should be met to achieve reasonable electromagnetic performance. As the form of the cable network is dependent on forces and vice versa, the optimization design for the antenna's cable forces is extremely important. The current optimization methods are usually conducted under ambient temperature, ignoring the shape errors caused by the on-orbit thermal effects in space. Besides, the application of the active shape adjustment method is also limited by the on-orbit measurement and on-orbit control techniques at present. To reduce the on-orbit thermal disturbances and relieve the burden of shape pre-adjustment before launch, we proposed an optimization design method focusing on the on-orbit performances. The antenna's uneven temperature filed at typical orbital positions was calculated based on the heat radiation and conduction theories. The thermal-structural model considering the cable network's and the truss's thermal deformation and elastic deformation was established. For the optimization, the cable force densities were chosen to be the optimization variables, the antenna's shape errors at typical orbital positions were taken as the objectives, and the tension distributions at these orbital positions were considered as the constraint conditions. Numerical examples demonstrated that the proposed method improved the antenna's on-orbit surface accuracy effectively. This work provided ideas and solutions for the cable network's optimization design considering the on-orbit performances in the space environment.

Thermal elastic deformation of the layered covering on the concave part of a road

The problem on numerical investigation of thermo-elastic deformation of a layered coating on the concave and rectilinear road parts is stated. The constitutive equations are formulated, their finite-element analogues are constructed. The load versions at different values of geometric, structural, and temperature parameters are taken into account.The influence of the door curvature on redistribution of the stress fields under action of thermal perturbations are analysed. As in a uniform heating (or cooling) the curvilinear layers change their lengths in different manure, then it can be supposed that even under small concentration in all direction of the road body are exhibited. At that, for the rectilinear segments of the roads, the stress, normal to the road surface, practically are equal to zero. With the curvature enlargement, the enlargement of tensile normal stress throughout the road length is observed. This lead to enlargement of the probability of the breakaway of the first layer from the second one.It is shown by numerous calculations that the peak values of the longitudinal ensile forces in the top layer and shear forces localized between the first and second layers can be a cause of the initial road destruction observed in practice and formation of transversal cracks.

Thermoelastic Stress-Strain Analysis of the Meshing Pairs of a Two-Tooth Difference Swing-Rod Movable Toothed Drive

Temperature distribution, thermal strain and thermal stress, as the major thermal characteristics influence considerably the performance of a two-tooth difference swing-rod movable toothed drive. By principles of heat transfer and tribology became the basis for deriving the calculation formulae for the frictional heat flux of meshing pairs, convective heat transfer coefficient of a meshing toothed surface, and end face under slip conditions to construct the movable teeth finite element model for the thermal analysis. Thermal strain and thermal stress distributions of a single tooth meshing model of the meshing pair were analyzed by thermal structural coupling using ANSYS package. The meshing stiffness in the case of thermal elastic deformation is also discussed. The surface heat transfer coefficient of the movable teeth is shown to be high, under favorable heat transfer conditions. In this region, the heat transfer coefficient of a ring gear becomes lower as the temperature is growing. Numerical simulation of thermal strain demonstrated a considerable reduction in the stiffness of meshing pairs. The above describes the effect of thermal behavior of the movable teeth transmission system on its dynamic performance.

Phase-field modeling of metallic powder-substrate interaction in laser melting process

Understanding fusion dynamics of metallic powders and powder-substrate interactions is important for reducing the defects, and thus improving surface and bulk quality of additive manufactured (AM) parts. Albeit recent advances in AM technology, there is a great need of theoretical analysis at the powder level to quantify and predict relevant mesoscale dynamics in the manufacturing process. We present a thermodynamically consistent phase-field modeling framework to integrate relevant thermal fluid phenomena and elastic structure response, including phase transition, thermal capillarity, interfacial deformation, and thermal stress induced by spot laser heating. The 2D results show that the fusion of pure titanium powder and titanium substrate can be significantly enhanced by the capillary effect when the partially melted powder is bridging the molten substrate, whereas the thermal-elastic deformation has a longer range effect, which is primarily influenced by the heating power of the laser beam.