Journal articles: 'Thermal and mechanical models'

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Wilson, D. A., and J. R. Warren. "Thermal Mechanical Crack Growth Rate of a High Strength Nickel Base Alloy." Journal of Engineering for Gas Turbines and Power 108, no. 2 (April 1, 1986): 396–402. http://dx.doi.org/10.1115/1.3239918.

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An understanding of thermal mechanical fatigue (TMF) crack propagation is fundamental to the application of fracture mechanics to gas turbine components. Typical operating conditions for a cooled turbine disk rim consist of a complex mechanical history and an associated variable amplitude thermal history. While thermally induced stress gradients are commonly incorporated in the mechanical history, the effects of thermal cycling on crack growth must be addressed in an appropriate fatigue model. A current computer-based empirical crack propagation modeling system has demonstrated effectiveness under isothermal conditions and can be readily expanded to include thermal-mechanical effects. The existing isothermal models were developed from an extensive data base and describe crack growth over a broad range of temperature and loading conditions. Building on this established system, a model of thermal-mechanical crack growth is being developed.

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Meena, Ayush, Tushar Sharma, Mohit Patodiya, and P. V. Ramana. "Chronology of Recycled Plastic Mathematical Models, Mechanical and Thermal Characterisation." Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, no. 1 (December 19, 2022): 499–506. http://dx.doi.org/10.38208/acp.v1.540.

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Recycled plastic fibers restrict the characteristics of hardened concrete. They offer no considerable ductility after the initial fracture. Their capacity to prevent bleed and separation helps preserve the original water-cemetery ratio of the surface mortar, thereby enhancing the abrasion resistance. Recycled plastic fibers can be efficient in dispersing stresses and improving frost resistance. The spilling of concrete into the fire has also proven to reduce. Recycled plastic fibers enhance initial characteristics in sprayed concrete and decrease the shedding and rebound. The tiny recycled plastic fibers, which should have similar structural advantages to steel fibers, must be distinguished from giant synthetic fibers. PP is fully resistant to acid and alkaline circumstances and is not affected by acid/alkaline environments, including marine conditions. Chemically PP is non-absorbent, i.e., no moisture absorption and associated characteristic changes.

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Hentati, Hamdi, Ilyes Ben Naceur, Wassila Bouzid, and Aref Maalej. "Numerical Analysis of Damage Thermo-Mechanical Models." Advances in Applied Mathematics and Mechanics 7, no. 5 (July 21, 2015): 625–43. http://dx.doi.org/10.4208/aamm.2014.m517.

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AbstractIn this paper, we present numerical computational methods for solving the fracture problem in brittle and ductile materials with no prior knowledge of the topology of crack path. Moreover, these methods are capable of modeling the crack initiation. We perform numerical simulations of pieces of brittle material based on global approach and taken into account the thermal effect in crack propagation. On the other hand, we propose also a numerical method for solving the fracture problem in a ductile material based on elements deletion method and also using thermo-mechanical behavior and damage laws. In order to achieve the last purpose, we simulate the orthogonal cutting process.

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Kan, Qian Hua, Jian Li, Han Jiang, and Guo Zheng Kang. "An Improved Thermo-Ratcheting Boundary of Pressure Pipeline." Key Engineering Materials 725 (December 2016): 311–15. http://dx.doi.org/10.4028/www.scientific.net/kem.725.311.

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The thermal ratcheting boundary of pressure pipeline is a popular topic in nuclear power engineering. The existed thermal ratcheting boundary based on the Bree diagram is conservative for structures subjected to the thermo-mechanically coupled loadings since it was obtained only from an elastic-perfectly plastic model. Therefore, it is necessary to improve the existed thermal ratcheting boundary based on a reasonable constitutive model. The Bree diagram was validated firstly by the linear relationship between the plastic strain increment and mechanical stress by finite element method. And then the influences of different constitutive models, such as elastic-perfectly plastic, multi-linear kinematic hardening, Chaboche and Abdel Karim-Ohno models, on the thermal ratcheting boundary of pressure pipeline were investigated numerically. It is found that the elastic-perfectly plastic and multi-linear kinematic hardening models provide the lower and upper bounds for the thermal ratcheting boundary, respectively. Finally, an improved thermal ratcheting boundary by introducing the dimensionless axial tensile stress was proposed based on the Bree diagram, the improved thermal ratcheting boundary covered the present cases with different ratios of mechanical stress over thermal stress.

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Slavik, D., and Huseyin Sehitoglu. "Constitutive Models Suitable for Thermal Loading." Journal of Engineering Materials and Technology 108, no. 4 (October 1, 1986): 303–12. http://dx.doi.org/10.1115/1.3225887.

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A non-unified creep plasticity constitutive model and a unified creep-plasticity model have been considered. In the non-unified model, creep and plastic strains were added separately; in the unified model, they were treated in a unified manner. These models were used to predict cyclic hardening and mean stress relaxation for isothermal loading conditions. The results indicate that certain instabilities occured in unified creep-plasticity simulations at low temperatures. Material behavior for thermal loading was studied using the two-bar structure. Both constitutive models were modified to handle material behavior changes with temperature. The thermal loading response was predicted satisfactorily with both models for most cases. However, certain model limitations were encountered in the unified model. The capabilities of both models are outlined and discussed.

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G. K, Mahadeva Raju, G. M. Madhu, P. Dinesh Sankar Reddy, and Karthik K V. "Mechanical and Thermal Properties of Epoxy Polymer Composites Reinforced with CuO." YMER Digital 20, no. 12 (December 15, 2021): 272–80. http://dx.doi.org/10.37896/ymer20.12/25.

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Polymer nano composites using CuO as filler material and epoxy as matrix materials were prepared with different concentrations of CuO nano particles (1-5 wt%) by shear mixing followed by ultra-sonication process. The mechanical properties such as compressive strength and modulus were characterized using ASTM standards. It was found that the addition of CuO nano particles both compressive strength and modulus increased. As the CuO content increased in epoxy matrix the moduli values found to increase and were further analyzed using micromechanical models. The analytical models discussed correlate well with experimental values. The models discussed include Nicolais – Narkis, Turcsanyi, Piggot – Leidner and Nielsen models for the tensile strength values and for tensile modulus the models discussed include Halpin Tsai, Kerner and Sato – Furukawa models. These micromechanics models predict stiffness of nanocomposites with both aligned and randomly oriented fillers. XRD pattern revealed the interaction between CuO nanoparticles and epoxy matrix. The thermal decomposition behaviour revealed that there is an enhancement of onset of decomposition temperature by 28oC for 5wt% CuO filled epoxy than that of pure epoxy

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Ali, Mahmoud, Thomas Sayet, Alain Gasser, and Eric Blond. "Transient Thermo-Mechanical Analysis of Steel Ladle Refractory Linings Using Mechanical Homogenization Approach." Ceramics 3, no. 2 (April 2, 2020): 171–89. http://dx.doi.org/10.3390/ceramics3020016.

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Mortarless refractory masonry structures are widely used in the steel industry for the linings of many high-temperature industrial applications including steel ladles. The design and optimization of these components require accurate numerical models that consider the presence of joints, as well as joint closure and opening due to cyclic heating and cooling. The present work reports on the formulation, numerical implementation, validation, and application of homogenized numerical models for the simulation of refractory masonry structures with dry joints. The validated constitutive model has been used to simulate a steel ladle and analyze its transient thermomechanical behavior during a typical thermal cycle of a steel ladle. A 3D solution domain and enhanced thermal and mechanical boundary conditions have been used. Parametric studies to investigate the impact of joint thickness on the thermomechanical response of the ladle have been carried out. The results clearly demonstrate that the thermomechanical behavior of mortarless masonry is orthotropic and nonlinear due to the gradual closure and reopening of the joints with the increase and decrease in temperature. In addition, resulting thermal stresses increase with the increase in temperature and decrease with the increase in joint thickness.

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Irving, A. D. "Validation of dynamic thermal models." Energy and Buildings 10, no. 3 (January 1988): 213–20. http://dx.doi.org/10.1016/0378-7788(88)90007-2.

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Bahrami, M., J. R. Culham, M. M. Yananovich, and G. E. Schneider. "Review of Thermal Joint Resistance Models for Nonconforming Rough Surfaces." Applied Mechanics Reviews 59, no. 1 (January 1, 2006): 1–12. http://dx.doi.org/10.1115/1.2110231.

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The thermal contact resistance (TCR) in a vacuum is studied. The TCR problem is divided into three different parts: geometrical, mechanical, and thermal. Each problem includes a macro- and microscale subproblem; existing theories and models for each part are reviewed. Empirical correlations for microhardness, and the equivalent (sum) rough surface approximation, are discussed. Suggested correlations for estimating the mean absolute surface slope are summarized and compared with experimental data. The most common assumptions of existing thermal analyses are summarized. As basic elements of thermal analyses, spreading resistance of a circular heat source on a half-space and flux tube are reviewed; also existing flux tube correlations are compared. More than 400 TCR data points collected by different researchers during the last 40years are grouped into two limiting cases: conforming rough and elastoconstriction. Existing TCR models are reviewed and compared with the experimental data at these two limits. It is shown that the existing theoretical models do not cover both of the above-mentioned limiting cases. This review article cites 58 references.

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Campano, Miguel Ángel, Samuel Domínguez-Amarillo, Jesica Fernández-Agüera, and Juan José Sendra. "Thermal Perception in Mild Climate: Adaptive Thermal Models for Schools." Sustainability 11, no. 14 (July 19, 2019): 3948. http://dx.doi.org/10.3390/su11143948.

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A comprehensive assessment of indoor environmental conditions is performed on a representative sample of classrooms in schools across southern Spain (Mediterranean climate) to evaluate the thermal comfort level, thermal perception and preference, and the relationship with HVAC systems, with a comparison of seasons and personal clothing. Almost fifty classrooms were studied and around one thousand pool-surveys distributed among their occupants, aged 12 to 17. These measurements were performed during spring, autumn, and winter, considered the most representative periods of use for schools. A new proposed protocol has been developed for the collection and subsequent analysis of data, applying thermal comfort indicators and using the most frequent predictive models, rational (RTC) and adaptive (ATC), for comparison. Cooling is not provided in any of the rooms and natural ventilation is found in most of the spaces during midseasons. Despite the existence of a general heating service in almost all classrooms in the cold period, the use of mechanical ventilation is limited. Heating did not usually provide standard set-point temperatures. However, this did not lead to widespread complaints, as occupants perceive the thermal environment as neutral—varying greatly between users—and show a preference for slightly colder environments. Comparison of these thermal comfort votes and the thermal comfort indicators used showed a better fit of thermal preference over thermal sensation and more reliable results when using regional ATC indicators than the ASHRAE adaptive model. This highlights the significance of inhabitants’ actual thermal perception. These findings provide useful insight for a more accurate design of this type of building, as well as a suitable tool for the improvement of existing spaces, improving the conditions for both comfort and wellbeing in these spaces, as well as providing a better fit of energy use for actual comfort conditions.

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Kato, K. "Classification of wear mechanisms/models." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 216, no. 6 (June 1, 2002): 349–55. http://dx.doi.org/10.1243/135065002762355280.

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Wear mechanisms may be briefly classified by mechanical, chemical and thermal wear whose wear modes are further classified into seven. Some of them have wear models and mathematical expressions of wear rate, but many of them have not satisfactory wear models and wear equations for reliable predictions. This paper reviews such present understanding on wear mechanisms and models.

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Chen, Fan, and Wentao Yan. "High-fidelity modelling of thermal stress for additive manufacturing by linking thermal-fluid and mechanical models." Materials & Design 196 (November 2020): 109185. http://dx.doi.org/10.1016/j.matdes.2020.109185.

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Lu, Ruxin, and Wencheng Tang. "Analytical calculation models for mesh stiffness and backlash of spur gears under temperature effects." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 236, no. 8 (December 27, 2021): 4450–62. http://dx.doi.org/10.1177/09544062211049860.

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The temperature has a great contribution to the mesh stiffness and backlash of the gear pair. Presence of thermal deformation caused by temperature will complicate the gear teeth interaction. In this paper, the thermal time-varying stiffness model and thermal time-varying backlash model are proposed with the consideration of tooth profile error and total thermo-elastic deformation consists of the teeth deformation, teeth contact deformation, and gear body-induced deformation. The key parameters of thermo-elastic coupling deformation affected by temperature are calculated. Based on the proposed models, the influencing mechanism of temperature on the tooth profile error, mesh stiffness, total deformation, and backlash are revealed. The effects of shaft radius and torque load on the thermal stiffness and thermal backlash are studied. The proposed thermal stiffness and backlash calculation model are proven to be more comprehensive and the correctness is validated.

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Rémy, L., F. Szmytka, and L. Bucher. "Constitutive models for bcc engineering iron alloys exposed to thermal–mechanical fatigue." International Journal of Fatigue 53 (August 2013): 2–14. http://dx.doi.org/10.1016/j.ijfatigue.2011.11.007.

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Burns, S. J., and S. P. Burns. "Is there a layer deep in the Earth that uncouples heat from mechanical work?" Solid Earth Discussions 6, no. 1 (February 11, 2014): 487–509. http://dx.doi.org/10.5194/sed-6-487-2014.

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Abstract. The thermal expansion coefficient is presented as the coupling between heat energy and mechanical work. It is shown that when heat and work are uncoupled then very unusual material properties occurs: for example, acoustic p waves are not damped and heat is not generated from mechanical motion. It is found that at pressures defined by the bulk modulus divided by the Anderson–Grüneisen parameter, then the thermal expansion coefficient approaches zero in linear-elastic models. Very large pressures always reduce thermal expansion coefficients; the importance of a very small or even negative thermal expansion coefficient is discussed in relation to physical processes deep in the core and mantle of Earth. Models of the thermal expansion coefficients based on interatomic potentials which are always relegated to isometric conditions preclude any changes in volume due to temperature changes. However, it is known that the pressures in the Earth are large enough to effectively reduce thermal expansion coefficients to near zero which decouples heat from mechanical work.

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Carson, James K. "Review of effective thermal conductivity models for foods." International Journal of Refrigeration 29, no. 6 (September 2006): 958–67. http://dx.doi.org/10.1016/j.ijrefrig.2006.03.016.

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Nowicki, Andrzej. "Safety of ultrasonic examinations; thermal and mechanical indices." Medical Ultrasonography 22, no. 2 (May 11, 2020): 203. http://dx.doi.org/10.11152/mu-2372.

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This review article combines the reports on the biophysical effects in ultrasonography and provides the rationale behind the mechanical index (MI) and thermal index (TI) complying with the Output Display Standard (ODS). Safe ultrasonic doses are determined according to specific rules, and the screen displays the associated quantities MI and TI. The introduced indices MI and TI take into account the physical mechanism of interaction between ultrasounds and biological tissue, which depends on the temporal and spatial parameters of the acoustic field generated by ultrasound transducers. The predicted temperature increase is determined using three different tissue models: homogeneous, layered and bone/tissue interface.

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Šulc, Stanislav, Vít Šmilauer, and František Wald. "COUPLED SIMULATION FOR FIRE-EXPOSED STRUCTURES USING CFD AND THERMO-MECHANICAL MODELS." Acta Polytechnica CTU Proceedings 13 (November 13, 2017): 121. http://dx.doi.org/10.14311/app.2017.13.0121.

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Fire resistance of buildings is based on fire tests in furnaces with gas burners. However, the tests are very expensive and time consuming. This article presents a coupled simulation of an element loaded by a force and a fire loading. The simulation solves a weakly-coupled problem, consisting of fluid dynamics, heat transfer and mechanical model. The temperature field from the computational fluid dynamics simulation (CFD) creates Cauchy and radiative boundary conditions for the thermal model. Then, the temperature field from element is passed to the mechanical model, which induces thermal strain and modifies material parameters. The fluid dynamics is computed with Fire Dynamics Simulator and the thermo-mechanical task is solved in OOFEM. Both softwares are interconnected with MuPIF python library, which allows smooth data transfer across the different meshes, orchestrating simulations in particular codes, exporting results to the VTK formats and distributed computing.

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Pyykkönen, Markus. "The use of heated models to describe the thermal environment in shelters for farm animals." Agricultural and Food Science 1, no. 6 (December 1, 1992): 539–45. http://dx.doi.org/10.23986/afsci.72466.

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The dry bulb air temperature is still the most commonly used parameter to characterize the thermal environment, even though it disregards the effect of air velocity and the thermal properties of the flooring material on the heat loss from the animal. Measurements in the laboratory confirmed that an uninsulated heated model with an overall thermal resistance of 0.11 m 2 KW-1 is sensitive enough to differentiate between changes in conduction, convection and radiation conditions. Measurements on farms showed that the heat loss simulated by mechanical models gives a more diversified description of the thermal environment than the dry bulb air temperature. Although the uninsulated mechanical model is not a standardized device, it is a useful method for measuring the thermalenvironment especially under sheltered winter conditions.

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Bruno, Giovanni, Alexander M. Efremov, Andrey N. Levandovskiy, Irina Pozdnyakova, Darren J. Hughes, and Bjørn Clausen. "Thermal and Mechanical Response of Industrial Porous Ceramics." Materials Science Forum 652 (May 2010): 191–96. http://dx.doi.org/10.4028/www.scientific.net/msf.652.191.

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In this study, the mechanical behavior of porous thermally microcracked ceramics has been compared with that of solely porous materials, under compressive applied stress. The different aspects of the micro and macroscopic stress-strain curves have been inserted into a coherent analytical model and compared with finite element modeling calculations. The agreement between experiments and models is very good. It is shown that mechanical microcracking, as opposed to thermal, introduces an irreversible aspect in the deformation mechanisms of porous ceramics. In this concern, mechanical loads differentiate themselves from thermal cycling. This leads for instance to a change of the Young’s modulus as a function of applied load, which qualifies those materials as visco-elastic.

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Variyam, Manjula N., Weidong Xie, and Suresh K. Sitaraman. "Role of Out-of-Plane Coefficient of Thermal Expansion in Electronic Packaging Modeling." Journal of Electronic Packaging 122, no. 2 (November 29, 1999): 121–27. http://dx.doi.org/10.1115/1.483143.

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Components in electronic packaging structures are of different dimensions and are made of dissimilar materials that typically have time, temperature, and direction-dependent thermo-mechanical properties. Due to the complexity in geometry, material behavior, and thermal loading patterns, finite-element analysis (FEA) is often used to study the thermo-mechanical behavior of electronic packaging structures. For computational reasons, researchers often use two-dimensional (2D) models instead of three-dimensional (3D) models. Although 2D models are computationally efficient, they could provide misleading results, particularly under thermal loading. The focus of this paper is to compare the results from various 2D, 3D, and generalized plane-deformation strip models and recommend a suitable modeling procedure. Particular emphasis is placed to understand how the third-direction coefficient of thermal expansion (CTE) influences the warpage and the stress results predicted by 2D models under thermal loading. It is seen that the generalized plane-deformation strip models are the best compromise between the 2D and 3D models. Suitable analytical formulations have also been developed to corroborate the findings from the study. [S1043-7398(00)01402-X]

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Mir Tamizdoust, Mohammadreza, and Omid Ghasemi-Fare. "Comparison of thermo-poroelastic and thermo-poroelastoplastic constitutive models to analyze THM process in clays." E3S Web of Conferences 205 (2020): 04008. http://dx.doi.org/10.1051/e3sconf/202020504008.

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Thermal pore pressurization in soil media has been investigated for the past few decades. It has been shown that temperature variations may significantly affect thermal pore pressure in clay soils confined deep into the ground. Moreover, thermal loading may lead to stress change and thermal deformation. Thermo-poroelastic and advance thermo-poroelastoplastic constitutive models have been formulated and incorporated numerically to simulate the thermo-hydro-mechanical process. However, the accurate response of soil media during THM process has not been completely understood. Although numerical modelling reasonably predicts the experimental observations, they still could not be used to completely justify the field observations. In this study, the main features of the thermo-poroelastic model are incorporated in a thermo-poroelastoplastic constitutive model (ACMEG-T) to further investigate the effect of different thermal and hydraulic properties on thermo-hydro-mechanical (THM) response of the soil media.

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Zimmermann, Nico, Sebastian Lang, Philip Blaser, and Josef Mayr. "Adaptive input selection for thermal error compensation models." CIRP Annals 69, no. 1 (2020): 485–88. http://dx.doi.org/10.1016/j.cirp.2020.03.017.

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Koch, Lukas, Julian Müller, Gordana Michos, Johannes Paulus, Markus Hubert, and Jörg Franke. "Coupled Thermal and Fluid Mechanical Modeling of a High Speed Motor Spindle." Applied Mechanics and Materials 871 (October 2017): 161–68. http://dx.doi.org/10.4028/www.scientific.net/amm.871.161.

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The objective of this survey is to evolve a better understanding of the complex thermal interactions inside a motor spindle. Therefore, the thermal behavior is investigated based on a simulation model and experiments. In contrast to existing simulation models, which either performed a complex thermal examination or an elaborate flow-mechanical analysis, a thermal (Finite Element Method) and fluid mechanical (Computational Fluid Dynamics) coupled simulation model was developed. Based on a comparative analysis, the usability of the currently available boundary conditions is scrutinized.

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Zhai, Siping, Ping Zhang, Yaoqi Xian, Jianhua Zeng, and Bo Shi. "Effective thermal conductivity of polymer composites: Theoretical models and simulation models." International Journal of Heat and Mass Transfer 117 (February 2018): 358–74. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2017.09.067.

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Sorkin, Linda S., Tony L. Yaksh, and Carmen M. Doom. "Pain Models Display Differential Sensitivity to Ca2+-Permeable Non-NMDA Glutamate Receptor Antagonists." Anesthesiology 95, no. 4 (October 1, 2001): 965–73. http://dx.doi.org/10.1097/00000542-200110000-00028.

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Background Ca2+-permeable non-N-methyl-D-aspartate receptors are found in the spinal dorsal horn and represent a presumptive target for glutamatergic transmission in nociceptive processing. This study characterized the analgesic profile associated with the blockade of these spinal receptors by intrathecally delivered agents known to act at these receptors, the spider venom Joro toxin (JST) and philanthotoxin. Methods Philanthotoxin (0.5, 2.5, or 5 microg) or JST (5 microg) was given spinally before thermal injury to the paw. JST (5 microg) was also given 10 min before subcutaneous formalin injection, after intraplantar administration of carrageenan, and to rats that were allodynic due to tight ligation of spinal nerves. Lower doses of JST (0.25 and 1.0 microg) were given before formalin injection and testing of thermal latencies. Thermal latencies were measured using a Hargreaves box, mechanical thresholds using von Frey hairs, and formalin response by means of counting flinches. Results Both agents blocked thermal injury-induced mechanical allodynia. JST (5 microg) given 1 h after carrageenan blocked induction of thermal hyperalgesia and mechanical allodynia. JST (5 microg) had no effect in the formalin test, on allodynia after spinal nerve ligation, or when given 3 h after carrageenan. The lowest dose (0.25 microg JST) at pretreatment intervals of 60-120 min resulted in modest hypoalgesia during phase 1 formalin and thermal testing. Conclusions The behavioral effect of intrathecal Ca2+-permeable non-N-methyl-D-aspartate antagonists indicates an important role for this spinal receptor in regulating hyperalgesic states induced by tissue injury and inflammation and reveals an action that is distinct from those observed with other glutamate receptor antagonists.

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Zhou, Chen, Zhijin Wang, and Paul M. Weaver. "Thermal-Mechanical Optimization of Folded Core Sandwich Panels for Thermal Protection Systems of Space Vehicles." International Journal of Aerospace Engineering 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/3030972.

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The integrated thermal protection system (ITPS) is a complicated system that addresses both mechanical and thermal considerations. An M-pattern folded core sandwich panel packed with low-density insulation material provides inherently low mass for a potential ITPS panel. Herein, we identify the most influential geometric parameters and establish a viable, computationally efficient optimization procedure. Variables considered for optimization are geometric dimensions of the ITPS, while temperature and deflection are taken as constraints. A one-dimensional (1D) thermal model based on a modified form of the rule of mixtures was established, while a three-dimensional (3D) model was adopted for linear static analyses. Parametric models were generated to facilitate a design of experiment (DOE) study, and approximate models using radial basis functions were obtained to carry out the optimization process. Sensitivity studies were first conducted to investigate the effect of geometric parameters on the ITPS responses. Then optimizations were performed for both thermal and thermal-mechanical constraints. The results show that the simplified 1D thermal model is able to predict temperature through the ITPS thickness satisfactorily. The combined optimization strategy evidently improves the computational efficiency of the design process showing it can be used for initial design of folded core ITPS.

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Xiang, Sitong, Xiaolong Zhu, and Jianguo Yang. "Modeling for spindle thermal error in machine tools based on mechanism analysis and thermal basic characteristics tests." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 18 (April 11, 2014): 3381–94. http://dx.doi.org/10.1177/0954406214531219.

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This paper proposes a method to accurately predict thermal errors in spindles by applying experimental modifications to preliminary theoretical models. First, preliminary theoretical models of the temperature field and the thermal deformation are built via mechanism analysis, which is based on the size of the spindle and the parameters of the bearing. Then, thermal basic characteristics tests are conducted at two different initial temperatures. Finally, the results of the thermal basic characteristic tests are evaluated, and the preliminary theoretical model is modified to obtain the final model. A simulation of axial thermal deformation under different speeds is conducted by finite element analysis. It shows that the relationship between the axial thermal deformation and the speed is approximately linear. The model is validated via some experiments on the spindle of a numerical control lathe. The results indicate that the proposed model precisely predicts the spindle’s temperature field and multi-degree of freedom thermal errors.

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Youssef, Hamdy M., and Mohammed W. Al-Hazmi. "The influence of the static-pre-stress and mechanical damage variable in the thermal quality factor of two-temperature viscothermoelastic resonators." Advances in Mechanical Engineering 12, no. 6 (June 2020): 168781402093045. http://dx.doi.org/10.1177/1687814020930454.

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The mechanical damage variable, as well as the thermal and mechanical relaxation times, plays essential roles in the thermal quality factor of the resonators, where controls energy damping through the coupling of mechanical and thermal behavior. In this article, we developed a mathematical model in which a static-pre-stress and mechanical damage variable in the context of a two-temperature viscothermoelasticity of silicon resonator has been considered. The effects of static-pre-stress, thermal relaxation time, mechanical relaxation time, mechanical damage variable, isothermal frequency, and length-scale on the quality factor have been discussed in the context of a one-temperature and two-temperature models. The model predicts that significant improvement in terms of quality factors is possible by tuning the static-pre-stress, isothermal frequency, and length-scale of the resonator. Moreover, the thermal and mechanical relaxation times and the mechanical damage variable have impacts on the thermal quality factor.

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Cole, K. D., C. M. Tarawneh, A. A. Fuentes, B. M. Wilson, and L. Navarro. "Thermal models of railroad wheels and bearings." International Journal of Heat and Mass Transfer 53, no. 9-10 (April 2010): 1636–45. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2010.01.031.

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Cichy, Marian, Zbigniew Kneba, and Jacek Kropiwnicki. "Causality in Models of Thermal Processes in Ship Engine Rooms with the Use of Bond Graph (BG) Method." Polish Maritime Research 24, s1 (April 25, 2017): 32–37. http://dx.doi.org/10.1515/pomr-2017-0018.

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AbstractWith a single approach to modeling elements of different physical nature, the method of Bond Graph (BG) is particularly well suited for modeling energy systems consisting of mechanical, thermal, electrical and hydraulic elements that operate in the power system engine room. The paper refers to the earlier presented [2] new concept of thermal process modeling using the BG method. The authors own suggestions for determining causality in models of thermal processes created by the said concept were given. The analysis of causality makes it possible to demonstrate the model conflicts that prevent the placement of state equations which allows for the direct conduct of simulation experiments. Attention has been drawn to the link between the energy systems models of thermal processes with models of elements of different physical nature. Two examples of determining causality in models of complex energy systems of thermal elements have been presented. The firs relates to the electrical system associated with the process of heat exchange. The second is a model of the mechanical system associated with the thermodynamic process.

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Hong, H. K., H. S. Lan, and J. K. Liou. "Study of Integration Strategy for Thermal-Elastic-Plastic Models." Journal of Pressure Vessel Technology 114, no. 1 (February 1, 1992): 39–45. http://dx.doi.org/10.1115/1.2929010.

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The accuracy of a new integration algorithm is examined for a von Mises-type model of thermal-elastic-plasticity with nonlinear, mixed isotropic-kinematic hardening. The algorithm is founded on the frame of an integral representation of the conventional rate constitutive equations in contrast to the conventional rate equations themselves. The thermal effect on the yield surface is built in this approach without any difficulty. Under a generalized assumption of a constant strain rate, the model can be reduced to two scalar first-order ordinary differential equations which make an error-controllable integration method possible. Furthermore, for a nonconstant strain rate, e.g., a linear strain rate, the same idea of derivation achieves a similar conclusion. Errors of single-step stress predictions for given total strain increments are discussed.

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Li, Zhi-Qiang, Wei-Dong Song, Hui-Ping Tang, Zhi-Hua Wang, and Long-Mao Zhao. "Thermal-mechanical behavior of sandwich panels with closed-cell foam core under intensive laser irradiation." Thermal Science 18, no. 5 (2014): 1607–11. http://dx.doi.org/10.2298/tsci1405607l.

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Temperature field and thermal deformation of sandwich panels with closed-cell aluminum alloy foam core and heat-protective layer, which are subjected to Gaussian laser beam intensively irradiating, are investigated numerically. In transient heat analysis models, the influence of thermal conductivity, specific heat, and thickness of heat-protective layer on the temperature rise of the sandwich panels is calculated. In stress analysis models, a sequence coupled numerical method is utilized to simulate the thermal stress and deformation of sandwich panels induced by thermal expansion. Simulation results indicate that the temperature at center of sandwich panel increases firstly and then drops gradually with the increase of thermal conductivity of heat-protective layer after laser irradiation, and the critical thermal conductivity is obtained, while it decreases with the increase of specific heat and thickness of heat-protective layer. The thermal stress verifies the ?Cyclo-hoop effect?, i. e. radial stress is compression stress in ?hot zone? and tension stress in ?cold zone?. The max thermal deformation of sandwich panels slightly increases with the increase of thickness of heat-protective layer for given specific heat and thermal conductivity.

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van der Beek, P. A., M. Rohrman, P. A. M. Andriessen, and S. Cloetingh. "Thermal modelling of apatite fission-track data; constraints on thermo-mechanical rifting models." Nuclear Tracks and Radiation Measurements 21, no. 4 (October 1993): 601. http://dx.doi.org/10.1016/1359-0189(93)90236-3.

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Choi, Seok-Ki, and Seong-O. Kim. "The Role of Turbulence Models for Predicting a Thermal Stratification." Journal of Pressure Vessel Technology 128, no. 4 (May 18, 2006): 656–62. http://dx.doi.org/10.1115/1.2371078.

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A numerical study of the evaluation of turbulence models for predicting the thermal stratification phenomenon is presented. The tested models are the elliptic blending turbulence model (EBM), the two-layer model, the shear stress transport model (SST), and the elliptic relaxation model (V2-f). These four turbulence models are applied to the prediction of a thermal stratification in an upper plenum of a liquid metal reactor experimented at the Japan Nuclear Cooperation (JNC). The EBM and V2-f models predict properly the steep gradient of the temperature at the interface of the cold and hot regions that is observed in the experimental data, and the EBM and V2-f models have the capability of predicting the temporal oscillation of the temperature. The two-layer and SST models predict the diffusive temperature gradient at the interface of a thermal stratification and fail to predict a temporal oscillation of the temperature. In general, the EBM predicts best the thermal stratification phenomenon in the upper plenum of the liquid metal reactor.

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Salehi, Sedigheh, Vasyl Ryukhtin, Petr Lukas, Omer Van der Biest, and Jef Vleugels. "Two-D Analysis of the Thermo-Mechanical Properties of ZrO2-Based Composites." International Journal of Chemoinformatics and Chemical Engineering 2, no. 1 (January 2012): 25–38. http://dx.doi.org/10.4018/ijcce.2012010103.

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In this paper, a fast and efficient tool for predicting a set of physical and mechanical composite properties such as thermal expansion coefficients, thermal and electrical conductivity, stiffness, and thermal residual stress is developed based on the analysis of a representative volume of ZrO2-based composite. Such an analysis allows an engineer to assess the mechanical and physical properties to design an optimum composite composition in terms of advantageous mechanical properties and at the same time a good electrical discharge machining performance. Thermal residual stresses in the constituent phases and thermal and electrical conductivity of ZrO2-based composites are assessed by a Finite Element (FE) model using 2 dimensional SEM micrographs. The FE models are verified by comparing numerically calculated results with experimentally measured data.

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Postlethwaite, S. R., J. P. Allen, and D. G. Ford. "The use of thermal imaging, temperature and distortion models for machine tool thermal error reduction." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 212, no. 8 (August 1, 1998): 671–79. http://dx.doi.org/10.1243/0954405981515932.

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Research has shown that up to 75 per cent of the total machining error can be produced by thermal distortion. Thermal error compensation can provide an attractive solution to this accuracy problem. Research has shown that thermal error compensation can reduce thermal errors to an acceptable level, but the techniques adopted have had inherent disadvantages that make them impractical for general use. This paper describes a novel indirect measurement based thermal error compensation technique that overcomes the main difficulties of applying thermal compensation, making it practical and generally applicable. The technique makes extensive use of thermal imaging for rapid assessment of machine tool thermal behaviour and off-line development of the compensation models. To illustrate the use of the technique it is applied to the head slide of a vertical machining centre.

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Deng, Fei, and Quanshui Zheng. "Interaction models for effective thermal and electric conductivities of carbon nanotube composites." Acta Mechanica Solida Sinica 22, no. 1 (February 2009): 1–17. http://dx.doi.org/10.1016/s0894-9166(09)60085-9.

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Jin, Ren Cheng, Ming Liang Shao, Li Sha Meng, Zhe Nan Tang, and Jia Qi Wang. "Coupled Electro-Thermal-Mechanical Micro-Hotplate-Based for Micro Gas Pressure Sensor." Advanced Materials Research 204-210 (February 2011): 1086–89. http://dx.doi.org/10.4028/www.scientific.net/amr.204-210.1086.

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In this paper, electro-thermal-mechanical theoretical analysis of micro-hotplate-based micro gas pressure sensor is carried out, which is on basis of the classical heat transfer theory and rarefied gas dynamics. Combined with micro-hotplate (MHP) theory analysis of heat transfer and thermal-mechanical finite element modeling, electro-thermal-mechanical coupled analysis of theoretical models with regard to the MHP-based micro gas pressure sensor is built. Then, through the ANSYS-one of the finite element analysis software-the simulation analysis of MHP went well. The simulation results show that MHP generates a smaller deformation because of adding the thermal conductivity, and MHP provides a more feasible analysis method in the theoretical study of micro hotplate.

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Shang, Liwei, Ming Liu, Sansiri Tanachutiwat, and Wei Wang. "Diameter-dependant thermal conductance models of carbon nanotubes." International Journal of Nanoparticles 1, no. 2 (2008): 85. http://dx.doi.org/10.1504/ijnp.2008.020264.

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Covill, D., Z. W. Guan, M. Bailey, and H. Raval. "Development of thermal models of footwear using finite element analysis." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 1, no. -1 (January 1, 2010): 1–14. http://dx.doi.org/10.1243/09544119jeim860.

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Solano, B., S. Rolt, and D. Wood. "Thermal and mechanical analysis of an SU8 polymeric actuator using infrared thermography." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, no. 1 (January 1, 2008): 73–86. http://dx.doi.org/10.1243/09544062jmes676.

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In the current paper, report the detailed thermomechanical analysis of a polymeric thermal actuator integrated in a microelectromechanical systems microgripper, is reported. The inclusion of an actuator design which eliminates completely the parasitic resistance of the cold arm improves considerably the thermal efficiency of the system and enables large displacements at lower input voltages and operating temperatures than reported previously. Two different microgrippers built using a trilayer polymer/metal/polymer combination of SU8/gold/SU8 have been modelled, fabricated, and tested. As opposed to standard models, heat transfer by conduction to the ambient as well as between adjacent beams has been modelled. A semi-empirical approach for the calculation of conductive heat transfer coefficients has also been provided. The analysis combines simulations with electrical, deflection, and spatially resolved temperature measurements. The latter was carried out using infrared thermography, its use in polymeric actuators reported here for the first time. The good agreement between the models and the experimental data support the conclusions of the basic analytical model, i.e. thermal losses are dominated by two conduction mechanisms (into the ambient and between the hot and cold arms), and encourage its use for qualitative thermal design assessment and optimization.

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Choi, Nam-Jin, and Jin-Won Joo. "The Effect of Finite Element Models in Thermal Analysis of Electronic Packages." Transactions of the Korean Society of Mechanical Engineers A 33, no. 4 (April 1, 2009): 380–87. http://dx.doi.org/10.3795/ksme-a.2009.33.4.380.

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Singh, Sundeep, and Roderick Melnik. "Fluid–Structure Interaction and Non-Fourier Effects in Coupled Electro-Thermo-Mechanical Models for Cardiac Ablation." Fluids 6, no. 8 (August 20, 2021): 294. http://dx.doi.org/10.3390/fluids6080294.

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In this study, a fully coupled electro-thermo-mechanical model of radiofrequency (RF)-assisted cardiac ablation has been developed, incorporating fluid–structure interaction, thermal relaxation time effects and porous media approach. A non-Fourier based bio-heat transfer model has been used for predicting the temperature distribution and ablation zone during the cardiac ablation. The blood has been modeled as a Newtonian fluid and the velocity fields are obtained utilizing the Navier–Stokes equations. The thermal stresses induced due to the heating of the cardiac tissue have also been accounted. Parametric studies have been conducted to investigate the effect of cardiac tissue porosity, thermal relaxation time effects, electrode insertion depths and orientations on the treatment outcomes of the cardiac ablation. The results are presented in terms of predicted temperature distributions and ablation volumes for different cases of interest utilizing a finite element based COMSOL Multiphysics software. It has been found that electrode insertion depth and orientation has a significant effect on the treatment outcomes of cardiac ablation. Further, porosity of cardiac tissue also plays an important role in the prediction of temperature distribution and ablation volume during RF-assisted cardiac ablation. Moreover, thermal relaxation times only affect the treatment outcomes for shorter treatment times of less than 30 s.

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Khan, Kamran A., Falah Al Hajeri, and Muhammad A. Khan. "Analytical and numerical assessment of the effect of highly conductive inclusions distribution on the thermal conductivity of particulate composites." Journal of Composite Materials 53, no. 25 (April 10, 2019): 3499–514. http://dx.doi.org/10.1177/0021998319843329.

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Highly conductive composites have found applications in thermal management, and the effective thermal conductivity plays a vital role in understanding the thermo-mechanical behavior of advanced composites. Experimental studies show that when highly conductive inclusions embedded in a polymeric matrix the particle forms conductive chain that drastically increase the effective thermal conductivity of two-phase particulate composites. In this study, we introduce a random network three dimensional (3D) percolation model which closely represent the experimentally observed scenario of the formation of the conductive chain by spherical particles. The prediction of the effective thermal conductivity obtained from percolation models is compared with the conventional micromechanical models of particulate composites having the cubical arrangement, the hexagonal arrangement and the random distribution of the spheres. In addition to that, the capabilities of predicting the effective thermal conductivity of a composite by different analytical models, micromechanical models, and, numerical models are also discussed and compared with the experimental data available in the literature. The results showed that random network percolation models give reasonable estimates of the effective thermal conductivity of the highly conductive particulate composites only in some cases. It is found that the developed percolation models perfectly represent the case of conduction through a composite containing randomly suspended interacting spheres and yield effective thermal conductivity results close to Jeffery's model. It is concluded that a more refined random network percolation model with the directional conductive chain of spheres should be developed to predict the effective thermal conductivity of advanced composites containing highly conductive inclusions.

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Vandevelde, Simon, Alain Daidié, and Marc Sartor. "Use of 1D mechanical and thermal models to predetermine the heat transferable by a thermal interface material layer in space applications." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 17 (April 11, 2020): 3459–73. http://dx.doi.org/10.1177/0954406220915508.

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This paper proposes the use of 1D basic models to build a design assistance tool capable of evaluating the heat transfer between a third-level electronic packaging and its support, considering a conventional configuration where a thermal interface material is placed between these two parts. Using this kind of tool early in the design process may facilitate choices concerning geometry and material. The packaging is modelled by a stepped beam (the equipment) and the interface layer by a nonlinear elastic foundation (the thermal interface material). Considering that the electronic equipment bends under the effect of the forces exerted by the fasteners, the tool makes it possible to determine the contact zone remaining operative after deformation, and the pressure distribution at the interface. Mechanical results are then used to calculate the steady-state heat transfer between the equipment and its support, taking into account the diffusion within the equipment and the thermal interface material, and also the thermal contact resistances, the latter being dependent on the contact pressure. A detailed case study is used to illustrate the utility of the approach. The 1D models are exploited to illustrate the interest of the design assistance tool. The influence of different parameters on the thermal performance is studied and a new innovative proposal is analyzed, which could lead to a significant increase in thermal performance.

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Su, Pei Fang, and Xing Li Lu. "Thermal Stress Analysis Based on Equivalent Age of Heterogeneous Mass Concrete." Applied Mechanics and Materials 353-356 (August 2013): 3256–62. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.3256.

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In order to analysis thermal stress of mass concrete accurately, material properties of mass concrete are studied by numerical simulation method, and the equivalent age is introduced to describe the mechanical properties of concrete. The calculation models of concrete mechanical parameters are summarized, and then the calculation procedures are established on the basis of equivalent age. In this way, the temperature and temperature history are considered in these models. Meanwhile, the governing equation and computer program of the thermal stress based on the equivalent age are developed. The comparison of the numerical example using proposed method and conventional FEM method shows that the proposed method performs more adaptable and accurate.

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Li, Hongqi, and Yung C. Shin. "Integrated Dynamic Thermo-Mechanical Modeling of High Speed Spindles, Part 1: Model Development." Journal of Manufacturing Science and Engineering 126, no. 1 (February 1, 2004): 148–58. http://dx.doi.org/10.1115/1.1644545.

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This paper presents a comprehensive integrated thermo-dynamic model for various high speed spindles. The entire model consists of fully coupled three sub-models: bearing, spindle dynamic and thermal models. Using a finite element approach, a new thermal model has been generated, which can describe complex structures of high-speed motorized spindles, and can predict more accurate temperature distributions. The spindle dynamic model is constructed using finite elements based on Timoshenko beam theory and has been improved by considering shear deformation, material and bearing damping, and the spindle/tool-holder interface. Using the new thermo-dynamic model, more general and detailed bearing configurations can be modeled through a systematic coupling procedure. The thermal expansions of the shaft, housing and bearings are calculated based on predicted temperature distributions and are used to update the bearing preloads depending on the operating conditions, which are again used to update the thermal model. Therefore, the model is fully integrated and can provide solutions in terms of all the design parameters and operating conditions.

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Nied, H. A. "Ceramic Coating Edge Failure Due to Thermal Expansion Interference." Journal of Engineering for Gas Turbines and Power 120, no. 4 (October 1, 1998): 820–24. http://dx.doi.org/10.1115/1.2818474.

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An investigation of thermal barrier coatings on a metal substrate was conducted when the assembly was subjected to both thermal heating and mechanical edge loads generated by interference in adjoining expansion gaps. Both finite element and closed form solution models were developed and compared. The results of the analyses predict that the application of both thermal and mechanical edge loads on the edge of ceramic/metal composites can produce severe local edge spallation in the ceramic coating when an inadequate expansion gap is provided.

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Dimitrijevic, Marija, Djordje Veljovic, Milica Posarac-Markovic, Radmila Jancic-Heinemann, Tatjana Volkov-Husovic, and Milorad Zrilic. "Mechanical properties correlation to processing parameters for advanced alumina based refractories." Science of Sintering 44, no. 1 (2012): 25–33. http://dx.doi.org/10.2298/sos1201025d.

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Alumina based refractories are usually used in metallurgical furnaces and their thermal shock resistance is of great importance. In order to improve thermal shock resistance and mechanical properties of alumina based refractories short ceramic fibers were added to the material. SEM technique was used to compare the microstructure of specimens and the observed images gave the porosity and morphological characteristics of pores in the specimens. Standard compression test was used to determine the modulus of elasticity and compression strength. Results obtained from thermal shock testing and mechanical properties measurements were used to establish regression models that correlated specimen properties to process parameters.

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Journal articles on the topic 'Thermal and mechanical models'

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