Thermo-mechanical Coupling Model Research Articles

Static/quasi-static thermomechanical analysis of 3D thin-walled beam structures based on CUF considering radiation dissipation condition

Thin-walled structures are widely applied in spacecraft as structural components due to their lightweight property. Extreme thermal environment in space may cause highly unfavorable thermal responses in thin-walled structures. Therefore, accurately predicting the thermal-coupling responses of thin-walled structures is of great engineering significance. In order to avoid the disadvantages of 3D finite element model caused by an abundance of computational degrees of freedom, the present paper proposes a thermo-mechanical coupling model based on Carrera Unified Formulation (CUF) for the static and quasi-static thermal response of space thin-walled structures. The longitudinal direction of the structures is discretized by one-dimensional linear and cubic finite elements (B2 and B4), whereas Lagrange expansion functions are used for the description of temperature fields and displacement fields within the cross-section. The governing differential equations of thermal-coupling problems are derived in a unified form according to the principle of virtual displacement and the weighted residual method. In order to demonstrate the accuracy of the numerical results, a convergence analysis is conducted on both beam elements and expansion forms. The results reveal that piece-wise quadratic beam theories approximated with B4 elements are accurate enough for the prediction of thermally-induced displacements, while the high-order cubic cross-sectional expansion is required for the description of stresses. Finally, influences of factors like angle of solar radiation, local shadows, emissivity and thermal conductivity on static and quasi-static displacement distributions are discussed. This research may pave a high-efficiency computational method for solving static/quasi-static thermally induced response of space thin-walled structures.

Numerical Simulation Study on the Response of Ship Engine Room Structure Under Fire Based on Thermo-Mechanical Coupling Model

Ship structures may collapse or be severely deformed during a fire. To precisely assess the post-fire structural integrity of ships, in this study, a thermal–mechanical coupling data interface was created, employing a significant eddy simulation algorithm for fire dynamics and a technique to analyze the structural thermal–mechanical coupling reaction. PyroSim was utilized to build a fire scenario, exporting 3D data through the device’s own program, and then the ANSYS thermal–mechanical coupling model was employed to study the spatial temperature distribution under fire-induced conditions. Data from the three-dimensional spatial temperature field served as the boundary condition for the determination of the structural temperature burden. Building on this, an analysis was conducted on the structural response of the intricate two-story interior compartment under fire conditions. The results showed that the location of the fire source and the structural distribution of the mechanical equipment inside the cabin had a great influence on the temperature and combustion heat, followed by the ventilation conditions, while the temperature variations in the parallel dual fuel tanks were greatly influenced by the stack effect. By comparing the stress and strain of the two-layer cabin under normal and fire conditions, the damage and mechanisms associated with important positions in the cabin under fire conditions were revealed.

A Thermomechanical Coupled Model for Unsaturated Soils

A Thermomechanical Coupled Model for Unsaturated Soils

Study on ablation behavior and mechanism for accurate determination of rare earth elements in CaF2 crystals by UV-LA-ICP-MS

Catastrophic ablation of CaF2 crystals is often observed in ultraviolet-laser ablation-inductively coupled plasma-mass spectrometry (UV-LA-ICP-MS) analysis, leading to variations in the volume of ablated material and resulting analytical errors in LA-ICP-MS microanalysis. Therefore, it is essential to understand the ablation behavior and the interaction mechanisms between the laser and CaF2 crystals. In this study, we examined the effects of crystal surface roughness and laser fluence on ablation behavior. The CaF2 crystal polished with 1500 mesh abrasive paper exhibited a stable signal profile, a regular ablation crater, and the formation of nanoparticles, which align with predictions from the thermo-mechanical coupling model. Both higher and lower roughness resulted in either unstable ablation or uncontrolled ejection of fragments; the latter occurred when the thermal stress from accumulated light energy significantly exceeded the compressive strength of CaF2. Consequently, a roughness of 1500 mesh at the bottom of the ablation craters was deduced. We also identified a laser fluence of 14 J·cm−2 as the threshold for effective LA-ICP-MS analysis of CaF2 crystals, based on consistent signal profiles, elemental fractionation index (EFI), and crater morphology as revealed by LA-ICP-MS and scanning electron microscope (SEM) analyses, along with theoretical calculations from the thermo-mechanical coupling model. The optimal roughness (1500 mesh) and fluence (14 J·cm−2), together with the thermo-mechanical coupling model, can serve as guidelines for UV-LA-ICP-MS settings in further quantitative analyses of CaF2 crystals.

Prediction of transient thermal stress distribution in SOFC based on coupled computational fluid dynamics and thermodynamics modeling

Long-term stability and safety are two key factors for the application of solid oxide fuel cell (SOFC) technology, with thermodynamics playing a central role in influencing this stability. Thus, understanding the thermodynamic behavior within SOFC and how it will depend on the stack structure are very important, especially at the start and stop stages. In this study, a 3D calculated fluid dynamics model and thermomechanical coupling model based on the actual component structures are established. We place emphasis on understanding how these factors evolve during dynamic phases, shedding light on the transient thermal stress behavior of the SOFC. The influence of different interconnect structures on the thermal stress distribution is studied. The coupling calculation results show that the first principal stress of the electrolyte is significantly affected by the specific interconnect structure. Adopting cylindrical ribs instead of rectangular ribs, the thermal stresses of the SOFC components can be reduced by 13–25 %, respectively.

Numerical modeling the process of deep slab dehydration and magmatism

This study uses a 2D high-resolution thermo-mechanical coupled model to investigate the dynamic processes of deep plate hydration, dehydration, and subsequent magmatic activity in ocean-continent subduction zones. We reveal the pathways and temporal evolution of water transport to the deep mantle during the subduction process. Plate dehydration plays a critical role in triggering partial melting of the deep mantle and related magmatic activity. Our study shows significant differences in the volumes of melt produced at different depths, with dehydration reactions in deeper regions being weaker compared to shallower ones. It takes a longer time to reach the suitable P-T conditions for hydrous melting in the deep mantle. The results highlight the geophysical significance of water transport in deep subduction zones and its role in magmatic processes, particularly in the formation of magma chambers beneath continental plates.

Establishment of the thermo-mechanical coupling model of axle box bearings with track irregularity excitation and analysis of its temperature characteristics

Establishment of the thermo-mechanical coupling model of axle box bearings with track irregularity excitation and analysis of its temperature characteristics

Thermo-mechanical coupling characteristics of the shearer’s guiding shoe during the friction

The reliability and longevity of the guiding shoe are crucial for the proper functioning of coal mining machines. The heavy wear of the sliding surface under thermal stress coupling is the primary factor influencing the service life of the guiding shoe. To reveal the heat flow distribution patterns and the thermo-stress coupling mechanisms of the guiding surface, a thermo-mechanical coupling model of the guiding shoe and the pin row is established. The transient thermodynamic behavior of the guiding shoe under different load and speed conditions is studied using the coupled temp-displacement analysis method in Abaqus. The results indicate that the overall temperature of the guiding shoe friction surface experiences a rapid increase during the initial running-in phase, followed by a progressively slower temperature increase over time. Temperature and stress concentration regions on the friction surface primarily localize at the corners of the shoe groove, and the distribution of temperature and stress shows a strong coupling. Furthermore, elevated traction speed and mechanical load exacerbate the thermo-elastic instability of the guiding shoe, consequently augmenting thermal stress on the friction surface. The increase in support load results in significant thermal shock on the lower area of the left side of the guiding shoe. The research provides a reference for exploring the fatigue failure and wear mechanisms of the guiding shoe while considering thermal effects.

Establishment of unified parametric equation and performance analysis of screw motor stator and rotor linetype

Aiming at the screw motor stator and rotor linetype parameter equations are not uniform and the linetype characteristics have not been completely studied, resulting in the linetype design and selection method is not perfect and poor interchangeability and so on. In this paper, the unified parameter of linetype equation of the screw motor stator and rotor and the thermo-mechanical coupling model and the shell-bushing cohesive zone model of the 5/6 screw motor under the three linetypes of equidistant hypocycloid, equidistant epicycloid and hypocycloid and epicycloid are established. The relationship between the three linetypes of stator and rotor and the lagging heat generation of the bushing, drilling fluid pressure, downhole temperature and shell-bushing bonding performance is studied. The results show that the stator temperature rise of the equidistant epicycloid method is 22%–30% lower than that of the other two types of stator. The stator with equidistant epicycloid is less affected by drilling fluid pressure and is more conducive to forming conjugate sealing cavity in deep wells. The downhole temperature has a certain influence on the stator linetype, which needs to be considered in the design. The CSMAXSCRT value of the bonding interface of the screw motor using the equidistant epicycloid method is 6.1%–10.1% higher than that of the screw motor using the other two linetypes, which is prone to bonding failure. When the interference is small, the equidistant hypocycloid method and the hypocycloid and epicycloid method can be used, and the equidistant hypocycloid method is recommended when the interference is large. The research in this paper provides a theoretical basis for the design and selection of screw motor linetypes, and has important engineering practical significance for realizing product interchangeability.

Analysis of extrusion characterization of Nd-Fe-B permanent magnet ring based on Normalized Cockcroft & Latham fracture criterion

The hot deformation behavior of hot-pressed Nd-Fe-B material was investigated using a Gleeble-3500 thermal simulation machine, with deformation of 50 %, temperatures ranging from 700 to 850 °C, and strain rates ranging from 0.01 to 1 s−1. A hyperbolic sine model was employed to establish a constitutive equation suitable for this material. In addition, the chosen fracture criterion and damage threshold in the simulations were validated against the experimental results. Then, a three-dimensional thermo-mechanical coupled model was developed to simulate the damage evolution of the material during the extrusion process. The effects of different extrusion processes and positions of the back pressure tool on the magnetic performance and forming quality of the material were investigated. The simulation results indicate that both the combined extrusion process and the back pressure tool located at the half of the workpiece will contribute to improve the uniformity of the magnetic properties, and effectively ensuring the regularity of the forming process at the top of the magnetic ring and suppressing the occurrence of cracks. The results of this paper will help to a better understanding of the deformation mechanism of Nd-Fe-B permanent magnet and provide a valuable theoretical guidance for the preparation of high-performance Nd-Fe-B magnetic rings.

A thermo-mechanical fully coupled model for high-speed machining of Ti6Al4V

PurposeThis study aims to further refine the model, explore the influence of cutting parameters on the machining process, and apply it to practical engineering to improve the efficiency and quality of titanium alloy machining.Design/methodology/approachThis paper establishes a comprehensive thermo-mechanical fully coupled orthogonal cutting model. This paper aims to couple the modified Johnson–Cook constitutive model, damage model and contact model to construct a two-dimensional orthogonal cutting thermo-mechanical coupling model for high-speed cutting of Ti6Al4V. The model considers the evolution of microstructures such as plastic deformation, grain dislocation rearrangement, dynamic recrystallization, as well as stress softening and hardening occurring continuously in Ti6Al4V metal during high-speed cutting. Additionally, the model incorporates friction and contact between the tool and the workpiece. It can be used to predict parameters such as cutting process, cutting force, temperature distribution, stress and strain in titanium alloy machining. The study establishes the model and implements corresponding functions by writing Abaqus VUMAT and VFRICTION subroutines.FindingsThe use of different material constitutive models can significantly impact the prediction of the cutting process. Some models may more accurately describe the mechanical behavior of the material, thus providing more reliable prediction results, while other models may exhibit larger deviations. Compared to the Tanh model, the proposed model achieves a maximum improvement of 8.9% in the prediction of cutting force and a maximum improvement of 20.9% in the prediction of chip morphology parameters. Compared to experiments, the proposed model achieves a minimum prediction error of 2.8% for average cutting force and a minimum error of 0.57% for sawtooth parameters. This study provides a comprehensive theoretical foundation and practical guidance for orthogonal cutting of titanium alloys. The model not only helps engineers and researchers better understand various phenomena in the cutting process but also serves as an important reference for optimizing cutting processes.Originality/valueThe originality of this research is guaranteed, as it has not been previously published in any journal or publication.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2024-0168/

Numerical investigation of deformation and residual stress in vacuum brazing of titanium alloy plate-fin structure

Various high-end equipment relies on titanium alloy plate-fin structure (PFS) as core components, owing to their remarkable advantages in terms of low density, superior mechanical strength and enhanced corrosion resistance. Brazing assumes a pivotal function in PFS connections, whereby the localized concentrated heat during the welding procedure can precipitate intricate structural deformation and generate residual stresses. A thermo-mechanical coupling model was developed, taking into account the service performance criteria of PFS. The effects of process parameters and clamping methods on the post-welding residual stress and deformation of PFS were investigated. The analytical expressions for the relationship between the process parameters and the stress/deformation were obtained by using the simulation outcomes. The constraint on the partition in the vacuum brazing process determines the extent of deformation and residual stress of PFS, with higher constraint leading to lower values. PFS generates z-directional displacement and y-directional warping deformation, and the weld seam between the fin and the partition is prone to stress concentration. As the brazing temperature and holding time increase, the PFS induces more deformation, while the residual stress value decreases. However, the deformation amount reaches a plateau when the holding time exceeds 30 min.

Study on thermo-mechanical coupling model in pantograph-catenary system of rail vehicle

Study on thermo-mechanical coupling model in pantograph-catenary system of rail vehicle

Fire resistance behavior and failure analysis of transmission tower exposed to wildfires

This paper deals with the fire resistance behavior and failure mode of transmission towers exposed to wildfires. A nonlinear thermo-mechanical coupling model of a latticed transmission tower was established by the finite element (FE) program ANSYS, which was validated from steel members’ perspectives. Wildfire analysis was conducted to determine the key parameters, including the number of legs in fire, fire intensity, and residence time, and the temperature–time curve was further proposed for parametric analysis. It reveals that the transmission tower may collapse under serviceability state loads in the wildfire, and the final failure mode was determined by the number of tower legs in the wildfire. A higher wildfire intensity will significantly reduce the wildfire resistance time of the transmission tower. Therefore, combustible materials around transmission towers need to be regularly cleaned to reduce the intensity and residence time of wildfires, which is an effective way to prevent wildfires. Moreover, a wildfire protection layer design process was proposed based on the environment surrounding the transmission tower, which proved reliable to provide valuable insights for the fire protection design of transmission towers in areas prone to wildfires.

Peridynamics thermomechanical coupling simulation of damage in engineered cementitious composite-concrete bonding specimens under high temperature

The current application of Peridynamics (PD) models in addressing thermally induced failures within Engineered Cementitious Composites (ECC) and concrete bonding specimens is relatively limited. This study introduces a novel semi-discrete PD model for ECC and a random heterogeneous PD model for concrete. These models are grounded in the microscopic constitutive relationships between ECC and concrete materials and incorporate the strain softening behavior of cement-based materials. The effectiveness of the interface model is evaluated through splitting tensile tests on ECC-concrete bonding specimens, employing a series model alongside PD surface effects for material interface correction. Considering the performance degradation of materials at elevated temperatures, a PD thermo-mechanical coupling model, which integrates PD thermal diffusion and motion equations, is proposed to analyze the failure of ECC and concrete under high thermal loads. The validity of both the thermo-mechanical coupling and concrete heterogeneity models is confirmed via thermal cracking tests on heated concrete columns subjected to drilling. Lastly, considering the dynamic response of fire, the Navier-Stokes equation are reformulated into a non-local form utilizing the Peridynamic differential operator (PDDO) to simulate fire environment. A thermo-fluid-mechanical coupling model is developed, and applied to analyze ECC and concrete bonding specimens’ failure behaviors under fire scenarios.

Thermal spalling failure mechanism of heterogeneous granite under moving heat source

The conventional mechanical methods employed for rock breaking encounter substantial challenges in deep, hard formation drilling, characterized by low penetration rates and exorbitant drilling costs. Consequently, there exists an urgent necessity to explore novel drilling methods and technologies. Thermal spallation drilling, as a non-contact rock breaking technique, offers high efficiency in rock fragmentation and substantially reduces drilling costs. However, the mechanism underlying rock fragmentation induced by thermal spallation remains unclear. Therefore, this study establishes a thermo-mechanical coupling model based on heterogeneous granite subjected to a high-temperature moving heat source. The model comprehensively considers the geometric shape, contact, and strength heterogeneity of rock minerals, and analyzes the effects of heating source speed, radius, mineral composition, heterogeneity index, and grain size on the thermal spallation mechanism of rock. The research findings indicate that lower heating source speeds and larger radii result in higher surface temperatures and greater damage volumes, whereas increasing speed and reducing radius enhance fragmentation efficiency, with speed exerting a more significant influence. Thermal spallation primarily results in tensile damage to rocks, with the surface damage and depth of damage being respectively influenced by the heating source speed and radius. Particle size exhibits minimal impact on thermal spallation, while increased quartz content enhances the rock's thermal properties, resulting in significant thermal spallation effects. Additionally, the location of rock damage is closely correlated with thermal parameters. These findings significantly contribute to a better understanding of the thermal spallation fracture mechanism in granite and facilitate the development of technical solutions for thermal spallation drilling methods.

Thermo-mechanical Stability Analysis of Hollow Cellular Concrete Block Air Convection Embankments for Cold Regions

Crushed-rock air convection embankment (ACE), as a highly open-graded porous medium, has been used to mitigate the thaw settlement of pavement structures in permafrost regions. Previous studies have revealed that cellular concrete has significant potential as a cost-effective material for ACE to solve the problem of crushed rock shortage in interior Alaska and improved the thermal stability of pavement structures in cold climates. The design configurations of the hollow cellular concrete block ACE were further designed to maximize the performance benefits and facilitate future implementation and field construction. However, the mechanical behaviors of the proposed structures and ice-rich subgrade were still unknown. In this study, a thermo-mechanical coupling model was developed to evaluate the thermal effect on the long-term mechanical stability of the selected pavement structures and subgrade soils. The results indicated that the thermal stability of the proposed hollow cellular concrete block ACEs was superior to that of the conventional crushed-rock ACE. The maximum thaw settlement of the proposed hollow cellular concrete block ACE was only 13.4% that of the conventional crushed-rock ACE. Thermal and mechanical analyses showed that the proposed cellular concrete ACEs have a significant advantage over conventional crushed-rock ACE.

Failure analysis and pin hole profile optimization design of combined piston for marine diesel engine based on Kriging model and NSGA-Ⅱ algorithm

Amidst the drive for enhanced performance and reliability in marine diesel engines, anti-fatigue design has emerged as a pivotal factor in ensuring safe operation. To investigate the cracking of a steel-topped aluminum-skirted combined piston in a marine diesel engine, thorough analyses were conducted on mechanical properties, chemical composition, and microscopic morphology. Subsequently, a piston thermo-mechanical coupling (TMC) model was established to simulate stress distribution and fatigue strength. Findings revealed that loose defects in the material and deformation mismatch in the pin hole bearing TMC were the primary factors contributing to cracking. Based on this, a multi-objective optimization (MOO) design method for piston pin hole profiles was proposed. Optimal pin hole profile design parameters were determined using the Kriging surrogate model and the second generation non-dominated sorting genetic algorithm (NSGA-II), and the nonlinear relationship between the design variables and the response objectives was obtained. Post-optimization, stress in the piston cracking source region decreased by 40.6%, peak contact pressure and stress in the pin hole decreased by 59.2% and 49.1%, respectively. Furthermore, the minimum fatigue safety coefficient improved from 0.86 to 1.18.

A multiscale thermo-mechanical coupling model for Fiber-Reinforced Cementitious Composite (FRCC)

This paper aims to develop a multiscale thermo-mechanical coupling model across from meso-scale to macro-scale to study the tensile thermos-mechanical behavior of fiber-reinforced cementitious composite (FRCC) on the base of thermodynamics. In meso-scale, the coupling process of thermal effect and the development law of a single crack were creatively presented and formulated in energy potential function. The effects of fiber dispersion on cracking behavior and crack strength of matrix were determined. In macro-scale, the multiple-fine-cracks and strain-hardening/softening behavior under tension were defined and studied. The bridging action stress of fibers is calculated by considering the bonding stress in the interface transition zone (ITZ). The model can be upgraded for FRCC materials ranges from strain-hardening cementitious composite (SHCC) and engineered cementitious composite (ECC). The numerical calculations of the proposed model were conducted based on the Fortran program for validation. The residual tensile strength, multiple-fine-cracks and strain-hardening/softening behaviors of FRCC were predicted. The behaviors of FRCC with different fiber types were accurately captured in a range of temperature from 20°C to 600°C through the comparative study with six groups test results in literatures. A sensibility study was carried out to analyze the impact of modelling parameters and thermal effect on the strain-hardening/softening behaviors of FRCC.

Finite element (FE) analysis of thermal stress in production process of multi-layer lining ladle

This paper presented the development of the thermo-mechanical coupling model and simulation analysis of a composite refractory layer ladle. The thermomechanical modeling of the ladle was carried out using the Finite Element Method (FEM), taking into account the joints between the slag line bricks as well as the contact between the composite refractory layers. The temperature and thermal stress characteristics of the overall ladle structure under different transit conditions were investigated using the finite element analysis software ANSYS. We also performed a comparative analysis on the improvement effect of thermal stresses by expansion joints of different sizes. The simulation results were validated with previous studies. The results showed that the installation of expansion joints within a suitable range did not significantly change the thermal expansion characteristics of the refractory lining, but it also reduced the thermal stress level of the lining to a large extent. A larger temperature gradient produced higher thermal stresses, and in the direction of the ladle height, the more downward the position of its maximum compressive stress was greater. Under different working conditions, compared with the axial and hoop stress, the radial stress was small in magnitude. Axial stress exhibited a greater degree of sensitivity to pressure variations than hoop stress. The developed thermodynamic model considering the full contact between the bricks and the refractory layer gave us a more complete view of the physical field laws inside the ladle.