In most previous models,simulation of the temperature generation in tissue is based on the Pennes bio-heat transfer equation,which implies an instantaneous thermal energy deposition in the medium.Due to the long therm...In most previous models,simulation of the temperature generation in tissue is based on the Pennes bio-heat transfer equation,which implies an instantaneous thermal energy deposition in the medium.Due to the long thermal relaxation time τ（20 s-30 s） in biological tissues,the actual temperature elevation during clinical treatments could be different from the value predicted by the Pennes bioheat equation.The thermal wave model of bio-heat transfer（TWMBT） defines a thermal relaxation time to describe the tissue heating from ultrasound exposure.In this paper,COMSOL Multiphysics 3.5a,a finite element method software package,is used to simulate the temperature response in tissues based on Pennes and TWMBT equations.We further discuss different factors in the bio-heat transfer model on the influence of the temperature rising and it is found that the temperature response in tissue under ultrasound exposure is a rising process with a declining rate.The thermal relaxation time inhibits the temperature elevation at the beginning of ultrasonic heating.Besides,thermal relaxation in TWMBT leads to lower temperature estimation than that based on Pennes equation during the same period of time.The blood flow carrying heat dominates most to the decline of temperature rising rate and the influence increases with temperature rising.On the contrary,heat diffusion,which can be described by thermal conductivity,has little effect on the temperature rising.展开更多
Active infrared thermography has gained increasing popularity for nondestructive testing and evaluation in various industrial fields,especially for composite structures.In this regard,thermal wave radar(TWR)imaging is...Active infrared thermography has gained increasing popularity for nondestructive testing and evaluation in various industrial fields,especially for composite structures.In this regard,thermal wave radar(TWR)imaging is recognized as the next-generation active thermography technology to obtain great resolution and depth range over the inspected objects.A critical aspect concerns the optimal test parameter selection to guarantee reliable quality assurance required for industrial products.In this work,single-and multiple-frequency TWR was investigated in a quantitative manner with the goal of optimizing the detection parameters in terms of probing range and lateral and depth resolution.The effects of test parameters,including sampling frequency,modulation frequency,chirp duration,chirp bandwidth,etc,were investigated in detail through experiments on a glass fiber reinforced polymer specimen with multi-scale diameter-to-depth ratio defects.This paper aims to help yield a better understanding of the physical mechanism behind TWR and propose a workable scheme for testing parameter selection in practical applications.展开更多
The effect of thermal wave at the initial stage for non-conductive Al_2 O_3 powders compact in field assisted sintering technique(FAST) was investigated. The Lord and Shulman type generalized thermoselastic theory was...The effect of thermal wave at the initial stage for non-conductive Al_2 O_3 powders compact in field assisted sintering technique(FAST) was investigated. The Lord and Shulman type generalized thermoselastic theory was introduced to describe the influence of thermal-mechanical interaction, as well as the heat transport and thermal focusing caused by thermal wave propagation. The expression of vacancy concentration difference of the particles was deduced by considering transient thermal stress. Subsequently, the relationship between activation energy and vacancy concentration difference was obtained. The mechanism of surface diffusion, volume diffusion, simultaneous surface and volume diffusion was analyzed. The numerical simulations indicate that low sintering temperature can obtain high local temperature by the superposition effect of thermal wave. Vacancy concentration differences were improved during FAST compared with hot-pressure and pressureless sintering, thereby decreasing the sintering time. By contrast, the activation energy declined with the decrease of vacancy concentration difference in the neck growth process.展开更多
The fact that the temperature of living tissue may respond oscillatorily to externalheating has been a classical difficulty in the field of bioheat transfer for a long time.Roemer et al. have carefully discussed this ...The fact that the temperature of living tissue may respond oscillatorily to externalheating has been a classical difficulty in the field of bioheat transfer for a long time.Roemer et al. have carefully discussed this in their serial articles, but experiments did notsupport their conclusions, Tharp et al. have artificially made a time-delay differential equs-tion to describe this phenomenon, but their model is short of a strict theoretical founda-展开更多
The conservation equations for heat conduction are established based on the concept of thermal mass.We obtain a general heat conduction law which takes into account the spatial and temporal inertia of thermal mass.The...The conservation equations for heat conduction are established based on the concept of thermal mass.We obtain a general heat conduction law which takes into account the spatial and temporal inertia of thermal mass.The general law introduces a damped thermal wave equation.It reduces to the well-known CV model when the spatial inertia of heat flux and temperature and the temporal inertia of temperature are neglected,which indicates that the CV model only considers the temporal inertia of heat flux.Numerical simulations on the propagation and superposition of thermal waves show that for small thermal perturbation the CV model agrees with the thermal wave equation based on the thermal mass theory.For larger thermal perturbation,however,the physically impossible phenomenon pre-dicted by CV model,i.e.the negative temperature induced by the thermal wave superposition,is eliminated by the general heat conduction law,which demonstrates that the present heat conduction law based on the thermal mass theory is more reasonable.展开更多
An analysis has been carried out to study the effects of radiation absorption and firstorder chemical reaction on unsteady mixed convective flow of a viscous incompressible electrically conducting fluid through a poro...An analysis has been carried out to study the effects of radiation absorption and firstorder chemical reaction on unsteady mixed convective flow of a viscous incompressible electrically conducting fluid through a porous medium of variable permeability between two long vertical non conducting wavy channels in the presence of heat generation.The unsteadiness in the flow is due to traveling thermal wave imposed on the walls.The governing equations are solved subject to the relevant boundary conditions with the assumption that the solution consists of a mean part and a perturbed part.The zeroth-order,the first order and the total solution of the problem are numerically evaluated and displayed graphically for pertinent parameters.This model finds applications in studying fixed-bed catalytic reactors and packed bed heat exchangers.展开更多
The transient heat conduction in both armchair and zigzag-edged graphene ribbons pulsed by local heating with a duration of 1 ps was studied using nonequilibrium molecular dynamics simulations. The results show that t...The transient heat conduction in both armchair and zigzag-edged graphene ribbons pulsed by local heating with a duration of 1 ps was studied using nonequilibrium molecular dynamics simulations. The results show that the heat pulse excites two waves which indicates non-Fourier heat conduction. One of the two waves is a sound wave(first sound), which has macroscopic momentum and propagates at the speed of sound. The other is a thermal wave(second sound), whose propagation speed is 1=ffiffi3pof the sound velocity. The sound wave excited by the heat pulse is a longitudinal wave, whose energy is only transported in the longitudinal direction. The thermal wave excited by the heat pulse is generated by transverse lattice vibrations, with the energy only having the transverse component. The observed anisotropy of the transient heat conduction suggests that the system is in a non-equilibrium state during propagation of the heat pulse. Further statistical analyses show that the displacement of the heat pulse energy is related to the time as hr2 i / t1:80, which implies that heat transport is ballistic-diffusive transport in graphene. The higher proportion of the ballistic transport will lead to stronger heat waves. At the crest of the thermal wave, energy is transported ballistically, while in the diffusive region and during attenuation of the thermal wave,the energy is transported diffusively.展开更多
Water is the most active component in all geological systems. It has an importanteffect on the physical properties of minerals and melts. It also plays a key role in the evolutionof the Earth. Accurate thermodynamics ...Water is the most active component in all geological systems. It has an importanteffect on the physical properties of minerals and melts. It also plays a key role in the evolutionof the Earth. Accurate thermodynamics data on water are currently confined to pressures below1.0 GPa and temperatures below 900℃. Presented in this paper are new data available on theP-T properties of water at pressures up t0 5. 0 GPa, developed from differential thermal analysis and ultrasonic wave amplitude analysis. It has been found that there may exist anotherternary point at 3. 0 GPa and that ultrasonic wave amplitude change of ice-water transitionshows two inflection points above 2. 0 GPa, consistent with the two peaks of differential thermal curves above 2. 0 GPa. It may be a new phenomenon which needs further study.展开更多
Ion-acoustic solitary (IAS) waves in electron-positron-ion (e-p-i) plasma have been of interest to many researchers probably due to their relevance in understanding the Universe. However, the study of non-linear ion-a...Ion-acoustic solitary (IAS) waves in electron-positron-ion (e-p-i) plasma have been of interest to many researchers probably due to their relevance in understanding the Universe. However, the study of non-linear ion-acoustic waves in e-p-i plasma with non-thermal electrons has not been adequately studied. A theoretical investigation on non-linear IAS waves in e-p-i plasma comprising of warm inertial adiabatic fluid ions and electrons that are kappa distributed, and Boltzman distributed positron is presented here using the Sagdeev potential technique. It was found that existence domains of finite amplitude IAS waves were confined within the limits of minimum and maximum Mach numbers with varying k values. For lower values of k, the amplitude of the solitary electrostatic potential structures increased as the width decreased, while for high values, the potential amplitude decreased as the width of the solitary structure increased.展开更多
The ASTER (Advanced Space-borne Thermal Emission and Reflection radiometer) data, including all the 3 parts: VNIR (Visible and Near-Infrared), SWIR (Short Wave Infrared), TIR (Thermal Infrared), were applied for extra...The ASTER (Advanced Space-borne Thermal Emission and Reflection radiometer) data, including all the 3 parts: VNIR (Visible and Near-Infrared), SWIR (Short Wave Infrared), TIR (Thermal Infrared), were applied for extraction of mineral deposits, such as the Ni-Cu deposit in eastern Tianshan, the gypsum in western Tianshan, and the borax in Tibetan. This paper discusses the extraction methodology using the ASTER remote sensing data and reveals the good extraction results. This paper bravely represents the summary of the main achievement for this field by the scientists in other countries and gives a comparison with the works by others. The new achievements, described in this paper, comprise the extraction of anomalies for Ni-Cu deposit, gypsum, and borax.展开更多
New results of two computer experiments on modeling of superthermal neutron-nuclear combustion of natural uranium for two different flux densities of external neutron source and duration of half a year each are presen...New results of two computer experiments on modeling of superthermal neutron-nuclear combustion of natural uranium for two different flux densities of external neutron source and duration of half a year each are presented. The simulation results demonstrate the dependence of the autowave combustion modes on the parameters of the external source.展开更多
针对可重复使用飞行器热防护结构在复杂多场耦合环境下易产生层间脱粘损伤的关键问题,提出基于超声导波与域自适应迁移学习的无损检测方法。通过设计4类典型粘接缺陷的隔热瓦试件,结合双向正交扫描策略与超声激励–接收机制,实现粘接区...针对可重复使用飞行器热防护结构在复杂多场耦合环境下易产生层间脱粘损伤的关键问题,提出基于超声导波与域自适应迁移学习的无损检测方法。通过设计4类典型粘接缺陷的隔热瓦试件,结合双向正交扫描策略与超声激励–接收机制,实现粘接区域的高效覆盖检测。针对试件个体差异引起的信号漂移问题,采用基于峰值比例阈值的相位对齐方法,通过优化窗口长度同步保留损伤敏感特征并抑制噪声干扰。进一步构建域自适应迁移学习网络(Domain-adaptive transfer learning,DATL),实现跨试件损伤特征的分布对齐。试验表明,在跨试件测试场景下,DATL模型准确率仅下降3.9%,域间分布差异指数从0.31降至0.10;在目标域数据量不足40%时,其准确率仍达85%,较卷积神经网络(Convolutional neural network,CNN)提升19.4%。该方法缓解了对损伤类型和试件一致性的依赖,可降低在役热防护结构脱粘检测的误报率与漏检率,为可重复使用飞行器的快速无损检测与健康评估提供了一种可行的解决参考方案。展开更多
Based on the generalized thermoelasticity proposed by Green and Lindsay, the dynamic response of generalized thermoelastic problems with temperature-dependent material properties is investigated. The governing equatio...Based on the generalized thermoelasticity proposed by Green and Lindsay, the dynamic response of generalized thermoelastic problems with temperature-dependent material properties is investigated. The governing equations are formulated and found to be nonlinear because of the temperature-dependence of properties. Owing to the nonlinearity of the governing equations, the finite element method is resorted to for solution. The results obtained show that the temperature-dependent properties influence the variables considered by reducing their magnitudes. This indicates that taking the temperature-dependence of properties into consideration in the investigation of generalized thermoelastic problems is necessary and practical for accurately predicting the thermoelastic behavior.展开更多
The nonlinear thermoelastic responses of an elastic medium exposed to laser generated shortpulse heating are investigated in this article. The thermal wave propagation of generalized thermoelastic medium under the imp...The nonlinear thermoelastic responses of an elastic medium exposed to laser generated shortpulse heating are investigated in this article. The thermal wave propagation of generalized thermoelastic medium under the impact of thermal loading with energy dissipation is the focus of this research. To model the thermal boundary condition(in the form of thermal conduction),generalized Cattaneo model(GCM) is employed. In the reference configuration, a nonlinear coupled Lord-Shulman-type generalized thermoelasticity formulation using finite strain theory(FST) is developed and the temperature dependency of the thermal conductivity is considered to derive the equations. In order to solve the time-dependent and nonlinear equations, Newmark’s numerical time integration technique and an updated finite element algorithm is applied and to ensure achieving accurate continuity of the results, the Hermitian elements are used instead of Lagrangian’s. The numerical responses for different factors such as input heat flux and nonlinear terms are expressed graphically and their impacts on the system’s reaction are discussed in detail.The results of the study are presented for Green–Lindsay model and the findings are compared with Lord-Shulman model especially with regards to heat wave propagation. It is shown that the nature of the laser’s thermal shock and its geometry are particularly determinative in the final stage of deformation. The research also concluded that employing FST leads to achieving more accuracy in terms of elastic deformations;however, the thermally nonlinear analysis does not change the results markedly. For this reason, the nonlinear theory of deformation is required in laser related reviews, while it is reasonable to ignore the temperature changes compared to the reference temperature in deriving governing equations.展开更多
基金Project supported by the National Basic Research Program of China (Grant Nos. 2011CB707902 and 2012CB921504)the National Natural Science Foundation of China (Grant No. 11274166)the State Key Laboratory of Acoustics,Chinese Academy of Sciences (Grant No. SKLA201207)
文摘In most previous models,simulation of the temperature generation in tissue is based on the Pennes bio-heat transfer equation,which implies an instantaneous thermal energy deposition in the medium.Due to the long thermal relaxation time τ（20 s-30 s） in biological tissues,the actual temperature elevation during clinical treatments could be different from the value predicted by the Pennes bioheat equation.The thermal wave model of bio-heat transfer（TWMBT） defines a thermal relaxation time to describe the tissue heating from ultrasound exposure.In this paper,COMSOL Multiphysics 3.5a,a finite element method software package,is used to simulate the temperature response in tissues based on Pennes and TWMBT equations.We further discuss different factors in the bio-heat transfer model on the influence of the temperature rising and it is found that the temperature response in tissue under ultrasound exposure is a rising process with a declining rate.The thermal relaxation time inhibits the temperature elevation at the beginning of ultrasonic heating.Besides,thermal relaxation in TWMBT leads to lower temperature estimation than that based on Pennes equation during the same period of time.The blood flow carrying heat dominates most to the decline of temperature rising rate and the influence increases with temperature rising.On the contrary,heat diffusion,which can be described by thermal conductivity,has little effect on the temperature rising.
基金supported by the National Natural Science Foundation of China under Grant No. 12104155the Canada Research Chairs program+2 种基金the Natural Sciences and Engineering Research Council of Canada (NSERC) for its support through and a Discovery Grantthe Canada Foundation for Innovation and the Ontario Research Fund for a John Evans Leaders Fund (CFIJELF) awardthe oNDuTy Create program funded by NSERC
文摘Active infrared thermography has gained increasing popularity for nondestructive testing and evaluation in various industrial fields,especially for composite structures.In this regard,thermal wave radar(TWR)imaging is recognized as the next-generation active thermography technology to obtain great resolution and depth range over the inspected objects.A critical aspect concerns the optimal test parameter selection to guarantee reliable quality assurance required for industrial products.In this work,single-and multiple-frequency TWR was investigated in a quantitative manner with the goal of optimizing the detection parameters in terms of probing range and lateral and depth resolution.The effects of test parameters,including sampling frequency,modulation frequency,chirp duration,chirp bandwidth,etc,were investigated in detail through experiments on a glass fiber reinforced polymer specimen with multi-scale diameter-to-depth ratio defects.This paper aims to help yield a better understanding of the physical mechanism behind TWR and propose a workable scheme for testing parameter selection in practical applications.
基金Funded by the National Natural Science Foundation of China(No.11602042)the Chongqing Research Program of Basic Research and Frontier Technology(No.cstc2016jcyjA0259)the Scientific and Technological Research Program of Chongqing Municipal Education Commission(No.KJ1601304)
文摘The effect of thermal wave at the initial stage for non-conductive Al_2 O_3 powders compact in field assisted sintering technique(FAST) was investigated. The Lord and Shulman type generalized thermoselastic theory was introduced to describe the influence of thermal-mechanical interaction, as well as the heat transport and thermal focusing caused by thermal wave propagation. The expression of vacancy concentration difference of the particles was deduced by considering transient thermal stress. Subsequently, the relationship between activation energy and vacancy concentration difference was obtained. The mechanism of surface diffusion, volume diffusion, simultaneous surface and volume diffusion was analyzed. The numerical simulations indicate that low sintering temperature can obtain high local temperature by the superposition effect of thermal wave. Vacancy concentration differences were improved during FAST compared with hot-pressure and pressureless sintering, thereby decreasing the sintering time. By contrast, the activation energy declined with the decrease of vacancy concentration difference in the neck growth process.
基金Project supported by the National Natural Science Foundation of China.
文摘The fact that the temperature of living tissue may respond oscillatorily to externalheating has been a classical difficulty in the field of bioheat transfer for a long time.Roemer et al. have carefully discussed this in their serial articles, but experiments did notsupport their conclusions, Tharp et al. have artificially made a time-delay differential equs-tion to describe this phenomenon, but their model is short of a strict theoretical founda-
基金Supported by the National Natural Science Foundation of China(Grant No.50606018)
文摘The conservation equations for heat conduction are established based on the concept of thermal mass.We obtain a general heat conduction law which takes into account the spatial and temporal inertia of thermal mass.The general law introduces a damped thermal wave equation.It reduces to the well-known CV model when the spatial inertia of heat flux and temperature and the temporal inertia of temperature are neglected,which indicates that the CV model only considers the temporal inertia of heat flux.Numerical simulations on the propagation and superposition of thermal waves show that for small thermal perturbation the CV model agrees with the thermal wave equation based on the thermal mass theory.For larger thermal perturbation,however,the physically impossible phenomenon pre-dicted by CV model,i.e.the negative temperature induced by the thermal wave superposition,is eliminated by the general heat conduction law,which demonstrates that the present heat conduction law based on the thermal mass theory is more reasonable.
文摘An analysis has been carried out to study the effects of radiation absorption and firstorder chemical reaction on unsteady mixed convective flow of a viscous incompressible electrically conducting fluid through a porous medium of variable permeability between two long vertical non conducting wavy channels in the presence of heat generation.The unsteadiness in the flow is due to traveling thermal wave imposed on the walls.The governing equations are solved subject to the relevant boundary conditions with the assumption that the solution consists of a mean part and a perturbed part.The zeroth-order,the first order and the total solution of the problem are numerically evaluated and displayed graphically for pertinent parameters.This model finds applications in studying fixed-bed catalytic reactors and packed bed heat exchangers.
基金supported by the National Natural Science Foundation of China (51322603, 51136001, 51356001)the Science Fund for Creative Research Groups (51321002)+2 种基金the Program for New Century Excellent Talents in UniversityTsinghua University Initiative Scientific Research Programthe Tsinghua National Laboratory for Information Science and Technology of China
文摘The transient heat conduction in both armchair and zigzag-edged graphene ribbons pulsed by local heating with a duration of 1 ps was studied using nonequilibrium molecular dynamics simulations. The results show that the heat pulse excites two waves which indicates non-Fourier heat conduction. One of the two waves is a sound wave(first sound), which has macroscopic momentum and propagates at the speed of sound. The other is a thermal wave(second sound), whose propagation speed is 1=ffiffi3pof the sound velocity. The sound wave excited by the heat pulse is a longitudinal wave, whose energy is only transported in the longitudinal direction. The thermal wave excited by the heat pulse is generated by transverse lattice vibrations, with the energy only having the transverse component. The observed anisotropy of the transient heat conduction suggests that the system is in a non-equilibrium state during propagation of the heat pulse. Further statistical analyses show that the displacement of the heat pulse energy is related to the time as hr2 i / t1:80, which implies that heat transport is ballistic-diffusive transport in graphene. The higher proportion of the ballistic transport will lead to stronger heat waves. At the crest of the thermal wave, energy is transported ballistically, while in the diffusive region and during attenuation of the thermal wave,the energy is transported diffusively.
文摘Water is the most active component in all geological systems. It has an importanteffect on the physical properties of minerals and melts. It also plays a key role in the evolutionof the Earth. Accurate thermodynamics data on water are currently confined to pressures below1.0 GPa and temperatures below 900℃. Presented in this paper are new data available on theP-T properties of water at pressures up t0 5. 0 GPa, developed from differential thermal analysis and ultrasonic wave amplitude analysis. It has been found that there may exist anotherternary point at 3. 0 GPa and that ultrasonic wave amplitude change of ice-water transitionshows two inflection points above 2. 0 GPa, consistent with the two peaks of differential thermal curves above 2. 0 GPa. It may be a new phenomenon which needs further study.
文摘Ion-acoustic solitary (IAS) waves in electron-positron-ion (e-p-i) plasma have been of interest to many researchers probably due to their relevance in understanding the Universe. However, the study of non-linear ion-acoustic waves in e-p-i plasma with non-thermal electrons has not been adequately studied. A theoretical investigation on non-linear IAS waves in e-p-i plasma comprising of warm inertial adiabatic fluid ions and electrons that are kappa distributed, and Boltzman distributed positron is presented here using the Sagdeev potential technique. It was found that existence domains of finite amplitude IAS waves were confined within the limits of minimum and maximum Mach numbers with varying k values. For lower values of k, the amplitude of the solitary electrostatic potential structures increased as the width decreased, while for high values, the potential amplitude decreased as the width of the solitary structure increased.
文摘The ASTER (Advanced Space-borne Thermal Emission and Reflection radiometer) data, including all the 3 parts: VNIR (Visible and Near-Infrared), SWIR (Short Wave Infrared), TIR (Thermal Infrared), were applied for extraction of mineral deposits, such as the Ni-Cu deposit in eastern Tianshan, the gypsum in western Tianshan, and the borax in Tibetan. This paper discusses the extraction methodology using the ASTER remote sensing data and reveals the good extraction results. This paper bravely represents the summary of the main achievement for this field by the scientists in other countries and gives a comparison with the works by others. The new achievements, described in this paper, comprise the extraction of anomalies for Ni-Cu deposit, gypsum, and borax.
文摘New results of two computer experiments on modeling of superthermal neutron-nuclear combustion of natural uranium for two different flux densities of external neutron source and duration of half a year each are presented. The simulation results demonstrate the dependence of the autowave combustion modes on the parameters of the external source.
文摘针对可重复使用飞行器热防护结构在复杂多场耦合环境下易产生层间脱粘损伤的关键问题,提出基于超声导波与域自适应迁移学习的无损检测方法。通过设计4类典型粘接缺陷的隔热瓦试件,结合双向正交扫描策略与超声激励–接收机制,实现粘接区域的高效覆盖检测。针对试件个体差异引起的信号漂移问题,采用基于峰值比例阈值的相位对齐方法,通过优化窗口长度同步保留损伤敏感特征并抑制噪声干扰。进一步构建域自适应迁移学习网络(Domain-adaptive transfer learning,DATL),实现跨试件损伤特征的分布对齐。试验表明,在跨试件测试场景下,DATL模型准确率仅下降3.9%,域间分布差异指数从0.31降至0.10;在目标域数据量不足40%时,其准确率仍达85%,较卷积神经网络(Convolutional neural network,CNN)提升19.4%。该方法缓解了对损伤类型和试件一致性的依赖,可降低在役热防护结构脱粘检测的误报率与漏检率,为可重复使用飞行器的快速无损检测与健康评估提供了一种可行的解决参考方案。
基金supported by the National Natural Science Foundation of China(Nos.11372123 and 11072101)the Natural Science Foundation of Gansu Province(No.1107RJZA151)+1 种基金the Fundamental Research Funds for the Universities of GansuHong-Liu Excellent Talents Program of Lanzhou University of Technology
文摘Based on the generalized thermoelasticity proposed by Green and Lindsay, the dynamic response of generalized thermoelastic problems with temperature-dependent material properties is investigated. The governing equations are formulated and found to be nonlinear because of the temperature-dependence of properties. Owing to the nonlinearity of the governing equations, the finite element method is resorted to for solution. The results obtained show that the temperature-dependent properties influence the variables considered by reducing their magnitudes. This indicates that taking the temperature-dependence of properties into consideration in the investigation of generalized thermoelastic problems is necessary and practical for accurately predicting the thermoelastic behavior.
文摘The nonlinear thermoelastic responses of an elastic medium exposed to laser generated shortpulse heating are investigated in this article. The thermal wave propagation of generalized thermoelastic medium under the impact of thermal loading with energy dissipation is the focus of this research. To model the thermal boundary condition(in the form of thermal conduction),generalized Cattaneo model(GCM) is employed. In the reference configuration, a nonlinear coupled Lord-Shulman-type generalized thermoelasticity formulation using finite strain theory(FST) is developed and the temperature dependency of the thermal conductivity is considered to derive the equations. In order to solve the time-dependent and nonlinear equations, Newmark’s numerical time integration technique and an updated finite element algorithm is applied and to ensure achieving accurate continuity of the results, the Hermitian elements are used instead of Lagrangian’s. The numerical responses for different factors such as input heat flux and nonlinear terms are expressed graphically and their impacts on the system’s reaction are discussed in detail.The results of the study are presented for Green–Lindsay model and the findings are compared with Lord-Shulman model especially with regards to heat wave propagation. It is shown that the nature of the laser’s thermal shock and its geometry are particularly determinative in the final stage of deformation. The research also concluded that employing FST leads to achieving more accuracy in terms of elastic deformations;however, the thermally nonlinear analysis does not change the results markedly. For this reason, the nonlinear theory of deformation is required in laser related reviews, while it is reasonable to ignore the temperature changes compared to the reference temperature in deriving governing equations.
