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Elastic-viscoplastic constitutive equations of K439B superalloy and thermal stress simulation during casting process

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中国铸造:英文版 2023年第5期20卷 403-413页

作者： Da-shan Sui Yu Shan Dong-xin Wang Jun-yi Li Yao Xie Yi-qun Yang An-ping Dong Bao-de Sun Institute of Forming Technology&Equipment School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200030China State Key Laboratory of Special Rare Metal Materials Northwest Rare Metal Materials Research Institute Ningxia Co.Ltd.Shizuishan 753000NingxiaChina Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

K439B nickel-based superalloy is a new type of high-temperature material.There is insufficient research on its constitutive equations and numerical modeling of thermal stress.Isothermal tensile experiments of K439B superalloy at different temperatures(20°C-1,000°C)and strain rates(1.33×10^(-3)s^(-1)-5.33×10^(-3)s^(-1))were performed by using a Gleeble-3800 simulator.The elastic moduli at different temperatures(20°C-650°C)were measured by resonance method.Subsequently,stress-strain curves were measured for K439B superalloy under different conditions.The elastic-viscoplastic constitutive equations were established and the correspongding parameters were solved by employing the Perzyna model.The verification results indicate that the calculated values of the constitutive equations are in good agreement with the experimental values.On this basis,the influence of process parameters on thermal stress was investigated by numerical simulation and orthogonal experimental design.The results of orthogonal experimental design reveal that the cooling mode of casting has a significant influence on the thermal stress,while pouring temperature and preheating temperature of shell mold have minimal impact.The distribution of physical fields under optimal process parameters,determined based on the orthogonal experimental design results,was simulated.The simulation results determine separately the specific positions with maximum values for effective stress,plastic strain,and displacement within the casting.The maximum stress is about 1,000.0 MPa,the plastic strain is about 0.135,and the displacement is about 1.47 mm.Moreover,the distribution states of thermal stress,strain,and displacement are closely related to the distribution of the temperature gradient and cooling rate in the casting.The research would provide a theoretical reference for exploring the stress-strain behavior and numerical modeling of the effective stress of the alloy during the casting process.

关键词： nickel-based superalloy investment casting Perzyna model elastic-viscoplastic thermal stress numerical simulation

Numerical simulation of coupling heat transfer and thermal stress for spent fuel dry storage cask with different power distribution and tilt angles

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Nuclear Science and Techniques 2023年第2期34卷 109-127页

作者： Wei‑Hao Ji Jian‑Jie Cheng Han‑Zhong Tao Wei Li College of Urban Construction Nanjing Tech UniversityNanjing 211800China School of Energy Science and Engineering Nanjing Tech UniversityNanjing 211800China

Dry storage containers must be secured and reliable during long-term storage,and the effect of decay heat released from the internal spent fuel on the cask has become an important research topic.In this paper,a 3D computational fluid dynamics model is presented,and the accuracy of the calculation is verified,with computational errors of less than 6.2%.The thermal stress of the dry storage cask was estimated by coupling it with a transient temperature field.The total power remained constant and adjusting the power ratio of the inner and outer zones had a small effect on the stress results,with a maximum equivalent stress of approximately 5.2 kPa,which occurred at the lower edge of the shell.In the case of tilt,the temperature gradient varied in a wavy distribution,and the wave crest moved from right to left.Altering the tilt angle affects the air distribution in the annular gap,leading to the shell temperature being transformed,with a maximum equivalent stress of 202 MPa at the bottom of the shell.However,the equivalent stress in both cases was less than the yield stress(205 MPa).

关键词： thermal stress CFD simulation Spent nuclear fuel Dry storage cask

thermal stress and Assembling Parameters Evolution of CMC Bolted Joint under Transient thermal Loads

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Journal of Harbin Institute of Technology(New Series) 2021年第3期28卷 1-8页

作者： Shuyuan Zhao Zhengyu Li Zeliang Pu Xinyang Sun Wenjiao Zhang National Key Laboratory of Science and Technology for National Defense on Advanced Composites in Special Environments Harbin Institute of TechnologyHarbin 150080China School of Aeronautics and Astronautics Harbin Institute of TechnologyHarbin 150001China Engineering College Northeast Agricultural UniversityHarbin 150030China

Ceramic matrix composite(CMC) and superalloy bolted joints have exhibited great potential for high temperature hot structure application in hypersonic aircraft. In service conditions, the thermal expansion mismatch between CMC and superalloy plates will cause complex thermal stress and strain distributions at hole-edge areas and assembly parameters changes of the joints under elevated temperatures. These effects might lead to early damage of joint structure, which will endanger the structural integrity and load carrying capacity of aircraft components. In the present study, transient heat transfer and thermo-structural analysis of C/SiC composite and superalloy bolted joint were carried out by using a commercial FEA software ABAQUS. The stress distributions at hole-edge areas, pre-load loosening, and variation of bolt-hole clearance of CMC bolted joints under transient temperature rises were discussed for better understanding of high temperature structural behaviors. Results showed that pre-load declined with the increase of imposed hot side temperature, due to the thermal expansion mismatch between CMC and superalloy. The bolt-hole clearance for the composite plate decreased, whereas the clearance for the superalloy plate increased with the rise of temperature.

关键词： ceramic matrix composite heat transfer thermal stress pre-load bolt-hole clearance

Influence of pore structure on thermal stress distribution inside coal particles during primary fragmentation

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Particuology 2024年第2期85卷 49-61页

作者： Kai Qiao Shan Zhong Siyang Tang Ke Yang Hairong Yue Kui Ma Lei Song Bin Liang School of Chemical Engineering Sichuan UniversityChengdu610065China Institute of New Energy and Low-carbon Technology Chengdu610207China

thermal stress is an important reason of coal particle primary fragmentation,during which the role of pore structure is ambiguous.thermal stress induced fragmentation experiments were conducted with low volatile coal/char particles,and the results show that the fragmentation severity enhances with increasing porosity.Various porous thermal stress models were developed with finite element method,and the influences of the pore shape,size,position and porosity on the thermal stress were discussed.The maximum thermal stress inside particle increases with pore curvature,the pore position affects the thermal stress more significantly at the particle center and surface.The expectation of the maximum tensile thermal stress linearly increases with porosity,making the particles with higher porosity easier to fragment,contrary to the conclusion deduced from the devolatilization theory.The obtained results are valuable for the analysis of different thermal processes concerning the thermal stresses of the solid feedstocks.

关键词： Coal particle Primary fragmentation thermal stress Pore structure Porosity

Voronoi Cell Finite Element Study on Particle-Reinforced Composites Containing Interphases Considering Both Interfacial Debonding and thermal stress

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Acta Mechanica Solida Sinica 2022年第6期35卷 1055-1067页

作者： Jianfei Li Rui Zhang Ran Guo Guohua Li Faculty of Civil Engineering and Mechanics Kunming University of Science and TechnologyKunming650000China

This paper derives the complementary energy functional based on the Voronoi element of particle-reinforced composites containing interphases to compute the interfacial debonding and thermal stress.When calculating interfacial debonding stress,it is assumed that the surface force is zero at the interface where debonding occurs,and a new modified complementary energy functional is derived with this boundary condition.When considering the thermal stress due to temperature change,the thermal strain is introduced into the complementary energy functional,and the thermal stress is then calculated.According to the derived formula,a Fortran program named Voronoi cell finite element model(VCFEM)is written.The interfacial debonding and thermal stress is calculated using both VCFEM and the finite element software MARC,and the calculation results are compared.It shows that the calculation results of the VCFEM are roughly comparable to those of the MARC,verifying the effectiveness of the VCFEM.

关键词： Voronoi VCFEM Interphase Interfacial debonding thermal stress

thermal stress damage mechanism in single-crystal germanium caused by 1080 nm laser irradiation

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中国物理B:英文版 2023年第10期32卷 572-578页

作者：沙银川李泽文贾志超韩冰倪晓武 School of Science Nanjing University of Science and TechnologyNanjing 210094China School of Materials Engineering Jinling Institute of TechnologyNanjing 211169China School of Electronic Engineering and Optical Engineering Nanjing University of Science and TechnologyNanjing 210094China

The process of thermal stress damage during 1080 nm laser ablation of single-crystal germanium was recorded in real time using a high-speed charge-coupled device.A three-dimensional finite element numerical model based on Fourier's heat conduction equation,Hooke's law and the Alexander–Hasson equation was developed to analyze the thermal stress damage mechanism involved.The damage morphology of the ablated samples was observed using an optical microscope.The results show that the cooling process has an important influence on fracture in the laser-irradiated region of single-crystal germanium.Fracture is the result of a combination of thermal stress and reduction in local yield strength.

关键词： thermal stress single-crystal germanium fracture damage mechanism

Impacts of Startup,Shutdown and Load Variation on Transient Temperature and thermal stress Fields within Blades of Gas Turbines

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Journal of thermal Science 2022年第3期31卷 727-740页

作者： CAI Liuxi HOU Yanfang LI Fang LI Yun WANG Shunsen MAO Jingru School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049China

Based on the actual operation parameters and temperature-dependent material properties of a gas turbine unit,composite cooling blade model and corresponding reliable boundary conditions were established.Transient thermal-fluid-solid coupling simulations were then comprehensively conducted to analyze the transient flow and the temperature field of the blade under startup,shutdown,and variable loads condition.Combined with the obtained transient temperature data,the non-linear finite element method was exploited to examine the effect of these transient operations on the turbine blade thermal stress characteristics.Results show that the temperature and pressure on the blade surface increase with the load level and vice versa.As the startup process progresses,the film cooling effectiveness and the heat convection of airflows inside the blade continuously grow;high-temperature areas on the pressure surface and along the trailing edge of the blade tip gradually disappear.Locally high-temperature zones with the maximum of 1280 K are generated at the air inlet and outlet of the blade platform and the leading edge of the blade tip.The high thermal stresses detected on the higher temperature side of the temperature gradient are commonly generated in places with large temperature gradients and significant geometry variations.For the startup/shutdown process,the rate of increase/decrease of the thermal stress is positively correlated with the load variation rate.A slight variation rate of the load(1.52%/min)can lead to an apparent alteration(41%)to the thermal stress.In operations under action of the variable load,although thermal stress is less sensitive to the load variation,the rising or falling rate of the exerted load still needs to be carefully controlled due to the highly leveled thermal stresses.

关键词： composite cooling blade thermal-fluid-solid coupling method transient temperature field load variation thermal stress

Effects of acute and chronic thermal stress on survival,apoptosis,and transcriptional responses of Scapharca broughtonii

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Journal of Oceanology and Limnology 2023年第6期41卷 2363-2373页

作者： Desheng ZOU Weian CAO Guilong LIU Junhao NING Xia LU Jinjing WANG Min CHEN Bo LIU Jinsheng ZHANG Chunde WANG Yantai Institute of Coastal Zone Research Chinese Academy of SciencesYantai 264003China University of Chinese Academy of Sciences Beijing 100049China Yantai Spring-Sea AquaSeed Co. Ltd.Yantai 264006China Qingdao Agricultural University Qingdao 266109China Zhaoyuan Xiadian Agricultural Technology Promotion Station Yantai 265415China

Ocean warming is altering the habitats of marine invertebrates,which has resulted in an increased physiological stress to marine molluscs,especially those intertidal bivalves,such as the ark shell Scapharca broughtonii.We investigated the physiological and transcriptional responses of ark shells to acute and chronic thermal stress results showed that at 33℃,a significantly higher cumulative mortality(55.7%)occurred under acute thermal stress than chronic thermal stress.The apoptosis rate of hemocytes was sustained at higher levels and the necrosis rate was increased significantly in a time-dependent manner under acute thermal stress.However,under chronic thermal stress,the apoptosis and necrosis rates exhibited similar change trends:a rapid increase followed by a gradual decline and sustained at a relatively high level until the end of the experiment.The expressions of heat shock protein genes(HSP20 and HSP90),apoptosis-related genes(TRAF6,GRP78,NIX,and Casp-3),antioxidative-related genes(GST and MRP)and cellular detoxification-related genes(HbⅡB,NOS-1,HO-1,and ENO-1)were upregulated significantly under both acute and chronic thermal stresses.These results demonstrated that the anti-apoptotic system,antioxidant defense system,cellular detoxification system,and heat shock proteins(HSPs)played vital roles for ark shells in response to thermal stress.As acute thermal stress can result in irreversible damage to marine molluscs,it is thus advised that chronic thermal stress should be used to select thermal-resistant ark shell strains.

关键词： Scapharca broughtonii thermal stress apoptosis necrosis gene expression

Experimental Study on thermal stress of Concrete with Different Expansive Minerals Using a Temperature stress Testing Machine

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Journal of Wuhan University of Technology(Materials Science) 2022年第2期37卷 222-228页

作者：贾福杰姚燕 ZHAO Shunzeng LIU Li LI Changcheng State Key Laboratory of Green Building Materials China Building Materials AcademyBeijing 100024China

In order to compare the compensation effect of expansive materials with different mineral sources on the temperature stress of concrete,we investigated the temperature stress of concrete when adding calcium sulfoaluminate type expansive materials(CSA)or CaO and calcium sulfoaluminate mixed type expansive materials(HCSA)at different temperatures by temperature-stress testing machine(TSTM)considering the influence of temperature history on the expansion.The experimental results show that the expansion characteristics of the two kinds of expansive materials with different mineral sources significantly vary.When adding expansive materials,the growth rate of compressive stress during the heating stage increases obviously,the maximum compressive stress is higher,while the decline rate of tensile stress in the late cooling stage becomes slow,and finally cracking temperature decreases.It is proved that concrete with HCSA has lower cracking temperatures and better temperature shrinkage compensation effect.Therefore,it is rational to choose HCSA when preparing concrete with high expansion energy to reduce thermal cracking.

关键词： thermal stress temperature-stress testing machine expansive materials cracking temperature compensation mechanism