Table of Content

    28 November 2021, Volume 55 Issue 11 Previous Issue    Next Issue
    Innovation and Design
    Algorithm and Experimental Verification of Self-Assembling Platform Based on Cooperative Control
    YU Te, WANG Lei
    2021, 55 (11):  1493-1498.  doi: 10.16183/j.cnki.jsjtu.2020.415
    Abstract ( 567 )   HTML ( 414 )   PDF (5600KB) ( 442 )   Save

    A method for constructing a novel offshore platform was proposed. Based on the cooperative control of multiple unmanned vessels, a self-assembling platform was realized, which could be reconfigured into different shapes according to requirements. A docking controller was designed to realize the docking of two modules. A connecting rod and electromagnetic forces were adopted to complete the docking and reduce the difficulty. Besides, a test site was constructed using the conditions of pool, and a model test was performed to verify the functions of the proposed self-assembling platform. The results show that the design can realize the docking of any unmanned vessel. Compared with the single platform, this self-assembling platform can perform more complex tasks, whose decentralized design makes it more flexible and reliable.

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    Batch Process Monitoring with Dynamic-Static Joint Indicator Based on GSFA-GNPE
    ZHAO Xiaoqiang, MOU Miao
    2021, 55 (11):  1417-1428.  doi: 10.16183/j.cnki.jsjtu.2020.290
    Abstract ( 620 )   HTML ( 12 )   PDF (2334KB) ( 306 )   Save

    Traditional process monitoring methods ignore the time-series correlation between variables, and do not distinguish the dynamic relationship and static relationship between variables, resulting in poor monitoring effect. To solve these problems, a dynamic-static joint indicator monitoring method of batch process based on global slow feature analysis(GSFA)-global neighborhood preserving embedding (GNPE) is proposed in this paper, which can effectively extract dynamic global features and static global features. First, the dynamic and static characteristics of the process variables are evaluated. Variables with weak autocorrelation and cross-correlation are regarded as static variables, and the remaining variables are regarded as dynamic ones. Next, the GSFA and GNPE models are constructed for dynamic and static subspaces, respectively. Finally, the statistical information from each subspace is combined by using Bayesian inference to obtain the joint indicator of the mixed model to realize process monitoring. Finally, the proposed algorithm is applied to a numerical example and the penicillin fermentation simulation process for simulation verification. The results show that the proposed GSFA-GNPE algorithm has better fault detection effects than other algorithms.

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    Optimization and Performance Analysis of Desiccant Wheel-Assisted Atmospheric Water Harvesting Processes
    TU Rang, LIU Mengdan, WANG Siqi
    2021, 55 (11):  1392-1400.  doi: 10.16183/j.cnki.jsjtu.2020.193
    Abstract ( 619 )   HTML ( 20 )   PDF (1225KB) ( 385 )   Save

    To solve the fresh water scarce problem in dry regions, a desiccant wheel-assisted atmospheric water harvesting system is designed. Using water production rate as the index, studies are conducted to find the optimized air handling process under typical ambient conditions, considering influencing factors such as air flow rate ratio, stage numbers, and regeneration temperature. Based on a three-stage-desiccant wheel air humidification system, power consumptions are calculated for ideal and actual thermodynamic processes. Besides, using water production efficiency as the index, at the same water production rate, this system is compared with the traditional air-cooling method. The results show that this system has higher performances than the traditional air-cooling method. Under the discussed working conditions, the water production rate of the proposed system is in the range of 15.8—30.9 kg/h and the water production efficiency is in the range of 1.3—2.1 kg/(kW·h). The water production efficiency can be enhanced to 3.3—4.4 kg/(kW·h)when solar heater is used to replace heat pump systems. The proposed method can effectively enrich fresh water sources in dry regions.

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    Element-Free Galerkin Scaled Boundary Method Based on Moving Kriging Interpolation for Steady Heat Conduction Analysis with Temperatures on Side-Faces
    WANG Feng, CHEN Jiali, CHEN Denghong, FAN Yong, LI Zhiyuan, HE Weiping
    2021, 55 (11):  1483-1492.  doi: 10.16183/j.cnki.jsjtu.2020.215
    Abstract ( 486 )   HTML ( 13 )   PDF (1618KB) ( 522 )   Save

    The element-free Galerkin scaled boundary method (EFG-SBM) based on moving Kriging (MK) interpolation is used to solve steady heat conduction problems with temperature loads on side-faces, in which the circumferential boundary is discretized based on MK interpolation and the element-free Galerkin (EFG) method. As the shape functions constructed from the MK interpolation possess the Kronecker delta interpolation property, the MK shape functions overcome the shortcomings of moving least squares (MLS) approximation which is difficult to impose essential boundary conditions directly and accurately. As a new boundary-type meshless method, EFG-SBM has advantages of the EFG and scaled boundary finite element method (SBFEM). This method inherits the semi-analytical property of SBFEM by introducing the scaled boundary coordinate system, in which the governing differential equations are weakened in the circumferential direction and can be solved analytically in the radial direction. Unlike the traditional SBFEM, the preprocessing and postprocessing processes of EFG-SBM are simplified since only the nodal data structure is required in the circumferential direction. Numerical examples show that the EFG-SBM based on MK interpolation can obtain a higher accuracy than the SBFEM based on Lagrange polynomials. Compared with the finite element method (FEM), this method can better characterize the thermal singularity at the sharp corner and the temperature distribution of the infinite region.

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    Unsteadiness and Modal Analysis of Ridge Ice-Induced Separation in Post-Stall Conditions via IDDES
    TAN Xue, ZHANG Chen, XU Wenhao, WANG Fuxin, WEN Minhua
    2021, 55 (11):  1333-1342.  doi: 10.16183/j.cnki.jsjtu.2020.427
    Abstract ( 670 )   HTML ( 27 )   PDF (15798KB) ( 653 )   Save

    High-resolution simulation of shear layer oscillation induced by ridge ice in post-stall condition is conducted via the improved delayed detached-eddy simulation (IDDES) method. The flow-field evolution characteristics of large scale separation in high Reynolds number condition are described. It is shown that the ridge ice and trailing edge of the lower surface induce the development of shear flow at the same time. The wall is not reattached by the shear layer induced by ridge ice, and the “up-wash” flow from the lower surface is interacted with the shear layer, which lead to the formation of large-scale coherent structures. Combined with the spectral analysis, the pressure pulsation located in the shear layer is characterized by two typical frequencies, which are associated with Kelvin-Helmholtz instability and appear as the vortex pairing and shedding. Based on the proper orthogonal decomposition, the dominant mode of pressure pulsation between shear layers is extracted as large-scale coherent structures. The same peak value is shown in power density spectrum of dominant mode temporal coefficient and lift coefficient, which indicates that the large-scale coherent structure is connected with lift fluctuation.

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    Numerical Simulation of Compressor Stall Recovery Control
    GAO Yuan, WU Yadong, OUYANG Hua
    2021, 55 (11):  1343-1351.  doi: 10.16183/j.cnki.jsjtu.2020.261
    Abstract ( 666 )   HTML ( 16 )   PDF (12908KB) ( 428 )   Save

    In order to explore the influencing factors of the effectiveness and stability for stall recovery and its flow mechanism when the antisurge valve is opened quickly, the dynamic stall recovery processes are simulated and the recovery processes at different discharging speeds are emphatically compared. Two numerical simulation methods, i.e., the distributed speed-changeable MG (Moore-Greitzer) model and the RANS (Reynolds Averaged Navier-Stokes) equation are used. The performance curves predicated by the two models agree well. The results of RANS show that the flow field changes are essentially the same when the valve is opened at different speeds. The disturbance, affected by the high-speed air flow generated at the inlet, moves downstream and finally reaches the leading edge of the rotor, whose scale will be further reduced with the impact of axial high-speed flow until completely dissipated. A comparison of different valve opening speeds indicates that the faster the valve is opened, the stronger the high-speed air flow generated at the inlet, shortening the stall recovery time. The greater the disturbance weakening degree, the faster the circumferential propagation speed of the disturbance, and the closer to the rotor speed. In the process of valve opening, the air flow fluctuation is more intense, and more energy is lost.

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    Numerical Simulation of Influence of Adsorption on Surface Heterogeneous Catalysis Process of Hypersonic Vehicles
    LI Qin, YANG Xiaofeng, DONG Wei, DU Yanxia
    2021, 55 (11):  1352-1361.  doi: 10.16183/j.cnki.jsjtu.2020.288
    Abstract ( 502 )   HTML ( 9 )   PDF (3404KB) ( 524 )   Save

    In view of the issue that surface catalysis has a significant influence on aerodynamic heating of hypersonic vehicle heatshield and is difficult to accurately predict, a four-step surface heterogeneous catalytic model including physisorption, chemisorption, Eley-Rideal (ER) recombination, and Langmuir-Hinshelwood (LH) recombination was established by combining theoretical analysis and numerical simulation. Based on the model, the nonequilibrium flow and the aerodynamic heat around a two-dimensional cylinder were simulated. The influence of the fraction of occupied physisorption and chemisorption sites on the catalysis rate and the aerodynamic heat was analyzed. The results show that the established model can improve the prediction accuracy of the aerodynamic heat. The surface adsorption has a nonlinear influence on the aerodynamic heat due to the competing and promoting between different reaction pathways. Based on the real physicochemical process, the model can reflect the catalytic properties of different materials and further provides theoretical support for the lightweight and low redundancy design of the thermal protection system.

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    Cooperative Control of Aircraft Ground Deicing Resources
    LI Biao, WANG Liwen, XING Zhiwei, WANG Sibo, LUO Qian
    2021, 55 (11):  1362-1370.  doi: 10.16183/j.cnki.jsjtu.2020.342
    Abstract ( 565 )   HTML ( 8 )   PDF (1454KB) ( 416 )   Save

    Aimed at the problem of weak coordination and low balance of distributed resources under multiple parallel deicing tasks, a cooperative control method of aircraft ground deicing resources based on multi-agent negotiation was proposed, which combined airport deicing resource allocation and space-time distribution. A framework for collaborative operation of multi-agent deicing resources was established, and a resource optimization method for the bidding mechanism of a global collaborative consortium was designed to improve the overall task balance. Based on the operating plan, an autonomous multi-agent resource collaborative optimization model was constructed. The model predictive control method was applied to generate a collaborative control strategy, and the feasibility was verified in actual scenarios. The results demonstrate that the resource coordination and anti-interference ability of the proposed method are significantly enhanced while meeting the real-time requirements. Compared with the results obtained by other methods, the average takeoff tolerance is 4.89 min, increased by 1.015 min, and the average utilization rate is increased by 15.28%, which can ensure the safety and synergy of deicing resources.

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    Strength Properties of Saturated Sand-Structure Interface by Triaxial Test Method
    LIU Shiao, LIAO Chencong, CHEN Jinjian, YE Guanlin, XIA Xiaohe
    2021, 55 (11):  1371-1379.  doi: 10.16183/j.cnki.jsjtu.2020.299
    Abstract ( 616 )   HTML ( 12 )   PDF (5166KB) ( 241 )   Save

    A novel test method for analyzing the influence of stress path and roughness of structure on the strength characteristics of saturated sand-structure interface by using triaxial apparatus is presented. By making a triaxial specimen with a slope structure with a certain inclination angle, the soil slides along the preset failure surface during the shearing process, and the slope surface roughness of the structure can be controlled and adjusted. A triaxial instrument is used to control the changes in axial pressure,confining pressure to achieve loading in different stress paths. The soil slides along the structure surface with a certain angle during shearing when preformed failure surface exists. The roughness of the structure can be controlled and adjusted. The triaxial apparatus is used to control the confining pressure change of the sample to realize loading under different drainage conditions and stress paths. To verify the effectiveness of the method, direct shear test and triaxial shear tests are carried out on the specimen composed of Fujian sand and steel structures with different roughness and different stress paths. The results show that at the beginning of sliding, the friction angle of the interface in the interfacial constant normal stress path is smaller than that in the conventional shear path. Under smooth conditions, the interface friction angle obtained by direct shear test is 30% to 40% lower than that obtained by triaxial test. Under rough conditions, the interface friction angle obtained by direct shear test is slightly smaller than that obtained by triaxial test, and closer to the friction angle in normal stress shear paths.

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    Risk-Based Evacuation Model for Steel Platform Formwork in Skyscraper Construction and Its Application
    HUA Ying, HE Jun, ZHAO Jincheng, ZOU Jiexin, ZHANG Jingjing, RUAN Shipeng
    2021, 55 (11):  1380-1391.  doi: 10.16183/j.cnki.jsjtu.2020.251
    Abstract ( 544 )   HTML ( 9 )   PDF (29439KB) ( 317 )   Save

    Integral steel platform formwork is widely used in the construction of super high-rise buildings, which brings a high degree of risk uncertainty to construction personnel. Therefore, it is crucial and necessary to establish a risk-based evacuation model for steel platform formwork in skyscraper construction. First, the spatial distribution of hazards sources on the steel platform is considered, hazardous areas are defined, and expert data are collected through survey questionnaires to assess the joint risk probability. Next, the joint risk probability of hazardous areas is coupled into the evacuation process based on the cellular automaton floor field model, and the evacuation process of construction personnel on the steel platform is simulated. Finally, the proposed risk-based evacuation simulation model is applied to an actual construction project. The results show that the influence of the top and lower hazardous areas on the evacuation process is significantly affected by the size of the exit. The model provides a new paradigm for experience-oriented construction safety management, with a theoretical and application value for the maintenance of the integral steel platform formwork system.

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    Intelligent Monitoring Micro-Electro-Mechanical-System Sensor of Herringbone Gate of Dateng Gorge
    XIE Ziyi, DUAN Li, WENG Haotian
    2021, 55 (11):  1401-1407.  doi: 10.16183/j.cnki.jsjtu.2020.102
    Abstract ( 507 )   HTML ( 13 )   PDF (10442KB) ( 276 )   Save

    Bottom pivot bearing acts as the supporting and rotating component of the important water conservancy structure. The wear in the turning and closing operation is directly related to the normal operation and reliability of the gate. To directly monitor the wear of the bearing under severe deep water working conditions, a novel thin film resistive wear sensor was designed and constructed by using the micro-electro-mechanical-system (MEMS) micro-manufacturing technology. The wear measurement and characterization experiments were conducted. Besides, a wear test was simulated by computer simulation modeling. The relationship between the measured resistance and the wear parameters under different working conditions was specifically analyzed. The results show that the production and installation process of the sensor is feasible, and the experimental results are basically consistent with the simulation results. In the allowable range of working conditions, as the resistance increases, the accuracy of wear measurement increases. The sensor is expected to be applied in the intelligent monitoring of the herringbone gate of Dateng Gorge, and realize the Internet of things (IoT) and intelligent monitoring of the water conservancy projects in the 21st century.

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    Unsupervised Transfer Learning for Remaining Useful Life Prediction of Elevator Brake
    JIANG Yudi, HU Hui, YIN Yuehong
    2021, 55 (11):  1408-1416.  doi: 10.16183/j.cnki.jsjtu.2020.175
    Abstract ( 622 )   HTML ( 21 )   PDF (3468KB) ( 645 )   Save

    In order to improve the life prediction effect of elevator brake in the real working environment, an unsupervised deep transfer learning (UDTL) method based on long short-term memory encoder-decoder (LSTM-ED) was proposed. The simulation data were used to analyze the health status of brake when it was working. First, the LSTM-ED and the fully connected network were initially trained through the source domain data. Then, the LSTM-ED was used as a feature extractor to map the simulated and actual data to the feature space, and the maximum mean discrepancy was adopted to achieve data alignment. Finally, the target domain data in the feature space was regressed through the fully connected network to predict the remaining useful life (RUL) of the real brake. In the training phase, a step-by-step training method was used to ensure the accuracy of a single module. The validity was verified by comparing the experimental simulation data with the real working data in the elevator tower. The results show that by introducing the transfer learning and step-by-step training methods, the proposed method can reduce the mean square error of RUL prediction to 0.0016, and can achieve accurate RUL prediction of elevator brakes in real working environment.

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    A Structural Reconstruction Method of Large Ship Based on Grey Theory
    WANG Zhikai, CHEN Jin, YAO Xiongliang, JIANG Zifei
    2021, 55 (11):  1429-1437.  doi: 10.16183/j.cnki.jsjtu.2020.056
    Abstract ( 474 )   HTML ( 10 )   PDF (3978KB) ( 299 )   Save

    Aimed at the reconstruction problem of foreign large-scale warships, the spacing and minimum plate thickness of some profiles of large-scale warships are obtained by adopting the grey theory method and taking the data in the design code of warships as samples. Based on the advantages of the grey theory in dealing with small data and uncertainties, the grey models of different captains and their corresponding profile parameters are built and compared with the data of foreign large ships. The results show that the method has a high accuracy in calculating structural parameters with a strong correlation with the total longitudinal strength. The reason for the deviation in calculating structural parameters with local strength as the main consideration factor lies in the fact that the captain parameters as the reference for modeling are highly correlated with the total longitudinal strength. The magnitude of the deviation by calculating the grey relational degree between the structural parameters and the captain is described, and the results obtained are of engineering application value.

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    An Operation Stability Assessment Method of a Single-Parameter in team Power System Based on MSOP
    ZHENG Yiyang, NI He, JIN Jiashan
    2021, 55 (11):  1438-1444.  doi: 10.16183/j.cnki.jsjtu.2020.256
    Abstract ( 464 )   HTML ( 11 )   PDF (972KB) ( 207 )   Save

    Aimed at the lack of effective stability evaluation methods for the current steam power system, an operation stability assessment method suitable for single parameter is proposed. This method is a composite method, which first applied the midpoint and regression based empirical mode decomposition (MREMD) and singular value decomposition (SVD) to decompose the time series of operation parameters and extract their hidden trend terms. Then, the components are selected for reconstruction according to the optimal algorithm parameter permutation entropy (OAPPE) of each component. Finally, the auto-regressive integrated moving average (ARIMA ) model commonly used in the non-stationary time series analysis is utilized to predict the trend and the disturbance of parameters, and their distribution characteristics are also extracted in this process, based on which, the probability of instability (PI) of operation parameters at each point on the predicted trend are calculated, and their stabilities are quantitatively evaluated. The actual case proves that this method can effectively assess the operation stability of a single parameter of the steam power system, which has a certain theoretical innovation and engineering application value.

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    Modeling and Experimental Study of Tin Whiskers for 3D Electronic Packaging
    WANG Zekun, ZHANG Fuxi
    2021, 55 (11):  1445-1452.  doi: 10.16183/j.cnki.jsjtu.2021.017
    Abstract ( 629 )   HTML ( 9 )   PDF (5353KB) ( 606 )   Save

    The release of compressive stress and atom diffusion have important influences on the growth of whiskers in 3D electronic packaging, and the compressive stress is also one of the main factors for dynamic recrystallization (DRX). By using the mathematical model of growth mechanism and the behavior of tin whisker based on the finite element method, the process of forming whiskers on silicon substrate by 3D electronic packaging tin layer with a typical physical size and structure was simulated. The qualitative analysis and growth of whiskers were realized. By controlling the key parameters such as gas pressure, thermal cycling temperature, and cycle of Ar in the background of the experiment, the external factors and plating process were constructed. The experimental system of accelerated test of internal pressure stress and whisker growth speed, length, and density in the film was constructed. The growth rate and density of whiskers were observed and detected by SEM. The effectiveness of the mathematical model of stress release, atom diffusion, and DRX in 3D electronic packaging tin whiskers was verified by SEM. The quantitative description of whiskers was realized, providing constructive suggestions for reducing whisker problems in future 3D packaging microstructure graphic design.

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    Dirac Cone Characteristics of Hexachiral Phononic Crystal
    CHEN Luyun, WANG Jian, CUI Yifeng, KONG Hui
    2021, 55 (11):  1453-1458.  doi: 10.16183/j.cnki.jsjtu.2020.242
    Abstract ( 551 )   HTML ( 9 )   PDF (3251KB) ( 418 )   Save

    The band structure properties of phononic crystal is important to evaluate the vibration and noise reduction of acoustic metamaterials. Taking the 2D hexachiral phononic crystal as an example, the band structure and Dirac cone properties were investigated by numerical analysis, and the four-fold accidental degenerate Dirac point was obtained in the center of Brillouin zone. By adjusting the design parameters of ligament structure, a double Dirac cone was broken and a novel directional band gap was formed. The influence of geometric parameters on the directional band gaps width was investigated, and the band structure inversion problem was further discussed. This research can provide support for the application of hexachiral phononic crystal in elastic wave manipulation and acoustic topological insulator.

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    Fitting Model to Compressive Strength of Composite Laminate After Impact
    GUAN Qingyu, XIA Pinqi, ZHENG Xiaoling, WU Guanghui
    2021, 55 (11):  1459-1466.  doi: 10.16183/j.cnki.jsjtu.2020.360
    Abstract ( 619 )   HTML ( 8 )   PDF (4702KB) ( 526 )   Save

    Carbon fiber-reinforced epoxy composites are widely used in the primary structure of aircraft, the compressive strength of which after impact is an important part in the evaluation of damage tolerance. At present, it mainly relies on a large number of tests to obtain compressive strength after impact in the engineering project. Therefore, it is necessary to develop a simple mathematical model to describe the compressive strength law after impact. A novel mathematical model for fitting compressive strength data of composite laminate after impact was proposed. Using the mathematical model and the initial model parameters, the compressive strength data after impact at different impact energy could be converted into some equivalent undamaged compressive strength data. Then, these equivalent undamaged compressive strength data were normally fitted using the maximum-likelihood estimate (MLE) method to obtain the standard deviation of normal distribution. The above steps was repeated until the minimum estimator of standard deviation was obtained. Hence, the best estimators of parameters for the mathematical model were determined. In order to further demonstrate the applicability of the mathematical model, post-impact compressive strength tests including different thicknesses, layup proportion, and material types were conducted, and the experimental data were fitted with the model. The results indicate that the mathematical model has a good applicability to the compressive strength test data after impact including different thicknesses, layup proportions, and material types.

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    Multi-Objective Optimization for Structural Parameters of Swing-Compliant Hook
    GE Shicheng, GUO Zhuoyu, LIANG Xi, MO Zonglai, LI Jun
    2021, 55 (11):  1467-1475.  doi: 10.16183/j.cnki.jsjtu.2020.283
    Abstract ( 521 )   HTML ( 12 )   PDF (1931KB) ( 415 )   Save

    To solve the problems of alignment for launch container loading in field-artillery rocket, a novel end-effector, i.e., a swing-compliant hook, is proposed, whose structural parameters are optimized. First, the theoretical model describing the performance of the swing-compliant hook is established based on the node displacement method. The static displacement, static stress, and swing curve of the swing-compliant hook are analyzed by MATLAB, which verifies the rationality of the model. Then, the main structure parameters on the performance of the swing-compliant hook are obtained by using the experimental design method. Additionally, a response surface model characterizing the comprehensive performance of the swing-compliant hook is established. The optimization results show that when the length and the installation height of the compliant mechanism are 90 mm and 23 mm, and the end height of the lifting hook is 110 mm, the swing-compliant hook has an excellent performance in docking, lifting, transferring, and locating.

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    Crystal Plasticity Modeling of Tension Process of QP980 Steel
    YANG Hao, WANG Huamiao, LI Dayong
    2021, 55 (11):  1476-1482.  doi: 10.16183/j.cnki.jsjtu.2020.391
    Abstract ( 506 )   HTML ( 10 )   PDF (8205KB) ( 369 )   Save

    The mechanical behavior of the quenching and partitioning 980 (QP980) steel is affected by martensitic transformation during deformation. The microstructure of QP980 steel before and after deformation is characterized by using the electron backscattered diffraction (EBSD) method. An elastic visco-plastic self-consistent (EVPSC) polycrystalline model considering phase transformation is established based on the phenomenological theory of martensite crystallography (PTMC). The macroscopic flow stress as well as texture evolution of QP980 steel during uniaxial tension process is reproduced by the model. The material consists of ferrite (F), martensite, and retained austenite (RA) with rolling texture in the initial state. After deformation, the content of RA decreases and the <111> fiber of the RA, the <110> fiber of the ferrite and martensite along the tensile direction are enhanced. Phase transformation enhances the strength and work hardening rate but has little effect on the texture evolution. According to the distribution of stress and strain during the calculation of deformation, ferrite and tempered martensite (TM) contribute most to the deformation, and the new martensite (NM) is the most probable nucleation sites of fracture due to its highest average stress.

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