Loading...

Table of Content

    For Selected: Toggle Thumbnails
    Metal Welding Technology
    Influence of Thermal Modification on Al-Si Coating of Hot-Stamped 22MnB5 Steel: Microstructure, Phase Transformation, and Mechanical Properties
    WANG Qiongyan (王琼燕), LIN Wenhu (林文虎),LI Fang∗ (李芳), SHEN Chen (沈忱), HUA Xueming (华学明)
    2021, 26 (6):  747-756.  doi: 10.1007/s12204-021-2267-7
    Abstract ( 194 )   PDF (3340KB) ( 83 )  
    The hot-stamped steel with ultrahigh strength is a promising material for the fabrication of automotivecomponents. However, the coating on the sheet surface leads to a softening problem in the welded joint. Instead ofthe costly coating removal process, heat treatment is an economical and effective method for the diffusion process,which can decrease the Al concentration in the coating. In this study, a preheating treatment was carried out onAl-Si-coated 22MnB5 hot-stamped steels for the homogeneity of Al, followed by laser welding and hot stamping.The effects of the preheating on the microstructure and mechanical properties of the laser-welded joints wereinvestigated. With the preheating treatment, the Al-Si coating transformed into an Fe-Al intermetallic compoundand the difference in Al content between the coating and substrate was reduced. The Al content in the weld ofthe specimen with the preheating treatment was reduced, compared with that without the preheating treatment.The amount of δ-ferrite in the weld after laser welding was reduced largely. The distribution of long-bland-likesegregation was changed to a fine and uniform distribution. With the preheating treatment, the tensile strengthof the welded joint was significantly improved and comparable to that of the decoated joint. In conclusion, thepreheating treatment before the welding is an effective method to suppress the formation of δ-ferrite and improvethe mechanical properties of the welded joint.
    References | Related Articles | Metrics
    Effect of Cu Addition on the Microstructure and Mechanical Properties of U-MIG Welds on Galvanized Steel Sheets
    YU Xiaokang (俞小康), YE Jia (叶佳), WU Chunxiang (吴春祥), MA Guohong∗ (马国红)
    2021, 26 (6):  757-764.  doi: 10.1007/s12204-021-2328-y
    Abstract ( 146 )   PDF (1675KB) ( 41 )  
    Ultrasonic-assisted metal inert gas (U-MIG) welding experiments were performed to analyze the effectof Cu addition on the microstructure and mechanical properties of galvanized steel sheet welds, and first-principlescalculations were undertaken to predict the effect of Cu on the mechanical properties of α-Fe based structures.As shown by scanning electron microscopy analysis, Cu is conducive to the refinement and uniformity of themicrostructure in the weld zone. Energy-dispersive spectrometry data indicated the presence of Cu in the weldsafter welding with Cu powder. The elastic moduli of the welds without and with Cu powder, obtained fromnanoindentation tests, were (217.66 ± 5.11) GPa and (223.13 ± 9.12) GPa, respectively, which were close to thecalculated results. The mechanical properties of the crystal structures of α-Fe and α-Fe1.9Cu0.1 were calculatedusing Materials Studio software. Both the experimental and calculated results showed that Cu doping reducedthe bulk modulus of the weld but increased its shear modulus.
    References | Related Articles | Metrics
    Material, Structure, Mechanics
    Experimental Study on Medium and Low Cycle Fatigue Properties of Cast Steel GS20Mn5V
    JIN Hui∗ (靳慧), MO Jianhua (莫建华), SUN Sijia (孙思嘉), ZHAO Jing (赵静)
    2021, 26 (6):  765-773.  doi: 10.1007/s12204-020-2237-5
    Abstract ( 152 )   PDF (1348KB) ( 37 )  
    Owing to the remarkable advantages in mechanical behavior, cast steel nodes have been widely usedin static structures. Nowadays, cast steel nodes also gain increasing popularity due to the superior fatigue performancein dynamic structures, but they are not yet widely used because the fatigue properties of cast steel arenot well understood. In this paper, the fatigue test of cast steel GS20Mn5V commonly used in steel castings iscarried out. The strength of medium and low cycle fatigue and the fatigue limit are obtained. The feasibilityof the estimated S-N (fatigue stress versus life) curve is tested. The double logarithmic linear model (DLLM)and the reversed generalized Pareto model (RGPM) are used to fit the experimental data, and the comparisonis made. The P-S-N (the relationship between fatigue stress and life at different survival rates) curve obtainedby the RGPM is proposed. The results show that the estimated S-N curve is not suitable for low cycle fatiguelife, fitting the experimental data with the RGPM is the best, and obtaining the P-S-N curve from the RGPM isfeasible.
    References | Related Articles | Metrics
    Nonlinear Finite Element Method Considering Martensite Plasticity for Shape Memory Alloy Structure
    ZHOU Bo∗ (周博), KANG Zetian (康泽天), WANG Zhiyong (王志勇), XUE Shifeng (薛世峰)
    2021, 26 (6):  774-785.  doi: 10.1007/s12204-021-2327-z
    Abstract ( 131 )   PDF (1371KB) ( 26 )  
    This work presents a nonlinear finite element method to simulate the macroscopic mechanical responsesand the effects of martensite plasticity in a shape memory alloy (SMA) structure. A linear relationshipformulation is adopted to express the influence of martensite plasticity on the inverse martensitic phase transitionof SMA material. Incorporating with a trigonometric-type phase transition evolution law and an exponential-typeplastic flow evolution law, an incremental mechanical model with two internal variables is supposed based onthe macroscopic experimental phenomena. A nonlinear finite element equation is formulated and solved by theprinciple of virtual displacement and Newton-Raphson method respectively. By employing the proposed nonlinearfinite element method, the uniform tensile bar and three-point bending beam are simulated and analyzed. Resultsillustrate that the presented nonlinear finite element method is suitable to act as an effective computational toolfor the wide applications based on the SMA material considering the effects of martensite plasticity because allmaterial constants related to the method can be obtained from macroscopic experiments.
    References | Related Articles | Metrics
    Speed Planning Algorithm Based on Improved S-Type Acceleration and Deceleration Model
    LUO Huimiao (罗晖淼), ZHAO Dongbiao∗ (赵东标), FU Wenqiang (付文强)
    2021, 26 (6):  786-793.  doi: 10.1007/s12204-021-2322-4
    Abstract ( 131 )   PDF (803KB) ( 34 )  
    The acceleration saltation of the traditional S-type acceleration model in the speed planning of theNURBS curve will result in the vibration and flexible impact of the machine tool. It will affect the surface qualityof the components. The high speed smooth S-type acceleration and deceleration model deals with flexible impact,but the calculation is tedious. Aimed at the above problems, the traditional S-type acceleration and decelerationmodel is improved to make the jerk change linearly at a certain slope to reduce the flexible impact. Before thespeed planning, it is needed to find the arc length and curvature of each point on the NURBS curve with atiny step, and to determine the speed sensitivity point on the curve accordingly. According to the speed sensitivepoint, the NURBS curve is segmented. The attribute parameters of each section are determined by adaptive speedplanning. Then, the speed planning can be performed on the NURBS curve according to the speed characteristicsclassification. The simulation results show that the algorithm can effectively reduce the flexible impact, improvethe machining precision and efficiency, and simplify the classification of speed characteristics.
    References | Related Articles | Metrics
    Hysteretic Model for Corroded Rectangular Reinforced Concrete Bridge Column Under Seismic Loading
    YANG Shuyan ∗ (杨淑雁), SONG Xiaobing (宋晓冰), JIA Hongxue (贾红学),CHEN Xi (陈溪), LIU Xila (刘西拉)
    2021, 26 (6):  794-803.  doi: 10.1007/s12204-021-2282-8
    Abstract ( 108 )   PDF (1107KB) ( 20 )  
    Additional hysteretic experiments for corroded rectangular reinforced concrete (RC) columns withan axial load ratio of 0.27 were implemented. A quasi-static cyclic lateral loading with constant axial force wassubjected to tests. Herein, a modified ductility factor model for corroded RC column is developed on the basisof the previous work and additional experiments. The model involves the influence of both the corrosion ratioof longitudinal rebar and the axial load ratio. A four-linear envelope curve model concerning lateral load anddisplacement is proposed in a combination of determination rules of the peak point and the failure strength point.The hysteretic model of corroded RC columns is developed by considering both degraded unloading stiffness andreloading stiffness on the history peak point. The hysteretic model can predict the residual life of corroded RCcolumns under seismic loading.
    References | Related Articles | Metrics
    Bond Mechanical Properties of Glass Fiber Reinforced Polymer Anti-Floating Anchor in Concrete Baseplate
    BAI Xiaoyu (白晓宇), ZHENG Chen (郑晨), ZHANG Mingyi ∗ (张明义),LIU Xueying (刘雪颖), KUANG Zheng (匡政)
    2021, 26 (6):  804-812.  doi: 10.1007/s12204-020-2241-9
    Abstract ( 105 )   PDF (860KB) ( 23 )  
    Combined with fiber Bragg grating (FBG) sensing technology, four glass fiber reinforced polymer(GFRP) anti-floating anchors and four steel anti-floating anchors were tested for on-site destructive failure toinvestigate the anchoring performance and the bonding characteristics between GFRP anti-floating anchor andconcrete floor. The test results show that bending GFRP anchor will be broken at the common boundary betweenvertical anchorage section and bending section during the pullout process, and the spring-back load provided bythe rupture contributes to a decrease of bearing capacity and an inflection point on the load-slip curve. The loaddisplacementcurve of the straight anchor GFRP anti-floating anchor is smoother and has better predictabilitythan the same type of steel anchor. Additionally, different forms of GFRP anti-floating bolt have different bondslipconstitutive relations. By introducing the sliding-slip correction factor of bending bolt, constitutive modelsdescribing the rising-section of sliding-slip relation of bending and straight-anchored GFRP anti-floating bolt areestablished respectively. The model can fit the test results rightly.
    References | Related Articles | Metrics
    Notched Component Fatigue Life Prediction in Torsional Loading
    LIU Jianhui (刘俭辉), L ¨U Xin (吕鑫), WEI Yaobing∗ (韦尧兵),ZHANG Rupeng (张如鹏), ZHANG Yonggui (张永贵)
    2021, 26 (6):  813-818.  doi: 10.1007/s12204-020-2247-3
    Abstract ( 93 )   PDF (613KB) ( 27 )  
    Considering the situation that fatigue life prediction of notched component is an indispensable partin the process of design in engineering, it is necessary to find some ways to solve such problems effectively. Thestress and strain state of notched specimen is more complex, compared with smooth specimen. As a result, someresearchers take advantage of the finite element method to analyze the mechanical properties of these kind ofspecimens, they can get the stress and strain state at the dangerous point directly instead of using theoreticalmethods. At the same time, the equation of shear stress is fitted by analyzing stress distribution of the section ofnotch root. The integral of shear stress in the section is equal to the external load, and the true stress value ofnotch root is derived. Then, the fatigue damage evolution equation of notched specimens under torsional load isproposed based on the closed-form solution in this paper. Meanwhile, the nonlinear fatigue life prediction model ofnotched specimens under the torsional load is given by using the damage mechanics theory. The proposed modelis validated by experimental data (30CrMnSiNi2A steel and 45# steel). The results show that the predicted lifeis not only close to the experimental results, but also tends to be safe. The fatigue life of notched specimen ispredicted by using notch geometric parameters and material constants. The model has more concise calculationprocess, avoids complicated fatigue tests, and facilitates engineering application.
    References | Related Articles | Metrics
    Parameter Identification of Structural Nonlinearity by Using Response Surface Plotting Technique
    LIU Xin ∗ (刘鑫), WANG Lixiao (王力晓), CHEN Qidong (陈启东), SUN Beibei (孙蓓蓓)
    2021, 26 (6):  819-827.  doi: 10.1007/s12204-020-2242-8
    Abstract ( 115 )   PDF (1769KB) ( 21 )  
    With rigorous dynamic performance of mechanical products, it is important to identify dynamicparameters exactly. In this paper, a response surface plotting method is proposed and it can be applied to identifythe dynamic parameters of some nonlinear systems. The method is based on the principle of harmonic balancemethod (HBM). The nonlinear vibration system behaves linearly under the steady-state response amplitude, whichpresents the equivalent stiffness and damping coefficient. The response surface plot is over two-dimensional space,which utilizes excitation as the vertical axis and the frequency as the horizontal axis. It can be applied to observethe output vibration response data. The modal parameters are identified by the response surface plot as linearityfor different excitation levels, and they are converted into equivalent stiffness and damping coefficient for eachresonant response. Finally, the HBM with first-order expansion is utilized for identification of stiffness and dampingcoefficient of nonlinear systems. The classical nonlinear systems are applied in the numerical simulation as theexample, which is used to verify its effectiveness and accuracy. An application of this technique for nonlinearityidentification by experimental setup is also illustrated.
    References | Related Articles | Metrics
    Automation, Image Processing
    Snubber Circuit for Marine Controlled-Source Electromagnetic Transmitter
    SONG Hongxi∗ (宋红喜), ZENG Yijin (曾义金), ZHANG Wei (张卫)
    2021, 26 (6):  828-839.  doi: 10.1007/s12204-021-2286-4
    Abstract ( 103 )   PDF (2790KB) ( 17 )  
    A high-power marine controlled-source electromagnetic transmitter (HP-MCSET) transmits a highfrequencyconversion current on the sea floor. Some problems exist when the direct-current to alternating-current(DC-AC) launch bridge (LB) is used in the marine controlled-source electromagnetic transmitter (MCSET). Thereis a high voltage peak in the LB when the insulated gate bipolar transistor (IGBT) is turned on and off. In somecases, the voltage stress of the IGBT can be exceeded, which may cause IGBT damage. Because the rise of thecurrent steepness is relatively low and the output voltage has a voltage peak in the LB, a snubber circuit is addedto the IGBT to suppress the voltage peak to improve the output current and voltage waveform. The suppressionof the voltage peaks is analyzed and compared for several groups of snubber circuits. To meet the performancerequirements of the MCSET, the optimal snubber circuit is selected to effectively suppress the voltage peaks atan output current of 1 kA. This method is verified by using a 70 kW MCSET and the experimental waveforms areprovided. The simulation of the inductance obstruction load in seawater is necessary to determine the conditionsfor actual marine environment experiments.
    References | Related Articles | Metrics
    Feature Selection Optimization for Mahalanobis-Taguchi SystemUsing Chaos Quantum-Behavior Particle Swarm
    LIU Jiufu ∗ (刘久富), ZHENG Rui (郑锐), ZHOU Zaihong ∗ (周再红), ZHANG Xinzhe (张信哲),YANG Zhong (杨忠), WANG Zhisheng (王志胜)
    2021, 26 (6):  840-846.  doi: 10.1007/s12204-020-2236-6
    Abstract ( 154 )   PDF (691KB) ( 28 )  
    The computational speed in the feature selection of Mahalanobis-Taguchi system (MTS) using standardbinary particle swarm optimization (BPSO) is slow and it is easy to fall into the locally optimal solution. Thispaper proposes an MTS variable optimization method based on chaos quantum-behavior particle swarm. Inorder to avoid the influence of complex collinearity on the distance measurement results, the Gram-Schmidtorthogonalization method is first used to calculate the Mahalanobis distance (MD) value. Then, the optimalthreshold point of the system classification is determined through the receiver operating characteristic (ROC)curve; the misclassification rate and the selected variables are defined; the multi-objective mixed programmingmodel is built. The chaos quantum-behavior particle swarm optimization (CQPSO) algorithm is proposed to solvethe optimization combination, and the algorithm performs binary coding on the particle based on probability.Using the optimized combination of variables, a new Mahalanobis-Taguchi metric based prediction system isestablished to complete the task of precise discrimination. Finally, a fault diagnosis for the steel plate is taken asan example. The experimental results show that the proposed method can effectively enhance the iterative speedand optimization precision of the particles, and the prediction accuracy of the optimized MTS is significantlyimproved.
    References | Related Articles | Metrics
    Fast Smooth Second-Order Sliding Mode Control with Disturbance Observer for Automatic Shell Magazine
    YAO Laipeng (姚来鹏), HOU Baolin ∗(侯保林), LIU Xi (刘曦)
    2021, 26 (6):  847-856.  doi: 10.1007/s12204-020-2218-8
    Abstract ( 139 )   PDF (1189KB) ( 27 )  
    This paper studies practical control design for a novel automatic shell magazine (ASM) with a newfast smooth second-order sliding mode (FSSOSM) control based on disturbance observer. The dynamic modelof the ASM with parameter perturbations and nonlinear friction is established. A higher order sliding modedisturbance observer based on super-twisting algorithm is utilized as a robust compensator to estimate the lumpeduncertainties. The proposed FSSOSM control is performed to obtain the continuous sliding mode control lawand inhibit the chattering phenomenon. The finite time convergence is investigated by utilizing the Lyapunovstability theorem. Three controllers, the traditional sliding mode controller, the proposed FSSOSM controller anda continuous fixed-time second-order sliding mode (CFTSOSM) controller, are compared. Extensive comparativesimulation results under three typical working conditions (no-loaded, half-loaded and full-loaded) demonstratethat the proposed control strategy has a high dynamic tracking performance along with a good robustness againstmodel uncertainty.
    References | Related Articles | Metrics
    Poisson Image Restoration via Transformed Network
    XU Xiaoling (徐晓玲), ZHENG Haiyu (郑海玉), ZHANG Fengqin (张凤芹),LI Hechen (李赫辰), ZHANG Minghui∗ (张明辉)
    2021, 26 (6):  857-868.  doi: 10.1007/s12204-020-2235-7
    Abstract ( 152 )   PDF (6975KB) ( 26 )  
    There is a Poisson inverse problem in biomedical imaging, fluorescence microscopy and so on. Sincethe observed measurements are damaged by a linear operator and further destroyed by Poisson noise, recoveringthe approximate original image is difficult. Motivated by the decouple scheme and the variance-stabilizing transformation(VST) strategy, we propose a method of transformed convolutional neural network (CNN) to restorethe observed image. In the network, the Conv-layers play the role of a linear inverse filter and the distributiontransformation simultaneously. Furthermore, there is no batch normalization (BN) layer in the residual block ofthe network, which is devoted to tackling with the non-Gaussian recovery procedure. The proposed method iscompared with state-of-the-art Poisson deblurring algorithms, and the experimental results show the effectivenessof the method.
    References | Related Articles | Metrics