3D quasi-transient thermo-mechanical analysis for vehicle brake disc

Biao Hu,Xingyan Zhang,Yang Liu,Junjie Yan,Xiaobing Liu,Xin Wang,Richard Sun 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.2

An alternative numerical method is developed to predict the thermo-mechanical behavior of brake disc during braking. Steady-state aerodynamic simulation for entire vehicle with variant speeds are conducted to analyze the convective heat transfer characteristic of the disc surface. Then the transient heat transfer boundary of the disc is obtained by interpolating the steady-state simulation results. Based on that, the transient thermo-mechanical coupled simulation for brake disc is performed via finite element method. With those work, the characteristics of transient temperature field and stress field of the brake disc are analyzed. Meanwhile, the characteristic of contact pressure distribution on friction interface is also obtained. The results show that during the braking process, for any node in the friction areas of the brake disc surface, its temperature rise curve fluctuates like a sawtooth. The temperature field has a significant effect on the stress field of the brake disc, both in distribution and variation. To verify the numerical method and validate the simulation results, a full-scale vehicle brake-thermalperformance test is carried out. By comparison, the simulation results show good agreement with the experimental results. The proposed numerical method enables an efficient and economical way to predict and evaluate the thermo-mechanical behavior of the brake disc in early phase of vehicle development.

Numerical investigation of heat transfer characteristics for Subsea Xmas tree assembly

Biao Hu,Hongwu Zhu,Kuang Ding,Fangling Xu,Youjiang Zhang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.11

This study focuses on the heat transfer characteristic of a horizontal subsea Xmas tree assembly at a high spatial resolution. Computationalfluid dynamics (steady Reynolds-averaged Navier-Stokes) in combination with Low Reynolds number modelling (LRNM) isadopted for heat transfer analysis, which has been validated against a full scale underwater gate valve heat transfer experiment with goodagreements. The characteristics of cold sea water flowing through the subsea tree, and of convection heat transfer between the subsea treeand ambient cold water are obtained. The typical “hot spots,” which have high Convection heat transfer coefficient (CHTC) and creategreat large amounts of heat loss, are numerically determined. Under the designed water depth, the effects of installation orientation, seawater velocity, and inner oil temperature on convection heat transfer are investigated as well. Such work is significant for thermal designof the subsea tree to increase structural reliability and flow assurance level.

Study on Thermodynamic Behavior, Microstructure and Mechanical Properties of Thin-Walled Parts by Selective Laser Melting

Biao Hu,Gaoshen Cai,Jinlian Deng,Kai Peng,Bingxu Wang 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.1

To investigate the thermodynamic behavior of thin-walled parts fabricated by selective laser melting, an indirect sequentiallycoupled thermal–mechanical numerical modeling was developed. The three-dimensional Gaussian attenuation bodyheat source model and thermophysical parameters varying with temperature were considered. To validate the numericalmodel, the thin-walled part was manufactured by selective laser melting, and the experiment results were compared with thesimulation results. It is found that the variation trend of residual stress in simulation and experiment is in good agreement. Moreover, The microstructure and mechanical properties of the thin-walled parts were analyzed. The simulation resultsshow that the thermal conductivity and the heat accumulation have a critical influence on the evolution of the molten pooland cooling rate. The thermal stress along the laser scanning direction is larger than the other two directions, and the highstressarea is mainly distributed in the middle position of the part and the joint of the part and the substrate. Besides that, theX-component of stress of the top layer gradually decreases as the deposition layer increases. The experiment results showthat the microstructure of thin-walled parts is mainly composed of acicular martensite under the action of complex thermalcycle. The fracture mode of thin-walled parts show a typical quasi-brittle fracture.

The Impact of Greenhouse Vegetable Farming Duration and Soil Types on Phytoavailability of Heavy Metals and Their Health Risk in Eastern China

Biao Huang,Lanqin Yang,Wenyou Hu 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

CONVERGENCE PROPERTIES OF A CORRELATIVE POLAK-RIBIERE CONJUGATE GRADIENT METHOD

Hu, Guofang,Qu, Biao 한국전산응용수학회 2006 Journal of applied mathematics & informatics Vol.22 No.1

In this paper, an algorithm with a new Armijo-type line search is proposed that ensure global convergence of a correlative Polak-Ribiere conjugate method for the unconstrained minimization of non-convex differentiable function.

COORDINATED COLLISION AVOIDANCE FOR CONNECTED VEHICLES USING RELATIVE KINETIC ENERGY DENSITY

Manjiang Hu,Jian Wu,Hongmao Qin,Yougang Bian,Biao Xu,Qing Xu,Jugang He,Jianqiang Wang 한국자동차공학회 2017 International journal of automotive technology Vol.18 No.5

Vehicular collision often leads to serious casualties and traffic congestion, and the consequences are worse for multiple-vehicle collision. Many previous works on collision avoidance have only focused on the case for two consecutive vehicles using on-board sensors, which ignored the influence on upstream traffic flow. This paper proposes a novel coordinated collision avoidance (CCA) strategy for connected vehicles, which has potential to avoid collision and smooth the braking behaviors of multiple vehicles, leading to an improvement of traffic smoothness. Specifically, model predictive control (MPC) framework is used to formulate the CCA into an optimization problem, where the objective is to minimize the total relative kinetic energy density (RKED) among connected vehicles. Monte Carlo simulations are used to demonstrate the effectiveness of proposed CCA strategy by comparison with other two strategies. Among all the three control strategies, the RKED based control strategy shows the best performance of collision avoidance, including the best crash prevention rates (99.2 % on dry asphalt road and 90.5 % on wet asphalt road) and the best control of distance headways between vehicles.

REGENERATIVE BRAKING CONTROL STRATEGY OF ELECTRIC VEHICLES BASED ON BRAKING STABILITY REQUIREMENTS

Jiang Biao,Zhang Xiangwen,Wang Yangxiong,Hu Wenchao 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.2

Electric vehicles are effective way to solve energy and environmental problems, but the promotion and application of electric vehicles are suppressed by their limited endurance range seriously. The regenerative braking technology is an important method to increase the endurance range of the electric vehicle. During the braking process, the kinetic energy of the electric vehicle can be converted into electric energy and stored in the energy source device with the regenerative braking system, so the endurance range of the electric vehicle can be increased accordingly. In order to increase the efficiency of energy recovery, a regenerative braking strategy with the optimization distribution algorithm is proposed in this paper, and the braking forces of the front and rear axles are distributed optimally with variable ratios based on the braking strength. With the optimal braking force distribution ratio and related constraint conditions, the regenerative braking control strategy was designed to meet the braking stability and the maximum braking energy recovery. And then a simulation model of the braking control strategy was built with MATLAB/Simulink software, and the simulation tests on UDDS and NEDC cycle conditions were done to verify the effectiveness of the designed regenerative braking control strategy. Compared with the control strategy of ADVISOR software, the braking energy recovery efficiency was improved more than 51.9 % while maintaining the braking stability.

Convergence Properties of a Correlative Polak-Ribiacuteere Conjugate Gradient Method

Guofang Hu,Biao Qu 한국전산응용수학회 2006 Journal of applied mathematics & informatics Vol.22 No.1-2

In this paper, an algorithm with a new Armijo-type line search is proposed that ensure global convergence of a correlative Polak-Ribi´ere conjugate method for the unconstrained minimization of non-convex differentiable function.

Elastic local buckling behaviour of corroded cold-formed steel columns

Nie Biao,Xu Shanhua,Hu WeiCheng,Chen HuaPeng,Li AnBang,Zhang ZongXing 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.48 No.1

Under the long-term effect of corrosive environment, many cold-formed steel (CFS) structures have serious corrosion problems. Corrosion leads to the change of surface morphology and the loss of section thickness, which results in the change of instability mode and failure mechanism of CFS structure. This paper mainly investigates the elastic local buckling behavior of corroded CFS columns. The surface morphology scanning test was carried out for eight CFS columns accelerated corrosion by the outdoor periodic spray test. The thin shell finite element (FE) eigen-buckling analysis was also carried out to reveal the influence of corrosion surface characteristics, corrosion depth, corrosion location and corrosion area on the elastic local buckling behaviour of the plates with four simply supported edges. The accuracy of the proposed formulas for calculating the elastic local buckling stress of the corroded plates and columns was assessed through extensive parameter studies. The results indicated that for the plates considering corrosion surface characteristics, the maximum deformation area of local buckling was located at the plates with the minimum average section area. For the plates with localized corrosion, the main buckling shape of the plates changed from one half-wave to two half-wave with the increase in corrosion area length. The elastic local buckling stress decreased gradually with the increase in corrosion area width and length. In addition, the elastic local buckling stress decreased slowly when corrosion area thickness was relatively large, and then tends to accelerate with the reduction in corrosion area thickness. The distance from the corrosion area to the transverse and longitudinal centerline of the plate had little effect on the elastic local buckling stress. Finally, the calculation formula of the elastic local buckling stress of the corroded plates and CFS columns was proposed.

Degradation of Out-of-plane Initial Stiffness of Steel-concrete Walls Exposed to Fire

Bo Hu,Jun-Qi Huang,Guo-biao Lou 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.1

Steel-concrete (SC) walls, as a main lateral resisting system in nuclear power plants, have serious fire resistance problem because of their exposed steel faceplates. The out-of-plane stiffness of SC walls will degrade when exposed to fire, which has significant influence on the mechanical performance of the composite walls and even the whole structure. In this paper, a finiteelement (FE) model was developed to simulate thermo-mechanical coupling behavior of SC walls exposed to fire. One conducted ISO-834 standard fire test and two reported thermal and mechanical loading tests were assembled to verify the developed FE model. Based on the validated FE model, numerical experiments of 15 SC walls in fire exposure durations of 0~3 h were conducted to investigate the effect of steel arrangement and geometrical size on the out-of-plane initial stiffness of SC walls under elevated temperatures. Numerical results indicate that the out-of-plane initial stiffness of SC walls under ambient temperature is mainly influenced by steel faceplate thickness and section depth, while the initial stiffness degradation under elevated temperature is mainly influenced by fire exposure duration or surface temperature of exposed steel faceplate. Then, two equations were proposed to predict the out-of-plane initial stiffness of SC walls exposed to fire. The predicted results agree well with the test and numerical results, which demonstrates that the proposed equations can be used to estimate the damage of SC walls in fire.