A hybrid method of modified NSGA-II and TOPSIS for lightweight design of parameterized passenger car sub-frame

Dengfeng Wang,Rongchao Jiang,Yinchong Wu 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.11

This paper presents a hybrid method integrating modified NSGA-II and TOPSIS, used for lightweight design of the front sub-frame of a passenger car. Firstly, the FE model of the sub-frame is constructed and is validated by modal test. Then, the strength performance of the sub-frame is analyzed under four typical load conditions consisting of braking, acceleration, steady state cornering and vertical bump. After that, a parameterized model of the sub-frame, in which 12 geometric parameters are defined as design variables, is developed based on the mesh morphing technology. Subsequently, modified NSGA-II is employed for multi-objective optimization of the sub-frame considering weight, maximum von-Mises stress and first order natural frequency as three conflicting objective functions. Accordingly, a set of Pareto-optimal solutions are obtained from the optimization process. Finally, the entropy weight theory and TOPSIS method are adopted to rank all these solutions from the best to the worst for determining the best compromise solution. In addition, the effectiveness of the proposed hybrid lightweight design method is demonstrated by the comparisons among baseline design and optimum solutions.

Preparation and Properties of Antistatic Polyethylene Film Coated Polypropylene Non-woven Fabrics

Zongqian Wang,Dengfeng Wang,Yinchun Fang,Jieliang Shen 한국섬유공학회 2018 Fibers and polymers Vol.19 No.5

In this paper, antistatic PE/PP coated non-woven fabrics were prepared by the coating process of the antistatic finished PE films and PP non-woven fabrics using the heat pressing process of the hot melt adhesives. The antistatic finishing of polyethylene (PE) films and polypropylene (PP) non-woven fabrics were processed by one face foam finishing and dippad finishing process, respectively. The antistatic properties of PE/PP coated non-woven fabrics which were influenced by the antistatic finishing processes and the thickness of PE films were investigated. The static charges transmission mechanism of these coated non-woven fabrics was illustrated. The results revealed that the static charges were transferred and dissipated by forming the continuous conductive path and network between the film-adhesive and adhesive-fabric due to the hot melt adhesion and squeezing of the antistatic agents existing inside of of the non-woven fabrics matrix and on the film surface. The antistatic properties of coated non-woven fabrics were improved with the increasing of the antistatic agent concentration on the finishing solution. And the antistatic properties of PE films were greatly influenced by the film thickness, the thinner of PE films the much more obvious improvement of the film surface antistatic properties. The finishing process wouldn’t reduce the peeling strength of the coated non-woven fabrics. The antistatic properties of the PE/PP coated non-woven fabrics possessed high washing durability due to the crosslinking fixation effect of the hot melt adhesives which wouldn’t be weakened after several times washing.

Dynamic Control Allocation Algorithm for a Class of Distributed Control Systems

Dengfeng Zhang,Shen-Peng Zhang,Zhi-Quan Wang,Baochun Lu 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.2

The control allocation algorithm is developed for a class of distributed control systems with hierarchical structure and similar models of the subsystems, to solve the real-time cooperative control taking the dynamics and possible variations of subsystems into consideration. The augmented state-space model of the subsystems is first established for the control allocation. Based on robust control theory, the constrained and convex optimization is then developed with LMIs form to design the gain matrix of the dynamic control allocation. Furthermore, the closed-loop stability of the distributed control system is analyzed on the basis of stable upper-level main control law. Finally, simulations on the four-corner leveling control system of an advanced hydraulic press demonstrate the effectiveness of the proposed control allocation algorithm.

Multi-objective optimization of the vehicle ride comfort based on Kriging approximate model and NSGA-II

Shuming Chen,Tianze Shi,Dengfeng Wang,Jing Chen 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.3

The RMS of weighted acceleration, wheel dynamic load and suspension dynamic deflection are determined as evaluation indices ofvehicle ride comfort performance. A multi-body dynamic rigid-flexible coupling model of an in-wheel motor vehicle is built based on themulti-body system dynamics. The ride comfort results of ride comfort simulation and road test are well fitted. A kriging model is createdto describe the relationship of vehicle ride comfort evaluation indices and suspension parameters. A multi-objective optimization usingNSGA-II is processed using this model, and the vehicle ride comfort performance is improved by using the optimized suspension parameters.

Parametric design and modeling method of carbon fiber reinforcement plastic-laminated components applicable for multi-material vehicle body development

Lv Tiantong,Chen Zipeng,Wang Dengfeng,Du Xuejing 한국CDE학회 2024 Journal of computational design and engineering Vol.11 No.1

Combined application of steel, aluminum, and carbon fiber reinforcement plastic (CFRP) is the main direction of future lightweight body development. However, the anisotropy and additional lamination design variables of CFRP parts pose significant challenges for the development of multi-material bodies. This study establishes a parametric design method for the variable-thickness lamination scheme based on non-uniform rational B-splines, it can be coupled with existing parametric design methods for structural shapes to formulate a complete parametric design and modeling of CFRP components. On this basis, a homogenized intermediate material property is derived from classic laminate theory by introducing lamination assumptions, it enables a stepwise multi-material body optimization method to solve the challenge that components’ material design variables switching between CFRP and alloy will introduce/eliminate lamination design variables iteratively, posing a great optimization convergence difficulty. The proposed parametric modeling method for CFRP components was validated by experimental tests of a fabricated roof beam, and the proposed optimization method was applied to a vehicle body, achieving 15.9%, 23.9%, 18.6%, and 12.2% increase in bending and torsional stiffness and modal frequencies; 20.2%, 9.3%, and 12.7% reduction of weight and peak acceleration in frontal and side collisions. This study enables the forward design of multi-material bodies compatible with CFRP parts.

Internal flow characteristics of a variable mixed flow turbine with partially-rotating vane nozzle

Hanzhi Zhang,Dazhong Lao,Ce Yang,Dengfeng Yang,Xiaoxiang Hou,Xinghua Wang 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.10

Variable nozzle turbine has advantages of improving engine low-speed performance; thus, it is widely applied in internal combustion engines. The present study analyzed the aerodynamic performance, especially the nozzle endwall leakage flow loss of a mixed flow turbine with variable nozzle, using 3D computational fluid dynamic simulation and test validation. Then, a partially-rotating vane nozzle was proposed to reduce the nozzle endwall clearance leakage flow to improve turbine efficiency. The results showed that at small nozzle opening condition, the front-part-vane rotating design can improve turbine efficiency up to 5.95 %, and the efficiency improvement of the rear-part-vane rotating design is approximately 5.08 %. At large nozzle opening condition, the front-part-vane rotating design has the same efficiency and flow capacity as the origin design, but the rear-part-vane rotating design cannot satisfy the flow capacity requirement. Detailed flow field analysis shows that the front-part-vane rotating design affects the velocity distribution at the rotor inlet due to nozzle endwall leakage flow. The leakage flow between the front part and the rear part of the nozzle causes a pressure jump at the pivoting axis.

Effect of Au on the Performance of Porous Silicon/V2O5 Nanorods Heterojunctions to NO2 Gas

Wenjun Yan,Minghui Zhou,Jiran Liang,Dengfeng Wang,Yulong Wei,Yuxiang Qin 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.7

A novel composite of Au-functionalized porous silicon (PS)/V2O5 nanorods (PS/V2O5:Au) was prepared to detect NO2 gas. PS/V2O5 nanorods were synthesized by a heating process of pure vanadium film on PS, and then the obtained PS/V2O5 nanorods were functionalized with dispersed Au nanoparticles. Various analytical techniques, such as field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), have been employed to investigate the properties of PS/V2O5:Au. Herein, the PS/V2O5:Au sample exhibited improved NO2-sensing performances in response, stability and selectivity at room temperature (25℃), compared with the pure PS/V2O5 nanorods. These phenomena were closely related to not only the dispersed Au nanoparticles acting as a catalyst but also the p-n heterojunctions between PS and V2O5 nanorods. Whereas, more Au nanoparticles suppressed the improvement of response to NO2 gas.

Workspace quality analysis and application for a completely restrained 3-Dof planar cable-driven parallel manipulator

Xiaoqiang Tang,Lewei Tang,Jinsong Wang,Dengfeng Sun 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.8

With the advantage of large workspace, low energy consumption and small inertia, the cable-driven parallel manipulator (CDPM) is suitable for heavy workpieces in rapid velocity and acceleration. We present a workspace analysis approach to solve force and torque equilibriums of completely restrained CDPMs. By this approach, not only the distribution but also the value of tensions driven by cables is investigated together. Two new indices, all cable tension distribution index (ACTDI) and area of the global quality workspace (AG)are proposed to evaluate the quality of the workspace. By concentrating on the workspace and its quality combined with the tension characteristics,these criteria are used to determine the optimal workspace in CDPMs. To verify the capacity of the proposed method, simulation examples are presented and the results demonstrate the approach’s effectiveness. In the end, the dimensional design for a planar CDPM is discussed with the indices of workspace quality.

The improvement effect of surfactants on hydrogenation at condition containing water for Cu/SiO2 catalysts

Zheng Chen,Xueying Zhao,Shuwei Wei,Dengfeng Wang,Xuelan Zhang,Jianfeng Shan 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.11

In the industrial production, water exists inevitably into feed stocks in the form of impurity, and it can produce a negative effect in the hydrogenation reaction due to the preferential adsorption of water on active sites. Here, the surfactants (polyvinylpyrrolidone, poloxamer, polyethylene glycol and hexadecyl trimethyl ammonium bromide) are used to improve physicochemical property of Cu/SiO2 catalysts, so that Cu/SiO2 catalysts had a good hydrogenation performance at condition containing water. The appropriate addition amount of surfactants in the catalyst preparation process effectively hindered the agglomeration of copper species by steric configuration and repulsion effect between Cu2+ and positive ionizable, which brought about high copper dispersion and small particle size. Meanwhile, the decomposition of surfactants produced many pores during calcination, resulting in the increased of specific surface area and average pore diameter. These advantages provided more chances for reactants to touch active sites due to spatial restriction and the increase of the number of active sites, so that the negative effects of water can be counteracted. The conversion of Cu/SiO2 catalysts, that the surfactants was added in the catalyst preparation process, increased 60% to 200% at reaction condition containing water.

An equivalent stiffness (ES) method for initial design of tube-based energy absorbers under lateral quasi-static compression

Lingyu Sun,Dingxin Leng,Juanjuan Sun,Yi Lin,Dengfeng Wang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.2

A tube is often applied as an energy absorber in structures subject to impact loads. However, when several tubes are combined to absorbenergy, how to arrange these tubes and match their dimensions has not been investigated. We provide a novel equivalent stiffness(ES) method for the initial design of tube-based energy absorbers, in which each tube is expressed by an equivalent spring with averagepost-buckling stiffness, and these springs are connected in series or parallel or hybrid. The plastic deformation and strain energy are distributedamong them according to their relative ES value. The relationship between plastic energy and post-buckling stiffness is derivedanalytically and verified numerically. Finally, an application example is provided and the optimal tube arrangement and dimensions areobtained by combining the proposed ES method with an optimization code. The results demonstrate that this method can provide aninitial design of tube-based energy absorbers efficiently.