检索结果-南通市图书馆

Size effects of effective Young's modulus for periodic cellular materials

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2009年第8期52卷 1262-1270页

作者： DAI GaoMing zhang weihong Engineering Simulation and Aerospace Computing Key Laboratory of Contemporary Design&Integrated Manufacturing TechnologyNorthwestern Polytechnical UniversityXi’an 710072China

With the wide demands of cellular materials applications in aerospace and civil engineering,research effort sacrificed for this type of materials attains nowadays a higher level than ever *** paper is focused on the prediction methods of effective Young's modulus for periodical cellular *** on comprehensive studies of the existing homogenization method(HM),the G-A meso-mechanics method(G-A MMM) and the stretching energy method(SEM) that are unable to reflect the size effect,we propose the bending energy method(BEM) for the first time,and a comparative study of these four methods is further made to show the generality and the capability of capturing the size effect of the BEM ***,the underlying characteristics of each method and their relations are *** do this,the detailed finite element computing and existing experimental results of hexagonal honeycombs from the literature are adopted as the standard of comparison for the above four *** and bending models of periodical cellular materials are taken into account,respectively for the comparison of stretch and flexural displacements resulting from the above *** conclude that the BEM has the strong ability of both predicting the effective Young's modulus and revealing the size *** a method is also able to predict well the variations of structural displacements in terms of the cell size under stretching and bending loads including the non-monotonous variations for the hexagonal *** the contrary,other three methods can only predict the limited results whenever the cell size tends to be infinitely small.

关键词： periodic cellular materials effective Young’s modulus size effect bending energy method homogenization method G-A mesomechanics method stretching energy method

Multiscale model of micro curing residual stress evolution in carbon fiber-reinforced thermoset polymer composites

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mechanical Engineering 2020年第3期15卷 475-483页

作者： Xinyu HUI Yingjie XU weihong zhang State IJR Center of Aerospace Design and Additive Manufacturing School of Mechanical EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Shaanxi Engineering Laboratory of Aerospace Structure Design and Application School of Mechanical EngineeringNorthwestern Polytechnical UniversityXi’an 710072China

In this study,the micro curing residual stresses of carbon fiber-reinforced thermoset polymer(CFRP)composites are evaluated using a multiscale modeling method.A thermochemical coupling model is developed at the macroscale level to obtain the distributions of temperature and degree of ***,a representative volume element model of the composites is established at the microscale *** introducing the information from the macroscale perspective,the curing residual stresses are calculated using the microscale *** evolution of curing residual stresses reveals the interaction mechanism of fiber,matrix,and interphase period during the curing *** show that the curing residual stresses mostly present a tensile state in the matrix and a compressive state in the ***,the curing residual stresses at different locations in the composites are calculated and *** results provide an important guideline for the analysis and design of CFRP composite structures.

关键词： CFRP curing residual stress multiscale modeling finite element method

Optimization design of chiral hexagonal honeycombs with prescribed elastic properties under large deformation

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2020年第3期33卷 902-909页

作者： Kepeng QIU Ruoyao WANG Jihong ZHU weihong zhang School of Mechanical Engineering Northwestern Polytechnical UniversityXi’an 710072China

Flexible chiral honeycomb cores generally exhibit nonlinear elastic properties due to large geometric *** effective elastic moduli and Poisson's ratio typically vary with an increase in ***,the size and shape optimization of the chiral hexagonal honeycombs was performed to keep the Young's moduli and Poisson's ratio unchanged under large *** size of the honeycomb unit cell and the position coordinates of the key points were defined simultaneously as design *** equivalent Young's modulus and Poisson's ratio of chiral honeycombs were calculated through geometric nonlinear *** objective was to minimize the allowable tolerance between the prescribed and actual properties within the range of the target strain.A genetic algorithm was then *** optimal results demonstrate that the chiral honeycombs can maintain effective elastic properties that do not vary under large *** results are meaningful to morphing aircraft designs.

关键词： Chiral hexagonal honeycombs Genetic algorithm Geometric nonlinearity Large deformation Shape optimization

Chip Formation Mechanism of Inconel 718: A Review of Models and Approaches

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2021年第2期34卷 52-67页

作者： Chun Liu Min Wan weihong zhang Yun Yang School of Mechanical Engineering Northwestern Polytechnical UniversityXi’an 710072China State IJR Center of Aerospace Design and Additive Manufacturing Northwestern Polytechnical UniversityXi’an 710072China

Inconel 718,a nickel,chrome and iron alloy,has special advantages,such as high-temperature strength,thermal resistance and corrosion resistance,which facilitate wide usage in the aerospace industry,especially in the hot sections of gas turbine ***,machining this alloy is correlated closely with the material’s inherent properties such as excellent combination of strength,hardness and toughness,low thermal conductivity and the tendency to adhere to cutting *** nickel alloy also contains inclusions of hard abrasive carbide particles that lead to work-hardening of the workpiece material and thus abrasive wear of the cutting *** is,the machining of Inconel 718 is always influenced by high mechanical and thermal *** article reviews the chip formation mechanism of Inconel *** of the main characteristics in machining of Inconel 718 is that it will produce serrated or segmented chips in a wide range of cutting speeds and *** studies show that the chip serration or segmentation by shear localization affects the machined surface integrity,and also contributes to the chip’s evacuation and the automation of machining ***,research conclusion indicates that the serrated or segmented chip phenomenon is desirable in reducing the level of cutting force,and detailed analysis of models and approaches to understand the chip formation mechanism of Inconel 718 is vital for machining this alloy effectively and ***,this article presents some summaries on the models and approaches on the chip formation in machining of Inconel 718.

关键词： Inconel 718 Chip formation mechanism Shear instability Segmented chip

Multiscale topology optimization using feature-driven method

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2020年第2期33卷 621-633页

作者： Zhao XU weihong zhang Ying ZHOU Jihong ZHU State IJR Center of Aerospace Design and Additive Manufacturing Northwestern Polytechnical UniversityXi’an 710072China

This paper presents a multiscale design method for simultaneous topology optimization of both macrostructures and *** features are extended as design primitives at both macro and micro scales and represented by Level Set Functions(LSFs).Parameters related to the locations,sizes,and orientations of macro and micro features are considered as design variables and optimized *** the overlapping areas of different macro features,embedded microstructures are optimally figured out as the solution of the corresponding sub-optimization,*** this study,the eXtended Finite Element Method(XFEM)is implemented for structural and sensitivity analyses with respect to design *** method has the advantage of using a fixed grid independent of the topology optimization *** homogenization procedure is applied to calculate the effective properties of considered microstructures in each macro *** examples are presented to illustrate the effectiveness of the proposed *** depict that the multiscale design cannot obviously improve structural stiffness compared with a solid-material design under the linear elastic condition.

关键词： Feature-driven method Level set function Multiscale design Topology optimization XFEM

Shape preserving topology optimization for structural radar cross section control

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2022年第6期35卷 198-210页

作者： Fei CHEN Jihong ZHU Xinxin DU Ruitong zhang weihong zhang State IJR Center of Aerospace Design and Additive Manufacturing Northwestern Polytechnical UniversityXi’an 710072China MIIT Lab of Metal Additive Manufacturing and Innovative Design Northwestern Polytechnical UniversityXi’an 710072China

The purpose of this paper is to present a shape preserving topology optimization method to prevent the adverse effects of the mechanical deformation on the Radar Cross Section(RCS).The optimization will suppress the variation of RCS on the perfect conductor surface by structural *** the one hand,the physical optics method is utilized to calculate the structural RCS,which is based on the surface displacement field obtained from the finite element analysis of the *** corresponding design sensitivities of topology optimization are derived analytically and solved by the adjoint *** the other hand,the RCS variation and mechanical performance are taken into account simultaneously by extending a standard compliance-based topology optimization *** optimization formulations are discussed in an illustrative example,where the influences of upper limits of the compliance and the RCS variation are *** more examples are further tested to show the ability and validity of the proposed optimization method.

关键词： Adjoint method Physical optics method Radar cross section Shape preserving design Topology optimization

Precise output loads control of load-diffusion components with topology optimization

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2020年第3期33卷 933-946页

作者： Yinfeng CAO Xiaojun GU Jihong ZHU weihong zhang State IJR Center of Aerospace Design and Additive Manufacturing Northwestern Polytechnical UniversityXi’an 710072China Institute of Intelligence Material and Structure Unmanned System TechnologiesNorthwestern Polytechnical UniversityXi’an 710072China MIIT Lab of Metal Additive Manufacturing and Innovative Design Northwestern Polytechnical UniversityXi’an 710072China

The purpose of this paper is to present a novel topology optimization approach to control precisely the output loads under static loads and harmonic *** introduce the Artificial Bar Element(ABE)at the designated output positions,where the output loads are equivalently measured and constrained with the nodal displacements of *** model is then formulated considering the output load constraints as well as the minimization of strain energy and dynamic displacement responses respectively under the static and dynamic *** influences of the ABEs stiffness,different material usages of the design domain,widths of the output loads constraint intervals and variation ratios of output loads are discussed in *** proposed method is verified with several numerical examples with clear and reasonable load transfer paths.

关键词： Artificial bar elements Dynamic response Kreisselmeier-Steinhauser(KS)function Precise control of output loads Topology optimization

Topology Optimal Design of Material Microstructures Using Strain Energy-based Method

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2007年第4期20卷 320-326页

作者： zhang weihong Wang Fengwen Dai Gaoming Sun Shiping The Key Laboratory of Contemporary Design and Integrated Manufacturing Technology Northwestern Polytechnical University Xi ＇an 710072 China

Sensitivity analysis and topology optimization of microstructures using strain energy-based method is presented. Compared with homogenization method, the strain energy-based method has advantages of higher computing efficiency and simplified programming. Both the dual convex programming method and perimeter constraint scheme are used to optimize the 2D and 3D microstructures. Numerical results indicate that the strain energy-based method has the same effectiveness as that of homogenization method for orthotropic materials.

关键词： strain energy-based method homogenization method microstructure design topology optimization

Structural topology optimization: Extensibility and attainability

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2014年第7期57卷 1310-1321页

作者： zhang weihong zhang ZhiDong ZHU JiHong GAO Tong Engineering Simulation and Aerospace Computing (ESAC) School of Mechanical Engineering Northwestern Polytechnical University

Extensibility and attainability of topology optimization are discussed by investigating a variety of simultaneous topology opti-mization methods extended from the standard ***,the state of the art is highlighted through systematic classification of developed methods,such as simultaneous topology optimizations of microstructure and macrostructure,structure and supports,structure and design-dependent loads,structure and locations of involved ***,some recent results about simultaneous topology optimization of structure and applied loads are *** is shown that the simultaneous topology optimization is an integrated methodology that extends the concept of standard topology optimization in the sense of systematic *** presence of more than one kind of design variable of different nature makes the optimization problem complex but enlarges the design space to attain the optimization.

关键词： topology optimization simultaneous optimization multi-component support design-dependent load load location