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Topology Optimization Method of Structures with Surface Corrosion Considered

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Acta Mechanica Solida Sinica 2023年第2期36卷 241-253页

作者： Ran li shutian liu State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116024China

Engineering equipment served in harsh environments for a long time will inevitably corrode,resulting in a loss of mechanical performance and a reduction in a lifetime,and even threatening production *** conventional post-treatment anti-corrosion technologies can slow down the corrosion rate,it is important to consider the corrosion effect on the structural performance in *** paper proposes a topology optimization method with prior consideration of structural corrosion resistance during the design phase,so the structures designed by the approach can have excellent corrosion resistance,considerably reducing the cost of post-treatment anti-corrosion ***,an erosion-based method is utilized to identify the structural surface *** the procedure,the initial structure is eroded to generate a reduced-scale eroded structure,and then,the eroded regions are specified as the surface ***,dual-material interpolation is used to create the corrosion model by modifying the material properties of elements on the structural surface layer,which is set to 0 to simulate uniform ***,the topology optimization method with structural surface corrosion considered is enforced through a two-step filtering/projection *** the entire lifetime corrosion analysis,various numerical examples indicate that the structural performance of the proposed method is superior to that of the standard method(SIMP interpolation)without considering the influence of corrosion,demonstrating the effectiveness of the proposed method.

关键词： Topology optimization Corrosion resistance Surface layer identification Surface corrosion

Topology Optimization Method for Microscale Structures Described with Integral Nonlocal Theory

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Acta Mechanica Solida Sinica 2024年第1期37卷 63-71页

作者： Jiayu li Quhao li shutian liu State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentDalian University of TechnologyDalian 116024China

The integration of additive manufacturing and topology optimization makes it possible to fabricate complex configurations,especially for microscale structures,which can guarantee the realization of high-performance structural ***,topology results often contain microstructures(several multicellular scales)similar to the characteristic length of local macrostructures,leading to errors in structural performance analysis based on classical ***,it is necessary to consider the size effect in topology *** this paper,we establish a novel topology optimization model utilizing the integral nonlocal theory to account for the size *** approach consists of an integral constitutive model that incorporates a kernel function,enabling the description of stress at a specific point in relation to strain in a distant *** optimization structures based on nonlocal theory are presented for some benchmark examples,and the results are compared with those based on classical medium *** material layout exhibits significant differences between the two approaches,highlighting the necessity of topology optimization based on nonlocal theory and the effectiveness of the proposed method.

关键词： Topology optimization Microstructures Integral nonlocal theory Size effect

Enhancing buckling capacity of a rectangular plate under uniaxial compression by utilizing an auxetic material

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Chinese Journal of Aeronautics 2016年第4期29卷 945-951页

作者： Zhang Yongcun li Xiaobin liu shutian State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering Mechanics Dalian University of Technology

Auxetic materials have previously been shown to enhance various performances due to its unusual property of becoming fatter when uniaxially stretched and thinner when uniaxially compressed (i.e., the materials exhibit a negative Poisson's ratio). The current study focuses on assessing the potential of an auxetic material to enhance the buckling capacity of a rectangular plate under uniaxial compression. The in-plane translational restraint along the unloaded edges that was often neglected in open literature is taken into consideration in our buckling model proposed in this study. The closed-form expressions for the critical buckling coefficient of the rectangle are provided and the predicted results agree well with those determined by the finite element method. Furthermore, the results indicate that the buckling performance of a rectangular plate under uniaxial compression can be significantly improved by replacing the traditional material that has a positive Poisson's ratio with an auxetic material when there is in-plane translation restraint along the unloaded edges. (C) 2016 Chinese Society of Aeronautics and Astronautics. Production and hosting by Elsevier Ltd.

关键词： Auxetic material Buckling Elastically restraint Negative Poisson's ratio Optimization

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Concurrent topology optimization design of stiffener layout and cross-section for thin-walled structures

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Acta Mechanica Sinica 2021年第3期37卷 472-481,I0003页

作者： Quhao li Yongxin Qu Yunfeng Luo shutian liu Key Laboratory of High Efficiency and Clean Mechanical Manufacture of MOE School of Mechanical EngineeringShandong UniversityJinan 250061China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116024China

Stiffened plates or shells are widely used in engineering structures as primary or secondary load-bearing *** to design the layout and sizes of the stiffeners is of great significance for structural *** this work,a new topology optimization method for simultaneously optimizing the layout and cross-section topology of the stiffeners is developed to solve this *** stilfeners and base plates are modeled by the beam and shell elements,respectively,significantly reducing the computational *** Giavotto beam theory,instead of the widely employed Euler or Timoshenko beam theory,is applied to model the stiffeners for considering the warping deformation in evaluating the section stiffness of the beam.A multi-scale topology optimization model is established by simultaneously optimizing the layout of the beam and the topology of the *** design space is significantly expanded by optimizing these two types of design *** numerical examples are applied to illustrate the validity and effectiveness of the proposed *** results show that the proposed two-scale optimization approach can generate better designs than the single-scale method.

关键词： Stiffener plate design Cross-section optimization Layout optimization Giavotto beam theory

A Realization Method for Transforming a Topology Optimization Design into Additive Manufacturing Structures

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Engineering 2018年第2期4卷 113-121页

作者： shutian liu Quhao li Junhuan liu Wenjiong Chen Yongcun Zhang State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian Liaoning 116024 China

Topology optimization is a powerful design approach that is used to determine the optimal topology in order to obtain the desired functional performance. It has been widely used to improve structural performance in engineering fields such as in the aerospace and automobile industries. However, some gaps still exist between topology optimization and engineering application, which significantly hinder the applica- tion of topology optimization. One of these gaps is how to interpret topology results, especially those obtained using the density framework, into parametric computer-aided design （CAD） models that are ready for subsequent shape optimization and manufacturing. In this paper, a new method for interpreting topology optimization results into stereolithography （STL） models and parametric CAD models is pro- posed. First, we extract the skeleton of the topology optimization result in order to ensure shape preser- vation and use a filtering method to ensure characteristics preservation. After this process, the distribution of the nodes in the boundary of the topology optimization result is denser, which will benefit the subsequent curve fitting. Using the curvature and the derivative of curvature of the uniform B-spline curve, an adaptive B-spline fitting method is proposed in order to obtain a parametric CAD model with the fewest control points meeting the requirement of the fitting error. A case study is presented to pro- vide a detailed description of the proposed method, and two more examples are shown to demonstrate the validity and versatility of the proposed method.

关键词： Topology optimization Additive manufacturing Characteristics preservation Adaptive fitting Shape optimization

Dissipation-induced topological phase transition and periodic-driving-induced photonic topological state transfer in a small optomechanical lattice

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Frontiers of physics 2021年第1期16卷 157-167页

作者： Lu Qi Guo-li Wang shutian liu Shou Zhang Hong-Fu Wang School of Physics Harbin Institute of TechnologyHarbin 150001China Department of Physics College of ScienceYanbian UniversityYanji 133002China

We propose a scheme to investigate the topological phase transition and the topological state transfer based on the small optomechanical lattice under the realistic parameters *** find that the optomechanical lattice can be equivalent to a topologically nontrivial Su-Schrieffer heeger(SSH)model via designing the effective optomechanical ***,the optomechanical lattice experiences the phase transition between topologically nontrivial SSH phase and topologically trivial SSH phase by controlling the decay of the cavity field and the opto mechanical *** stress that the to pological phase transition is mainly induced by the decay of the cavity field,which is counter-intuitive since the dissipation is usually detrimental to the ***,we investigate the photonic state transfer between the two cavity fields via the topologically protected edge channel based on the small optomechanical *** find that the quantum st ate transfer assisted by the topological zero energy mode can be achieved via implying the external lasers with the periodical driving amplitudes into the cavity *** scheme provides the fundamental and the insightful explanations towards the mapping of the photonic topological insulator based on the micro-nano optomechanical quantum optical platform.

关键词： to pological phase transition topological state transfer optomechanical lattice

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Factors associated with gastric adenocarcinoma and dysplasia in patients with chronic gastritis:a population-based study

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Chinese Journal of Cancer Research 2017年第4期29卷 341-350页

作者： Jie Xing li Min Shengtao Zhu Hao Zhang Yu Zhao hengcun li Zheng Zhangl Peng li shutian Zhang Department of Gastroenterology Beiiing Friendship Hospital Capital Medical University National Clinical Research Center for Digestive Disease Beijing Digestive Disease Center Beijing Key Laboratory for Precancerous Lesion of Digestive Disease Beiiing 100050 China Department of Gastroenterology Jizhong Energy Fengfeng Group Hospital Handan 056200 China Correspondence to： Prof. Shutian Zhang MD PhD. Department of Gastroenterology Beiiing Friendship Hospital Capital Medical University National Clinical Research Center for Digestive Disease Beiiing Digestive Disease Center Beiiing Key Laboratory for Precancerous Lesion of Digestive Disease Beiiing 100050 China.

Objective： Gastric cancer （GC） is one of the leading causes of death in China and other Asian countries. Recently, gastric endoscopy has become the main approach for GC screening, but the identification of high-risk individuals remains a challenge in GC screening programs. Methods： There were 7,302 patients with chronic gastritis involved in this study. Endoscopic examinations were performed, and their demographic characteristics and lifestyle data were collected. Each possible associated factor of GC/premalignant and precursor lesions was evaluated by univariate and multivariate logistic regressions. Nomograms were used for visualization of those models, and receiver operating characteristic （ROC） curve analysis was used to present the predictive accuracy. Resu Its： We detected 8 （0.11% ） gastric adenocarcinomas, 17 （0.23 %） dysplasia cases, 14 （0.19%） hyperplasia cases, 52 （0.71%） intestinal metaplasia cases, 217 （2.97%） inflammatory lesions, 141 （1.93%） gastric ulcers, 10 （0.14%） atrophic gastritis cases, 1,365 （18.69%） erosive gastritis cases, and 5,957 （81.58%） superficial gastritis cases in 7,302 patients. The age （P〈0.001）, gender （P=0.086）, labor intensity （P=0.018） and leek food intake （P=0.143） were identified as independent predictive factors of GC/premalignant lesions possibility. The corresponding nomogram exhibited an area under the curve （AUC） [95% confidence interval （95% CI）] of 0.82 （0.74-0.89） for the modeling group and 0.80 （0.75-0.85） for the validation group. The age （P=0.002）, gender （P=0.024）, smoldng （P=0.002） and leek food intake （P=0.039） were independent predictive factors of precursor lesions possibility. The corresponding nomogram exhibited an AUC （95% CI） of 0.62 （0.60-0.65） for the modeling group and 0.61 （0.59-0.63） for the validation group. Conclusions： We identified several potential associated factors and provided a preclinical nomogram with the potential to predict the possibility of GC/premalignant and precursor lesions.

关键词： Risk GC dysplasia gastritis population-based study

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An identification method for enclosed voids restriction in manufacturability design for additive manufacturing structures

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Frontiers of Mechanical Engineering 2015年第2期10卷 126-137页

作者： shutian liU Quhao li Wenjiong CheN liyong TONG Gengdong CheNG State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 ChinaE-mail: stliu@*** School of Aerospace Mechanical and Mechatronic EngineeringUniversity of Sydney NSW 2006 Australia

Additive manufacturing （AM） technologies, such as selective laser sintering （SLS） and fused deposition modeling （FDM）, have become the powerful tools for direct manufacturing of complex parts. This breakthrough in manufacturing technology makes the fabrication of new geometrical features and multiple materials possible. Past researches on designs and design methods often focused on how to obtain desired functional performance of the structures or parts, specific manufacturing capabilities as well as manufacturing constraints of AM were neglected. However, the inherent constraints in AM processes should be taken into account in design process. In this paper, the enclosed voids, one type of manufacturing constraints of AM, are investigated. In mathematics, enclosed voids restriction expressed as the solid structure is simply- connected. We propose an equivalent description of simply-connected constraint for avoiding enclosed voids in structures, named as virtual temperature method （VTM）. In this method, suppose that the voids in structure are filled with a virtual heating material with high heat conductivity and solid areas are filled with another virtual material with low heat conductivity. Once the enclosed voids exist in structure, the maximum temperature value of structure will be very high. Based upon this method, the simplyconnected constraint is equivalent to maximum temperature constraint. And this method can be easily used to formulate the simply-connected constraint in topology optimization. The effectiveness of this description method is illustrated by several examples. Based upon topology optimization, an example of 3D cantilever beam is used to illustrate the trade-off between manufacturability and functionality. Moreover, the three optimized structures are fabricated by FDM technology to indicate further the necessity of considering the simply-connected constraint in design phase for AM.

关键词： additive manufacturing topology optimiza-tion manufacturability constraints design for additivemanufacturing simply-connected constraint

The Analysis of Wall Shear Stress Modulated by Acute Exercise in the Human Common Carotid Artery with an Elastic Tube Model

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Computer Modeling in Engineering & Sciences 2018年第8期116卷 127-147页

作者： Yanxia Wang Yu Wang Siqi li Aziz ur Rehman Aziz shutian liu Kairong Qin Department of Engineering Mechanics State Key Laboratory of Structural Analysis for Industrial EquipmentDalian University of TechnologyNo.2Linggong RoadDalian116024China. School of Optoelectronic Engineering and Instrumentation Science Dalian University of TechnologyNo.2Linggong RoadDalian116024China. School of Biomedical Engineering Dalian University of TechnologyNo.2Linggong RoadDalian116024China.

Assessment of the magnitude and pattern of wall shear stress(WSS)in vivo is the prerequisite for studying the quantitative relationship between exercise-induced WSS and arterial endothelial *** the previous studies,the calculation of the WSS modulated by exercise training was primarily based upon the rigid tube model,which did not take non-linear effects of vessel elastic deformation into *** this study,with an elastic tube model,we estimated the effect of a bout of 30-minute acute cycling exercise on the WSS and the flow rate in the common carotid artery according to the measured inner diameter,center-line blood flow velocity,heart rates and the brachial blood pressures before and after exercise ***,the roles of exerciseinduced arterial diameter and blood flow rate in the change of WSS were also *** numerical results demonstrate that acute exercise significantly increases the magnitudes of blood flow rate and ***,the vessel elastic deformation is a non-negligible factor in the calculation of the WSS induced by exercise,which generates greater effects on the minimum WSS than the maximum ***,the contributions of exercise-induced variations in blood flow rate and diameter are almost identical in the change of the mean WSS.

关键词： Acute cycling exercise blood flow wall shear stress common carotid artery elastic tube model rigid tube model