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| 1 | A Bayesian Updating Method for Non-Probabilistic Reliability Assessment of Structures with Performance Test Data显示文摘For structures that only the predicted bounds of uncertainties are available,this study proposes a Bayesianmethod to logically evaluate the nonprobabilistic reliability of structures based on multi-ellipsoid convex model and performance test data.According to the given interval ranges of uncertainties,we determine the initial characteristic parameters of a multi-ellipsoid convex set.Moreover,to update the plausibility of characteristic parameters,a Bayesian network for the information fusion of prior uncertainty knowledge and subsequent performance test data is constructed.Then,an updated multi-ellipsoid set with the maximum likelihood of the performance test data can be achieved.The credible non-probabilistic reliability index is calculated based on the Kriging-based surrogate model of the performance function.Several numerical examples are presented to validate the proposed Bayesian updating method. | Jiaqi He Yangjun Luo | 2020 | Computer Modeling in Engineering & Sciences2020，，11： | 5 |
| 2 | Robust topology optimization of hinge-free compliant mechanisms with material uncertainties based on a non-probabilistic field model显示文摘This paper presents a new robust topology optimization framework for hinge-free compliant mechanisms with spatially varying material uncertainties,which are described using a non-probabilistic bounded field model.Bounded field uncertainties are efficiently represented by a reduced set of uncertain-but-bouncled coeflficients on the basis of the series expansion method.Robust topology optimization of compliant mechanisms is then defined to minimize the variation in output displacement under constraints of the mean displacement and predefined material volume.The nest optimization problem is solved using a gradient-based optimization algorithm.Numerical examples are presented to illustrate the effectiveness of the proposed method for circumventing hinges in topology optimization of compliant mechanisms. | Junjie ZHAN Yangjun LUO | 2019 | Frontiers of Mechanical Engineering2019，14，2： | 5 |
| 3 | Improving the performance of ducted fans for VTOL applications:A review显示文摘Ducted fans have been widely used in VTOL aircraft due to the high propulsion efficiency and safety.The efficiency and stability of ducted fans deteriorate in some flight conditions such as hovering in crosswinds or ground effect.It is necessary to optimize the ducted fan’s structures or apply flow control methods for better adaptions to the typical conditions.This paper presents a detailed review on the ducted fan technology for VTOL applications,especially the methods for improving its efficiency and stability.We first simplified the classification categories based on boundary conditions instead of flight conditions,since the new classification method covers more situations and is easier to distinguish flow field characteristics.The flow characteristics,thrust properties and the optimal structures under different boundary conditions were summarized and discussed.Finally,new configurations and flow control methods for increasing the efficiency and stability were introduced.The newly proposed integration design between the ducted fan and the motor was emphasized for increasing the power density of the ducted fans.This review would be helpful to improve our understanding of the relationship between the structures,flow characteristics and thrust properties of ducted fans under different flight conditions,and inspires scientists to design high-efficiency and high-stability propulsion systems with ducted fans. | QIAN YuPing LUO YiWei HU XuanYang ZENG ZeZhi ZHANG YangJun | 2022 | Science China(Technological Sciences)2022，65，11： | 3 |
| 4 | A MATLAB code for the material-field series-expansion topology optimization method显示文摘This paper presents a MATLAB implementation of the material-field series-expansion(MFSE)topology optimization method.The MFSE method uses a bounded material field with specified spatial correlation to represent the structural topology.With the series-expansion method for bounded fields,this material field is described with the characteristic base functions and the corresponding coefficients.Compared with the conventional density-based method,the MFSE method decouples the topological description and the finite element discretization,and greatly reduces the number of design variables after dimensionality reduction.Other features of this method include inherent control on structural topological complexity,crisp structural boundary description,mesh independence,and being free from the checkerboard pattern.With the focus on the implementation of the MFSE method,the present MATLAB code uses the maximum stiffness optimization problems solved with a gradientbased optimizer as examples.The MATLAB code consists of three parts,namely,the main program and two subroutines(one for aggregating the optimization constraints and the other about the method of moving asymptotes optimizer).The implementation of the code and its extensions to topology optimization problems with multiple load cases and passive elements are discussed in detail.The code is intended for researchers who are interested in this method and want to get started with it quickly.It can also be used as a basis for handling complex engineering optimization problems by combining the MFSE topology optimization method with non-gradient optimization algorithms without sensitivity information because only a few design variables are required to describe relatively complex structural topology and smooth structural boundaries using the MFSE method. | Pai LIU Xiaopeng ZHANG Yangjun LUO Yi YAN | 2021 | Frontiers of Mechanical Engineering2021，16，3： | 1 |
| 5 | Structural relia- bility assessment based on probability and convex set mixed model 显示文摘 | LUO Yangjun KANG Zhan LI A | 2009 | Computers and Structures2009，87，： | 1 |
| 6 | Structural reliability assessment based on probability and convex set mixed model 显示文摘 | Luo Yangjun Kang Zhan Li A | 2009 | Computers and Structures2009，87，： | 1 |
| 7 | On non-probabilistic reliability-based design optimization of structures with uncertain-but-bounded parameters显示文摘 | Kang Zhan Luo Yangjun Li A | 2011 | Structural Safety2011，33，： | 1 |
| 8 | Continuum topology optimization with non-probabilistic reliability constraints based on multi-ellipsoid convex model显示文摘 | Luo Yangjun Kang Zhan Luo Zhen | 2009 | Structural and Multidisciplinary Optimization2009，39，3： | 1 |
| 9 | Structural reliability assess- ment based on probability and convex set mixed model 显示文摘 | Luo Yangjun Kang Zhan Li Alex | 2009 | Computers and Structures2009，87，2122： | 1 |
| 10 | Reliability-based structural optimization with probability and convex set hybrid models 显示文摘 | KANG Zhan LUO Yangjun | 2010 | Structural and Multidisciplinary Optimization2010，，： | 1 |
| 11 | Structural reliability assessment based on probability and convex set mixed model显示文摘 | LUO Yangjun KANG Zhan ALEX L | 2009 | Computers and Structures2009，87，2122： | 1 |
| 12 | Continuum topology optimization with non-probabilistic reliability constrains based on multi-ellipsoid convex model显示文摘 | Luo Yangjun Kang Zhan Luo Zhen | 2008 | Structural and Multidisciplinary Optimization Published online2008，10，31： | 1 |
| 13 | Continuum topology optimization with non-probabilistic reliability constraints based on multi-ellipsoid convex model显示文摘 | Luo Yangjun Kang Zhan Luo Zhen | 2009 | Structure Multidiscipline Optimization2009，39，3： | 1 |
| 14 | On non-probabilistic reliability-based design optimization of structures with uncertain but bounded parameters显示文摘 | Zhang Kang Yangjun Luo Alex Li | 2011 | Structural Safety2011，33，3： | 1 |
| 15 | Structural relia- bility assessment based on probability and convex set mixed model显示文摘 | Luo Yangjun Kang Zhan Li Alex | 2009 | Computers and Structures2009，87，2122： | 1 |
| 16 | Numerical investigation on unsteady characteristics of ducted fans in ground effect显示文摘Ducted fans are widely used in various applications of Unmanned Aerial Vehicles(UAVs)due to the high efficiency,low noise and high safety.The unsteady characteristics of ducted fans flying near the ground are significant,which may bring stability problems.In this paper,the sliding mesh technology is applied and the Unsteady Reynolds Averaged Navier-Stokes(URANS)method is adopted to evaluate the influence of ground on the aerodynamic performance of ducted fans.The time-averaged results show that the ground leads to the decrease of duct thrust,the increase of rotor thrust and the decrease of total thrust.The transient results show that there exist small-scale stall cells with circumferential movements in ground effect.The stall cells start to appear at the blade root when the height is 0.8 rotor radius distance,and arise at both the blade root and tip when the height drops to 0.2.It is found that the unsteady cells rotate between blade passages with an approximate relative speed of 30%-80%of the fan speed,and lead to thrust fluctuations up to 37%of the total thrust.The results are essential to the flight control design of the ducted fan flying vehicle,to ensure its stability in ground effect. | Yiwei LUO Tianfu AI Yuhang HE Bin XU Yuping QIAN Yangjun ZHANG | 2023 | Chinese Journal of Aeronautics2023，36，9： | 0 |
| 17 | Introduction to the Special Issue on NovelMethods for Reliability Evaluation and Optimization of ComplexMechanical Structures显示文摘Reliability of mechanical structures is an important issue in the engineering field,especially in the field of aerospace and other high-tech sophisticated fields.Up to now,reliability-based evaluation and optimization methods have been widely applied in the safety analysis and design of mechanical structures.Many advanced algorithms for significantly improving the calculation efficiency and accuracy of solutions have been developed and gained successful applications in real engineering problems.Recently,with the advantages of strong versatility and well global-searching ability,more and more attention has been paid to the intelligent algorithm of mechanical structure reliability optimization design. | Feng Zhang Yangjun Luo | 2021 | Computer Modeling in Engineering & Sciences2021，，2： | 0 |
| 18 | Biomimetic hybrid hydrogel for hemostasis,adhesion prevention and promoting regeneration after partial liver resection显示文摘Partial liver resection is an established treatment for hepatic disorders.However,surgical bleeding,intra-abdominal adhesion and rapid liver regeneration are still major challenges after partial liver resection,associated with morbidity and mortality.Herein,a biomimetic hybrid hydrogel,composed of oxidized hyaluronic acid,glycol chitosan and MenSCs-derived conditioned medium(CM),is presented to address these issues.The hybrid hydrogel is formed through reversible Schiff base,and possesses injectability and self-healing capability.Moreover,hybrid hydrogel exhibits the capabilities of hemostasis,anti-infection,tissue adhesion and controllable release of cargoes.Based on in vivo studies of the multifunctional hybrid hydrogel,it is demonstrated that acute bleeding in partial liver resection can be ceased immediately by virtue of the hemostasis features of hybrid hydrogel.Also,a significant reduction of intra-abdominal adhesion is confirmed in hybrid hydrogel-treated resection surface.Furthermore,upon the treatment of hybrid hydrogel,hepatic cell proliferation and tissue regeneration can be significantly improved due to the controllably released cytokines from MenSCs-derived CM,exerting the effects of mitogenesis and anti-inflammation in vivo.Thus,the biomimetic hybrid hydrogel can be a promising candidate with great potential for application in partial liver resection. | Zuhong Li Yalei Zhao Xiaoxi Ouyang Ya Yang Yangjun Chen Qixia Luo Yanhong Zhang Danhua Zhu Xiaopeng Yu Lanjuan Li | 2022 | Bioactive Materials2022，7，5： | 0 |
| 19 | Achieving desired nodal lines in freely vibrating structures via material-field series-expansion topology optimization显示文摘Accurately controlling the nodal lines of vibrating structures with topology optimization is a highly challenging task.The major difficulties in this type of problem include a large number of design variables,the highly nonlinear and multi-peak characteristics of iteration,and the changeable orders of eigenmodes.In this study,an effective material-field series-expansion(MFSE)-based topology optimization design strategy for precisely controlling nodal lines is proposed.Here,two typical optimization targets are established:(1)minimizing the difference between structural nodal lines and their desired positions,and(2)keeping the position of nodal lines within the specified range while optimizing certain dynamic performance.To solve this complex optimization problem,the structural topology of structures is first represented by a few design variables on the basis of the MFSE model.Then,the problems are effectively solved using a sequence Kriging-based optimization algorithm without requiring design sensitivity analysis.The proposed design strategy inherently circumvents various numerical difficulties and can effectively obtain the desired vibration modes and nodal lines.Numerical examples are provided to validate the proposed topology optimization models and the corresponding solution strategy. | Yi YAN Xiaopeng ZHANG Jiaqi HE Dazhi WANG Yangjun LUO | 2023 | Frontiers of Mechanical Engineering2023，18，3： | 0 |
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