Jian Hua Rong

Changsha University of Science and Technology · School of Automobile and Mechanic Engineering

This work proposes a method for optimizing the continuum structural topology under multiple load cases considering frequency constraints and the effect of self-weight. An improved Solid Isotropic Material with Penalization (SIMP) model is proposed to avoid the parasitic effect. At the same time, new matching smooth penalty functions on the element...

At present, most of the researches on topology optimization focus on continuum structures, but few on frame structures. This paper presents a methodology for topology optimization of frame structures with stress and stability constraints under a prescribed volume. In order to solve the pseudo buckling mode issues and calculation efficiency caused b...

Background Ischaemia-reperfusion injury is considered an inevitable component of organ transplantation, compromising organ quality and outcomes. Although several treatments have been proposed, none has avoided graft ischaemia and its detrimental consequences.Methods Ischaemia-free liver transplantation (IFLT) comprises surgical techniques enabling...

Abstract: Similar periodic structures have been widely used in engineering. In order to obtaining the optimal similar periodic structures, a topology optimiza­tion method of similar periodic structures with multiple displacement constraints is proposed in this paper. Firstly, in the proposed method, the design domain is di­vided into sub-domains. S...

In practical engineering, due to the lack of information, it is impossible to accurately determine the distribution of all variables. Therefore, time-variant reliability problems with both random and interval variables may be encountered. However, this kind of problem usually involves a complex multilevel nested optimization problem, which leads to...

Considering structural strength and castability in topology optimization is very attractive from the perspective of theory and application. This paper introduces stress considerations into casting‐oriented topology optimization to explore structural optimization methods that simultaneously consider the above two vital design indicators. Two stress‐...

In practical engineering, it is a cost-consuming problem to consider the time-variant reliability of both random variables and interval variables, which usually requires a lot of calculation. Therefore, a time-variant reliability analysis approach with hybrid uncertain variables is proposed in this paper. In the design period, the stochastic proces...

Structural topology optimization considering both performance and manufacturability is very attractive in engineering applications. This work proposes a formulation for structural topology optimization to achieve such a design, in which material strength, structural stiffness, and connectivity are simultaneously considered by integrating stress and...

The effect of large thickness-reduction on microstructure evolution and tensile properties of Mg-9Al-1Zn alloy (AZ91) processed by hard-plate rolling (HPR) was investigated. Increasing rolling reduction from 55 % to 85 % increases the volume fraction and refines average size of fine grains (< 3 μm, FGs), leading to an optimized bimodal-grained stru...

Compliant mechanisms with multiple inputs and multiple outputs have a wide range of applications in precision mechanics, e.g., cell manipulations, electronic microscopes, and etc. The movement uncoupling and maximum desired output displacements among these devices all become critical because many inputs and outputs are involved. The topology optimi...

Topology optimization of cast parts involving parting surface position is one of the main challenges in engineering design. This work presents a study on topology optimization of cast parts considering various cases of parting surface position. Two casting constraint models for different parting surface position requirements are developed and evalu...

This paper proposes a concurrent topology optimization method of macrostructural material distribution and periodic microstructure considering dynamic stress response under random excitations. The optimization problem is the minimization of the dynamic stress response of the macrostructure subject to volume constraints in both macrostructure and mi...

Suppressing enclosed voids in topology optimization is an important problem in design for manufacturing. The method of Poisson equation-based scalar field constraint (i.e., Poisson method) can effectively address this problem. Nevertheless, the numerical performance of this method is not well understood. This paper investigates the numerical functi...

It has been shown that normothermic machine perfusion (NMP), a novel preservation method, is able to assess and resuscitate liver grafts with risk factors. However, there is no consistent criteria for assessment of liver graft with NMP. Ischemia‐free liver transplantation (IFLT) includes innovative surgical techniques and NMP, which can protect liv...

Minimum length scale control on real and void material phases in topology optimization is an important topic of research with direct implications on numerical stability and solution manufacturability. And it also is a challenge area of research due to serious conflicts of both the solid and the void phase element densities in phase mixing domains o...

Most of the current time-variant reliability analysis methods are applicable for only random variables. However, some of the uncertain parameters can only be easily modeled by interval variables in many engineering applications. The main contribution of this paper is to propose a new time-variant reliability analysis method for nonlinear limit stat...

Introduction During conventional liver transplantation (CLT), ischaemia-reperfusion injury (IRI) is inevitable and is associated with complications such as early allograft dysfunction (EAD), primary non-function and ischaemic-type biliary lesions. We have established a novel procedure called ischaemia-free liver transplantation (IFLT). The results...

BACKGROUND Ischemia-reperfusion injury is considered an inevitable event that compromises posttransplant outcomes. Numerous treatments have been proposed to reduce its impact. However, most of them have had limited success, as none of them can completely avoid graft ischemia. METHODS Ischemia-free liver transplantation (IFLT) comprises surgical tec...

More attention has been attracted to engineering structural design on fatigue failure, while few works are devoted to topology optimizations considering dynamic fatigue failure under random vibrations. In this paper, a new layout optimization method is proposed to consider high-cycle dynamic fatigue constraints which are caused by periodic random d...

Commercial wrought Mg alloys normally contain low alloying contents to ensure good formability. In the present work, high-alloyed Mg-6Al-4Zn-xSn (x = 1, 2 and 3 wt.%, respectively) alloys were fabricated by extrusion. Hereinto, Sn was proven to play an effective contribution to simultaneous improvement in strength and ductility that are traditional...

This study aims to investigate the promotion effect of twinning-induced nucleation vs the inhibition effect of Mg17Al12 particles pinning for recrystallization, achieved through gradient rolling for Mg‒3Al‒1Zn (AZ31) and Mg‒9Al‒1Zn (AZ91) alloys as well as pure Mg. Through gradient rolling, a transition zone from the initial to deformed microstruct...

In many practical applications, probabilistic and bounded uncertainties often arise simultaneously, and these uncertainties can be described by using probability and convex set models. However, the computing cost becomes unacceptable when directly solving the reliability-based design optimization (RBDO) problem with these uncertainties involved. To...

This study aims to investigate the promotion effect of twinning-induced nucleation vs the inhibition effect of Mg17Al12 particles pinning for recrystallization, achieved through gradient rolling for Mg-3Al-1Zn (AZ31) and Mg-9Al-1Zn (AZ91) alloys as well as pure Mg. Through gradient rolling, a transition zone from the initial to deformed microstruct...

A novel Mg-8Al-2Sn-1Zn alloy with a bimodal structure prepared by hard-pate-rolling (HPR) exhibits both higher tensile strength and ductility than its fine-grained counterparts prepared by conventional rolling. By delicate electron back-scatter diffraction (EBSD) analysis, we found fine grains with weak basal texture is beneficial for basal slip an...

Most of engineering structures work under multiple load cases, and topology compliance minimization under multiple load cases are of important engineering value. A new compliance topology optimization method of continuum structures under multiple load cases with a volume constraint is proposed. Firstly, being referred to the bound formulation metho...

In the present study, the application of hard–plate rolling (HPR) on the hard-to-deform Mg–7Al–5Zn (AZ75) alloy resulted in a homogeneous fine grained (∼6 μm) microstructure, where numerous micron/nano Mg17(Al, Zn)12 precipitates with spherical morphology uniformly dispersed both at grain boundaries and within grain interiors. More importantly, the...

The gray problem of displacement constrained topology volume minimization under multiple load cases still is an opening topic of research. A series of topologies with clear profiles generated from an optimization process are very beneficial to method engineering applications. In this paper, a novel displacement constrained optimization approach for...

A reliability-based design optimization method was presented based on the sequential Kriging method to decrease the computational intensity and to improve the accuracy of the traditional reliability-based design optimization of automobile body structure for the lightweight design of vehicle body. The vehicle mass was selected as the objective of op...

In order to describe the different types of uncertainty parameters for the thickness and material parameters of absorbing energy structure, probability and convex set models were adopted. The reliability indices for vehicle frontal impact safety were chosen as the reliability constraints and the weight of absorbing energy structure was selected as...

Stress-related problems have not been given the same attention as the minimum compliance topological optimization problem in the literature. Continuum structural topological optimization with stress constraints is of wide engineering application prospect, in which there still are many problems to solve, such as the stress concentration, an equivale...

To analyze interchange guide signs' influence on vehicle speed in three kinds of interchange ramps of an urban expressway, vehicle operating data through a driving simulator experiment which was composed of twelve scenarios on basis of guide signs and different kinds of interchange ramps as two sorts of experiment controlling factors were obtained....

Based on the idea of structural topology optimization, a structural material optimization method considering varying frequency interval constraints was proposed. By use of homogenization and ICM (Independence, Continuity and Mapping) method, the effective mass matrix and its derivatives were established by taking the reciprocal topological variable...

Uniaxial tensile tests were performed on fine-grained, rolled AT33 alloy at strain rates of 1.0 × 10−4–1.0 × 10−1 s−1 and temperatures of 25–250 °C. The rolled AT33 alloy with an average grain size of 7 μm was produced by cast-rolling and hot-rolling. The relative deformation mechanisms at high temperature were investigated in this study. It was fo...

The new type of Mg-8Al-1Sn (AT81) magnesium matrix composites reinforced with different volume fractions (5, 10, 15, 20, 25 and 30 vol.-%) of SiC particles (average size of 10 mm) was fabricated by powder metallurgy. With the increasing volume fraction of SiC particles (SiCp), the particles gradually show more homogeneous distribution. Compared wit...

There has been considerable interest in materials exhibiting negative or zero compressibility. Such materials are desirable for various applications. A number of models or mechanisms have been proposed to characterize the unusual phenomena of negative linear compressibility (NLC) and negative area compressibility (NAC) in natural or synthetic syste...

According to the Chinese Design Specification for Highway Alignment (JTG D20-2006), eight-lane expressways should be paved with an inside shoulder of 2.5 m; however, this regulation is rarely obeyed in engineering practice. On the basis of driving simulator experiment, this research examined the impacts of inside shoulder on vehicle operation with...

In present time, the guidelines on warning sign position in the China National Standard lack detailed and standard regulations of placing warning signs on sharp curves, which may cause road safety problems. Therefore, this paper briefly discussed how to optimize the position of a warning sign on a sharp curve through a driving simulator experiment....

A methodology for topology optimization based on element independent nodal density (EIND) is developed. Nodal densities are implemented as the design variables and interpolated onto element space to determine the density of any point with Shepard interpolation function. The influence of the diameter of interpolation is discussed which shows good ro...

This paper presents a topology optimization method for continua that minimizes the volume subject to global displacement constraint. The method uses the p-norm displacement to represent the equivalent maximum displacement so as to avoid non-differentiability of the maximum function. Using nodal densities as design variables, a new topology optimiza...

More and more stringent structural performance requirements are imposed in advanced engineering application, only a limited number of works have been devoted to the topology optimization of the structures with random vibration response requirements. In this study, the topology optimization problem with the objective function being the structural we...

This paper aims to propose a non-probabilistic reliability-based multi-objective optimization method for structures with uncertain-but-bounded parameters. A combination of the interval and ellipsoid convex models is used to account for the different groups of uncertain parameters, in which the interval model accounts for uncorrelated parameters, wh...

This paper introduces a hierarchical concurrent design approach to maximizing the natural frequency of a structure. Multiple material phases are considered in the topology optimization performed on both the macro and micro scales. A general problem for composite structure and material design is formulated that contains the cellular design problem a...

In this paper, a topology optimization method based on the element independent nodal density (EIND) is developed for continuum solids with multiple load cases and multiple constraints. The optimization problem is formulated ad minimizing the volume subject to displacement constraints. Nodal densities of the finite element mesh are used a the design...

The optimal design of periodic structures under the macro scale and that of periodic materials under the micro scale are treated differently by the current topology optimization techniques. Nevertheless, a material point in theory could be considered as a unit cell in a periodic structure if the number of unit cells approaches to infinity. In this...

An orthotropic material is characterized by nine independent moduli. The ratios between the Young’s moduli in three directions are indicative of the level of orthotropy and the bulk modulus is indicative of the overall stiffness. In this paper we propose a method for designing the stiffest orthotropic material which has prescribed ratios for Young’...

Driver fatigue is a significant contributing factor to numerous traffic crashes, which brings great socioeconomic concerns to policy makers, the general public as well as transportation professionals. There is an emerging consensus that the monotonous road environments are the major exogenous factor causing driver fatigue. This study aims to reveal...

The current techniques for topology optimization of material microstructure are typically based on infinitely small and periodically repeating base cells. These base cells have no actual size. It is uncertain whether the topology of the microstructure obtained from such a material design approach could be translated into real structures of macrosca...

Measuring rock stratum displacement in dam grouting process is very important. A new displacement system is designed, comprising a programmable microcontroller Atmega16, a new grating capacitive displacement sensor(GCDS), DS1302 real time clock chip and announciator etc. The system has high sampling rate of 9600 baud rate and can trap the displacem...

An efficient structural topological optimization method is proposed in this paper to obtain a well defined final design with multi-displacement constraints. In the proposed method, the whole optimization process is divided into two optimization phases and a phase transferring step. An optimization model is developed to deal with the varied displace...

Based on the fact that the structural domain need be divided into some finite element meshes when structural topology optimization is made, and some optimization problems may need a large finite element mesh, a new structural topology optimization method was proposed. The minimum compliance topology optimization of continuum structures was dealt wi...

This paper presents the bidirectional evolutionary structural optimization (BESO) method for the design of two-phase composite materials with optimal properties of stiffness and thermal conductivities. The composite material is modeled by microstructures in a periodical base cell (PBC). The inverse homogenization method is used to derive the proper...

In density-based topological design, one expects that the final result consists of elements either black (solid material) or white (void), without any grey areas. Moreover, one also expects that the optimal topology can be obtained by starting from any initial topology configuration. An improved structural topological optimization method for multi-...

Stress related problems have not been given the same attention as the minimum compliance problem in the literature. A topological optimization method of continuum structures with the stress constraints and any initial configuration requirements has been presented in this paper. In order to greatly reduce stress sensitivity cost, all element stress...

In the proposed topology optimization method, the whole optimization process is divided into two phases. Firstly，an optimization model dealing with varying displacement limits and design space adjustment approaches， after the combination of structural discrete topology variable condition and the original objective， are built. Secondly，incorporating...

Although a discrete solid and void structural topology is typically desired, a continuous material density design field is usually assigned to the material points within the design domain to spatially indicate regions of solid and void material. The solid isotropic microstructure with penalization material (SIMP) formulation is easy to implement in...

Stress constrained topology optimization problem has not been paid the same attention as the minimum compliance problem in the literatures. The traditional minimum compliance formulations offer some obvious advantages to avoid dealing with a large number of highly non-linear constraints. This could be considered crucial, if one takes into account t...

In each sub-loop solving of the ICM (Independent, Continuous and Mapping) method, whether in what quantities do topology design variables change, structural displacements etc. characteristic quantities and their derivatives are approximately obtained by using their values at the beginning of the sub-loop iterations. This measurement may lead to lar...

Sizing and shape structural optimization problems are normally stated in terms of a minimum weight approach with constraints that limit the maximum allowable stresses and displacements. However, topology structural optimization problems have been usually stated in terms of a maximum stiffness (minimum compliance) approach. In this kind of formulati...

A distinctive topology configuration can be obtained when the design domain has a similar size in all directions for a plane or three-dimensional problem. However, it is difficult to solve the topology optimization problem for a long-and-thin structure with variable cross-section using conventional algorithm. In order to solve this problem, a new m...

For structural topologic optimization problems with an objective function being structural weight and only frequency constraints, based on the ICM method and the evolutionary structural optimization method, a new structural topologic optimization method is proposed. At the beginning of each sub-loop optimization iteration process, in order to contr...

In practice, a continuum structure is usually designed to carry the traction applied to the boundary of the structure subject to prescribed displacements imposed on its boundary. The design domains of practical structures are often limited and significantly affect the final optimal design of the structures. Structural boundaries under traction and...

In this paper, a topology optimization method mixed structures with continuum and discrete elements is proposed. First, based on the stress and displacement formulations of the finite element analysis, a set of stress sensitivity numbers for beam and plane-stress structures are derived. Then, relative difference quotients for topology and size vari...

The level set method was first introduced into the structural topology optimization by Sethian et al. Wang et al. studied structural topology optimization by incorporating the shape derivative or sensitivity analysis with the level set model. In essence, the method employs the implicit moving material interface models or the level set vector to rep...

The topology optimization of large and complex structures is important in theory and application. Based on the idea that finite elements with artificial material property are inserted around the cavities and boundaries of the structure to approximately transform the singular topology optimization model into a non-singular one, this paper has made a...

In practice, a continuum structure is usually designed with tractions applied to a part of its boundary and prescribed displacements imposed on other part of the boundary. The design domains of practical structures are often limited and significantly affect the final optimal design of the structures. Structural boundaries under tractions and prescr...

Based on the modal truncation method and some approximate treatments, a structural mean square dynamic response expression under narrow-band random excitations as well as their sensitivities are derived. According to engineering practical requirements, a set of topology optimization formula and its procedure, with static loads and narrowband random...

In the optimization process of a complex three-dimensional continuum structure by using the conventional evolutionary structural optimization method, some isolated groups of elements or a few elements being of rigid movements, often appear in the optimized structure, which becomes singular so that the optimization process can’t continue. In order t...

According to stress minimization and material utility, which are two major aspects of structural optimization in a wide range of engineering designs, a stress estimate parameter is introduced and derived in this paper. Then a new stress criterion is presented for the problems of minimizing the maximum stress while low-stressed elements are removed....

An idea to insert man-made material around structural cavities and boundaries is presented. Combining evolutionary structural optimization method with stress sensitivity, criteria for adding and removing finite elements are developed, and a new topology optimization procedure is given. Several examples show that the optimal topology can be obtained...

The man-made material is added around optimal structural cavities and boundaries. Based on evolutionary structural optimization(ESO) method and element strain energy analysis, a structural topology optimization method was developed with strain energy analysis. The basic theory of topology optimization was given, and the formulae of ESO method with...

In this paper, an improved method for evolutionary structural optimisation against buckling is proposed for maximising the critical buckling load of a structure of constant weight. First, based on the formulations of derivatives for eigenvalues, the sensitivity numbers of the first eigenvalue or the first multiple eigenvalues (for closely spaced an...

In recent years, the Evolutionary Structural Optimization (ESO) method has been developed into an effective tool for engineering design. However, no attempts have been made to incorporate random dynamic response constraints. The optimum design of structures with dynamic response constraints is of great importance, particularly in the aeronautical a...