Topological Optimization of Coronary Stents

2015 ◽  
Author(s):  
Shijia Zhao ◽  
Linxia Gu
Keyword(s):  
Radial Stress ◽  
Optimization Method ◽  
Homogenization Method ◽  
Topology Design ◽  
Topological Optimization ◽  
Optimal Topology ◽  
Patient Specific ◽  
Stent Design ◽  
Restenosis Rate ◽  
Radial Stiffness

The structural topological optimization method is an effective way to find the optimal topology of stents, which could be tailored for targeted stent performance, such as scaffolding ability, foreshortening, potential restenosis rate, etc. The radial stiffness is one of the major characteristics about stent performance. In this work, the homogenization method was utilized for the optimization of stent designs with the objective of maximizing the scaffolding ability of stent, i.e. its radial stiffness. A few design choices were presented by changing the number and distribution of strut connectors while keeping the void volume as 80%. The obtained optimal topology illustrated that the material distribution was mainly determined by the radial stress applied onto the stent. The optimal topology design in this work paves the way for the following dimension design, which can be targeted to the customized stent design for patient-specific lesions.

Application of Topological Optimization on Aluminum Alloy Automobile Wheel Designing

2012 ◽  
Vol 562-564 ◽  
pp. 705-708
Author(s):  
Zhi Jun Zhang ◽  
Hong Lei Jia ◽  
Ji Yu Sun ◽  
Ming Ming Wang
Keyword(s):  
Topology Optimization ◽  
Lightweight Design ◽  
Optimization Method ◽  
Variable Density ◽  
Topological Optimization ◽  
Optimal Topology ◽  
Element Analysis ◽  
Material Interpolation ◽  
Strength And Stiffness

Topology optimization method based on variable density and the minimum compliance objective function was used on designing the wheel spokes. SIMP material interpolation model was established to compensate these deficiencies of variable density method. Considering manufacturing process and stress distribution, five bolt wheels was chose to topology optimization. The percentage of material removal of the optimal topology 40% was reasonable. Finite element analysis was used to test the strength and stiffness of the structure of the wheel, the result meets the requirements after wheel topology optimization, and reduces the quality of wheels to 7.76kg, achieve the goals of lightweight design.

Finite Element Calculation of the Polymer Stamp Material Redistribution under Restrictions on Fatigue Life

2022 ◽  
Vol 1049 ◽  
pp. 248-254
Author(s):  
Ivan Andrianov
Keyword(s):  
Finite Element ◽  
Fatigue Strength ◽  
Stress State ◽  
Geometric Model ◽  
Optimization Methods ◽  
Optimization Method ◽  
Topological Optimization ◽  
Optimal Topology ◽  
Calculation Results ◽  
Rejection Coefficient

The numerical method of stamp topological optimization taking into account fatigue strength is presented in the work. It is proposed to take into account the restrictions on the stress state in accordance with the curve of the dependence of the maximum stresses on the number of loading cycles in the ESO topological optimization method. An approach to the selection of the evolutionary coefficient with a step-by-step increase in the rejection coefficient is proposed when constructing an iterative scheme for the rejection of elements by the method of topological optimization. The calculation of the stamp optimal topology with a decrease in volume due to the removal and redistribution of material was carried out in the study. The new geometric model of the optimal topology stamp is based on the predicted distribution of elements with a minimum stress level. The verification calculation of the stress state of the stamp of optimal topology with an assessment of fatigue strength was carried out in the work. The numerical calculation was carried out using the finite element method in the Ansys software package. The minimized stamp volume decreased by 35% according to the calculation results. The results of the study can be further applied in the development of topological optimization methods and in the design of stamping tools of optimal topology.

scholarly journals Development of the Sequential Voids Creation Approach in Axisymmetric Forming Dies

2021 ◽  
Vol 2096 (1) ◽  
pp. 012116
Author(s):  
I K Andrianov
Keyword(s):  
Elastic Modulus ◽  
Fatigue Strength ◽  
Stress State ◽  
Metal Forming ◽  
State Level ◽  
Optimization Methods ◽  
Optimization Method ◽  
Topological Optimization ◽  
Optimal Topology ◽  
Strength Curve

Abstract The study deals with the problem of topological optimization of forming dies with a limitation on fatigue strength. As a model of a stamp, a typical geometric configuration of stamps for the manufacture of parts of the " cup " type is considered. The algorithm for finding the optimal topology is proposed to be built separately in the internal areas under the stamp flanges and under the bottom of the "cup" of forming. Mathematical regularities are presented, according to which elements that fall into the area of predicted removal have a very small elastic modulus, which is widely used in topological optimization methods, then the stress state level is analyzed according to the fatigue strength curve. In the area of the flanges, there is a "build-up" of the mass according to the quadratic law with a variation in the depth of removal of the material. In the area of the bottom of the " cup " of forming, a step-by-step addition of rod elements is proposed until the level of the stress state meets the specified restrictions. Thus, this study is a modification of the topological optimization method. The novelty of the research lies in the construction of a new geometric scheme for determining the area of stored and deleted elements. The results of the study can be further developed in the development of methods for effective redistribution of material, as well as significantly reduce the material costs for the production of metal forming dies.

scholarly journals Topological Optimization of Auxetic Coronary Stents Considering Hemodynamics

2021 ◽  
Vol 9 ◽  
Author(s):  
Huipeng Xue ◽  
Suvash C. Saha ◽  
Susann Beier ◽  
Nigel Jepson ◽  
Zhen Luo
Keyword(s):  
Optimization Method ◽  
Homogenization Method ◽  
Coronary Stents ◽  
Topological Optimization ◽  
Stent Restenosis ◽  
Fluid Permeability ◽  
Design Variables ◽  
New Type ◽  
Mechanical Factors ◽  
New Generation

This paper is to design a new type of auxetic metamaterial-inspired structural architectures to innovate coronary stents under hemodynamics via a topological optimization method. The new architectures will low the occurrence of stent thrombosis (ST) and in-stent restenosis (ISR) associated with the mechanical factors and the adverse hemodynamics. A multiscale level-set approach with the numerical homogenization method and computational fluid dynamics is applied to implement auxetic microarchitectures and stenting structure. A homogenized effective modified fluid permeability (MFP) is proposed to efficiently connect design variables with motions of blood flow around the stent, and a Darcy-Stokes system is used to describe the coupling behavior of the stent structure and fluid. The optimization is formulated to include three objectives from different scales: MFP and auxetic property in the microscale and stenting stiffness in the macroscale. The design is numerically validated in the commercial software MATLAB and ANSYS, respectively. The simulation results show that the new design can not only supply desired auxetic behavior to benefit the deliverability and reduce incidence of the mechanical failure but also improve wall shear stress distribution to low the induced adverse hemodynamic changes. Hence, the proposed stenting architectures can help improve safety in stent implantation, to facilitate design of new generation of stents.

3-D optimal design of laminated yoke of billet heater for rolling wire rod using ON/OFF method

2012 ◽  
Vol 61 (1) ◽  
pp. 115-123 ◽  
Author(s):  
Norio Takahashi ◽  
Shunsuke Nakazaki ◽  
Daisuke Miyagi ◽  
Naoki Uchida ◽  
Keiji Kawanaka ◽  
...  
Keyword(s):  
Optimal Design ◽  
Local Heating ◽  
Optimization Method ◽  
Optimal Topology ◽  
Field Problem ◽  
Heating Efficiency ◽  
Magnetic Devices ◽  
Wire Rod ◽  
Magnetic Recording Heads ◽  
Sensitivity Method

3-D optimal design of laminated yoke of billet heater for rolling wire rod using ON/OFF method The optimization method using the ON/OFF sensitivity analysis has an advantage that an epoch-making construction of magnetic circuit may be obtained. Therefore, it is attractive for designers of magnetic devices. We have already developed the ON/OFF method for the optimization of a static magnetic field problem, and the effectiveness is verified by applying it to the optimization of magnetic recording heads. In this paper, the ON/OFF sensitivity method is extended to the optimization of the eddy current problem using the adjoint variable. The newly developed ON/OFF method is applied to the determination of the optimal topology of the yoke of the billet heater for rolling wire rod. As a result, the optimal shape of yoke, which we could not imagine beforehand can be obtained. It is shown that the local heating of the yoke was reduced without decreasing the heating efficiency.

Reverse Modeling and Topological Optimization for Lightweight Design of Automobile Wheel Hubs with Hollow Ribs

2019 ◽  
Vol 17 (09) ◽  
pp. 1950064
Author(s):  
P. F. Xu ◽  
S. Y. Duan ◽  
F. Wang
Keyword(s):  
Finite Element ◽  
Lightweight Design ◽  
Element Model ◽  
Optimization Method ◽  
Modeling Technique ◽  
Topological Optimization ◽  
Time Interval ◽  
Braking Performance ◽  
Existing Structures ◽  
Physical Conditions

Lightweight of wheel hubs is the linchpin for reducing the unsprung mass and improving the vehicle dynamic and braking performance of vehicles, thus, sustaining stability and comfortability. Current experience-based lightweight designs of wheel hubs have been argued to render uneven distribution of materials. This work develops a novel method to combine the reverse modeling technique with the topological optimization method to derive lightweight wheel hubs based on the principles of mechanics. A reverse modeling technique is first adopted to scan and reproduce the prototype 3D geometry of the wheel hub with solid ribs. The finite element method (FEM) is then applied to perform stress analysis to identify the maximum stress and its location of wheel hub under variable potential physical conditions. The finite element model is then divided into optimization region and nonoptimized region: the former is the interior portion of spoke and the latter is the outer surface of the spoke. A topology optimization is then conducted to remove the optimization region which is interior material of the spokes. The hollow wheel hub is then reconstructed with constant wall thickness about 5[Formula: see text]mm via a reverse modeling technique. The results show that the reconstructed model can reduce the mass of 12.7% compared to the pre-optimized model. The present method of this paper can guarantee the optimal distribution of wheel hub material based on mechanics principle. It can be implemented automatically to shorten the time interval for optimal lightweight designs. It is especially preferable for many existing structures and components as it maintains the structural appearance of optimization object.

scholarly journals Strut-and-tie models for linear and nonlinear behavior of concrete based on topological evolutionary structure optimization (ESO)

2019 ◽  
Vol 12 (1) ◽  
pp. 87-100
Author(s):  
R. M. LANES ◽  
M. GRECO ◽  
M. B. B. F. GUERRA
Keyword(s):  
Nonlinear Behavior ◽  
Structure Optimization ◽  
Internal Flow ◽  
Optimization Method ◽  
Topological Optimization ◽  
Structural Elements ◽  
Stress Concentrations ◽  
Progressive Reduction ◽  
Strut And Tie ◽  
Safety And Reliability

Abstract The search for representative resistant systems for a concrete structure requires deep knowledge about its mechanical behavior. Strut-and-tie models are classic analysis procedures to the design of reinforced concrete regions where there are stress concentrations, the so-called discontinuous regions of the structure. However, this model is strongly dependent of designer’s experience regarding the compatibility between the internal flow of loads, the material’s behavior, the geometry and boundary conditions. In this context, the present work has the objective of presenting the application of the strut-and-tie method in linear and non-linear on some typical structural elements, using the Evolutionary Topological Optimization Method (ESO). This optimization method considers the progressive reduction of stiffness with the removal of elements with low values of stresses. The equivalent truss system resulting from the analysis may provide greater safety and reliability.

Topology Optimization Algorithm for Plates and Shells Subjected to Plastic Deformations

1998 ◽  
Author(s):  
Kohei Yuge ◽  
Nobuhiro Iwai ◽  
Noboru Kikuchi
Keyword(s):  
Topology Optimization ◽  
Optimization Method ◽  
Homogenization Method ◽  
Finite Deformations ◽  
Thin Shells ◽  
Plastic Deformations ◽  
Material Tensor ◽  
Design Variables ◽  
Interpolation Technique ◽  
Plates And Shells

Abstract A topology optimization method for plates and shells subjected to plastic deformations is presented. The algorithms is based on the generalized layout optimization method invented by Bendsϕe and Kikuchi (1988), where an admissible design domain is assumed to be composed of microstructures with periodic cavities. The sizes of the cavities and the rotational angles of the microstructures are design variables which are optimized so as to minimize the applied work. The macroscopic material tensor for the porous material is numerically calculated by the homogenization method for the sensitivity analysis. In this paper, the method is applied to two-dimensional elasto-plastic problems. A database of the material tensor and its interpolation technique are presented. The algorithm is expanded into thin shells subjected to finite deformations. Several numerical examples are shown to demonstrate the effectiveness of these algorithms.

scholarly journals A Novel Permutation Entropy-Based EEG Channel Selection for Improving Epileptic Seizure Prediction

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7972
Author(s):  
Jee S. Ra ◽  
Tianning Li ◽  
Yan Li
Keyword(s):  
Sensitivity And Specificity ◽  
Epileptic Seizure ◽  
Epileptic Seizures ◽  
Optimization Method ◽  
Channel Selection ◽  
Permutation Entropy ◽  
Patient Specific ◽  
Support Vector ◽  
Seizure Prediction ◽  
Epileptic Seizure Prediction

The key research aspects of detecting and predicting epileptic seizures using electroencephalography (EEG) signals are feature extraction and classification. This paper aims to develop a highly effective and accurate algorithm for seizure prediction. Efficient channel selection could be one of the solutions as it can decrease the computational loading significantly. In this research, we present a patient-specific optimization method for EEG channel selection based on permutation entropy (PE) values, employing K nearest neighbors (KNNs) combined with a genetic algorithm (GA) for epileptic seizure prediction. The classifier is the well-known support vector machine (SVM), and the CHB-MIT Scalp EEG Database is used in this research. The classification results from 22 patients using the channels selected to the patient show a high prediction rate (average 92.42%) compared to the SVM testing results with all channels (71.13%). On average, the accuracy, sensitivity, and specificity with selected channels are improved by 10.58%, 23.57%, and 5.56%, respectively. In addition, four patient cases validate over 90% accuracy, sensitivity, and specificity rates with just a few selected channels. The corresponding standard deviations are also smaller than those used by all channels, demonstrating that tailored channels are a robust way to optimize the seizure prediction.

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