scholarly journals Multiscale design of nonlinear materials using a Eulerian shape optimization scheme

2021 ◽  
Author(s):  
Ahmad R. Najafi ◽  
Masoud Safdari ◽  
Daniel A. Tortorelli ◽  
Philippe H. Geubelle
Keyword(s):  
Shape Optimization ◽  
Optimization Scheme ◽  
Nonlinear Materials

Network Redundancy: A Key Design Factor for Cooling Networks

2020 ◽  
Author(s):  
Reza Pejman ◽  
Ahmad Raeisi Najafi
Keyword(s):  
Shape Optimization ◽  
Design Optimization ◽  
Cooling Efficiency ◽  
Temperature Uniformity ◽  
Optimization Scheme ◽  
Design Factor ◽  
Numerical Examples ◽  
Optimization Framework ◽  
Hybrid Topology ◽  
Operating Constraints

Abstract Microvascular composite offers a variety of multi-functionality based on the choice of fluid flowing through the embedded microchannels. The design of the microchannel network in microvascular composites is quite challenging. Indeed, the design is often expected to have high cooling efficiency, satisfy the manufacturing and operating constraints, and also have redundancy to increase the temperature uniformity and alleviate the destructive effects of potential microchannel blockage. In this study, we present a design optimization framework to satisfy these requirements. We use the Hybrid Topology/Shape (HyTopS) optimization scheme to design a redundant blockage-tolerant cooling network. In this method, the optimizer can change the topology of the design during the shape optimization process. Being able to modify the topology of the network enables the optimizer to provide network redundancy to effectively optimize the design for blockage tolerance. We also solve several numerical examples to show the unique features of the proposed method.

A gradient-based shape optimization scheme using an interface-enriched generalized FEM

2015 ◽  
Vol 296 ◽  
pp. 1-17 ◽  
Author(s):  
Ahmad R. Najafi ◽  
Masoud Safdari ◽  
Daniel A. Tortorelli ◽  
Philippe H. Geubelle
Keyword(s):  
Shape Optimization ◽  
Optimization Scheme ◽  
Generalized Fem ◽  
Gradient Based

Stator tooth shape optimization for double salient hybrid excitation generator based on asymmetric circuit analysis

2019 ◽  
Vol 38 (6) ◽  
pp. 1738-1755 ◽  
Author(s):  
Shuchun Yao ◽  
Wei Zhang
Keyword(s):  
Shape Optimization ◽  
Optimization Scheme ◽  
Voltage Fluctuation ◽  
Tooth Shape ◽  
Content Type ◽  
Dc Voltage ◽  
Excitation Generator ◽  
Finite Element Analysis Simulation ◽  
Hybrid Excitation ◽  
The Asymmetry

Purpose This paper aims to clarify the relationship between stator tooth shape and DC voltage fluctuation of a double salient hybrid excitation generator (DSHEG). It analyzes the asymmetrical characteristics of the magnetic circuit and inductance between each phase. The study aims to reduce voltage fluctuation by using a stator shape optimization scheme, which helps reducing inductance difference. Design/methodology/approach This paper opted for a method combined with theoretical analysis, simulation and experimental verification. The stator tooth optimization scheme is given based on theoretical asymmetrical analysis and Taguchi method. A series of two-dimensional finite element analysis simulation of different conditions are conducted. Two prototypes with different stator tooth shape are made and experiments are carried out. Findings The paper provides empirical insights into how the stator tooth shape influences the asymmetry of inductance and DC voltage fluctuation. Compensation adjustments to the stator tooth shape can narrow the inductance differences of each phase. It suggests that “LTL” shaped DSHEG has lower voltage ripple than “III” shaped DSHEG without sacrificing output power. Research limitations/implications Because of the chosen research approach, the gap between magnets and stator and end effect are not considered. Errors exist between simulation and experimental results. Practical implications The paper includes implications for other “C” shaped tooth optimization. Study on phase asymmetry of the special machine can further improve quality testing and simplify control strategy. Originality/value This paper analyzes the asymmetry of DSHEG and proposes an optimized stator tooth shape to reduce DC voltage fluctuation.

A Genetic Algorithm Based Multi-Objective Shape Optimization Scheme for Cementless Femoral Implant

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Souptick Chanda ◽  
Sanjay Gupta ◽  
Dilip Kumar Pratihar
Keyword(s):  
Genetic Algorithm ◽  
Bone Resorption ◽  
Shape Optimization ◽  
Interface Debonding ◽  
Objective Functions ◽  
Optimization Scheme ◽  
Interface Failure ◽  
Trade Off ◽  
Bone Interface ◽  
Multi Objective

The shape and geometry of femoral implant influence implant-induced periprosthetic bone resorption and implant-bone interface stresses, which are potential causes of aseptic loosening in cementless total hip arthroplasty (THA). Development of a shape optimization scheme is necessary to achieve a trade-off between these two conflicting objectives. The objective of this study was to develop a novel multi-objective custom-based shape optimization scheme for cementless femoral implant by integrating finite element (FE) analysis and a multi-objective genetic algorithm (GA). The FE model of a proximal femur was based on a subject-specific CT-scan dataset. Eighteen parameters describing the nature of four key sections of the implant were identified as design variables. Two objective functions, one based on implant-bone interface failure criterion, and the other based on resorbed proximal bone mass fraction (BMF), were formulated. The results predicted by the two objective functions were found to be contradictory; a reduction in the proximal bone resorption was accompanied by a greater chance of interface failure. The resorbed proximal BMF was found to be between 23% and 27% for the trade-off geometries as compared to ∼39% for a generic implant. Moreover, the overall chances of interface failure have been minimized for the optimal designs, compared to the generic implant. The adaptive bone remodeling was also found to be minimal for the optimally designed implants and, further with remodeling, the chances of interface debonding increased only marginally.

A Shape Optimization Scheme With Coupling of Parametric and Freeform Shape Evolution

2004 ◽  
Author(s):  
Jie Shen ◽  
David Yoon ◽  
Nilesh Patel
Keyword(s):  
Numerical Experiment ◽  
Shape Optimization ◽  
Large Scale ◽  
Geometric Design ◽  
Optimization Process ◽  
Shape Evolution ◽  
Optimization Scheme ◽  
Polygonal Mesh ◽  
Mesh Model ◽  
Surface Partitioning

In this paper we propose a new shape optimization scheme for better geometric design starting from a base polygonal mesh model. The important features of our approach include: 1) surface partitioning scheme for handling large-scale polygonal meshes; 2) coupling of parametric and freeform shape evolution for efficient and effective solutions. 3) an optimization process constrained by constant volume in 3D cases. Numerical experiment indicates the effectiveness of the proposed approach.

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