scholarly journals Inverse Optimum Safety Factor Method for Reliability-Based Topology Optimization Applied to Free Vibrated Structures

2019 ◽  
pp. 8-19 ◽  
Author(s):  
Ghias Kharmanda ◽  
Imad R. Antypas ◽  
Alexey G. Dyachenko
Keyword(s):  
Topology Optimization ◽  
Structure Function ◽  
Modal Analysis ◽  
Safety Factor ◽  
Optimization Model ◽  
High Performance ◽  
Structural Type ◽  
Efficient Tool ◽  
Performance Levels ◽  
Reliability Level

Introduction. The classical topology optimization leads to a prediction of the structural type and overall layout, and gives a rough description of the shape of the outer as well as inner boundaries of the structure. However, the probabilistic topology optimization (or reliability-based topology optimization) model leads to several reliability-based topologies with high performance levels. The objective of this work is to provide an efficient tool to integrate the reliability-based topology optimization model into free vibrated structure. Materials and Methods. The developed tool is called inverse optimum safety method. When dealing with modal analysis, the choice of optimization domain is highly important in order to be able to eliminate material taking account of the constraints of fabrication and without affecting the structure function. This way the randomness can be applied on certain boundary parameters. Results. Numerical applications on free vibrated structures are presented to show the efficiency of the developed strategy. When considering a required reliability level, the resulting topology represents a different topology relative to the deterministic resulting one. Discussion and Conclusion. In addition to its simplified implementation, the developed inverse optimum safety factor strategy can be considered as a generative tool to provide the designer with several solutions for free vibrated structures with different performance levels.

scholarly journals Reliability-Based Topology Optimization Using Two Alternative Inverse Optimum Safety Factor Approaches: Application to Bridge Structures

2020 ◽  
Vol 30 (3) ◽  
pp. 498-511
Author(s):  
Ghias Kharmanda ◽  
Imad R. Antypas ◽  
Alexey G. Dyachenko
Keyword(s):  
Topology Optimization ◽  
Safety Factor ◽  
Optimization Model ◽  
High Performance ◽  
Bridge Structure ◽  
Objective Performance ◽  
Bridge Structures ◽  
Alternative Approaches ◽  
Alternative Choice

Introduction. The Deterministic Topology Optimization model provides a single solution for a given design space, while the Reliability-Based Topology Optimization model provides several reliability-based topology layouts with high-performance levels. The objective of this work is to develop two strategies that can provide the designer with two categories of resulting topologies. Materials and Methods. Two alternative approaches based on the Inverse Optimum Safety Factor are developed: the first one is called the Objective-Based IOSF Approach and the second one is called Performance-Based IOSF Approach. When dealing with bridge structures, the uncertainty on the input parameters (boundary conditions, material properties, geometry, etc.) and also output parameters (compliance, etc.) should not be ignored. The sensitivity analysis is the fundamental idea of both developed approaches, identifies the role of each parameter on the structural performance. In addition, the optimization domain choice is important when eliminating material that should not affect the structure functioning. Results. Two numerical examples on a 2D bridge structure are presented to demonstrate the efficiency of the developed approaches. When considering a certain reliability level, the Reliability-Based Topology Optimization leads to two different configurations relative to the Deterministic Topology Optimization one. When increasing the reliability levels, the quantity of materials decreases that leads to an increase in the number of holes in the structures. Discussion and Conclusion. In addition to their simplified implementation, the developed alternative approaches can be considered as two generative tools to produce two different categories (families) of solutions where an alternative choice between two functions (objective/performance) is presented.

scholarly journals Integration of reliability-based topology optimization into biomechanics: Application on hollow stems used in cementless total hip arthroplasty

2020 ◽  
Vol 210 ◽  
pp. 06003
Author(s):  
Ghais Kharmanda ◽  
Imad Antypas ◽  
Alexey Dyachenko
Keyword(s):  
Topology Optimization ◽  
Hip Replacement ◽  
High Performance ◽  
Design Space ◽  
Design Stage ◽  
Manufacturing Constraints ◽  
Element Discretization ◽  
Performance Levels ◽  
Total Hip ◽  
Alternative Approaches

The integration of topology optimization into biomechanical applications possesses an important key to increase the performance levels. In literature, two models can be found: Deterministic Topology Optimization (DTO) and Reliability-Based Topology Optimization (RBTO). The DTO leads to a single layout for a given design space. However, the RBTO generates several reliability-based topologies with high performance levels. Topology optimization has been already integrated into biomechanical applications such as prosthesis design. The filter-based approaches being tied to the element discretization, are previously used to control the resulting topologies or to prevent undesirable designs. These are expensive operations for fine meshes or complex domains and numerous numerical difficulties can be met. In this work, the RBTO is integrated at the conceptual design stage of the total hip replacement to control the resulting topologies to meet different constraints such as manufacturing constraints. This can provide several types of hollow stems considering the daily loading cases. Two alternative approaches based on the Optimum Safety Factors (OSF) are developed to provide two categories of solutions. The RBTO model can be integrated into the additive manufacturing technology as a topology generator satisfying several manufacturing constraints. The resulting different configurations can then be provided for various patients.

scholarly journals Buffer Placement and Sizing for High-Performance Dataflow Circuits

2022 ◽  
Vol 15 (1) ◽  
pp. 1-32
Author(s):  
Lana Josipović ◽  
Shabnam Sheikhha ◽  
Andrea Guerrieri ◽  
Paolo Ienne ◽  
Jordi Cortadella
Keyword(s):  
Performance Optimization ◽  
Optimization Model ◽  
High Performance ◽  
Control Flow ◽  
High Level Synthesis ◽  
Software Applications ◽  
Marked Graphs ◽  
Variable Latency ◽  
High Level ◽  
Strong Contrast

Commercial high-level synthesis tools typically produce statically scheduled circuits. Yet, effective C-to-circuit conversion of arbitrary software applications calls for dataflow circuits, as they can handle efficiently variable latencies (e.g., caches), unpredictable memory dependencies, and irregular control flow. Dataflow circuits exhibit an unconventional property: registers (usually referred to as “buffers”) can be placed anywhere in the circuit without changing its semantics, in strong contrast to what happens in traditional datapaths. Yet, although functionally irrelevant, this placement has a significant impact on the circuit’s timing and throughput. In this work, we show how to strategically place buffers into a dataflow circuit to optimize its performance. Our approach extracts a set of choice-free critical loops from arbitrary dataflow circuits and relies on the theory of marked graphs to optimize the buffer placement and sizing. Our performance optimization model supports important high-level synthesis features such as pipelined computational units, units with variable latency and throughput, and if-conversion. We demonstrate the performance benefits of our approach on a set of dataflow circuits obtained from imperative code.

scholarly journals Efficient optimum safety factor approach for system reliability-based design optimization with application to composite yarns

2019 ◽  
Vol 19 (3) ◽  
pp. 221-230 ◽  
Author(s):  
Gh. Kharmanda ◽  
I. R. Antypas
Keyword(s):  
Design Optimization ◽  
Safety Factor ◽  
Reliability Index ◽  
Performance Measure ◽  
Alternative Methods ◽  
Reliability Based Design Optimization ◽  
Implementation Framework ◽  
Reliability Level ◽  
Reliability Based Design ◽  
Convergence Stability

Introduction. The integration of reliability and optimization concepts seeks to design structures that should be both economic and reliable. This model is called Reliability-Based Design Optimization (RBDO). In fact, the coupling between the mechanical modelling, the reliability analyses and the optimization methods leads to very high computational cost and weak convergence stability. Materials andMethods. Several methods have been developed to overcome these difficulties. The methods called Reliability Index Approach (RIA) and Performance Measure Approach (PMA) are two alternative methods. RIA describes the probabilistic constraint as a reliability index while PMA was proposed by converting the probability measure to a performance measure. An Optimum Safety Factor (OSF) method is proposed to compute safety factors satisfying a required reliability level without demanding additional computing cost for the reliability evaluation. The OSF equations are formulated considering RIA and PMA and extended to multiple failure case.Research Results. Several linear and nonlinear distribution laws are applied to composite yarns studies and then extended to multiple failure modes. It has been shown that the idea of the OSF method is to avoid the reliability constraint evaluation with a particular optimization process.Discussion and Conclusions. The simplified implementation framework of the OSF strategy consists of decoupling the optimization and the reliability analyses. It provides designers with efficient solutions that should be economic satisfying a required reliability level. It is demonstrated that the RBDO compared to OSF has several advantages: small number of optimization variables, good convergence stability, small computing time, satisfaction of the required reliability levels.

Adapting Ant Colony for Topology Optimization of Compliant Mechanisms With Variable Material Density

2017 ◽  
Author(s):  
Nadim Diab
Keyword(s):  
Topology Optimization ◽  
Ant Colony Optimization ◽  
High Performance ◽  
Compliant Mechanisms ◽  
Optimization Technique ◽  
Optimization Techniques ◽  
Ant Colony ◽  
Intensity Level ◽  
Material Density ◽  
Swarm Intelligence Optimization

Swarm intelligence optimization techniques are widely used in topology optimization of compliant mechanisms. The Ant Colony Optimization has been implemented in various forms to account for material density distribution inside a design domain. In this paper, the Ant Colony Optimization technique is applied in a unique manner to make it feasible to optimize for the beam elements’ cross-section and material density simultaneously. The optimum material distribution algorithm is governed by two various techniques. The first technique treats the material density as an independent design variable while the second technique correlates the material density with the pheromone intensity level. Both algorithms are tested for a micro displacement amplifier and the resulting optimized topologies are benchmarked against reported literature. The proposed techniques culminated in high performance and effective designs that surpass those presented in previous work.

Structural optimization design for antenna bracket manufactured by selective laser melting

2018 ◽  
Vol 24 (3) ◽  
pp. 539-547 ◽  
Author(s):  
Zefeng Xiao ◽  
Yongqiang Yang ◽  
Di Wang ◽  
Changhui Song ◽  
Yuchao Bai
Keyword(s):  
Structural Optimization ◽  
Modal Analysis ◽  
Selective Laser Melting ◽  
Optimization Model ◽  
Optimization Design ◽  
Analysis Data ◽  
Laser Melting ◽  
Design Rules ◽  
Content Type ◽  
Process Characteristics

Purpose This paper aims to summarize design rules based on the process characteristics of selective laser melting (SLM) and structural optimization and apply the design rules in the lightweight design of an aluminum alloy antenna bracket. The design goal is to reduce 30 per cent of the weight while maintaining the stress levels in the original part. Design/methodology/approach To reduce weight as much as possible, the titanium alloy with higher specific strength was selected during the process of optimization. The material distribution of the bracket was improved by the topology optimization design. The redesign for SLM was used to obtain an optimization model, which was more suitable for SLM. The component performance was improved by shape optimization. The modal analysis data of the structural optimization model were compared with those of the stochastic lightweight model to verify the structural optimization model. The scanning data were compared with those of the original model to verify whether the model was suitable for SLM. Findings Structural optimization design for antenna bracket realized the mass decrease of 30.43 per cent and the fundamental frequency increase of 50.18 per cent. The modal analysis data of the stochastic lightweight model and the structural optimization model indicated that the optimization performance of structural optimization method was better than that of the stochastic lightweight method. The comparison results between the scanning data of the forming part and the original data confirmed that the structural optimization design for SLM lightweight component could achieve the desired forming accuracy. Originality/value This paper summarizes geometric constraints in SLM and derives design rules of structural optimization based on the process characteristics of SLM. SLM design rules make structural optimization design more reasonable. The combination of structural optimization design and SLM can improve the performance of lightweight antenna bracket significantly.

scholarly journals Investigating the structure–function relationship in triple cation perovskite nanocrystals for light-emitting diode applications

2020 ◽  
Vol 8 (34) ◽  
pp. 11805-11821 ◽  
Author(s):  
Parth Vashishtha ◽  
Sjoerd A. Veldhuis ◽  
Sai S. H. Dintakurti ◽  
Nicole L. Kelly ◽  
Benjamin E. Griffith ◽  
...  
Keyword(s):  
Structure Function ◽  
High Performance ◽  
Surface Passivation ◽  
Light Emitting Diode ◽  
Environmental Stability ◽  
Light Emitting ◽  
Perovskite Nanocrystals ◽  
Structure Function Relationship ◽  
Function Relationship

Novel Cs-containing triple cation perovskite nanocrystals produce high-performance LEDs as a result of improved surface passivation and environmental stability.

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