Integrated Structure Decomposition, Optimization and Control Design

2007 ◽  
Author(s):  
Shaoluo L. Butler ◽  
Anoop K. Dhingra
Keyword(s):  
Finite Element ◽  
Multiobjective Optimization ◽  
Controller Design ◽  
Design System ◽  
Element Analysis ◽  
Reduced Order ◽  
Stability Robustness ◽  
Entire Structure ◽  
Structure Decomposition ◽  
And Control

In this paper, an integrated optimization, controller design and reduced order finite element modeling based approach is presented for structural design. The proposed approach involves structure decomposition, subcontroller design, system controller assembly, and multiobjective optimization. The concept of structure decomposition with compatible and incompatible interfaces is presented for a control/optimum system problem, and developed for problems with compatible interfaces involving substructure controller design and multiobjective optimization. The substructure information obtained through finite element analysis is synthesized to reconstruct a reduced order model for the entire structure. Based on SSSC (Substructure Synthesis-Substructure Controller), a controller is designed for each substructure. The global controller is obtained by assembling all subcontrollers designed at the substructure level. A multiobjective optimum formulation is presented based on structure decomposition and controller design. Four objective functions are simultaneously optimized. These include a stability robustness index, structural weight, controller energy, and a controller performance index. Numerical examples are presented to demonstrate the effectiveness of the proposed methodology. Results obtained using the proposed approach are compared with those obtained from optimization of the entire structure.

CONSTRUCTION OF A 3-D FINITE ELEMENT MODEL OF THE HUMAN FOREARM COMPLEX USING A SERIES OF 2-D COLOR IMAGES

2005 ◽  
Vol 09 (03) ◽  
pp. 103-111 ◽  
Author(s):  
Kyu-Jung Kim ◽  
Il-Kyu Hwang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mesh Generation ◽  
Geometric Model ◽  
Design System ◽  
Element Analysis ◽  
Boundary Points ◽  
Geometric Mesh ◽  
Human Forearm ◽  
Boundary Curves

A simple yet efficient paradigm for geometric mesh generation using the Visible Human Project Male dataset for further finite element analysis was presented. The minimum distance classifier was used for the discriminant function between the class centers classified by the fuzzy c-means clustering method in the RGB space. Furthermore, based on two major geometric assumptions on the boundary curves, star-shaped polygon and geometric conformity, a points-on-line search technique was devised for efficient computation of the boundary points of the contours for each anatomical component of the human forearm complex. The computed boundary points in each slice were fitted to a closed spline curve and resampled and then refitted for correct alignment with the consecutive boundary curves in order to improve geometric fidelity. By using the refitted contours, a 3-D geometric model of the human radius, ulna, and surrounding soft tissue was generated in a commercial computer–aided design system and exported to a commercial finite element analysis package for meshing with its built-in automatic mesh generator. The proposed method can be applied to geometric mesh generation of other long bones, which allows easy handling, storage, and exchange of the model.

Piezothermoelasticity and Precision Control of Piezoelectric Systems: Theory and Finite Element Analysis

1994 ◽  
Vol 116 (4) ◽  
pp. 489-495 ◽  
Author(s):  
H. S. Tzou ◽  
R. Ye
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Degrees Of Freedom ◽  
Piezoelectric Sensor ◽  
Temperature Fields ◽  
Element Analysis ◽  
Energy Functionals ◽  
System Equation ◽  
Distributed Controls ◽  
And Control

Piezothermoelastic effects of distributed piezoelectric sensor/actuator and structural systems are studied. Distributed controls (static and dynamic) of piezoelectric laminates subjected to a steady-state temperature field are investigated. Piezothermoelastic constitutive equations are defined, followed by three energy functionals for the displacement, electric, and temperature fields, respectively. A new 3-D piezothermoelastic thin hexahedron finite element with three internal degrees of freedom is formulated using a variational formulation which includes thermal, electric, and mechanical energies. A system equation for the piezoelectric continuum exposed to combined displacement, electric, and temperature fields is formulated. Distributed sensing and control equations of piezoelectric laminates in a temperature field are derived. Thermal influences on the sensing and control of piezoelectric PZT/steel laminates are investigated in case studies.

Reduced Order Model for Efficient Engineering Analysis

2020 ◽  
Author(s):  
Allan X. Zhong ◽  
Haoyue Zhang
Keyword(s):  
Finite Element ◽  
Design Of Experiments ◽  
Reduced Order Model ◽  
Reduced Model ◽  
Complex Structures ◽  
Engineering Analysis ◽  
Order Model ◽  
Element Analysis ◽  
Reduced Order ◽  
Numerical Design

Abstract Engineering analysis of complex structures or mechanical systems typically involves contact with multiple components, large deformation, and material nonlinearity, which requires the application of nonlinear finite element methods. Despite the advancement of commercial software for finite element analysis (FEA), nonlinear FEA of a multi-component mechanical assembly will take hours to days, and even weeks to complete. It is highly desired to develop a reduced-order model for a family of complex structures that can reduce an original problems’ complexity and degree of freedom but has a reasonably small discrepancy with the full model and significantly reduces the computation time. The typical approach to construct a reduced model includes 1) the response surface method via numerical design of experiments and, 2) the simplified physics approach. In this paper, it is proposed to develop a reduced model through the combination of simplified physics, dimensional analysis [1], and numerical design of experiments. The approach is applied to the construction of a reduced model for the analysis of a downhole plug [2]. The developed reduced model is verified by full-scale FEA models and validated through physical tests. The reduced model is implemented in a spreadsheet and takes only seconds to complete a calculation in contrast to hours using a full FEA model, enabling engineers’ quick evaluation of the corresponding designs.

A Nonlinear Dynamic Reduced-Order Model for a Large Gas Turbine Outer Casing Low Cycle Fatigue Prediction

2021 ◽  
Author(s):  
Aditya Dubey ◽  
Rishi Relan ◽  
Uwe Lohse ◽  
Jaroslaw Szwedowicz
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Gas Turbine ◽  
Nonlinear Dynamic ◽  
Low Cycle Fatigue ◽  
Reduced Order Model ◽  
Cycle Fatigue ◽  
Order Model ◽  
Element Analysis ◽  
Reduced Order

Abstract The secondary stresses that result from nonlinear and transient thermal gradients during the start-up and shut down of the large gas turbine engines drive low-cycle fatigue at specific locations of the outer casing. Typical service inspection of the outer casing is primarily based on finite element analysis estimates, considering various safety factors. However, as finite element analysis includes the worst possible combination of loading scenarios and operating conditions any engine may encounter in actual operation, this results in a conservative estimation of the service interval. Therefore, a generic preventive maintenance plan for the whole fleet often underutilises the casing capability and added cost. Hence, this paper proposes a data-driven nonlinear dynamic reduced-order model developed using the temperature data from low-cycle fatigue critical casing locations, ramp rates, and the percentage load of operation to predict the stresses. As a result, a reduced-order model can assess the damage for low-cycle fatigue critical locations in real-time using the operational data and propose an appropriate service intervention plan for each casing in a fleet.

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