Fuzzy Heuristic Gradient Projection for Frame Topology Optimization

2005 ◽  
Author(s):  
Mohamed S. Senousy ◽  
Hesham A. Hegazi ◽  
Sayed M. Metwalli
Keyword(s):  
Fuzzy Logic ◽  
Fuzzy Logic Controller ◽  
Axial Stress ◽  
Equivalent Stress ◽  
Optimal Solution ◽  
Bending Moment ◽  
Gradient Projection ◽  
Bending Stress ◽  
Allowable Stress ◽  
Bending Stresses

In this paper, a new methodology to obtain an optimal structure size considering geometries nonlinearity is presented. This method makes use of Heuristic Gradient Projection method in addition to Fuzzy Logic. The Heuristic Gradient Projection (HGP) method, a previously developed method for 3D-frame design and optimization, utilizes mainly bending stress relations in order to simplify the process of iterations. HGP is based on comparing the resulting equivalent stress with the allowable stress value. The proposed Fuzzy Heuristic Gradient Projection (FHGP) approach incorporates both bending stress and axial stress when processing with the allowable stress value. The weighting factors of both axial and bending stresses are found using a Fuzzy Logic controller. Fuzzy logic is incorporated to reach an optimal solution with lesser number of function evaluations. A simple cantilever example, subjected to axial force and bending moment, is presented to illustrate this approach in addition to a 10-member planar frame that is used to prove the efficacy of the new method. FHGP approach generally results in faster convergence.

Fuzzy Vibration Control of Flexible Solar Panel Using Piezoelectric Stack

2011 ◽  
Vol 50-51 ◽  
pp. 214-218 ◽  
Author(s):  
Rui Xu ◽  
Dong Xu Li ◽  
Jian Ping Jiang
Keyword(s):  
Fuzzy Logic ◽  
Fuzzy Logic Controller ◽  
Bending Moment ◽  
Finite Element Method Simulation ◽  
Positive Control ◽  
Smart Structure ◽  
Solar Panel ◽  
The Finite Element Method ◽  
Dynamical Equations ◽  
Logic Control

To effectively suppress vibrations of the flexible solar panel, the fuzzy logic control with piezoelectric smart structure is studied. The bending moment induced in the solar panel by the PZT stack actuator is formulated. The dynamical equations of the solar panel are derived. A fuzzy logic controller which uses universal fuzzy sets is designed. Considered the characteristic of the PZT stack, only positive control voltages were loaded to it. The finite element method simulation results demonstrate that the fuzzy logic controller can suppress the vibrations of the flexible spacecraft solar panel effectively.

scholarly journals Optimization of Fuzzy Logic Controller by Using Heuristic Algorithms

2019 ◽  
pp. 13-18
Author(s):  
Sinan Unsal ◽  
Ibrahim Aliskan
Keyword(s):  
Fuzzy Logic ◽  
Systematic Approach ◽  
Fuzzy Logic Controller ◽  
Heuristic Algorithms ◽  
Algorithm Design ◽  
Optimal Solution ◽  
Design Parameters ◽  
Fuzzy Logic Controllers ◽  
Swarm Optimization ◽  
Design And Optimization

There are many design parameters in the structure of fuzzy logic controllers. Conventional methods that don't have a systematic approach are often used in determining of these parameters. However, setting the controller parameters in this way leads to long experiments and this takes a lot of time. For this reason, design parameters of the fuzzy logic controller are usually determined by using heuristic algorithms. Because, heuristic algorithms can offer solutions that are very close to the optimal solution for the problems where exact solution cannot be obtained. In this study, output membership functions of a fuzzy logic controller are optimized using particle swarm optimization and genetic algorithm. Design and optimization stages are explained in detail and results are compared with each other.

An Investigation of Drawbead Models for Springback Prediction

2006 ◽  
Author(s):  
F. Ren ◽  
Z. C. Xia
Keyword(s):  
Computational Efficiency ◽  
Force Control ◽  
Bending Moment ◽  
Bending Stress ◽  
Displacement Control ◽  
The Real ◽  
Part Geometry ◽  
Significant Challenge ◽  
Bending Stresses ◽  
Springback Prediction

Accurate prediction of springback for rail-type structures remains a significant challenge for automotive stamping. A major characteristic of forming such parts is that metals go through drawbeads and die-entry radii and often end up within part geometry (i.e., inside trimline). The bending-unbending stresses generated by drawbeads contribute significantly to the eventual springback. In production springback simulation, line drawbead models are generally used to represent the restraining forces provided by the real drawbeads for computational efficiency. While such models can be well correlated to match overall deformation of the part, the bending stresses could not be accurately captured. In the present study, a model of an aluminum U-channel is used to evaluate springback predictability of line drawbead model, which is then compared against simulations that employ detailed drawbead geometry. The results show that the line drawbead model largely under-predicts the springback and the bending moment. The accuracy of the prediction cannot be improved through different binder simulation strategies such as displacement-control or force-control. The study suggests that either real drawbeads be modeled, or the bending stress be incorporated into the line model to improve springback prediction.

Theoretical Analysis of SSCC Floor System of through Truss High-Speed Railway Bridges

2011 ◽  
Vol 250-253 ◽  
pp. 1728-1733 ◽  
Author(s):  
Ye Zhi Zhang ◽  
Liang Chen
Keyword(s):  
High Speed ◽  
Concrete Slab ◽  
Axial Stress ◽  
Bending Moment ◽  
Bending Stress ◽  
Inertia Moment ◽  
High Speed Railway ◽  
Railway Bridges ◽  
Floor Systems ◽  
Floor System

In SSCC floor systems the concrete slab is composite with both steel stringers and crossbeams or only with stringers. The horizontal bending of the crossbeams of SSCC floor systems is not ignorable. From the deformation conforming condition, theoretical formulas for SSCC floor systems of double-railway bridges with two stringers are developed. The factors which influence the horizontal bending of crossbeams are discussed. Some conclusions are obtained. When the width of the SSCC floor system is given, the main factors which influence the horizontal bending of the crossbeams are the axial stress of the lower chords, the distance between the side stringers and the lower chords, and the continuous length of SSCC floor system. Increasing the horizontal inertia moment of crossbeams almost cannot reduce the horizontal bending stress of crossbeams. A slight horizontal rotation of the lower joints such as 10-4 rad can release more than 3% crossbeam end horizontal bending moment.

Plastic Collapse Stresses for Pipes With Inner and Outer Circumferential Cracks

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Vratislav Mares ◽  
Kunio Hasegawa ◽  
Yinsheng Li ◽  
Valery Lacroix
Keyword(s):  
Outer Surface ◽  
Bending Moment ◽  
Thick Wall ◽  
Plastic Collapse ◽  
Surface Cracks ◽  
Bending Stress ◽  
Moment Equations ◽  
Bending Stresses ◽  
Crack Angle ◽  
Uncracked Ligament

Bending stresses at incipient plastic collapse for pipes with circumferential surface cracks are predicted by net-section stress approach. Appendix C-5320 of ASME B&PV Code Section XI provides an equation of bending stress at the plastic collapse, where the equation is applicable for both inner and outer surface cracks. That is, the collapse stresses for pipes with inner and outer surface cracks are the same, because of the pipe mean radius at the cracked section being entirely the same. Authors considered the separated pipe mean radii at the cracked ligament and at the uncracked ligament. Based on the balances of axial force and bending moment, equations of plastic collapse stresses for both inner and outer cracked pipes were developed. It is found that, when the crack angle and depth are the same, the collapse stress for inner cracked pipe is slightly higher than that calculated by the Appendix C equation, and the collapse stress for outer cracked pipe is slightly lower than that by the Appendix C equation, as can be expected. The collapse stresses derived from the three equations are almost the same in most instances. However, for less common case where the crack angle and depth are very large for thick wall pipes, the differences among the three collapse stresses become large. Code users pay attention to the margins of plastic collapse stresses for outer cracked pipes, when using Appendix C equation.

Prediction for Plastic Collapse Stresses for Pipes With Inner and Outer Circumferential Flaws

2018 ◽  
Author(s):  
Kunio Hasegawa ◽  
Yinsheng Li ◽  
Vratislav Mares ◽  
Valery Lacroix
Keyword(s):  
Axial Force ◽  
Outer Surface ◽  
Bending Moment ◽  
Thick Wall ◽  
Plastic Collapse ◽  
Bending Stress ◽  
Surface Flaws ◽  
Bending Stresses

Bending stresses at incipient plastic collapse for pipes with circumferential surface flaws are predicted by net-section stress approach. Appendix C-5320 of ASME B&PV Code Section XI provides a formula of bending stress at the plastic collapse, where the formula is applicable for both inner and outer surface flaws. That is, the collapse stresses for pipes with inner and outer surface flaws are the same, because of the pipe mean radius at the flawed section being entirely the same. Authors considered the separated pipe mean radii at the flawed ligament and at the un-flawed ligament. Based on the balances of axial force and bending moment, formulas of plastic collapse stresses for each inner and outer flawed pipe were obtained. It is found that, when the flaw angle and depth are the same, the collapse stress for inner flawed pipe is slightly higher than that calculated by Appendix C-5320 formula, and the collapse stress for outer flawed pipe is slightly lower than that by Appendix C-5320 formula, as can be expected. The collapse stresses derived from the three formulas are almost the same in most instances. For less common case where the flaw angle and depth are very large for thick wall pipes, the differences amongst the three collapse stresses become large.

The Limit Load Calculations for Pipe Bend With Axial Part-Through Defect

2010 ◽  
Author(s):  
I. V. Orynyak ◽  
I. V. Lokhman ◽  
S. O. Okhrimchuk
Keyword(s):  
Bending Moment ◽  
Limit Load ◽  
Strength Reduction ◽  
Simultaneous Action ◽  
Bending Stress ◽  
Pipe Bend ◽  
Inner Pressure ◽  
Axial Part ◽  
Load Calculation ◽  
Bending Stresses

Pipe bend is very complicated element for the structural integrity assessment. Up to day there is no conventionally adopted technique for limit load calculation of pipe bend even without any defect. The problem is that at application of outer bending moment the pipe bend cross section ovalizes and the process of deformation can be described only with accounting for the geometrical nonlinearity. The paper deal with limit load calculation for pipe bend with axial part-through defect for particular case when circumferential stresses originated both from inner pressure and outer bending moment dominate over axial stresses from the moment and axial force. Two extreme cases are considered at start. First one is the action of the inner pressure only. The “Institute for Problems of Strength limit load model” (IPS model) can be applied here without any restrictions. The second case is consideration of circumferential bending stresses which have appeared due to ovalization from the outer bending moment. The model of the transmission of stresses from the defected region to the undamaged regions is suggested and the resulting formula for the stress concentration (or strength reduction) coefficient is obtained. At last the simultaneous action of both loadings is considered. As result the analytical formula for the reference stress calculation which is similar in appearance to that of API 579 for accounting for membrane stress as well as bending stress is suggested. The only difference is that strength reduction coefficients are considered for both the membrane stresses from inner pressure and bending stress from ovalization. This differs from API 579 approach where the influence of the defects length on the bending stresses is not taken into account.

Application Fuzzy Logic System for Accurate Sheet Trim Shower Position

2019 ◽  
Vol 3 (1) ◽  
pp. 186-192
Author(s):  
Yudi Wibawa
Keyword(s):  
Fuzzy Logic ◽  
Fuzzy Logic Controller ◽  
Dc Motor ◽  
Automation System ◽  
Paper Making ◽  
System A ◽  
Accurate Position ◽  
And Performance ◽  
Better Than ◽  
Logic System

This paper aims to study for accurate sheet trim shower position for paper making process. An accurate position is required in an automation system. A mathematical model of DC motor is used to obtain a transfer function between shaft position and applied voltage. PID controller with Ziegler-Nichols and Hang-tuning rule and Fuzzy logic controller for controlling position accuracy are required. The result reference explains it that the FLC is better than other methods and performance characteristics also improve the control of DC motor.

STABILISASI TEGANGAN KELUARAN BUCK CONVERTER DENGAN METODE FUZZY LOGIC CONTROLLER

JURNAL ELTEK ◽  
2018 ◽  
Vol 16 (2) ◽  
pp. 125
Author(s):  
Oktriza Melfazen
Keyword(s):  
Fuzzy Logic ◽  
Steady State ◽  
Rise Time ◽  
Fuzzy Logic Controller ◽  
Buck Converter ◽  
Settling Time

Buck converter idealnya mempunyai keluaran yang stabil, pemanfaatandaya rendah, mudah untuk diatur, antarmuka yang mudah dengan pirantiyang lain, ketahanan yang lebih tinggi terhadap perubahan kondisi alam.Beberapa teknik dikembangkan untuk memenuhi parameter buckconverter. Solusi paling logis untuk digunakan pada sistem ini adalahmetode kontrol digital.Penelitian ini menelaah uji performansi terhadap stabilitas tegangankeluaran buck converter yang dikontrol dengan Logika Fuzzy metodeMamdani. Rangkaian sistem terdiri dari sumber tegangan DC variable,sensor tegangan dan Buck Converter dengan beban resistif sebagaimasukan, mikrokontroler ATMega 8535 sebagai subsistem kontroldengan metode logika fuzzy dan LCD sebagai penampil keluaran.Dengan fungsi keanggotaan error, delta error dan keanggotaan keluaranmasing-masing sebanyak 5 bagian serta metode defuzzifikasi center ofgrafity (COG), didapat hasil rerata error 0,29% pada variable masukan18V–20V dan setpoint keluaran 15V, rise time (tr) = 0,14s ; settling time(ts) = 3,4s ; maximum over shoot (%OS) = 2,6 dan error steady state(ess) = 0,3.

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