Optimization Approaches for the Numerical Design of Structures Under Consideration of Polymorphic Uncertain Data

2019 ◽  
Vol 5 (4) ◽  
Author(s):  
Philipp Edler ◽  
Steffen Freitag ◽  
Katharina Kremer ◽  
Günther Meschke
Keyword(s):  
Failure Probability ◽  
Optimization Problems ◽  
Structural Parameters ◽  
Uncertain Data ◽  
Design Parameters ◽  
Fe Model ◽  
Reinforced Concrete Bridge ◽  
Numerical Design ◽  
New Space ◽  
Probability Constraint

Abstract In this paper, optimization approaches for the numerical design of structures are presented. The uncertainty of structural parameters is considered by means of random variables and interval design parameters within the optimization. A new space subdividing technique is introduced to substitute time-consuming failure probability constraint evaluations. In order to solve optimization problems with polymorphic uncertain parameters, surrogate objectives are formulated and solved by means of a particle swarm optimization (PSO) approach in combination with Monte Carlo simulation and interval analysis. Two computational schemes are presented and verified by a benchmark example. Finally, an application is shown, where the reinforcement layout of a reinforced concrete bridge structure is optimized by minimizing the crack widths at the reinforcement layers in order to improve the durability of the structure. A nonlinear finite element (FE) model is used to compute the uncertain crack patterns and the load bearing capacity. The stochastic objective function and the failure probability constraint are approximated by neural network based surrogate models.

scholarly journals Vision-Based Structural FE Model Updating Using Genetic Algorithm

2021 ◽  
Vol 11 (4) ◽  
pp. 1622
Author(s):  
Gun Park ◽  
Ki-Nam Hong ◽  
Hyungchul Yoon
Keyword(s):  
Genetic Algorithm ◽  
Model Updating ◽  
Structural Parameters ◽  
Fe Model ◽  
Structural Members ◽  
Stiffness Reduction ◽  
Before And After ◽  
Scale Test ◽  
Fe Model Updating ◽  
Story Building

Structural members can be damaged from earthquakes or deterioration. The finite element (FE) model of a structure should be updated to reflect the damage conditions. If the stiffness reduction is ignored, the analysis results will be unreliable. Conventional FE model updating techniques measure the structure response with accelerometers to update the FE model. However, accelerometers can measure the response only where the sensor is installed. This paper introduces a new computer-vision based method for structural FE model updating using genetic algorithm. The system measures the displacement of the structure using seven different object tracking algorithms, and optimizes the structural parameters using genetic algorithm. To validate the performance, a lab-scale test with a three-story building was conducted. The displacement of each story of the building was measured before and after reducing the stiffness of one column. Genetic algorithm automatically optimized the non-damaged state of the FE model to the damaged state. The proposed method successfully updated the FE model to the damaged state. The proposed method is expected to reduce the time and cost of FE model updating.

scholarly journals Relaxed gradient projection algorithm for constrained node-based shape optimization

2021 ◽  
Author(s):  
Ihar Antonau ◽  
Majid Hojjat ◽  
Kai-Uwe Bletzinger
Keyword(s):  
Shape Optimization ◽  
Optimization Problems ◽  
Gradient Projection ◽  
Projection Algorithm ◽  
Design Parameters ◽  
Active Set ◽  
Physical Constraints ◽  
Original Algorithm ◽  
Gradient Projection Algorithm ◽  
Non Linear

AbstractIn node-based shape optimization, there are a vast amount of design parameters, and the objectives, as well as the physical constraints, are non-linear in state and design. Robust optimization algorithms are required. The methods of feasible directions are widely used in practical optimization problems and know to be quite robust. A subclass of these methods is the gradient projection method. It is an active-set method, it can be used with equality and non-equality constraints, and it has gained significant popularity for its intuitive implementation. One significant issue around efficiency is that the algorithm may suffer from zigzagging behavior while it follows non-linear design boundaries. In this work, we propose a modification to Rosen’s gradient projection algorithm. It includes the efficient techniques to damp the zigzagging behavior of the original algorithm while following the non-linear design boundaries, thus improving the performance of the method.

A Study of the Anchor Effect Based on Structural Parameters of Flexible Pressurized Anchor and Pressure from Surrounding Rock

2011 ◽  
Vol 71-78 ◽  
pp. 4634-4637
Author(s):  
Tian Lin Cui ◽  
Jing Kun Pi ◽  
Yong Hui Liu ◽  
Zhen Hua He
Keyword(s):  
Structural Parameters ◽  
Structural Features ◽  
Surrounding Rock ◽  
Design Parameters ◽  
Optimized Design ◽  
Anchor Effect ◽  
The Finite Element Method ◽  
Anchor System ◽  
New Type ◽  
Stress Relation

In order to optimize the design of flexible pressurized anchor, this paper gives a further analysis on structural features of the new type of flexible pressurized anchor and carries out a contact analysis on anchor system by using the finite element method. It calculates as well as researches the contact stress relation of interactional anchor rod and surrounding rock under the circumstance of anchoring, obtaining the law of all major design parameters of anchor rod structure and pressure from surrounding rock influencing the anchoring performance and arriving at the conclusion that the anchor rod is adapted to various conditions of surrounding rock. They not only serve as important references for optimized design and application of anchor rod, but also provide a basis for the experiment of new type of anchor rod.

Analysis of Structural Parameters of MSCS on of the Overall Failure Probability of the Structure

2012 ◽  
Vol 256-259 ◽  
pp. 635-640
Author(s):  
Jian Jun Ye ◽  
Xun An Zhang ◽  
Xian Jie Wang
Keyword(s):  
Seismic Response ◽  
Dynamic Characteristics ◽  
Failure Probability ◽  
Structural Parameters ◽  
Seismic Intensity ◽  
Regular Pattern ◽  
Actual Design ◽  
Structural Mass ◽  
Overall Reliability

The randomness of value of tuned sub-structure mass and rigidity is comparatively large because of the needs of actual projects. Based on the dynamic characteristics and reliability of MSCS, the seismic response of the mega structure and the overall failure probability are discussed with the value of tuned sub structural mass and rigidity under different seismic intensity. It is shown that tuned sub structural mass and rigidity have significant affection on the overall reliability of structure, and seismic intensity has not interfere this regular pattern. Therefore, structural parameters of optimization which are referred to the regular pattern should be considered in the actual design in order to further enhance seismic capability of MSCS.

Reliability of Buried Pipeline Using a Theory of Probability of Failure

2006 ◽  
Vol 110 ◽  
pp. 221-230 ◽  
Author(s):  
Ouk Sub Lee ◽  
Dong Hyeok Kim ◽  
Seon Soon Choi
Keyword(s):  
Failure Probability ◽  
Probability Of Failure ◽  
Operating Conditions ◽  
Reliability Estimation ◽  
Design Parameters ◽  
Buried Pipeline ◽  
Safety Level ◽  
First Order ◽  
Reliability Method ◽  
Corrosion Defects

The reliability estimation of buried pipeline with corrosion defects is presented. The reliability of corroded pipeline has been estimated by using a theory of probability of failure. And the reliability has been analyzed in accordance with a target safety level. The probability of failure is calculated using the FORM (first order reliability method). The changes in probability of failure corresponding to three corrosion models and eight failure pressure models are systematically investigated in detail. It is highly suggested that the plant designer should select appropriate operating conditions and design parameters and analyze the reliability of buried pipeline with corrosion defects according to the probability of failure and a required target safety level. The normalized margin is defined and estimated accordingly. Furthermore, the normalized margin is used to predict the failure probability using the fitting lines between failure probability and normalized margin.

A Multi-State Strategy for Structural Damage Detection Using Sensitivity of Weighted Transmissibility Function

2021 ◽  
pp. 2150144
Author(s):  
Ziwei Luo ◽  
Huanlin Liu ◽  
Ling Yu
Keyword(s):  
Damage Detection ◽  
Structural Damage ◽  
Model Updating ◽  
Structural Parameters ◽  
Experimental Studies ◽  
Fe Model ◽  
Limited Information ◽  
Structural Damage Detection ◽  
State Strategy ◽  
Output Only

In practice, a model-based structural damage detection (SDD) method is helpful for locating and quantifying damages with the aid of reasonable finite element (FE) model. However, only limited information in single or two structural states is often used for model updating in existing studies, which is not reasonable enough to represent real structures. Meanwhile, as an output-only damage indicator, transmissibility function (TF) is proven to be effective for SDD, but it is not sensitive enough to change in structural parameters. Therefore, a multi-state strategy based on weighted TF (WTF) is proposed to improve sensitivity of TF to change in parameters and in order to further obtain a more reasonable FE model for SDD in this study. First, WTF is defined by TF weighted with element stiffness matrix, and relationships between WTFs and change in structural parameters are established based on sensitivity analysis. Then, a multi-state strategy is proposed to obtain multiple structural states, which is used to reasonably update the FE model and detect structural damages. Meanwhile, due to fabrication errors, a two-stage scheme is adopted to reduce the global and local discrepancy between the real structure and the FE model. Further, the [Formula: see text]-norm and the [Formula: see text]-norm regularization techniques are, respectively, introduced for both model updating and SDD problems by considering the characteristics of problems. Finally, the effectiveness of the proposed method is verified by a simply supported beam in numerical simulations and a six-storey frame in laboratory. From the simulation results, it can be seen that the sensitivity to structural damages can be improved by the definition of WTF. For the experimental studies, compared with the FE model updated from the single structural state, the FE model obtained by the multi-state strategy has an ability to more reasonably describe the change of states in the frame. Moreover, for the given structural damages, the proposed method can detect damage locations and degrees accurately, which shows the validity of the proposed method and the reliability of the updated FE model.

Local Mass Addition and Data Fusion for Structural Damage Identification Using Approximate Models

2020 ◽  
Vol 20 (11) ◽  
pp. 2050124
Author(s):  
Jilin Hou ◽  
Zhenkun Li ◽  
Qingxia Zhang ◽  
Łukasz Jankowski ◽  
Haibin Zhang
Keyword(s):  
Data Fusion ◽  
Objective Function ◽  
Structural Damage ◽  
Damage Identification ◽  
Structural Parameters ◽  
Identification Accuracy ◽  
Fe Model ◽  
Local Damage ◽  
Approximate Models ◽  
Structural Damage Identification

In practical civil engineering, structural damage identification is difficult to implement due to the shortage of measured modal information and the influence of noise. Furthermore, typical damage identification methods generally rely on a precise Finite Element (FE) model of the monitored structure. Pointwise mass alterations of the structure can effectively improve the quantity and sensitivity of the measured data, while the data fusion methods can adequately utilize various kinds of data and identification results. This paper proposes a damage identification method that requires only approximate FE models and combines the advantages of pointwise mass additions and data fusion. First, an additional mass is placed at different positions throughout the structure to collect the dynamic response and obtain the corresponding modal information. The resulting relation between natural frequencies and the position of the added mass is sensitive to local damage, and it is thus utilized to form a new objective function based on the modal assurance criterion (MAC) and [Formula: see text]-based sparsity promotion. The proposed objective function is mostly insensitive to global structural parameters, but remains sensitive to local damage. Several approximate FE models are then established and separately used to identify the damage of the structure, and then the Dempster–Shafer method of data fusion is applied to fuse the results from all the approximate models. Finally, fractional data fusion is proposed to combine the results according to the parametric probability distribution of the approximate FE models, which allows the natural weight of each approximate model to be determined for the fusion process. Such an approach circumvents the need for a precise FE model, which is usually not easy to obtain in real application, and thus enhances the practical applicability of the proposed method, while maintaining the damage identification accuracy. The proposed approach is verified numerically and experimentally. Numerical simulations of a simply supported beam and a long-span bridge confirm that it can be used for damage identification, including a single damage and multiple damages, with a high accuracy. Finally, an experiment of a cantilever beam is successfully performed.

Finite Element Analysis of the Nut-Supports Subassembly Based on ANSYS

2012 ◽  
Vol 215-216 ◽  
pp. 847-850
Author(s):  
Shou Jun Wang ◽  
Xing Xiong ◽  
Hong Jie Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Reference Data ◽  
Three Dimensional ◽  
Design Parameters ◽  
Weak Links ◽  
Fe Model ◽  
Element Analysis ◽  
Design And Optimization ◽  
Wave Maker

In the condition of alternating impact ,the nut-supports subassembly is analyzed according to uncertainty of design parameters. Firstly, a three-dimensional (3-D) finite element (FE) model of the nut-supports subassembly is built and is meshed,and the constraints and loads are imposed.Secondly,the model of nut-supports was assembled using the software ANSYS to understand the stress distribution and various parts of the deformation of the nut-supports and its weak links in the harmonic forces.Finally,socket head cap screw has not enough pre-load in the condition of alternating impact and will be simplified.It is analyzed and checked whether it is cut or not; which provides the reference data for design and optimization of the wave maker.

Optimizing Roll Forming Processes with the Aid of a New Numerical Algorithm

2012 ◽  
Vol 504-506 ◽  
pp. 857-862 ◽  
Author(s):  
Ahmad Abrass ◽  
Thomas Kessler ◽  
Peter Groche
Keyword(s):  
Numerical Algorithm ◽  
Numerical Algorithms ◽  
Roll Forming ◽  
Design Parameters ◽  
Fe Model ◽  
Forming Process ◽  
Cross Sectional ◽  
Cross Sectional Profile ◽  
Sectional Profile ◽  
Roll Forming Process

For the manufacturing of large quantities of profile-shaped products, the roll forming process represents one of the most effective metal forming technologies. During this process, the sheet metal will be formed into a desired cross-sectional profile using successive pairs of forming rolls. This process is well known as a very complex process in industry because of the multiplicity of the process and design parameters. For that reason, the optimization of roll forming processes using numerical methods like the finite element method is very complex and time-consuming. In this paper, a numerical method will be introduced to accelerate the simulation and to optimize the roll forming process. The newly developed algorithm will be illustrated and validated by analyzing the roll forming process. The details of the FE-model and the numerical algorithm will be described. Furthermore, the results of the numerical simulation with and without the application of the numerical algorithms will be compared. Finally, the process will be optimized using the newly developed method.

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