scholarly journals Motion-Based Design of Passive Damping Devices to Mitigate Wind-Induced Vibrations in Stay Cables

Vibration ◽  
2018 ◽  
Vol 1 (2) ◽  
pp. 269-289 ◽  
Author(s):  
Javier Naranjo-Pérez ◽  
Javier Jiménez-Manfredi ◽  
Javier Jiménez-Alonso ◽  
Andrés Sáez
Keyword(s):  
Objective Function ◽  
Design Method ◽  
Optimization Method ◽  
Design Criterion ◽  
Passive Damping ◽  
Characteristic Parameters ◽  
Additional Function ◽  
Wind Action ◽  
Multi Objective ◽  
Stay Cables

Wind action can induce large amplitude vibrations in the stay cables of bridges. To reduce the vibration level of these structural elements, different types of passive damping devices are usually installed. In this paper, a motion-based design method is proposed and implemented in order to achieve the optimum design of different passive damping devices for stay cables under wind action. According to this method, the design problem is transformed into an optimization problem. Thus, its main aim is to minimize the different terms of a multi-objective function, considering as design variables the characteristic parameters of each considered passive damping device. The multi-objective function is defined in terms of the scaled characteristic parameters, one single-function for each parameter, and an additional function that checks the compliance of the considered design criterion. Genetic algorithms are considered as a global optimization method. Three passive damping devices have been studied herein: viscous, elastomeric and friction dampers. As a benchmark structure, the Alamillo bridge (Seville, Spain), is considered in order to validate the performance of the proposed method. Finally, the parameters of the damping devices designed according to this proposal are successfully compared with the results provided by a conventional design method.

A Structural Optimization Method for Universal Design of Compliant Mechanism Scissors

2009 ◽  
Author(s):  
Kazuhiro Izui ◽  
Kiyoshi Yokota ◽  
Takayuki Yamada ◽  
Shinji Nishiwaki ◽  
Masataka Yoshimura
Keyword(s):  
Structural Optimization ◽  
Universal Design ◽  
Compliant Mechanism ◽  
Design Method ◽  
Optimization Technique ◽  
Optimization Method ◽  
Design Criterion ◽  
Design Solution ◽  
Design Criteria ◽  
Level Set Function

This paper proposes a structural optimization-based method for the design of compliant mechanism scissors in which the proposed design criteria are based on universal design principles. The first design criterion is the distance from the hand-grip to the center of gravity of the scissors, which should be minimized to reduce the physical effort required of the people using the device. The second design criterion is that of failure tolerance, where the effects of traction applied in undesirable directions upon the performance of the compliant mechanism should be minimized. Based on the proposed design criteria, a multiobjective optimization problem for the universal design of a compliant mechanism scissors is formulated. Furthermore, to obtain an optimal configuration, a new type of topology optimization technique using the level set function to represent structural boundaries is employed. This optimization technique enables rapid verification of resulting design configurations since the boundary shapes of the obtained design solution candidates can be easily converted to finite element models which are then used in large deformation analyses. Finally, the proposed design method is applied to design examples. The optimal configurations obtained by the proposed method provide good universal design performance, indicating the effectiveness and usefulness of the proposed method.

Strength Optimization of Infant Pop-Up Seat Frame Using Discrete Material and Thickness Optimization

2021 ◽  
Vol 11 (3) ◽  
pp. 1-20
Author(s):  
YeongJo Ju ◽  
Euysik Jeon
Keyword(s):  
Optimal Design ◽  
High Strength Steel ◽  
Design Method ◽  
High Strength ◽  
Optimization Method ◽  
Design Criterion ◽  
Thickness Optimization ◽  
Element Analysis ◽  
Strength Design ◽  
Seat Frame

In this paper, the authors proposed an optimal design method for the strength design of infant pop-up seat frame combined with rear seats for infants, children, and adults, not removable booster seats or car seats. Frame strength design was performed using discrete material and thickness optimization (DMTO) method considering high strength steel (HSS) and advanced high strength steel (AHSS). Structural design using the Section 4 link mechanism was performed, and the weakness of the seat frame due to static load was confirmed through finite element analysis. An optimal design criterion was established by carrying out a case study to derive the limiting conditions according to static and dynamic loads. In consideration of these criteria, the optimal design according to d-optimal and discrete Latin-hypercube (DLH) was performed among the design of experiments (DOE). And the strength of the pop-up seat frame for infants according to each DOE was checked, and the strength optimization method was suggested by comparing the lightweight ratio.

Determination of the Optimum Partial Factors in Structural Reliability Analysis

1998 ◽  
Vol 05 (02) ◽  
pp. 169-180 ◽  
Author(s):  
D. H. Li ◽  
C. Y. Tang ◽  
M. Jie ◽  
Albert H. C. Tsang ◽  
Y. C. Tsim
Keyword(s):  
Objective Function ◽  
Reliability Analysis ◽  
Structural Reliability ◽  
Optimization Method ◽  
Design Criterion ◽  
Resistance Force ◽  
Reliability Design ◽  
Structural Reliability Analysis ◽  
Live Loads ◽  
Partial Factor

In this paper, an optimization method is used to determine the values of partial factors in structural reliability analysis. Once the proper objective function is defined, a group of optimum partial factors, which enable the objective function to take its minimum value, will need to be determined. In the present study, two kinds of objective function are considered. The conditions that have to be satisfied for optimum partial factors of these two kinds of objective function are then derived. In both cases, the result shows that the partial factors of both dead and live loads should satisfy the same proportional expression and should be inversely proportional to the partial factor of resistance force. A simple beam is used as an example to illustrate the computations involved. It is found that the design concept proposed in this paper leads to a design criterion similar to that which applies to the conventional deterministic method. Thus, this concept can be easily used in practice. The illustrative example shows that the values of the dead load and live load have a significant effect on the reliability design criteria.

scholarly journals Motion-Based Design of Passive Damping Systems to Reduce Wind-Induced Vibrations of Stay Cables under Uncertainty Conditions

2020 ◽  
Vol 10 (5) ◽  
pp. 1740 ◽  
Author(s):  
Javier Naranjo-Pérez ◽  
Javier F. Jiménez-Alonso ◽  
Iván M. Díaz ◽  
Giuseppe Quaranta ◽  
Andrés Sáez
Keyword(s):  
Robust Design ◽  
Passive Control ◽  
Design Method ◽  
Limit State ◽  
Inequality Constraint ◽  
Stay Cable ◽  
Passive Damping ◽  
Stay Cables ◽  
The Cost ◽  
Damping Systems

Stay cables exhibit both great slenderness and low damping, which make them sensitive to resonant phenomena induced by the dynamic character of external actions. Furthermore, for these same reasons, their modal properties may vary significantly while in service due to the modification of the operational and environmental conditions. In order to cope with these two limitations, passive damping devices are usually installed at these structural systems. Robust design methods are thus mandatory in order to ensure the adequate behavior of the stay cables without compromising the budget of the passive control systems. To this end, a motion-based design method under uncertainty conditions is proposed and further implemented in this paper. In particular, the proposal focuses on the robust design of different passive damping devices when they are employed to control the response of stay cables under wind-induced vibrations. The proposed method transforms the design problem into a constrained multi-objective optimization problem, where the objective function is defined in terms of the characteristic parameters of the passive damping device, together with an inequality constraint aimed at guaranteeing the serviceability limit state of the structure. The performance of the proposed method was validated via its application to a benchmark structure with vibratory problems: The longest stay cable of the Alamillo bridge (Seville, Spain) was adopted for this purpose. Three different passive damping devices are considered herein, namely: (i) viscous; (ii) elastomeric; and (iii) frictions dampers. The results obtained by the proposed approach are analyzed and further compared with those provided by a conventional method adopted in the Standards. This comparison illustrates how the newly proposed method allows reduction of the cost of the three types of passive damping devices considered in this study without compromising the performance of the structure.

Multi-Objective Aerodynamic Optimization of Axial Turbine Blades Using a Novel Multilevel Genetic Algorithm

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Özhan Öksüz ◽  
İbrahim Sinan Akmandor
Keyword(s):  
Genetic Algorithm ◽  
Gas Turbine ◽  
Design Method ◽  
Turbine Blades ◽  
Optimization Method ◽  
Navier Stokes ◽  
Test Cases ◽  
Aerodynamic Optimization ◽  
Multi Objective ◽  
Design Variables

In this paper, a new multiploid genetic optimization method handling surrogate models of the CFD solutions is presented and applied for a multi-objective turbine blade aerodynamic optimization problem. A fast, efficient, robust, and automated design method is developed to aerodynamically optimize 3D gas turbine blades. The design objectives are selected as maximizing the adiabatic efficiency and torque so as to reduce the weight, size, and cost of the gas turbine engine. A 3D steady Reynolds averaged Navier–Stokes solver is coupled with an automated unstructured grid generation tool. The solver is verified using two well-known test cases. The blade geometry is modeled by 36 design variables plus the number of blade variables in a row. Fine and coarse grid solutions are respected as high- and low-fidelity models, respectively. One of the test cases is selected as the baseline and is modified by the design process. It was found that the multiploid multi-objective genetic algorithm successfully accelerates the optimization and prevents the convergence with local optimums.

scholarly journals Lightweight Design of Multi-Objective Topology for a Large-Aperture Space Mirror

2018 ◽  
Vol 8 (11) ◽  
pp. 2259 ◽  
Author(s):  
Yanjun Qu ◽  
Yanru Jiang ◽  
Liangjie Feng ◽  
Xupeng Li ◽  
Bei Liu ◽  
...  
Keyword(s):  
Objective Function ◽  
Design Method ◽  
Lightweight Design ◽  
Multi Objective ◽  
Large Aperture ◽  
A Value ◽  
Sensitivity Analysis Method ◽  
Key Techniques ◽  
Surface Figure ◽  
Polishing Pressure

For a large-aperture space telescope, one of the key techniques is the method for designing the lightweight primary mirror assembly (PMA). In order to minimize the mirror surface error under axial gravity, lateral gravity, and polishing pressure at the same time, a method for topology optimization with multi-objective function combined with parametric optimization is introduced in this paper. The weighted compliance minimum is selected as the objective function to maximum the mirror structural stiffness. Then sensitivity analysis method and size optimization are used to determine the mirror structure parameters. Compared with two types of commonly used lightweight configurations, the new configuration design shows obvious superiority. In addition, the surface figure root mean square (RMS) of the mirror mounted by given bipod flexure (BF) under 1 g lateral gravity is minimized only with a value of 3.58 nm, which proves the effectiveness of the design method proposed in this paper.

Multi-Objective Optimization of a Wedged-Ring Joint Structure

2010 ◽  
Vol 150-151 ◽  
pp. 503-507
Author(s):  
Yuan Dong Liu ◽  
Yi Hui Yin
Keyword(s):  
Maximum Stress ◽  
Design Method ◽  
Optimization Method ◽  
Ring Structure ◽  
Geometrical Parameters ◽  
Multi Objective Optimization ◽  
Surface Design ◽  
Multi Objective ◽  
Engineering Software ◽  
Joint Structure

Finite element method and optimization method are two major ones in engineering analysis. The optimization of a wedged-ring joint structure can be performed by using these two methods unitedly. The response surface design method was employed to determine the combination of geometrical parameters to be designed of the wedged-ring joint structure. The stress of the wedged-ring joint structure which has the different geometrical parameters was numerically simulated and analyzed by using engineering software ANSYS. The optimized geometrical parameters of the wedged-ring structure were obtained by using MATLAB multi-objective optimization method. The results show that the maximum stress and the mass of the optimized wedged-ring structure decrease 13.6% and 12.5%, respectively.

Multi-Objective Optimization for Gas Distribution in Continuous Annealing Process

2019 ◽  
Vol 23 (2) ◽  
pp. 229-235
Author(s):  
Yongyue Zhang ◽  
Weihua Cao ◽  
Qilin Qu ◽  
◽  
◽  
...  
Keyword(s):  
Prediction Model ◽  
Objective Function ◽  
Optimization Method ◽  
Annealing Process ◽  
Continuous Annealing ◽  
Multi Objective Optimization ◽  
Gas Distribution ◽  
Furnace Temperature ◽  
Multi Objective ◽  
Constraint Set

In this study, the phenomenon of uneven gas distribution at different sections in the continuous annealing process, which affects the instability of the section furnace temperature and can cause accidents that exceed safety thresholds for a long period, was analyzed to establish a furnace temperature prediction model and a multi-objective optimization method for section gas was proposed. First, the industrial production process was analyzed to extract key factors that affect furnace temperature and combine them with the SVR algorithm to establish a prediction model for furnace temperature. Then, a multi-objective optimization constraint set and optimization objective function were constructed based on the constraints of the production process and equipment conditions. Finally, based on the prediction model, the constraint set, and the objective function, a multi-objective optimization algorithm was employed to optimize section gas based on the NSGA-III. The experimental verification and production results demonstrate that a model constructed using actual collected data yields excellent prediction results. When the multi-objective optimization method was implemented and put into production, the steel coil over-temperature alarm ratio was reduced and the average over-temperature alarm time was greatly reduced. The proposed method improves the production environment and ensures that the procss is safe and stable.

scholarly journals Non-Axisymmetric Shroud Profiled Endwall Optimization of an Embedded Stator and Experimental Investigation

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 726
Author(s):  
Jiayu Wang ◽  
Jun Hu ◽  
Chao Jiang ◽  
Jun Li
Keyword(s):  
Energy Conversion ◽  
Objective Function ◽  
Optimization Design ◽  
Design Method ◽  
Optimization Method ◽  
Energy Conversion Efficiency ◽  
Loss Coefficient ◽  
Local Loss ◽  
Real Effects ◽  
Multi Stage

Turbomachinery has been widely used in the energy systems as an energy conversion device, such as gas turbine and aero-engine. The losses in the turbomachinery, especially in the multi-stage conditions, restrict the energy conversion efficiency and corresponding fuel economy. Previous studies show that non-axisymmetric endwall could be used to decrease the losses in compressors, but the real effects in the rig tests are usually inconsistent with the numerical simulation. In this paper, a shroud profiled endwall optimization method with the strategy of local loss as the objective function is proposed, aiming at reducing the tip loss of an embedded stator under the operating point. The traditional total loss coefficient and four local loss functions are studied to investigate how the objective functions influence the optimization results. Three optimized endwall geometries are tested in the embedded test platform. It showed that the strategy of loss coefficient above 90% span as the objective function was best at decreasing the stator loss in the tip region as well as the whole span. Under this strategy, the loss above 90% span was suppressed by 48.17% and the loss of the whole span decreased 9.27%, which proved the PEW optimization design method with the strategy of local loss as the objective function is potential.

Multi-Objective Optimization of a Bolt-Flange Structure

2011 ◽  
Vol 233-235 ◽  
pp. 2800-2804
Author(s):  
Yuan Dong Liu ◽  
Yi Hui Yin ◽  
Ying Chun Lu
Keyword(s):  
Response Surface ◽  
Design Method ◽  
Equivalent Stress ◽  
Optimization Method ◽  
Surface Model ◽  
Geometrical Parameters ◽  
Multi Objective Optimization ◽  
Surface Design ◽  
Multi Objective ◽  
Maximum Equivalent Stress

The bolt-flange structure is most one of joint mode, and stress and mass are its major performance parameters. The multi-object optimization of a bolt-flange structure can be performed by using Finite element method and optimization method unitedly. The response surface design method was employed to determine the combination of geometrical parameters to be designed of the bolt-flange structure. The stress of the bolt-flange structure which has the different geometrical parameters was numerically simulated and analyzed by using the software ANSYS. The response surface model is obtained. The optimized geometrical parameters of the bolt-flange structure were obtained by using MATLAB multi-objective optimization method. The results showed that the maximum equivalent stress in the optimized bolt-flange structure decreased 13.4% than that in the original one and the mass of the optimized bolt-flange structure was lower 14.3% than that of the original one.

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