scholarly journals Reliability based design optimization using a genetic algorithm: application to bonded thin films areas of copper/polypropylene

2016 ◽  
Vol 24 (3) ◽  
pp. 510-519 ◽  
Author(s):  
Leandro Luis Corso ◽  
Alexandre Luis Gasparin ◽  
Herbert Martins Gomes
Author(s):  
Heeralal Gargama ◽  
Sanjay K Chaturvedi ◽  
Awalendra K Thakur

The conventional approaches for electromagnetic shielding structures’ design, lack the incorporation of uncertainty in the design variables/parameters. In this paper, a reliability-based design optimization approach for designing electromagnetic shielding structure is proposed. The uncertainties/variability in the design variables/parameters are dealt with using the probabilistic sufficiency factor, which is a factor of safety relative to a target probability of failure. Estimation of probabilistic sufficiency factor requires performance function evaluation at every design point, which is extremely computationally intensive. The computational burden is reduced greatly by evaluating design responses only at the selected design points from the whole design space and employing artificial neural networks to approximate probabilistic sufficiency factor as a function of design variables. Subsequently, the trained artificial neural networks are used for the probabilistic sufficiency factor evaluation in the reliability-based design optimization, where optimization part is processed with the real-coded genetic algorithm. The proposed reliability-based design optimization approach is applied to design a three-layered shielding structure for a shielding effectiveness requirement of ∼40 dB, used in many industrial/commercial applications, and for ∼80 dB used in the military applications.


Author(s):  
Mohammadreza Seify Asghshahr

This paper introduces a new framework for reliability based design optimization (RBDO) of the reinforced concrete (RC) frames. This framework is constructed based on the genetic algorithm (GA) and finite element reliability analysis (FERA) to optimize the frame weight by selecting appropriate sections for structural elements under deterministic and probabilistic constraints. Modulus of elasticity of the concrete and steel bar, dead load, live load, and earthquake equivalent load are considered as random variables. Deterministic constraints include the code design requirements that must be satisfied for all the frame elements according to the nominal values of the aforementioned random variables. On the other hand, this framework provides the minimum required reliability index as the probabilistic constraint. The first-order reliability method (FORM) using the Newton-type recursive relationship will be used to compute the reliability index. The maximum inter-story drift is considered as an engineering demand parameter to define the limit-state function in FORM analysis. To implement the proposed framework, a mid-rise five-story RC frame is selected as an example. Based on the analysis results, increasing the minimum reliability index from 6 to 7 causes an 11 % increase in the weight of the selected RC frame as an objective function. So, we can obtain a trade-off between the optimized frame weight and the required reliability index utilizing the developed framework. Furthermore, the high values of the reliability index for the frame demonstrate the conservative nature of code requirements for interstory drift limitations based on the linear static analysis method.


2010 ◽  
Vol 29-32 ◽  
pp. 1258-1262
Author(s):  
Hin Xin Guo ◽  
Juan Dai ◽  
Guan Yu Hu ◽  
Li Zhi Cheng

The design optimization of valve-spring is achieved under the condition of expected reliability. The restrain conditions about the reliability of static strength and fatigue strength are considered, and then a dual-objective optimal problem of valve spring is modeled to obtain the lightest mass of valve-spring and the minimum error of spring stiffness. The feasibility of reliability condition is discussed based on evidence theory in order to improve the computational efficiency. By means of the combination of evidence, the upper and lower bounds of reliability are obtained, and a substituting model of restrain condition about reliability is proposed based on the obtained bounds of reliability. After the weighted combination of two objective functions is made, the optimization model is solved by using genetic algorithm. An example is given and it shows that the proposed method is effective.


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