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RISS 인기검색어
- 검색키워드
- 저자 : Narges Fallah (검색결과 4 건)
- 무료
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Damage identification in laminated composite plates using a new multi-step approach
Narges Fallah,Seyed Rohollah Hoseini Vaez,Hossein Fasihi 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.29 No.1
In this paper a new multi-step damage detection approach is provided. In the first step, condensed modal residual vector based indicator (CMRVBI) has been proposed to locate the suspected damaged elements of structures that have rotational degrees of freedom (DOFs). The CMRVBI is a new indicator that uses only translational DOFs of the structures to localize damaged elements. In the next step, salp swarm algorithm is applied to quantify damage severity of the suspected damaged elements. In order to assess the performance of the proposed approach, a numerical example including a three-layer square laminated composite plate is studied. The numerical results demonstrated that the proposed CMRVBI is effective for locating damage, regardless of the effect of noise. The efficiency of proposed approach is also compared during both steps. The results demonstrate that in noisy condition, the damage identification approach is capable for the studied structure.
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Damage identification of a 2D frame structure using two-stage approach
Seyed Rohollah Hoseini Vaez,Narges Fallah 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.3
In this article, a two-stage damage identification approach is employed to detect the site and extent of multiple damage cases in a 2D frame structure. In the first stage, Damage locating vector (DLV) method based on a new indicator called EDS (Exponential decreased stress) is applied to localize the damaged elements. Next, the damage extents of suspected elements are quantified using two metaheuristic algorithms, Water evaporation optimization (WEO) and accelerated WEO. Numerical example consists of a 2D frame structure with two types of meshing elements, 35 and 105 frame elements. For every state, two multiple damage cases are tested in noisy condition. To compare performance of the two-stage method with one-stage optimization method, the studied cases are also run using these two metaheuristic algorithms. The results indicate that the two-stage approach is more effective than one-stage because the number of intact element detected as damaged one and computational errors for actual damaged elements in one-stage method are more while the two-stage approach spends a much shorter time.
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Sayed Javid Royaee,Morteza Sohrabi,Narges Fallah 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.11
The degradation of phenol was investigated in a continuous flow impinging streams system. In the first step, statistical experimental designs were used to optimize the process of phenol degradation in a photo-impinging streams reactor. The more important factors affecting phenol degradation (p<0.05) were screened by a two-level Plackett-Burman design. Four of the latter parameters, namely phenol concentration, catalyst loading, pH and slurry flow rate,were selected for final process optimization, applying central composite design (CCD). The predicted data showed that the maximum removal efficiency of phenol (99%) could be obtained under the optimum operating conditions (phenol concentration=50 mg l−1, catalyst loading=2.1 g l−1, pH 6.2 and slurry flow rate=550ml min−1). These predicted values were then verified by certain validating experiments. A good correlation was observed between the predicted data and those determined by the experimental study. This may confirm the validity of the statistical optimum strategy. Finally,continuous degradation of phenol was performed, and the results indicated a higher efficiency and an increased performance capability of the present reactor in comparison with the conventional processes.
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Ali Kaveh,Seyed Rohollah Hoseini Vaez,Pedram Hosseini,Narges Fallah 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.18 No.5
Nowadays, there are two classes of methods for damage detection in structures consisting of static and dynamic. The dynamic methods are based on studying the changes in structure\'s dynamic characteristics. The theoretical basis of this method is that damage causes changes in dynamic characteristics of structures. The dynamic methods are divided into two categories: signal based and modal based. The modal based methods utilize the modal properties consisting of natural frequencies, modal damping and mode shapes. As the modal properties are sensitive to changes in the structure, these can be used for detecting the damages. In this study, using dynamic method and modal based approach (natural frequencies and mode shapes), the objective function is formulated. Then, detection of damages of truss structures is addressed by using Simplified Dolphin Echolocation algorithm and solving inverse optimization problem. Many scenarios are used to simulate the damages. To demonstrate the ability of the algorithm, different truss structures with several multiple elements scenarios are tested using a few runs. The influence of the two different levels of noise in the modal data for these scenarios is also considered. The last example of this article is investigated using a different mutation. This mutation obtains the exact answer with fewer loops and population by limited computational effort.
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