Browsing by Author "Firoozi, Behnam"

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Development of novel methodologies for the damage detection in mechanical systems
(2020-12-31) Firoozi, Behnam; Şendur, Polat; Şendur, Polat; Poyrazoğlu, Göktürk; Tunç, B.; Department of Mechanical Engineering; Firoozi, Behnam
The present study examines the capability of various optimization algorithms and proposes novel hybrid algorithms for the more precise prediction of open-edge cracks in mechanical systems. The natural frequencies of the beam with crack are obtained by modal analysis and experimentally validated from impact testing. In the first part of the thesis, the performance of novel HHO, ESDA, PFA, and HGSO algorithms from literature are evaluated to determine the location and depth of an open-edge crack for an Euler–Bernoulli beam. Subsequently, hybrid algorithms such as HHO-NM, ESDA-NM, and PF-NM are proposed for improving the results. Optimization parameters are tuned systematically using the Taguchi design of experiments (DOE) method. Simulation results show that the proposed hybrid algorithms yield much more precise results with fewer function evaluations compared to previously introduced algorithms and, therefore, have a superior crack detection capability. Furthermore, the statistical post hoc analysis has shown that the proposed hybrid algorithm can be considered as a high performance algorithm, which can significantly improve the performance of algorithms. In the second part of this thesis we study the static deflection, natural frequency, primary resonance of electrostatically actuated cracked gas sensor. Besides, a novel hybrid metaheuristic algorithm is proposed to detect the location and depth of possible crack on the systems. The gas sensor configuration consists of a microcantilever with a rigid plate attached to its end. In the first part, the effect of crack on the static and dynamic pull-in instability are studied. The equations of motion are solved by the application of the perturbation method. Next, an inverse problem is formulated to predict the location and depth of the crack in the gas sensor.
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Multi-strategy Gaussian Harris hawks optimization for fatigue life of tapered roller bearings
(Springer, 2022-12) Abbasi, Ahmad; Firoozi, Behnam; Şendur, Polat; Heidari, A. A.; Tiwari, R.; Mechanical Engineering; ŞENDUR, Polat; Abbasi, Ahmad; Firoozi, Behnam
Bearing is one of the most fundamental components of rotary machinery, and its fatigue life is a crucial factor in designing. The design optimization of tapered roller bearing (TRB) is a complex design problem because various arrays of designing parameters and functional requirements should be fulfilled. Since there are many design variables and nonlinear constraints, presenting an optimal design of TRBs poses some challenges for metaheuristic algorithms. The Harris hawks optimization (HHO) algorithm is a robust nature-inspired method with unique exploitation and exploration phases due to its time-varying structure. However, this metaheuristic algorithm may still converge to local optima for more challenging problems such as the design of TRBs. Therefore, this study aims to improve the accuracy and efficiency of the shortcomings of this algorithm. The performance of the proposed algorithm is first evaluated for the TRB optimization problem. The TRB optimization design has nine design variables and 26 constraints because of geometrical dimensions and strength conditions. The productivity of the proposed method is compared with diverse metaheuristic algorithms in the literature. The results demonstrate the significant development of dynamic load capacity in comparison to the standard value. Furthermore, the enhanced version of the HHO algorithm presented in this study is benchmarked with various well-known engineering problems. For supplementary materials regarding algorithms in this research, readers can refer to https://aliasgharheidari.com.