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您的检索式：作者名="Mahmoud Fakih"
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| 1 | Cost Optimized Non-Contacting Experimental Modal Analysis Using a Smartphone显示文摘The vibrations behavior analysis is an essential step in the mechanical design process.Several methods such as analytical modelling,numerical analysis and experimental measurements can be used for this purpose.However,the numerical or analytical models should be validated through experimental measurements,usually expensive.This paper introduces an inexpensive smartphone as an accurate,non-intrusive vibrations’behavior measurement device.An experimental measurement procedure based on the video processing method is presented.This procedure allows the measurement of the natural frequencies and the mode shapes of a vibrating structure,simply by using a smartphone built-in camera.The experimental results are compared to those obtained using an accurate analytical model,where the natural frequencies error is less than 2.7%and the modal assurance criterion is higher than 0.89.In order to highlight the obtained results,a comparison has been done using a high quality and high frame per second(fps)camera-based measurement of material properties.Since the highest recovered natural frequency and its associated mode shape depend on the frame per second rate of the recorded video,this procedure has great potential in low frequencies problems such as for big structures like buildings and bridges.This validated technique re-introduces the personal smartphone as an accurate inexpensive non-contacting vibration measurement tool. | Jaafar Hallal Mohammad Hammoud Mahmoud Fakih Ali Hallal | 2020 | Sound & Vibration2020，54，4： | 1 |
| 2 | Experimental Modal Damping Identification of a Mechanical Structure Using Video Magnification Technique显示文摘Vibration can be introduced in all mechanical fields in our life.Engineers try to avoid its negative effect leading in some cases to deformation in the machines.Many researches are dedicated to study the identification of damping especially in multi degree of freedom systems with particular attention to the source of energy dissipation.They focus on developing new tools or methods which may be used in real problems to obtain accurate results about the amount(or value)and the location of energy dissipation in the structure.The aim of this paper is to present an original procedure aims to experimentally determine the modal damping ratio of a mechanical structure.The proposed procedure consists of extracting the Frequency Response Function of the vibrating system using the video magnification method and then calculate the modal damping ratio using the 3-dB method.These experimental measurements are carried out by giving an external force on a cantilever beam,then the modal damping ratios are extracted using motion magnification.The obtained results show a relative error less than 4.2% between the experimental measurements and the analytical calculation for the Frequency Response Function(FRF)curves.The novelty of the paper is to combine the video magnification technique and the 3dB method in a procedure that aims to experimentally measure the modal damping of a mechanical structure.The proposed procedure in this paper represents the damping identification as a simple and easy engineering application. | Jaafar Hallal Mahmoud Fakih Hala Damerji Mohammad Hammoud Mehdi Chouman | 2021 | Sound & Vibration2021，55，2： | 0 |
| 3 | Effect of Lead-Rubber Bearing Isolators in Reducing Seismic Damage for a High-Rise Building in Comparison with Normal Shear Wall System显示文摘Seismic earthquakes are a real danger for the construction evolution of high rise buildings.The rate of earthquakes around the world is noteworthy in a wide range of construction areas.In this study,we present the dynamic behavior of a high-rise RC building with dynamic isolators(lead-rubber-bearing),in comparison with a traditional shear wall system of the same building.Seismic isolation has been introduced in building construction to increase the structural stability and to protect the non-structural components against the damaging effects of an earthquake.In order to clarify the influence of incorporating lead rubber bearing isolators in the seismic response and in reducing seismic damages;a comparative study is performed between a fixed base system(shear wall system)and an isolated base system(Lead Rubber Bearing)on an irregular high rise reinforced concrete(RC)building located in Beirut consisting of 48 storeys almost asymmetric orthogonally.For this purpose,a non-linear analysis of a real earthquake acceleration record(EI Centro seismic signal)is conducted,so that the mode shapes,the damping ratio and the natural frequencies of the two models are obtained using ETABS software.The results prove a substantial elongation of the building period,as well as a reduction in the building displacement,the roof acceleration,the inter-storey drift ratio and the base shear force of isolated building relative to fixed-base building.This study proves that this technology is applicable to high rise buildings with acceptable results. | Mahmoud Fakih Jaafar Hallal Hassan Darwich Hala Damerji | 2021 | Structural Durability & Health Monitoring2021，15，3： | 0 |
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