Papers by Keyword: Vibration

Abstract: In the paper presented are given oscillation amplitude threshold compaction and vibrating platform, stiffness and viscosity of the concrete, and the frequency and amplitude of movement on compacting concrete.

Abstract: The present work proposes a vibration study with different surface and layers orientations at 0°, 15°, 30°, 45°, 60°, 75° and 90°using the Abaqus finite element code, the frequencies Stratified laminate composite panels were studied and the comparison between damaged structures and perfect structures we used stiffened panels based on T-shaped reinforced fibers. Lamb waves (LW) were widely proposed for the long-range inspection of Structural Structural Health Monitoring (SHM) oriented composite structures, the obtained results show the angle effects on the natural frequency increase at a peak then decrease in the form of a sinusoidal half-curve and the numerical results found in this work can be compared to those of other authors in the same area of ​​research, A piezoelectric actuator is used to design acoustic waves and a sensor is used for signal acquisition.

Abstract: To study the vibrations of a Multiparker lift lift model, use various models for the lifting mechanism. Calculate the first pulsation using the Dunkerley method. Behavior of the elevator to the action of an explosive task. We intend to evaluate the own pulsations in case of free vibrations of a lifting mechanism at an elevator within a multiparker parking lot. IT is absolutely necessary that the wave pulsation is different from the own pulsation of the studied system so as to avoid the resonance phenomenon leading to the system’s destruction. We shall establish a work algorithm using several models of the system as following: the model of the system with an autonomy degree; the calculation of the first own pulsations is used by the Dunkerley method; the model of the continuous system.A model is executed for the lifting mechanism of the Multiparker parking lot, considered as being composed of a continuous and homogeneous bar, embedded at the base, becoming a common unit with the mass M of the elevator. The own pulsations are determined in case of free vibrations for this bar.

Abstract: The development of CubeSats has been advanced significantly during the past two decades for both scientific research and industrial purposes. During the manufacturing process, every CubeSat must satisfy various system requirements in which the structural analysis is one of the most vital necessity in order to assure a normal operation of the CubeSat during its working time in space. In the conceptual design phase, structural dynamics is a mandatory step to determine the natural frequencies of individual bodies, the deformation and stress induced at the corresponding vibration modes to prevent structural failure. In this work, IGOSat, a 3-Unit CubeSat, which was developed at the Paris Diderot University is exanimated in term of modal, harmonic response, and random vibration analysis at the time of ground testing as well as the launching phase using ANSYS software. These numerical simulations conducted according to the CubeSat Design Specification and the system requirements of QB50 project. The minimum natural frequency of the CubSat obtained to be 363.17 (Hz), which passed the required frequency of 90 (Hz). Moreover, the Harmonic and Random vibration analyses indicate that the peak response of normal stress, as well as deformation values obtained, are far lesser compared to the yield strength of the frame structure and subsystem materials. Hence, our numerical analysis found that the CubeSat remains intact during the launch environment.

Abstract: Multi-axial mechanical systems commonly encounter the problem of vibration while attempting to drive machining systems at high speed. Many effective methods based on feed-forward and feedback control have been proposed and applied for vibration reduction. In order to design controllers all methods require the exact knowledge of system parameters: vibration frequency and damping ratio. In recent years, low-cost Micro Electro Mechanical Systems (MEMS) accelerometers have been used for many applications in industry. This paper presents the advantage of low cost MEMS accelerometer to identify vibration parameters of mechanical systems in comparison to conventional expensive devices.

Abstract: The paper deals with the fluxgate transducer intended for navigation and attitude control systems for moving vehicles. The finite element modeling of the half-sine and sawtooth pulse loads of various durations is performed for the proposed fluxgate configuration with regard to the properties of materials used.

Abstract: In the present experimental study, the effect of turning tool overhang on the chip morphology and vibrations during orthogonal turning has been investigated. Orthogonal cutting (turning) setup was developed to ensure the cutting process happens in a 2-dimesional plane. Orthogonal cutting was realized by turning a circular tube with geometry of 33.88 mm external diameter and 3.5 mm wall thickness (7075-T6 Alloy). High speed steel (HSS) rod with a square cross-section (1⁄2 x 1⁄2 square inch) was used to fabricate the orthogonal turning tool with a geometry of 15 ̊ back rake angle and 9 ̊ clearance angle. The cutting experiments were conducted for different tool overhang lengths (2cm, 3cm, 4cm, 5cm & 6cm) by keeping constant cutting speed (25 m/min) and feed (0.15mm/rev). The vibrational characteristics were measured using accelerometer and Ni-DAQ card. The morphology and microstructure of the chips collected during cutting were studied under optical microscope using metallographic procedures. It was found that for increasing overhang length of cutting tool the chips serrations was found increasing. The frequency of cutting tool and amplitude of vibration was found increasing with increasing tool overhang length.

Abstract: Poor heat treatment of the generator may cause cracks during operation. The presence ofcracks on the rotor causes the rotor to vibrate. The paper establishes a finite element modeling of aunit. The model is used to study the vibration response characteristics of the shafting system when thesupport characteristics of the generator are similar and the difference is significant. When thedifference in support characteristics between the two ends of the generator is large, the first-orderunbalance of the generator not only causes a large in-phase vibration at the first-order critical speed ofthe generator, but also causes a large reverse component. Finally, the reliability of the conclusion isfurther verified by combining the abnormal vibration diagnosis and processing cases of a generator.The innovation of the paper is to diagnose the possible cracks in the generator through the vibration ofthe generator, and then look at the original data in the generator manufacturing process to find that theheat treatment process of the generator rotor is poor.

Abstract: In this article, the analyses of free vibration of nanoplates, such as single-layered graphene sheets (SLGS), lying on an elastic medium is evaluated and analyzed via a novel refined plate theory mathematical model including small-scale effects. The noteworthy feature of theory is that the displacement field is modelled with only four unknowns, which is even less than the other shear deformation theories. The present one has a new displacement field which introduces undetermined integral variables, the shear stress free condition on the top and bottom surfaces of the plate is respected and consequently, it is unnecessary to use shear correction factors. The theory involves four unknown variables, as against five in case of other higher order theories and first-order shear deformation theory. By using Hamilton’s principle, the nonlocal governing equations are obtained and they are solved via Navier solution method. The influences played by transversal shear deformation, plate aspect ratio, side-to-thickness ratio, nonlocal parameter, and elastic foundation parameters are all examined. From this work, it can be observed that the small-scale effects and elastic foundation parameters are significant for the natural frequency.

Abstract: The need for quality control of biodiesel is important to ensure the development of a clean, trouble free and safe alternative fuel technology to fossil diesel. In this work, the gas chromatography analysis of the biodiesel produced from used frying oil was carried out using PerkinElmer Clarus 500 Gas Chromatograph (GC), fitted with a capillary split injector and Fourier Infrared Detector (FID). Also, the Fourier Transform Infrared Spectroscopy was used to determine and monitor the concentration of biodiesel produced from used and unused palm olein oil. The Fourier Transform Infrared (FTIR) analysis was carried out using the FTIR Spectroscopy (FTIR 1-S Shimadzu, Japan, Model 4100) and Microlab software as well as Attenuated Total Reflectance (ATR) sample interface system. 0.5 ml of samples of the unused palm olein oil and biodiesel were taken in at the interface at a resolution of 4 cm^-1 within the region of 4000 cm^-1 to 400 cm^{-1 .} The GC-MS analysis did not indicate any soap-like material, indicating that the catalyst was able to handle transesterification reaction without transition to saponification reaction. The results of the interaction between the components of the fuel samples and the radiation as a function of wavelength indicates the functional groups and the type of vibration in the fuel samples. The results obtained indicate the presence of an intense band of C=O stretching of methyl ester and O-CH₃ group. It also show concentration of the five main fatty acids that are present in most biodiesel; palmitic, stearic, oleic, linoleic, and linolenic acids indicating the successful transesterification of palm olein oil to biodiesel.