Volume 5 Issue 1
Authors: A.V. Borisov
Abstract: The phenomenon of synchronization in core mechanical systems is considered in the article. Synchronization is the most important phenomenon while steady human motion and while motion in exoskeleton, which actually makes this article urgent. The aim of this article is to study different models: two - and four-with one-dimensional, two-dimensional translational and rotational movement of the suspension point. The differential equations of motion are used for dynamic models, and their numerical solution is carried out. The result is graphs of solutions, presented in the article, which demonstrate the existence of the phenomenon of synchronization in various modes of movement and control. In the issue, the study of the phenomenon of synchronization is a creation of the exoskeleton, most comfortable for human use, performing synchronous movements.
Keywords: Synchronization; Exoskeleton; Musculoskeletal System of a Human; Core Mechanical System; Control
Authors: Sebhi Amar; Douib Nadir
Abstract: The machining of superalloy parts remains a dark area in mechanical manufacturing. It is limited in particular areas such as gas turbines, rocket engines, space vessels, nuclear reactors and pumps. Friction theory still seems to be in arrears with respect to the practice, although friction is implicated in many scientific disciplines. Industrials have been interested for many years in the development and characterization of materials in order to provide wear-resistant mechanical parts. In this context, study of the tribological behaviour of the cobalt based superalloy FXS-414 standard 9001F against the metallic carbide coated inserts TiN provides important information in the case of the turbine blades industry. The three main mechanisms responsible for the wear of the cutting tools are adhesion, abrasion and diffusion. The life of the cutting tool is primarily related to the development of two types of wear: flank wear and crater wear. This wear phenomenon appears to be scalable. It is developed during cutting, which impairs the quality of machining and the productivity, and it may even lead to the destruction of the tool in the case of excessive wear. The durability of machine tools often depends on tribological characteristics of the couple cutting tool material / workpiece. The characterization of superalloys is late compared to other materials. The choice of the cutting tool for machining superalloys is not really invested because of the high cost of machining means. It has been shown that the coating is the most influential parameter, followed by the sliding velocity and feed rate.
Keywords: Cutting Speed; Crater Wear; Drilling; Flank Wear; Friction; Tribology; Wear
Authors: D.A. Mamatova; Shangyong Zhang; A. Djuraev; M.A. Mansurova
Abstract: The aims of this research are to develop a new scheme of belt transmission with an integral driven pulley and tensioning roller as well as to determine the laws of motion for the main and bottom shafts of the sewing machine as they depend on the rigidity of the elastic elements of the driven belt pulley with justification of settings. The article describes a new diagram of a belt drive with a split driven pulley and eccentric tension roller. The laws of the driver masses’ motion of the sewing machine were obtained and analyzed.
Keywords: Belt Drive; Split Pulley; Torsion; Sewing Machine; Rigidity; Torque
Authors: Olurotimi Akintunde Dahunsi
Abstract: The International Organization for Standard ISO 2631-1 (1997), EU Directive 2002/44/EU, British Standard BS6841:87 and other standards of international repute have specified the acceptable levels of whole-body vibration (WBV) exposure for operators of mobile equipment and work vehicles. Compliance with these standards has not guaranteed absolute eradication or prevention of epidemiological disorders or injuries associated with low frequency vibrations, shocks, bumps, jolts and other irregularities. Therefore, effective and economic vibration isolation based on appropriate suspension seats is still necessary. This paper presents the findings of a practical study of the frequency response of a loaded X-type mechanism work suspension seat that was subjected to low frequency vertical sinusoidal vibrations in the range of 1-10Hz at three levels of amplitude on a test rig. The resulting transmissibilities of the seat due to the input excitations were analysed. The scissors mechanism work suspension seat had a static stiffness of 5.4kN/m, while the maximum travel attained was 82mm. Resonance occured mostly between 1.0 and 3.0Hz. However, the overall performance of the seat over the entire low frequency range provided an acceptable comfort level for the work vehicle operator, according to ISO standards.
Keywords: Whole-Body Vibrations; Low Frequency Vibrations; Frequency Response; Transmissibility; Resonance
Authors: Makoto Katoh; Koji Umegaki
Abstract: This paper presents experiments for determining the rotational stiffness coefficient kθ for water, and the restoring-force coefficient γθ of the gyroscopic moment. These parameters are based on non-autonomous basic equations derived from the autonomous roll-stability equation for a floating body, the wind force moment, and the gyroscopic moment of the Flettner rotor dynamics for a single-rotor boat model with various wind speeds from both the port and starboard sides in a small pool. The tilt angle of the rotor boat was measured with 3D accelerometers, and the restoration angle was computed. The nonlinearity of the stiffness coefficient was identified, and in a simulation, accurate results for roll stability were obtained.
Keywords: Eco-ship; Flettner Rotor; Rolling Stability; Gyro
Authors: Aaron R. Rababaah; Joseph Arumala; Ibibia K. Dabipi; Kenny Fotouhi; Gurdeep Hura; Gurdeep Hura; Avinash Dudi
Abstract: This paper presents an intelligent method for failure detection based on digital signal analysis in offshore wind turbines. The primary goal of this research is to build an intelligent method which can detect mechanical failure in offshore wind turbines. The proposed method is a multi-stage process including signal acquisition, pre-processing, model training, testing, defect pattern detection and result verification. Two primary stages were investigated for design choice: signal characterization which includes feature selection and extraction, and defect classification. For the characterization stage, two techniques were investigated: discrete cosine transform (DCT) and fast Fourier transform (FFT). A pre-examination of the similarity measure among the resulting vectors of the two techniques was conducted and results indicate that a Euclidian-based similarity measure was superior to a correlation-based similarity measure of the signal vectors by a significant factor. FFT was chosen over DCT because FFT naturally relates to the frequency domain of a signal and signifies a direct interpretation of the primary harmonics of the original signal. For the classification stage, two implementations of the process were executed and compared: one implementation did not utilize an intelligent agent and the other utilized a neural network model to classify signal vectors into healthy and damaged classes. The difference between the two implementations was very significant: the intelligent agent demonstrated a very reliable classification accuracy > 90% while the other demonstrated an accuracy of only 53%.
Keywords: Wind Turbine Health Monitoring; NREL Gearbox Data; Artificial Neural Networks; Fourier Transform; Randomized Sampling
Authors: Makoto Katoh; Atsushi Fujiwara
Abstract: This paper proposes an ideal-input model reference simple adaptive control scheme (MRSACS) with an adaptive proportional internal derivative (PID) mechanism in a reference model for anti-sway and position control of an overhead travelling crane that uses various pendulum (rope) lengths, after which its performance is verified via various simulations. It was found that the system’s parallel PID adaptive mechanism was robust against load change properties, and the simulation results showed that the effectiveness of pendulum length and weight changes were satisfactory for simultaneous position control and anti-sway measures.
Keywords: Overhead Travelling Crane Model; Model Reference Adaptive Control; Position Control