scholarly journals Full dynamic reactions in the main links of big band saw machines

2021 ◽  
Vol 9 (3) ◽  
pp. 092-104
Author(s):  
Boycho Marinov
Keyword(s):  
Rotating Disk ◽  
Operating Mode ◽  
Big Band ◽  
Band Saw ◽  
External Forces ◽  
External Loads

In this study, the full dynamic reactions in the bearing supports of the leading wheel of big band saw machines are determined. These reactions are caused by both the external loads and the kinematic and mass characteristics of the rotating disk. Expressions for calculating the dynamic reactions caused by external forces and moments that occur in the operating mode are obtained. The influence of the kinematic and mass characteristics of the rotating disk is studied and expressions for calculating the dynamic reactions caused by these characteristics are obtained. Expressions for calculating the full dynamic reactions that load the bearing supports of the leading wheel are obtained. With the help of these expressions, the parameters of the band saw machine can be selected in such a way as to ensure a minimum load on the shaft and bearings.

Full Dynamic Reactions in the Basic Shaft Bearings of Big Band Saw Machines

2013 ◽  
Vol 43 (1) ◽  
pp. 3-18 ◽  
Author(s):  
Boycho Marinov
Keyword(s):  
Rotating Disk ◽  
External Loading ◽  
Centre Of Mass ◽  
Big Band ◽  
Axis Of Rotation ◽  
Wood Cutting ◽  
Saw Blade ◽  
Band Saw

Abstract The band saws machines are a certain class woodworking machines for longitudinal or transversal cutting as well as for curvilinear wood cutting. These machines saw the wood through a band-saw blade and two feeding wheels. These wheels usually are very large and they are produced with inaccuracies. The centre of mass of the disc is displaced from the axis of rotation of the distance e (eccentricity) and the axis of the disk makes an angle with the axis of rotation. In this paper, the dy- namic reactions in the bearings of the basic shaft, which drives the band saw machines, are analyzed. These reactions are caused by the external loading and the kinematics and the mass characteristics of the rotating disk. The expressions for the full dynamic reactions are obtained. These expressions allow the parameters of the machines to be chosen in such a way that the loading in the shaft and the bearings to be minimal.

DISTRIBUTION OF ESCAPE TIMES OVER A FLUCTUATING BARRIER IN A MECHANICAL SYSTEM

2005 ◽  
Vol 15 (05) ◽  
pp. 1809-1814
Author(s):  
O. F. DE ALCANTARA BONFIM ◽  
JENNIFER MAE GOIN ◽  
JOHN ASAY
Keyword(s):  
Mechanical System ◽  
External Force ◽  
Driving Force ◽  
Transition Rate ◽  
Rotating Disk ◽  
Random Force ◽  
Periodically Driven ◽  
Chaotic Region ◽  
External Forces

We consider the problem of transitions between states of a bistable mechanical system induced by a harmonically, and a randomly oscillating barrier. We study the problem both experimentally and numerically. The system consists of a mass attached to a rotating disk, nonlinearly coupled to a spring subject to an external force. For periodically driven external forces, the transition rate across the barrier increases linearly with the frequency of the driving force until the system reaches the boundary of a chaotic region. Beyond this boundary, the rate drops sharply until it is fully suppressed at the end of this region. When the driving force is stochastic we find that the transition rate also has a maximum, and that its position depends on the rate of switching of the random force.

An Analytical Method for Cylindrical Shells With Nozzles Due to Internal Pressure and External Loads—Part II: Design Method

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Ming-De Xue ◽  
Qing-Hai Du ◽  
Keh-Chih Hwang ◽  
Zhi-Hai Xiang
Keyword(s):  
Internal Pressure ◽  
Design Method ◽  
Cylindrical Shells ◽  
Theoretical Method ◽  
Combined Loads ◽  
Stress Components ◽  
Bending Stresses ◽  
External Forces ◽  
External Loads ◽  
Theoretical Stress

A universal design method for pressurized cylindrical shells with attached nozzles subjected to external forces (moments) and internal pressure are presented, based on theoretical stress analysis. The applicable ranges of the presented design methods are extended to ρ0=d/D≤0.9 and λ=d/(DT)1/2≤12. As a first step of design, the required reinforcement thicknesses, both of the main shell and nozzle due to internal pressure, can be determined by the presented theoretical solutions. When the junction is subjected to external nozzle loads, the next step is to determine the absolute values of dimensionless longitudinal and circumferential, normal and shear, membrane and bending stresses in the shell at the junction subjected to internal pressure, and six external nozzle load components by reading out from a number of sets of curves calculated by the present theoretical method. Then the stress components at eight examination points are calculated and superimposed for the combined loads. Finally, the membrane and primary plus secondary stress intensities can be calculated, respectively, to meet the design criteria.

scholarly journals Frequency and Force Effects on Psychophysical and Myoelectric Variables in Low-Intensity Pinching Tasks

2000 ◽  
Vol 44 (22) ◽  
pp. 612-615
Author(s):  
Bart Visser ◽  
Jaap H. van Dieën ◽  
DirkJan (H.E.J.) Veeger ◽  
Michiel P. de Looze ◽  
Marjolein Douwes
Keyword(s):  
Risk Factors ◽  
External Load ◽  
Prime Mover ◽  
Subjective Ratings ◽  
Upper Arm ◽  
Work Related ◽  
Low Intensity ◽  
Manual Handling ◽  
External Forces ◽  
External Loads

Force and frequency in manual handling tasks are known risk factors for work related upper arm disorders. Three force levels and three frequencies are used to define the external load in a pinching task. The effects of these external loads on subjective and objective responses are studied. Subjective ratings poorly reflect the levels of external load. EMG variables P50 en P10 of the prime mover muscle seem useful variables in evaluating the effects of task frequency above a certain threshold in task frequency. P90 of the prime mover muscle is useful in evaluating the effects of external forces. It can be concluded that the P50 does not reflect the differences in force levels in tasks with low intensities.

Online Prediction of Plate Deformations Under External Forces Using Neural Networks

2006 ◽  
Author(s):  
M. T. Ahmadian ◽  
A. Mobini
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Artificial Neural Network ◽  
Deformation Pattern ◽  
Functional Relationships ◽  
Online Computation ◽  
Online Prediction ◽  
Artificial Neural ◽  
External Forces ◽  
External Loads

Recently online prediction of plate deformations in modern systems have been considered by many researchers, common standard methods are highly time consuming and powerful processors are needed for online computation of deformations. Artificial neural networks have capability to develop complex, nonlinear functional relationships between input and output patterns based on limited data. A good trained network could predict output data very fast with acceptable accuracy. This paper describes the application of an artificial neural network to identify deformation pattern of a four-side clamped plate under external loads. In this paper the distributed loads are approximated by a set of concentrated loads. An artificial neural network is designed to predict plate deformation pattern under external forces. Results indicate a well trained artificial neural network reveals an extremely fast convergence and a high degree of accuracy in the process of predicting deformation pattern of plates. Additionally this paper represents application of neural network in inverse problem. This part illustrates the capability of neural networks in identification of plate external loads based on plate deformations. Load identification has many applications in identification of real loads in machineries for design and development.

scholarly journals Progressive Collapse Test of Ship Structures in Waves

2018 ◽  
Vol 25 (s3) ◽  
pp. 91-98
Author(s):  
Zhiyong Pei ◽  
Tao Xu ◽  
Weiguo Wu
Keyword(s):  
External Load ◽  
Progressive Collapse ◽  
Time History ◽  
Collapse Mechanism ◽  
Ship Structure ◽  
Hull Girder ◽  
Structural Capacity ◽  
Collapse Behavior ◽  
External Forces ◽  
External Loads

Abstract The external loads and structural ultimate strength are two important aspects for the safety of ship hull girder. It may collapse in case the structural capacity is less than the external forces in extreme seas. In the present research, progressive collapse test is performed to investigate the collapse mechanism of ship structure in waves. External load with time history and corresponding structural collapse behavior are measured and discussed to demonstrate the interaction of fluid and structures.

scholarly journals Methods of determining hydrodynamic bending moments having effect on ship shaft

2020 ◽  
Vol 2020 (3) ◽  
pp. 47-53
Author(s):  
Guriy Alekseevich Kushner ◽  
Victor Andreevich Mamontov ◽  
Dmitry Aleksandrovich Volkov
Keyword(s):  
Computer Aided Design ◽  
Design Procedure ◽  
Systems Design ◽  
Operating Mode ◽  
Interpolation Polynomial ◽  
Cyclic Strength ◽  
Software Implementation ◽  
Bending Moments ◽  
Shaft Line ◽  
External Forces

The paper considers the problem of engineering systems design in modern shipbuilding, which is based on using the computer-aided design systems. In today’s environment, not all engineering calculations can be implemented in the form of an algorithm for a specific design procedure. One of these calculations is determining the resonant frequency of transverse vibrations of a ship shaft line. Analyzing the parameters of such a dynamic system is a serious task even at the stage of preliminary design. The urgent task in the design and strength calculations of the shaft line is to calculate the hydrodynamic bending moments resulting from the operation of the propeller in an uneven velocity field. There has been presented a software implementation of the semi-empirical methodology for determining the hydrodynamic bending moments acting on ship shaft lines. The main principles of the methodology, the initial data on the vessel hull, and the quantities characterizing the operating mode of the propeller are described. There is proposed a sequence and software implementation of the method for determining hydrodynamic bending moments in the environment of Maple computer algebra. The problem of representing empirical data in the form of bilinear interpolation and interpolation polynomial is solved. The results of a numerical experiment to determine the constant and amplitude values of the hydrodynamic bending moments for shaft shafts of full-scale vessels are presented. The software implementation of the technique proposed made it possible to automate the process of determining external forces in the calculations of the cyclic strength of the propeller shaft at the early stages of the design of the vessel. The research results are in addition to existing automation tools.

Effect of Actuating Forces on Aeroelastic Characteristics of a Morphing Aircraft Wing

2011 ◽  
Vol 52-54 ◽  
pp. 308-317 ◽  
Author(s):  
Suwin Sleesongsom ◽  
Sujin Bureerat
Keyword(s):  
Flight Control ◽  
Mechanical Characteristics ◽  
Aircraft Design ◽  
Design Parameters ◽  
Morphing Aircraft ◽  
Control Effectiveness ◽  
Wing Structure ◽  
External Forces ◽  
Lift Control ◽  
External Loads

An aircraft with morphing or adaptive wings can achieve its flight control through structural flexibility. In order to carry out such aircraft control, the wing structure is actuated by an external force. This leads to a change in aircraft aeroelastic and mechanical characteristics during flight such as lift, control effectiveness, divergence, flutter, buckling, and stress. The objective of this research is to demonstrate the aeroelastic and mechanical behaviors of a wing being actuated by external forces. Static and dynamic aeroelastic models of a wing structure subject to external loads are derived. An un-swept rectangular wing box, using a twisting morphing concept, is used for the demonstration. By applying various values of an actuator moment to the wing, aircraft design parameters e.g. flutter, divergence, lift effectiveness, buckling factor, and stress are computed. The investigation shows that the actuating force has an impact on the aeroelastic and mechanical characteristics. This effect should be taken into account during the design/optimization process of a morphing aircraft structure.

Enhancement of Contrast in the CEM and STEM Using Bumpy Specimens and Employing the “Dappled Field” Mode of Operation

1974 ◽  
Vol 32 ◽  
pp. 552-553 ◽  
Author(s):  
L. Gandolfi ◽  
J. Reiffel
Keyword(s):  
Operating Mode ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Specimen Preparation ◽  
Field Mode ◽  
Preparation Methods ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Mode Of Operation ◽  
Scanning Transmission

Calculations have been performed on the contrast obtainable, using the Scanning Transmission Electron Microscope, in the observation of thick specimens. Recent research indicates a revival of an earlier interest in the observation of thin specimens with the view of comparing the attainable contrast using both types of specimens.Potential for biological applications of scanning transmission electron microscopy has led to a proliferation of the literature concerning specimen preparation methods and the controversy over “to stain or not to stain” in combination with the use of the dark field operating mode and the same choice of technique using bright field mode of operation has not yet been resolved.

A Sectional Model for Investigating Microcontamination in a Rotating Disk CVD Reactor

2004 ◽  
Vol 38 (12) ◽  
pp. 1161-1170 ◽  
Author(s):  
Z. Sun ◽  
R. L. Axelbaum ◽  
R. W. Davis
Keyword(s):  
Rotating Disk ◽  
Sectional Model
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