scholarly journals Evaluation of Seasonal Effects and degrees of freedom on Dynamic Response and Impact Forces on Leg Mating Unit in Persian Gulf

2020 ◽  
Vol 16 (32) ◽  
pp. 85-95
Author(s):  
Erfan Arabshahy ◽  
Mohammad Kasaeyan ◽  
Naser Shabakhty ◽  
◽  
◽  
...  
Keyword(s):  
Dynamic Response ◽  
Persian Gulf ◽  
Degrees Of Freedom ◽  
Seasonal Effects ◽  
Impact Forces ◽  
Mating Unit

Accelerometer correction for the dynamic analysis of damped multi-degree of freedom systems

1969 ◽  
Vol 59 (4) ◽  
pp. 1591-1598
Author(s):  
G. A. McLennan
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Degrees Of Freedom ◽  
Degree Of Freedom ◽  
Exact Method ◽  
Three Degrees Of Freedom

Abstract An exact method is developed to eliminate the accelerometer error in dynamic response calculations for damped multi-degree of freedom systems. It is shown that the exact responses of a system can be obtained from the approximate responses which are conventionally calculated from an accelerogram. Response calculations were performed for two typical systems with three degrees of freedom for an assumed pseudo-earthquake. The results showed that the approximate responses may contain large errors, and that the correction developed effectively eliminates these errors.

scholarly journals Dynamic response of a wedge through asymmetric free fall in 2 degrees of freedom

2017 ◽  
Vol 233 (1) ◽  
pp. 229-250 ◽  
Author(s):  
Parviz Ghadimi ◽  
Sasan Tavakoli ◽  
Abbas Dashtimanesh ◽  
Pouria Taghikhani
Keyword(s):  
Experimental Data ◽  
Dynamic Response ◽  
Degrees Of Freedom ◽  
Time Derivative ◽  
Free Fall ◽  
Added Mass ◽  
Roll Motion ◽  
Physical Parameters ◽  
Two Dimensional ◽  
Roll Speed

In this article, a mathematical model is presented for simulation of the coupled roll and heave motions of the asymmetric impact of a two-dimensional wedge body. This model is developed based on the added mass theory and momentum variation. To this end, new formulations are introduced which are related to the added mass caused by heave and roll motions of the wedge. These relations are developed by including the asymmetrical effects and roll speed. In addition, by considering the roll speed, a particular method is presented for the time derivative of half-wetted beam of an asymmetric wedge. Furthermore, two equations are derived for the roll and heave motions in which damping terms appear. Validity of the proposed method is verified by comparing the predicted results against available experimental data in two conditions of roll motion and no roll motion. Favorable agreement is observed between the predicted results and experimental data. The pressure and hydrodynamic load are computed, and the differences between the results associated with the considered conditions are explored. Subsequently, the effects of different physical parameters including deadrise angle, initial roll angle, and initial velocity on the dynamic response of a two-dimensional wedge section are investigated. Ultimately, time histories of hydrodynamic coefficients are determined in order to provide a better understanding of the derived equations.

scholarly journals Spatial Finite Element Analysis for Dynamic Response of Curved Thin-Walled Box Girder Bridges

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yinhui Wang ◽  
Yidong Xu ◽  
Zheng Luo ◽  
Haijun Wu ◽  
Liangliang Yan
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Degrees Of Freedom ◽  
Response Analysis ◽  
Box Girder Bridges ◽  
Element Analysis ◽  
Box Girder ◽  
Girder Bridges ◽  
System A ◽  
Thin Walled

According to the flexural and torsional characteristics of curved thin-walled box girder with the effect of initial curvature, 7 basic displacements of curved box girder are determined. And then the strain-displacement calculation correlations were established. Under the curvilinear coordinate system, a three-noded curved girder finite element which has 7 degrees of freedom per node for the vibration characteristic and dynamic response analysis of curved box girder is constructed. The shape functions are used as the interpolation functions of variable curvature and variable height to accommodate to the variation of curvature and section height. A MATLAB numerical analysis program has been implemented.

Dynamic Response Analysis of Large Latticed Space Structures

1989 ◽  
Vol 4 (1) ◽  
pp. 25-42 ◽  
Author(s):  
A.R. Kukreti ◽  
N.D. Uchil
Keyword(s):  
Dynamic Response ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Computational Time ◽  
Space Structures ◽  
Response Analysis ◽  
Actual System ◽  
Large Space ◽  
Element Analysis ◽  
Dynamic Response Analysis

In this paper an alternative method for dynamic response analysis of large space structures is presented, for which conventional finite element analysis would require excessive computer storage and computational time. Latticed structures in which the height is very small in comparison to its overall length and width are considered. The method is based on the assumption that the structure can be embedded in its continuum, in which any fiber can translate and rotate without deforming. An appropriate kinematically admissable series function is constructed to descrbe the deformation of the middle plane of this continuum. The unknown coefficients in this function are called the degree-of-freedom of the continuum, which is given the name “super element.” Transformation matrices are developed to express the equations of motion of the actual systems in terms of the degrees-of-freedom of the super element. Thus, by changing the number of terms in the assumed function, the degrees-of-freedom of the super element can be increased or decreased. The super element response results are transformed back to obtain the desired response results of the actual system. The method is demonstrated for a structure woven in the shape of an Archimedian spiral.

scholarly journals THE INFLUENCE OF FOUNDATION MASS ON DYNAMIC RESPONSE OF TRACK-VEHICLE INTERACTION

2018 ◽  
Author(s):  
Pham Dinh Trung
Keyword(s):  
Dynamic Response ◽  
Degrees Of Freedom ◽  
Dynamic Balance ◽  
Mass Parameter ◽  
Numerical Results ◽  
Integrated System ◽  
Railway Track ◽  
Moving Vehicle ◽  
Balance Principle ◽  
Foundation Model

The influence of foundation mass on the dynamic response of track-vehicle interaction is studied in this paper. The moving vehicle is modeled as a two-axle mass-spring-damper system having four degrees of freedom. The new foundation model, called “Dynamic foundation model” including linear elastic spring, shear layer, viscous damping and special consideration of foundation mass parameter, is used to analyze dynamic response of the track-vehicle interaction. Then, the railway track on dynamic foundation model subjected to a moving vehicle is regarded as an integrated system. By means of finite element method and dynamic balance principle, the governing equation of motion for railway track-vehicle-foundation interaction is derived and solved by step-by-step integration method. The accuracy of the algorithm is also verified by comparing the numerical results with the other numerical results in the literature. The influence of foundation mass parameter on the dynamic response of railway track-vehicle interaction is investigated. The numerical results show that the foundation mass effects significantly on the dynamic response of track-vehicle interaction and it is more increasing dynamic displacements than others without foundation mass. The study has meaning practice and the foundation quite agrees to describe true behavior of soil in the problems of the analyzing dynamic response of structures on the foundation.

scholarly journals Study on Dynamic Response of Straddle-Type Monorail Vehicle with Single-Axle Bogie Under Curve Condition

Mechanika ◽  
2021 ◽  
Vol 27 (2) ◽  
pp. 122-129
Author(s):  
Liang XIN ◽  
Zixue DU ◽  
Junchao ZHOU ◽  
Zhen YANG ◽  
Zhouzhou XU
Keyword(s):  
Dynamic Response ◽  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Contact Model ◽  
Beam Model ◽  
Test Results ◽  
Motion Equations ◽  
Lagrange’S Equation ◽  
Curve Radius ◽  
Track Beam

This paper is concerned with the dynamic response of straddle-monorail with single-axle bogie under curve condition. A 15 degrees-of-freedom(DOF) dynamic model is established for straddle-type monorail vehicle with single-axle bogie, which consists driving wheels, steering wheels and stabilizing wheels. The motion equations of the straddle-type monorail vehicle are derived using the Lagrange's equation, and the wheel-rail contact model and the curving track beam model are created. Compared with the test results, the accuracy of the method is verified. Finally, the influence of curve radius, curve superelevation rate, number of passengers and stiffness of driving wheels on dynamic response is discussed.

Nonlinear Sensitivity Analysis of Twin Non-Symmetric Micro-Cantilever Beams

2017 ◽  
Author(s):  
M. Amin Changizi ◽  
Ion Stiharu ◽  
Peyman Hajheidari ◽  
Davut Erdem Sahin
Keyword(s):  
Differential Equations ◽  
Dynamic Response ◽  
Degrees Of Freedom ◽  
Nonlinear Differential Equations ◽  
Dynamic Performance ◽  
High Sensitivity ◽  
Numerical Approach ◽  
Cantilever Beams ◽  
Micro Cantilever ◽  
Deflection Theory

In this paper, the dynamic performance of two parallel micro-cantilever beams is investigated and the results are presented. The dynamic response is of high interest in MEMS structures as it is related to the performance of the micro-devices. The micro-cantilever beams can be easily fabricated and yield high sensitivity to variations of physical quantities. In this work, the dynamic response of two parallel flexible cantilever beams subjected to a difference of potential is analyzed. This configuration was modeled as mass-damper spring systems with two degrees of freedom. Such a system can be used to measure the viscosity of liquids. This viscosity is related to damping between two masses representing the two beams in the discrete system model. The fabrication of two identical beams using MEMS fabrication processes may be difficult as the fabrication process may yield some variabilities. Thus, the two beams may be slightly different which will be reflected in their mass and stiffness. This condition was assumed in the proposed model. As the system is sensitive to the applied difference of potential such that the pull-in voltage represents a good indicator of the sensitivity performance. The dynamic analysis was carried out at potentials close to the pull-in value. Stability of the system was evaluated and the responses of the beams were calculated at a potential close to the pull-in voltage. The sensitivity of the system was calculated for different viscosities of liquid between two beams. It was found that an increase of the viscosity yields higher nonlinearity and consequently loose of accuracy while assuming linear stiffness for the beams. In this research, the stiffness of micro-cantilever beams was calculated from small deflection theory of beams. However, there are other methods that could be considered to evaluate the stiffness of the beams. One of this different methods was considered and the sensitivity of the modeled stiffness is discussed. Since the stiff nonlinear differential equations cannot be solved analytically, the numerical approach was exploited. In this work ISODE method from Maple software was used to solve the model described by the two differential equations.

Nonlinear Dynamic Behavior of Fixed Jacket-Type Offshore Platforms Subjected to Simultaneously Acting Wave and Earthquake Loads

2004 ◽  
Author(s):  
A. K. Etemad ◽  
A. R. M. Gharabaghi ◽  
M. R. Chenaghlou
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Response ◽  
Dynamic Behavior ◽  
Persian Gulf ◽  
Nonlinear Dynamic ◽  
Longitudinal Component ◽  
Offshore Platforms ◽  
Nonlinear Dynamic Response ◽  
Earthquake Loads

The nonlinear dynamic response of jacket-type offshore platform (which has been installed in Persian Gulf) under simultaneously wave and earthquake loads is conducted. The interaction between soil and piles is modeled by Konagai-Nogami model. The structure is modeled by finite element method. The analyses include models with the longitudinal component of earthquake and wave in the same direction and in different directions. The results indicate that when the longitudinal component of earthquake and wave are in the same direction, wave may reduce the response of studied platform and when they are in different directions, in some cases there is an increase in the response of platform.

Comparative Study of the Linear and Non-Linear Locomotive Response

1979 ◽  
Vol 101 (3) ◽  
pp. 263-271 ◽  
Author(s):  
E. H. Chang ◽  
V. K. Garg ◽  
C. H. Goodspeed ◽  
S. P. Singh
Keyword(s):  
Dynamic Response ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Design Parameters ◽  
Suspension Systems ◽  
Damping Characteristics ◽  
Time Histories ◽  
Steady State Responses ◽  
Stiffness And Damping ◽  
State Responses

A mathematical model for a six-axle locomotive is developed to investigate its dynamic response on tangent track due to vertical and/or lateral track irregularities. The model represents the locomotive as a system of thirty-nine degrees of freedom. The nonlinearities considered in the model are primarily associated with stiffness and damping characteristics of the primary suspension system. The transient and steady-state responses of the locomotive are obtained for the linear and nonlinear primary suspension systems. The response time-histories of the locomotive obtained by integrating the generalized equations of motion are presented. The potential uses of the model are indicated for studying the influence of different design parameters and predicting subsequent dynamic response.

Analysis of Grinding Dynamic Based on Grind Teeth Vibration Model of Spiral Bevel Gears

2014 ◽  
Vol 602-605 ◽  
pp. 176-179
Author(s):  
Miao Xin Xiao ◽  
Jian Jun Yang
Keyword(s):  
Phase Diagram ◽  
Dynamic Response ◽  
Degrees Of Freedom ◽  
Time Course ◽  
Transmission Error ◽  
Spiral Bevel Gear ◽  
Bevel Gears ◽  
Vibration Model ◽  
Braking Torque ◽  
Spiral Bevel

Starting from the fact of backlash and gear transmission error, it is established vibration model of spiral bevel gear lapping system with two degrees of freedom. Through normalized calculate, it is obtained dynamic response of lapping vibration model under different braking torque. According to the time course and the phase diagram, during the process that brake torque switch from small to big, teeth meshing, collision and disengaged alternately goes on, and with the braking torque increases to a certain value, the teeth collision disappear and then back into the complete meshing state.

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