Modeling of wedge-pin joint for the dynamic analysis of a planar temporary demountable structure

2020 ◽  
pp. 136943322097173
Author(s):  
Qingshan Yang ◽  
Liang Xu ◽  
Yi Hui ◽  
Huihui Li ◽  
Jinwei Qin
Keyword(s):  
Dynamic Analysis ◽  
Analytical Model ◽  
Element Model ◽  
Dynamic Responses ◽  
Bipedal Walking ◽  
Future Research ◽  
Harmonic Load ◽  
Slip Mechanism ◽  
Hysteretic Effect ◽  
Strong Excitation

In order to understand deeply the dynamic behavior of a Temporary Demountable Structure (TDS), a 2-D analytical model of the Wedge-Pin Joint (WPJ) is established. This model takes into account of the semi-rigidness of the vertical contact and the sliding between beam and column based on the frictional shear-slip mechanism. The analytical WPJ model is validated by comparing with the dynamic responses of the TDS modeled with that obtained from the finite element model under harmonic load. Furthermore, a thorough dynamic analysis of the TDS subjected to a bipedal walking force is conducted. Results show that the hysteretic effect of the WPJs can be induced in the system. It is strongly affected by the amplitude of excitation, and a larger excitation does not mean a stronger hysteresis. This can be interpreted by that large horizontal contact force for joints resulted from strong excitation in horizontal direction yields high friction, which enhances the clamping effects in vertical and then weakens the hysteretic effect of WPJs. In addition, the vertical slip for joint is limited to a small value due to a relative small acceleration, this small vertical slip leads to a small of hysteretic loop. Finally, it is also found that the semi-rigidness of WPJs can apparently increase the deformation and acceleration of the system in both horizontal and vertical directions. This research provides for the first time an analytical model of WPJs of TDS, which will be beneficial to the future research of human-TDS interaction.

Wind-induced response analysis of wind turbine tubular towers with consideration of rotating effect of blades

2019 ◽  
Vol 23 (2) ◽  
pp. 289-306
Author(s):  
Tao Huo ◽  
Lewei Tong
Keyword(s):  
Wind Turbine ◽  
Wind Direction ◽  
Calculation Method ◽  
Large Scale ◽  
Element Model ◽  
Dynamic Responses ◽  
Future Research ◽  
Induced Response ◽  
Response Analysis ◽  
Aerodynamic Loads

This study discusses the wind-induced response of existing pitch-controlled 1.25 MW wind turbine structures, with a particular focus on the influence of the blade-rotation effect, cross-wind loads of the tubular tower and the wind direction, and compares numerical responses with the measured dynamic responses. An integrated finite-element model consisting of blades, a nacelle, a tower and a foundation is established. The aerodynamic loads exerted on the rotating blades and the aerodynamic loads acting on the tubular tower are then obtained. A wind-induced response calculation method of the wind turbine structures corresponding to different wind speeds and wind directions is established for performing a wind-induced response analysis. Finally, comparisons between the measured responses and the corresponding numerical response results are performed to verify the accuracy of the proposed wind-induced response calculation method. The results indicate that neglecting the cross-wind aerodynamic loads of large-scale wind turbine structures can lead to unsafe design. The wind direction has different influences on the along-wind and cross-wind dynamic responses. The statistical values of the measured dynamic responses are slightly greater than those of the numerical analysis results, but the magnitudes of the responses are the same. Therefore, the proposed wind-induced response calculation method for wind turbine structures is feasible and reasonable. It can be used to conduct the fatigue life prediction of wind turbine tubular towers in future research which is an important issue in the structural design of wind turbine tubular tower structures.

Dynamic Analysis of a Spur Geared Rotor-Bearing System with Nonlinear Gear Mesh Stiffness

2014 ◽  
Vol 945-949 ◽  
pp. 853-861 ◽  
Author(s):  
Ying Chung Chen ◽  
Chung Hao Kang ◽  
Siu Tong Choi
Keyword(s):  
Dynamic Analysis ◽  
Equations Of Motion ◽  
Element Model ◽  
Dynamic Responses ◽  
Mesh Stiffness ◽  
Gear Mesh ◽  
Lagrange’S Equation ◽  
Rotor Bearing ◽  
Gear Mesh Stiffness ◽  
Bearing System

The gear mesh stiffnesses have been regarded as constants in most previous models of geared rotor-bearing systems. In this paper, a dynamic analysis of a spur geared rotor-bearing system with nonlinear gear mesh stiffness is presented. The nonlinear gear mesh stiffness is accounted for by bending, fillet-foundation and contact deflections of gear teeth. A finite element model of the geared rotor-bearing system is developed, the equations of motion are obtained by applying Lagrange’s equation, and the dynamic responses are computed by using the fourth-order Runge-Kutta numerical method. Numerical results indicate that the proposed gear mesh stiffness provides a realistic dynamic response for spur geared rotor-bearing system.

scholarly journals Experimental Setup for Dynamic Analysis of Micro- and Nano-Mechanical Systems in Vacuum, Gas, and Liquid

Micromachines ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 162 ◽  
Author(s):  
Bram van den Brink ◽  
Farbod Alijani ◽  
Murali Ghatkesar
Keyword(s):  
Dynamic Analysis ◽  
Element Model ◽  
Dynamic Responses ◽  
Experimental Setup ◽  
Force Microscopy ◽  
Frequency Responses ◽  
Atomic Force ◽  
Different Types ◽  
Langevin Transducer ◽  
Good Agreement

An experimental setup to perform dynamic analysis of a micro- and nano-mechanical system in vacuum, gas, and liquid is presented. The setup mainly consists of a piezoelectric excitation part and the chamber that can be either evacuated for vacuum, or filled with gas or water. The design of the piezoelectric actuator was based on a Langevin transducer. The chamber is made out of materials that can sustain: vacuum, variety of gases and different types of liquids (mild acids, alkalies, common alcohols and oils). All the experiments were performed on commercial cantilevers used for contact and tapping mode Atomic Force Microscopy (AFM) with stiffness 0.2 N/m and 48 N/m, respectively, in vacuum, air and water. The performance of the setup was evaluated by comparing the measured actuator response to a finite element model. The frequency responses of the two AFM cantilevers measured were compared to analytical equations. A vacuum level of 0.6 mbar was obtained. The setup has a bandwidth of 10–550 kHz in vacuum and air, and a bandwidth of 50–550 kHz in liquid. The dynamic responses of the cantilevers show good agreement with theory in all media.

Investigation of the Stability of a Squeak Test Apparatus Based on an Analytical and Finite Element Models

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Gil Jun Lee ◽  
Jay Kim
Keyword(s):  
Finite Element ◽  
Analytical Model ◽  
Large Amplitude ◽  
Element Model ◽  
Design Parameters ◽  
Complex Eigenvalue ◽  
Test Apparatus ◽  
Vehicle Interior ◽  
Slip Mechanism ◽  
The Stability

Squeak is an unwanted, annoying noise generated by self-excited, friction-induced vibration. A unique squeak test apparatus that can generate squeak noises consistently was developed by modifying and employing a sprag-slip mechanism. Such an apparatus enables building database that accurately ranks squeak propensity of material pairs and will be highly useful for noise, vibration, and harshness (NVH) engineers and vehicle interior designers. An analytical model of the apparatus was developed to identify instability conditions that induce unstable, large-amplitude vibration, therefore squeak noises. A finite element model was established and studied in this work to refine the design of the apparatus and better understand underlying phenomena of the squeak generation. Complex eigenvalue analysis (CEA) was used to study the instability of the system and results show that the instability occurs by the coalescence of two modes, which makes the effective damping of one of the coalesced modes negative. The instability condition from the CEA shows good agreement with the results obtained from the analytical model. Furthermore, dynamic transient analysis (DTA) was performed to investigate the stability of the system and confirm the instability conditions identified from the CEA. The effects of main design parameters on the stability were investigated by DTA. The results obtained from the actual tests show that the test apparatus consistently generates unstable vibration of a very large amplitude, indicating generation of squeak noises.

Dynamic analysis of a helical gear reduction by experimental and numerical methods

2020 ◽  
Vol 68 (1) ◽  
pp. 48-58
Author(s):  
Chao Liu ◽  
Zongde Fang ◽  
Fang Guo ◽  
Long Xiang ◽  
Yabin Guan ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Fourth Order ◽  
Numerical Models ◽  
Helical Gear ◽  
Operating Conditions ◽  
Dynamic Responses ◽  
Lumped Mass ◽  
Gear Mesh

Presented in this study is investigation of dynamic behavior of a helical gear reduction by experimental and numerical methods. A closed-loop test rig is designed to measure vibrations of the example system, and the basic principle as well as relevant signal processing method is introduced. A hybrid user-defined element model is established to predict relative vibration acceleration at the gear mesh in a direction normal to contact surfaces. The other two numerical models are also constructed by lumped mass method and contact FEM to compare with the previous model in terms of dynamic responses of the system. First, the experiment data demonstrate that the loaded transmission error calculated by LTCA method is generally acceptable and that the assumption ignoring the tooth backlash is valid under the conditions of large loads. Second, under the common operating conditions, the system vibrations obtained by the experimental and numerical methods primarily occur at the first fourth-order meshing frequencies and that the maximum vibration amplitude, for each method, appears on the fourth-order meshing frequency. Moreover, root-mean-square (RMS) value of the acceleration increases with the increasing loads. Finally, according to the comparison of the simulation results, the variation tendencies of the RMS value along with input rotational speed agree well and that the frequencies where the resonances occur keep coincident generally. With summaries of merit and demerit, application of each numerical method is suggested for dynamic analysis of cylindrical gear system, which aids designers for desirable dynamic behavior of the system and better solutions to engineering problems.

scholarly journals Vibration characteristics of triple-gear-rotor system in compressed air energy storage under variable torque load

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042098705
Author(s):  
Xinran Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Dongxu Hu ◽  
Xuehui Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Element Model ◽  
Rotor System ◽  
Dynamic Responses ◽  
System Response ◽  
Rotating Speed ◽  
Torque Load ◽  
Set Up ◽  
Two Stages

This paper focuses on the effects of the off-design operation of CAES on the dynamic characteristics of the triple-gear-rotor system. A finite element model of the system is set up with unbalanced excitations, torque load excitations, and backlash which lead to variations of tooth contact status. An experiment is carried out to verify the accuracy of the mathematical model. The results show that when the system is subjected to large-scale torque load lifting at a high rotating speed, it has two stages of relatively strong periodicity when the torque load is light, and of chaotic when the torque load is heavy, with the transition between the two states being relatively quick and violent. The analysis of the three-dimensional acceleration spectrum and the meshing force shows that the variation in the meshing state and the fluctuation of the meshing force is the basic reasons for the variation in the system response with the torque load. In addition, the three rotors in the triple-gear-rotor system studied show a strong similarity in the meshing states and meshing force fluctuations, which result in the similarity in the dynamic responses of the three rotors.

scholarly journals Modeling in ADAMS of a 6R industrial robot

2018 ◽  
Vol 184 ◽  
pp. 02006
Author(s):  
Mariana Ratiu ◽  
Alexandru Rus ◽  
Monica Loredana Balas
Keyword(s):  
Dynamic Analysis ◽  
Industrial Robot ◽  
Kinematic Model ◽  
Future Research ◽  
Robot Motion ◽  
Cad Model ◽  
3D Cad ◽  
Revolute Joints ◽  
Real Model ◽  
Articulated Robot

In this paper, we present the first steps in the process of the modeling in ADAMS MBS of MSC software of the mechanical system of an articulated robot, with six revolute joints. The geometric 3D CAD model of the robot, identical to the real model, in the PARASOLID format, is imported into ADAMS/View and then are presented the necessary steps for building the kinematic model of the robot. We conducted this work, in order to help us in our future research, which will consist of kinematic and dynamic analysis and optimization of the robot motion.

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