scholarly journals Numerical and Experimental Investigations on Dynamic Response of Hydraulic Cylinder with 3D Spatial Joints considering Radial and Axial Clearances

2019 ◽  
Vol 2019 ◽  
pp. 1-24 ◽  
Author(s):  
Ke Chen ◽  
Guojun Zhang ◽  
Haishuo Wang ◽  
Rui Wu ◽  
Hongmei Zheng ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Hydraulic Cylinder ◽  
Dynamic Responses ◽  
Radial Clearance ◽  
Experimental Investigations ◽  
Force Frequency ◽  
Clearance Joints ◽  
Input Force ◽  
Contact Points ◽  
Potential Contact

Radial clearance, particularly the axial clearance in the 3D joint of a mechanism owing to the assemblage, manufacturing tolerances, wear, and other conditions, has become a research focus in the field of multibody dynamics in recent years. In this study, a hydraulic cylinder model with 3D clearance joints was constructed by combining various potential contact scenarios. The novelty of this study is that potential contact points between the bearing wall and journal were calculated when the bearing wall circle was projected to an ellipse owing to misalignment of axes. Moreover, the simulation model considered the effective bulk modulus of the hydraulic oil and applied the Lagrange multiplier method. Subsequently, an experiment was conducted to verify the simulation results. The simulation and experimental results indicated that the dynamic responses of the hydraulic cylinder with 3D clearance joints can be classified as free, rebound, slide, and contact. The effects of input force, frequency, and clearance size on the dynamic behavior of the hydraulic cylinder were also investigated. Increasing the input force and clearance size will degrade the hydraulic cylinder dynamic response; however, the input force frequency can reduce the deterioration of the dynamic response. This study aids in providing improved understanding of the hydraulic cylinder with 3D clearances in the theoretical field and for practical engineering applications.

Experimental Investigation on the Dynamic Response of a Three Legged Articulated Type Offshore Wind Tower

2016 ◽  
Author(s):  
Chinsu Mereena Joy ◽  
Anitha Joseph ◽  
Lalu Mangal
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Renewable Energy Sources ◽  
Offshore Structures ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Experimental Investigations ◽  
Offshore Wind Turbine ◽  
Ocean Engineering ◽  
Study Results

Demand for renewable energy sources is rapidly increasing since they are able to replace depleting fossil fuels and their capacity to act as a carbon neutral energy source. A substantial amount of such clean, renewable and reliable energy potential exists in offshore winds. The major engineering challenge in establishing an offshore wind energy facility is the design of a reliable and financially viable offshore support for the wind turbine tower. An economically feasible support for an offshore wind turbine is a compliant platform since it moves with wave forces and offer less resistance to them. Amongst the several compliant type offshore structures, articulated type is an innovative one. It is flexibly linked to the seafloor and can move along with the waves and restoring is achieved by large buoyancy force. This study focuses on the experimental investigations on the dynamic response of a three-legged articulated structure supporting a 5MW wind turbine. The experimental investigations are done on a 1: 60 scaled model in a 4m wide wave flume at the Department of Ocean Engineering, Indian Institute of Technology, Madras. The tests were conducted for regular waves of various wave periods and wave heights and for various orientations of the platform. The dynamic responses are presented in the form of Response Amplitude Operators (RAO). The study results revealed that the proposed articulated structure is technically feasible in supporting an offshore wind turbine because the natural frequencies are away from ocean wave frequencies and the RAOs obtained are relatively small.

scholarly journals Dynamic Analysis of a Planar Hydraulic Rock-Breaker Mechanism with Multiple Clearance Joints

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Ke Chen ◽  
Guojun Zhang ◽  
Rui Wu ◽  
Li Wang ◽  
Hongmei Zheng ◽  
...  
Keyword(s):  
Hydraulic Cylinder ◽  
Dynamic Responses ◽  
Force Model ◽  
Engineering Applications ◽  
Mass System ◽  
Clearance Joints ◽  
Cylinder Model ◽  
Practical Engineering ◽  
Manufacturing Tolerances ◽  
Joint Clearances

Clearance exists in the joint of a mechanism because of the assemblage, manufacturing tolerances, wear, and other conditions, and it is a focus of research in the field of multibody dynamics. This study built a planar hydraulic rock-breaker model with multiple joint clearances by combining the hydraulic cylinder model, the clearance joints based on the Lankarani–Nikravesh contact force model, and the Lagrange multiplier method. Dynamic simulation results indicated that multiple clearance joints can degrade the dynamic responses of a rock-breaker model, which can be decomposed to rapid vibrations and slow movements. The rapid vibrations are excited by coupling the spring-mass system of hydraulic cylinder and clearances. The effects of the clearance size, input force, damping coefficient, and friction on the dynamic behaviour of the rock-breaker mechanism are also investigated. The friction could reduce the rapid vibration state significantly, which is feasible for practical engineering applications. As compared with the traditional models without clearances, the present model provides not only better predictions for the theoretical study of the hydraulic rock-breaker but also useful guidance for reducing the vibrations of the hydraulic rock-breaker in practical engineering applications.

Dynamic analysis of mechanical system considering radial and axial clearances in 3D revolute clearance joints

2020 ◽  
pp. 107754632095051
Author(s):  
Zheng Feng Bai ◽  
Xin Jiang ◽  
Ji Yu Li ◽  
Ji Jun Zhao ◽  
Yang Zhao
Keyword(s):  
Mechanical System ◽  
Dynamic Characteristics ◽  
Mathematic Model ◽  
Contact Forces ◽  
Dynamic Responses ◽  
Radial Clearance ◽  
Double Pendulum ◽  
Clearance Joints ◽  
Revolute Clearance Joint ◽  
Clearance Joint

In the dynamic modeling and simulation of mechanical system with revolute clearance joint, it is usually assumed that the revolute joint is planar joint with radial clearance, but the axial clearance is ignored. In this article, the dynamic responses of a mechanical system considering both radial and axial clearances in 3D revolute clearance joint are investigated using a computational methodology. First, the mathematic model of 3D revolute clearance joint is established considering the radial and axial clearances. The definitions of the radial and axial clearances, the potential contact modes, contact conditions, and contact detection for 3D revolute clearance joint are presented. Furthermore, the normal and tangential contact force models are established to describe the contact phenomenon and determine the contact forces in revolute clearance joints. Finally, two demonstrative application examples are presented to illustrate the dynamic characteristics of mechanical systems considering both radial and axial clearances in revolute clearance joints. A slider-crank mechanism with planar motion and a double pendulum with spatial motion are investigated. Different cases are presented to analyze the dynamic characteristics of a mechanical system considering radial and axial clearances in 3D revolute clearance joints.

scholarly journals Experimental investigations of the dynamic responses of a multi-link mechanism with revolute clearance joints

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110125
Author(s):  
Xiaofeng Li ◽  
Deng Zhao ◽  
Fuqi Xie ◽  
Shijing Wu ◽  
XiaoYong Li
Keyword(s):  
Dynamic Responses ◽  
Joint Clearance ◽  
Experimental Investigations ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Clearance Joint ◽  
Link Mechanism ◽  
Driving Speed ◽  
Noise Vibration ◽  
Set Up

Joint clearance is unavoidable in the revolute joint of multi-link mechanism. Excessive value of joint clearance generally leads to the noise, vibration, and fatigue failure. In this paper, a multi-link articulated mechanism system with three revolute clearance joints is selected as the study object. At first, its ideal motion equations and dynamic responses without joint clearance are outlined. Then an experimental rig is set up, and the acceleration responses of the mechanism in different scenarios are investigated. Comparative analysis indicates that in the presence of joints clearance, clear periodic transient impacts appear in the acceleration outputs while this mechanism moves to specific positions, and the impacts amplitude increases along with the clearance size and driving speed. Also, certain sequence among three motion states of clearance joint, named free flight, penetration and continuous-contact is observed twice in one circle movement of the mechanism. Besides, the clearance joint at the end of the transmission chain has greater effects on the mechanism system than the other joints. Finally, flexible rubber sleeves are set into the clearance joints, and the obtained experimental results indicate that the undesired transient impact by clearance joints on the mechanical system can be suppressed by flexible sleeves.

An Experimental Investigation of the Dynamic Response of a Mechanical System With Bearing Clearance

1987 ◽  
Author(s):  
K. Soong ◽  
B. S. Thompson
Keyword(s):  
Experimental Investigation ◽  
Dynamic Response ◽  
Computational Models ◽  
Design Guidelines ◽  
Rigid Bodies ◽  
Radial Clearance ◽  
Experimental Investigations ◽  
Similar System ◽  
Response Data ◽  
Bearing Clearance

Abstract Numerous publications have been devoted to the development of analytical and computational models for predicting the dynamic response of mechanical systems comprising assemblages of rigid-bodies with clearance at the joints. However, there is a dearth of experimental investigations in this area which focus on furnishing complementary response data, consequently the predictive capabilities of these theoretical models are largely unknown. The experimental investigation presented herein, is motivated by this observation and is directed towards partially filling this significant void in the literature. In order to accomplish this goal, a comprehensive experimental study was undertaken of a slider-crank mechanism in which the radial clearance at the gudgeon-pin bearing was carefully controlled. Response data at different operating speeds are presented, along with an investigation of the bearing characteristics from which the coefficient of restitution, which features in many of the proposed mathematical models, was evaluated. Finally, design guidelines are distilled from the experimental data to relate the response of the system to the response of a similar system without bearing clearance.

scholarly journals Dynamic response analysis for multi-degrees-of-freedom parallel mechanisms with various types of three-dimensional clearance joints

2021 ◽  
Vol 18 (3) ◽  
pp. 172988142110177
Author(s):  
Jia Yonghao ◽  
Chen Xiulong
Keyword(s):  
Dynamic Response ◽  
Multibody Systems ◽  
Parallel Mechanism ◽  
Three Dimensional ◽  
Response Analysis ◽  
Parallel Mechanisms ◽  
Dynamics Model ◽  
Clearance Joints ◽  
Clearance Joint ◽  
Spatial Parallel Mechanism

For spatial multibody systems, the dynamic equations of multibody systems with compound clearance joints have a high level of nonlinearity. The coupling between different types of clearance joints may lead to abundant dynamic behavior. At present, the dynamic response analysis of the spatial parallel mechanism considering the three-dimensional (3D) compound clearance joint has not been reported. This work proposes a modeling method to investigate the influence of the 3D compound clearance joint on the dynamics characteristics of the spatial parallel mechanism. For this purpose, 3D kinematic models of spherical clearance joint and revolute joint with radial and axial clearances are derived. Contact force is described as normal contact and tangential friction and later introduced into the nonlinear dynamics model, which is established by the Lagrange multiplier technique and Jacobian of constraint matrix. The influences of compound clearance joint and initial misalignment of bearing axes on the system are analyzed. Furthermore, validation of dynamics model is evaluated by ADAMS and Newton–Euler method. This work provides an essential theoretical basis for studying the influences of 3D clearance joints on dynamic responses and nonlinear behavior of parallel mechanisms.

3-D elastic coupling vibration and acoustical radiation characteristics of cracked gear under elastic support condition

2015 ◽  
Vol 23 (9) ◽  
pp. 1548-1568 ◽  
Author(s):  
Shao Renping ◽  
Purong Jia ◽  
Xiankun Qi
Keyword(s):  
Dynamic Response ◽  
Support System ◽  
Three Dimensional ◽  
Elastic Support ◽  
Dynamic Responses ◽  
Tooth Root ◽  
Support Condition ◽  
Elastic Boundary ◽  
Root Crack ◽  
Elastic Disc

According to the actual working condition of the gear, the supporting gear shaft is treated as an elastic support. Its impact on the gear body vibration is considered and investigated and the dynamic response of elastic teeth and gear body is analyzed. On this basis, the gear body is considered as a three-dimensional elastic disc and the gear teeth are treated as an elastic cantilever beam. Under the conditions of the elastic boundary (support shaft), combining to the elastic disk and elastic teeth, the influence of three-dimensional elastic discs on the meshing tooth response under an elastic boundary condition is also included. A dynamic model of the gear support system and calculated model of the gear tooth response are then established. The inherent characteristics of the gear support system and dynamics response of the meshing tooth are presented and simulated. It was shown by the results that it is correct to use the elastic support condition to analyze the gear support system. Based on the above three-dimensional elastic dynamics analysis, this paper set up a dynamics coupling model of a cracked gear structure support system that considered the influence of a three-dimensional elastic disc on a cracked meshing tooth under elastic conditions. It discusses the dynamic characteristic of the cracked gear structure system and coupling dynamic response of the meshing tooth, offering a three-dimensional elastic body model of the tooth root crack and pitch circle crack with different sizes, conducting the three-dimensional elastic dynamic analysis to the faulty crack. ANSYS was employed to carry out dynamic responses, as well as to simulate the acoustic field radiation orientation of a three-dimensional elastic crack body at the tooth root crack and pitch circle with different sizes.

Evaluation of the Dynamic-Response-Based Intact Stability Criterion for Floating Wind Turbines

2015 ◽  
Author(s):  
Marco Masciola ◽  
Xiaohong Chen ◽  
Qing Yu
Keyword(s):  
Wind Speed ◽  
Dynamic Response ◽  
Wind Turbines ◽  
Stability Criterion ◽  
Area Ratio ◽  
Operating Conditions ◽  
Dynamic Responses ◽  
Stability Criteria ◽  
Intact Stability ◽  
Overturning Moment

As an alternative to the conventional intact stability criterion for floating offshore structures, known as the area-ratio-based criterion, the dynamic-response-based intact stability criteria was initially developed in the 1980s for column-stabilized drilling units and later extended to the design of floating production installations (FPIs). Both the area-ratio-based and dynamic-response-based intact stability criteria have recently been adopted for floating offshore wind turbines (FOWTs). In the traditional area-ratio-based criterion, the stability calculation is quasi-static in nature, with the contribution from external forces other than steady wind loads and FOWT dynamic responses captured through a safety factor. Furthermore, the peak wind overturning moment of FOWTs may not coincide with the extreme storm wind speed normally prescribed in the area-ratio-based criterion, but rather at the much smaller rated wind speed in the power production mode. With these two factors considered, the dynamic-response-based intact stability criterion is desirable for FOWTs to account for their unique dynamic responses and the impact of various operating conditions. This paper demonstrates the implementation of a FOWT intact stability assessment using the dynamic-response-based criterion. Performance-based criteria require observed behavior or quantifiable metrics as input for the method to be applied. This is demonstrated by defining the governing load cases for two conceptual FOWT semisubmersible designs at two sites. This work introduces benchmarks comparing the area-ratio-based and dynamic-response-based criteria, gaps with current methodologies, and frontier areas related to the wind overturning moment definition.

scholarly journals A New Optimal DTC Switching Strategy for Open-End Windings Induction Machine using Dual Inverter

2021 ◽  
Vol 12 (3) ◽  
pp. 1405
Author(s):  
Nabilah Aisyah ◽  
Maaspaliza Azri ◽  
Auzani Jidin ◽  
M. Z. Aihsan ◽  
MHN Talib
Keyword(s):  
Dynamic Response ◽  
High Speed ◽  
Dynamic Condition ◽  
Dynamic Control ◽  
Direct Torque Control ◽  
Torque Control ◽  
Dynamic Responses ◽  
Voltage Source ◽  
Optimal Switching ◽  
Stator Flux

<span>Since the early 1980s, fast torque dynamic control has been a subject of research in AC drives. To achieve superior torque dynamic control, two major techniques are used, namely Field Oriented Control (FOC) and Direct Torque Control (DTC), spurred on by rapid advances in embedded computing systems. Both approaches employ the space vector modulation (SVM) technique to perform the voltage source inverter into over modulation region for producing the fastest torque dynamic response. However, the motor current tends to increase beyond its limit (which can damage the power switches) during the torque dynamic condition, due to inappropriate flux level (i.e. at rated stator flux). Moreover, the torque dynamic response will be slower, particularly at high speed operations since the increase of stator flux will produce negative torque slopes more often. The proposed research aims to formulate an optimal switching modulator and produce the fastest torque dynamic response. In formulating the optimal switching modulator, the effects of selecting different voltage vectors on torque dynamic responses will be investigated. With greater number of voltage vectors offered in dual inverters, the identification of the most optimal voltage vectors for producing the fastest torque dynamic responses will be carried out based on the investigation. The main benefit of the proposed strategy is that it provides superior fast torque dynamic response which is the main requirements for many AC drive applications, e.g. traction drives, electric transportations and vehicles.</span>

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