A refined stiffness model of rolling lobe air spring with structural parameters and the stiffness characteristics of rubber bellows

Measurement ◽  
2021 ◽  
Vol 169 ◽  
pp. 108355
Author(s):  
Jun-Jie Chen ◽  
Zhi-Hong Yin ◽  
Xian-Ju Yuan ◽  
Guang-Qi Qiu ◽  
Kong-Hui Guo ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Air Spring ◽  
Stiffness Model ◽  
Stiffness Characteristics

scholarly journals Mathematical Modeling and Characteristic Analysis of the Vertical Stiffness for Railway Vehicle Air Spring System

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Liufeng Xu
Keyword(s):  
Experimental Tests ◽  
Geometric Parameters ◽  
Railway Vehicle ◽  
Characteristic Analysis ◽  
Air Spring ◽  
Vertical Stiffness ◽  
Stiffness Model ◽  
Spring System ◽  
Stiffness Characteristics ◽  
The Impact

Establishing a correct and reliable vertical stiffness model has an important significance on reproducing the characteristics of an air spring system. In this paper, a dynamic vertical stiffness model is developed based on thermodynamics and fluid dynamics, and geometric parameters are identified by an approximate analytical method. Meanwhile, experimental tests are performed to verify the accuracy and reliability of the proposed model. Furthermore, the impact of geometric parameters on the vertical stiffness characteristics is discussed through a sensitivity analysis. The conclusions show that the dynamic vertical stiffness model can well characterize the dynamic characteristics of the air spring system, which provides a theoretical basis for the optimal design of air spring parameters and the study of mechanical properties.

scholarly journals Research on nonlinear modeling and dynamic characteristics of lateral stiffness of vehicle air spring system

2020 ◽  
Vol 12 (6) ◽  
pp. 168781402093045
Author(s):  
Liufeng Xu
Keyword(s):  
Ride Comfort ◽  
Mechanical Performance ◽  
Nonlinear Modeling ◽  
Lateral Stiffness ◽  
Air Spring ◽  
Damping Force ◽  
Stiffness Model ◽  
Spring System ◽  
Stiffness Characteristics ◽  
The Impact

This paper established a lateral stiffness coupling model to investigate the lateral characteristics of air spring system under crosswind conditions. The nonlinear super-elastic characteristics, coupling characteristics of the air spring, lateral stiffness characteristics of emergency spring, and damping force are studied. The accuracy of the lateral stiffness model is validated by comparing with experimental data. In addition, the impact of geometric parameters on the lateral stiffness characteristics is discussed by a sensitivity analysis method, as well as the effect of the lateral stiffness model on vehicle mechanical performance is analyzed. The conclusions show that the lateral stiffness model can well predict the lateral characteristics of the air spring system, and provide theoretical guidance for the parameter design of rail vehicles and vehicle ride comfort improvement.

Model and Simulaiton of Air Spring Stiffness Characteristics Based on van der Waals Equation

2013 ◽  
Vol 779-780 ◽  
pp. 380-383
Author(s):  
Li Qin Sun ◽  
Zhong Xing Li ◽  
Xu Feng Shen ◽  
Hua Wei Zhao
Keyword(s):  
Van Der Waals ◽  
Ideal Gas ◽  
Factor H ◽  
Spring Stiffness ◽  
Air Spring ◽  
Real Gas ◽  
Van Der Waals Equation ◽  
Working Temperature ◽  
Stiffness Model ◽  
Stiffness Characteristics

Air spring gas is generally regarded as an ideal gas in analysis , but this is not consistent with the actual work . Considerring influence of non-ideal gas to air spring stiffness ,and based on van der Waals equation which is closed to the real gas equation, stiffness characteristics model of air spring and air spring with auxiliary chamber are re-derived and established. Influence of non ideal gas correction factor H to air spring stiffness is analysed within the range of pressure 0.2MPa to 5 MPa and working temperature -50 °C to 50°C,and results show that , there are big errors in air spring stiffness model in the conditon of low temperature and high pressure based on ideal gas equation, and range of application of the stiffness model is expanded when H is introduced and amended.

Decoupling Capability of Levitation Frames for Medium-Low Speed Maglev Trains

2021 ◽  
pp. 2150178
Author(s):  
Junxiong Hu ◽  
Weihua Ma ◽  
Shihui Luo ◽  
Wan Liu ◽  
Tianwei Qu ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Stability Control ◽  
Test Method ◽  
Air Spring ◽  
Low Speed ◽  
End Set

Medium-low speed maglev trains (MSMTs) with a levitation gap of only 8–10[Formula: see text]mm need an adequate decoupling capability on the levitation frames to ensure stability control in levitation, while preventing the train from rolling sideways when in landing. Based on the geometric and kinematic relationships, two types of levitation frames are studied, i.e. levitation frame with end-set air spring (LFEAS) and levitation frame with mid-set air spring (LFMAS). For each levitation frame, the decoupling process and mechanism are analyzed, the analytical equations for the kinematic attitude are derived, the decoupling capability under different excitations is calculated, along with the effect of various structural parameters assessed. In addition, a test method is designed for the rolling of the levitation frame, particularly with the anti-rolling capability of the LFMAS measured. The results indicate that oscillation of the hanger rods and anti-rolling beams can compensate for displacement when the motion of the levitation frame is decoupled, which is the key to the decoupling capability. Also, the position of the anti-rolling devices and the length of hanger rods do not affect significantly the decoupling capability. However, a longer anti-rolling beam is more conducive to decoupling, but it does not affect the anti-rolling capacity of the levitation frame. The maximum roll computed of the LFMAS is 2.84[Formula: see text]mm, which meets the anti-rolling requirement.

scholarly journals Modeling Study on Stiffness Characteristics of Hydraulic Cylinder under Multi-Factors

2017 ◽  
Vol 63 (7-8) ◽  
pp. 447 ◽  
Author(s):  
Hao Feng ◽  
Qungui Du ◽  
Yuxian Huang ◽  
Yongbin Chi
Keyword(s):  
Mechanical System ◽  
Volume Expansion ◽  
Hydraulic Cylinder ◽  
Experimental Results ◽  
Axial Deformation ◽  
Response Characteristics ◽  
Stiffness Model ◽  
Hydraulic Cylinders ◽  
Stiffness Characteristics ◽  
Cylinder Barrel

For a complex mechanical system driven by hydraulic cylinders, the dynamic response characteristics of the mechanical system are significantly affected by the stiffness characteristics of hydraulic cylinders. This paper comprehensively studies the impacts of various factors on the stiffness characteristics of the hydraulic cylinders, including the oil bulk modulus, the air content in the hydraulic oil, the axial deformation of the piston rod, the volume expansion of the cylinder barrel, the volume expansion of the metal pipes and the flexible hoses, and the deformation of the hydraulic cylinder sealing. By combining the theoretical analysis and the experimental results, the level of each impacting factor was quantified, and the stiffness model of the hydraulic cylinder was established. Finally, comparative analysis of the stiffness was conducted by taking the experimental hydraulic cylinder as an example; it was verified that the calculated results of the proposed hydraulic cylinder stiffness model approximated the experimental results. Compared with stiffness models presented in current literature, the average accuracy was improved by more than 15 %.

EFFECTIVE DYNAMIC STIFFNESS MODEL AND ITS EFFECTS ON ROBOT SAFETY AND PERFORMANCE

2013 ◽  
Vol 37 (3) ◽  
pp. 395-403
Author(s):  
Dongjun Shin ◽  
Zhan Fan Quek
Keyword(s):  
Dynamic Stiffness ◽  
Joint Stiffness ◽  
Optimization Strategy ◽  
Design Guideline ◽  
Controller Gain ◽  
Stiffness Model ◽  
Effective Dynamic ◽  
Stiffness Characteristics ◽  
And Performance ◽  
The Impact

Due to the limited control bandwidth of pneumatic artificial muscles, joint stiffness characteristics and their effects on safety and performance of human-friendly robots should be considered in the frequency domain. This paper introduces the concept of effective dynamic stiffness and validates its model with the Stanford Safety Robot. Experimental results show that the dynamic stiffness demonstrates limited effects on the impact acceleration given the same impact velocity and controller gain, whereas it significantly affects control performance of position tracking due to pressure-induced non-linearities. A stiffness optimization strategy for safety and performance is discussed as a design guideline of human-friendly robots.

Analysis and Optimal Design for the Static Stiffness of a 2UPS-UPR Parallel Machine Tool

2009 ◽  
Vol 626-627 ◽  
pp. 429-434 ◽  
Author(s):  
Liang Zhao ◽  
Ya Dong Gong ◽  
Guang Qi Cai
Keyword(s):  
Machine Tool ◽  
Structural Design ◽  
Machine Tools ◽  
Structural Parameters ◽  
Parallel Machine ◽  
Static Stiffness ◽  
Stiffness Analysis ◽  
Stiffness Model ◽  
Parallel Machine Tool ◽  
Stiffness Distribution

The stiffness model of the parallel machine tool is established by static analysis, the static stiffness analysis is carried out through numerical Simulation and the stiffness distribution is given. On the basis of this, the optimal objective is given which is the average of 729 values of -axis stiffness and -axis stiffness corresponding to 729 positions in the workspace. With MATLAB software, the effects are simulated which the structural parameters of the parallel machine tool have on their stiffness, their change rules are gained, and this provides a basis for the structural design of this type of machine tools.

scholarly journals A novel stiffness model for a wall-climbing hexapod robot based on nonlinear variable stiffness

2018 ◽  
Vol 10 (1) ◽  
pp. 168781401775248 ◽  
Author(s):  
Bin He ◽  
Shoulin Xu ◽  
Zhipeng Wang
Keyword(s):  
Structural Parameters ◽  
Variable Stiffness ◽  
Load Force ◽  
Nonlinear Stiffness ◽  
Hexapod Robot ◽  
Maximum Stiffness ◽  
Stiffness Model ◽  
Linear And Nonlinear ◽  
Serial Mechanism ◽  
Selection Of

In this article, the most contribution is to propose a novel general stiffness model to analyze the stiffness of a wall-climbing hexapod robot. First, we propose a new general stiffness model of serial mechanism, which includes the linear and nonlinear stiffness models. By comparison, the nonlinear stiffness model is a variable stiffness model which introduces the external load force as a variable, obtaining that the nonlinear stiffness model can greatly improve the accuracy of stiffness model than linear stiffness model. Then, the stiffness model of one leg of the robot and the overall stiffness model of the robot are derived based on the general stiffness model. Next, to improve the stiffness of the robot, a new minimum and maximum stiffness are introduced, which provide with effective reference for the selection and optimization of the structural parameters of the robot. Finally, we develop a new wall-climbing hexapod robot based on selection and optimization of the structural parameters, then the experiments are used to show that the selection of structure parameters of the robot effectively improve the stiffness of the robot.

scholarly journals Theoretical modeling of the vertical stiffness of a rolling lobe air spring

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042094089
Author(s):  
Liufeng Xu
Keyword(s):  
Analytical Model ◽  
Ride Comfort ◽  
Experimental Tests ◽  
Geometric Parameters ◽  
Air Spring ◽  
Vertical Stiffness ◽  
Approximate Analytic Method ◽  
Proposed Model ◽  
Stiffness Characteristics ◽  
The Relationship

In order to study the characteristics of a rolling lobe air spring, a vertical stiffness analytical model is constructed based on thermodynamics and hydrodynamics. The merit of this vertical stiffness analytical model is that an analytical solution of geometric parameters is obtained by an approximate analytic method. Meanwhile, experimental tests are carried out to verify the accuracy of the vertical stiffness analytical model. The vertical stiffness analytical model can be used to qualitatively analyze the influence of geometric parameters on the vertical stiffness characteristics of a rolling lobe air spring. Therefore, the relationship between geometric parameters and the vertical stiffness characteristics is analyzed based on the proposed model. The conclusions show that the vertical stiffness analytical model can well predict the mechanical characteristics of a rolling lobe air spring and provide guidance for parameter design and vehicle ride comfort improvement.

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