Stiffness Analysis of a Variable Stiffness Joint Using a Leaf Spring

Author(s):  
Lijin Fang ◽  
Yan Wang
2020 ◽  
Vol 56 (9) ◽  
pp. 36 ◽  
Author(s):  
YAO Ligang ◽  
LI Jingyi ◽  
DONG Hui

Symmetry ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 101 ◽  
Author(s):  
Shan Zhang ◽  
Zheng Sun ◽  
Jili Lu ◽  
Lei Li ◽  
Chunlei Yu ◽  
...  

This paper aims to investigate how to determine the basic parameters of the helical compression spring which supports a symmetrical cable-driven hybrid joint (CDHJ) towards the elbow joint of wheelchair-mounted robotic manipulator. The joint design of wheelchair-mounted robotic manipulator needs to consider lightweight but robust, workspace requirements, and variable stiffness elements, so we propose a CDHJ which becomes a variable stiffness joint due the spring under bending and compression provides nonlinear stiffness characteristics. Intuitively, different springs will make the workspace and stiffness of CDHJ different, so we focus on studying the spring effects on workspace and stiffness of CDHJ for its preliminary design. The key to workspace and stiffness analysis of CDHJ is the cable tension, the key to calculate the cable tension is the lateral bending and compression spring model. The spring model is based on Castigliano’s theorem to obtain the relationship between spring force and displacement. The simulation results verify the correctness of the proposed spring model, and show that the spring, with properly chosen parameters, can increase the workspace of CDHJ whose stiffness also can be adjusted to meet the specified design requirements. Then, the modelling method can be extended to other cable-driven mechanism with a flexible compression spring.


2020 ◽  
Vol 12 (3) ◽  
Author(s):  
Zhongyi Li ◽  
Shaoping Bai ◽  
Weihai Chen ◽  
Jianbin Zhang

Abstract A mechanism with lumped-compliance can be constructed by mounting springs at joints of an inverted slider crank mechanism. Different mounting schemes bring change in the stiffness performance. In this paper, a unified stiffness model is developed for a comprehensive analysis of the stiffness performance for mechanisms constructed with different spring mounting schemes. With the model, stiffness behaviors of spring-loaded inverted slider crank mechanisms are analyzed. Influences of each individual spring on the overall performance are characterized. The unified stiffness model allows designing mechanisms for a desired stiffness performance, such as constant-torque mechanism and variable stiffness mechanism, both being illustrated with a design example and experiments.


2013 ◽  
Vol 37 (3) ◽  
pp. 505-521 ◽  
Author(s):  
D.M. Brouwer ◽  
J.P. Meijaard ◽  
J.B. Jonker

2005 ◽  
Vol 11 (3) ◽  
pp. 381-396 ◽  
Author(s):  
Johan M. Cronjé ◽  
P. Stephan Heyns ◽  
Nico J. Theron ◽  
Philip W. Loveday

In this paper we report on the development of a variable stiffness and damping Liquid Inertia Vibration Eliminator (LIVE) vibration isolator. The result is the ability to shift the isolation frequency of the isolator and also to change the amplification at resonance. A practical variable stiffness spring was developed by using a compound leaf spring with circular spring elements. A wax actuator, controlled by a hot-air gun with a closed-loop displacement and velocity feedback control system, was used to separate the springs at the center. An experimental isolator was constructed and tested. The isolation frequency was shifted from 22.8 to 36.2 Hz by changing the stiffness of the spring by 270%. A transmissibility of less than 10% was achieved over the whole range. The viscous damping ratio was changed from 0.001 to 0.033 by increasing the flow losses in the system.


2014 ◽  
Vol 538 ◽  
pp. 118-121
Author(s):  
De Guang Fang ◽  
Guo Xin Wei ◽  
Wen Ku Shi ◽  
Chang Xin Wang

In order to meet the ride comfort requirements of the light bus under no load and full-load condition,its rear suspension employs two-level variable stiffness leaf spring. For reasonably matching the two values of the variable stiffness and the damping force curve of the damper, one kind of virtual prototype technology was used. The virtual spring model of two-level variable stiffness was created in Adams-Chassis and the center-curve of the leaves was based at the free-state of the leaf spring. Then the front suspension, the rear suspension, the steering system, the powertrain & drineline system, the braking system, the wheels and bus body were respectively builded in Adams_Car, and they consituted the virtual assembly model of the light bus. So we could use the virtual model to conveniently test the performance of the ride comfort and handling stability under the no load and full-load state. Based on the ISO test standards, the virtual objective evaluation indexes were all calculated. According to these indexes, the two-level variable stiffness and the damping force curve were optimized. At last, the optimization results were verified by testing the optimized light bus. Experimental results shows that virtual optimization technology could play an important role in solving engineering problems.


2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
Wen-ku Shi ◽  
Cheng Liu ◽  
Zhi-yong Chen ◽  
Wei He ◽  
Qing-hua Zu

The composite stiffness of parabolic leaf springs with variable stiffness is difficult to calculate using traditional integral equations. Numerical integration or FEA may be used but will require computer-aided software and long calculation times. An efficient method for calculating the composite stiffness of parabolic leaf springs with variable stiffness is developed and evaluated to reduce the complexity of calculation and shorten the calculation time. A simplified model for double-leaf springs with variable stiffness is built, and a composite stiffness calculation method for the model is derived using displacement superposition and material deformation continuity. The proposed method can be applied on triple-leaf and multileaf springs. The accuracy of the calculation method is verified by the rig test and FEA analysis. Finally, several parameters that should be considered during the design process of springs are discussed. The rig test and FEA analytical results indicate that the calculated results are acceptable. The proposed method can provide guidance for the design and production of parabolic leaf springs with variable stiffness. The composite stiffness of the leaf spring can be calculated quickly and accurately when the basic parameters of the leaf spring are known.


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