An analytical joint stiffness model for load transfer analysis in highly torqued multi-bolt composite joints with clearances

2015 ◽  
Vol 131 ◽  
pp. 625-636 ◽  
Author(s):  
Fengrui Liu ◽  
Jianyu Zhang ◽  
Libin Zhao ◽  
An Xin ◽  
Longwei Zhou
Keyword(s):  
Load Transfer ◽  
Joint Stiffness ◽  
Composite Joints ◽  
Stiffness Model ◽  
Load Transfer Analysis

An Improved Stiffness Model for Bolted Joints

2009 ◽  
Vol 131 (12) ◽  
Author(s):  
Sayed A. Nassar ◽  
Antoine Abboud
Keyword(s):  
Joint Stiffness ◽  
Effective Area ◽  
Accurate Estimate ◽  
Diameter Ratio ◽  
Bolted Joints ◽  
Plate Material ◽  
Reliable Prediction ◽  
Novel Approach ◽  
Stiffness Model ◽  
Initial Assembly

An improved stiffness model is proposed for bolted joints made of similar and dissimilar plates. A novel approach is used to obtain an expression for the effective area used for determining the joint stiffness. More accurate estimate of the joint stiffness provides a more reliable prediction of the joint behavior both during its initial assembly, as well as under subsequently applied tensile loads in service. The effect of the grip length-to-diameter ratio, joint sizes, underhead contact radii ratio, hole clearance, and plate material/thickness ratio are investigated. Experimental data are used for determining the envelope angle α in the proposed analytical model. Finite element modeling is used for evaluating the accuracy of the proposed stiffness model.

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.

Torsional Stiffness Model of an Industrial Robotic Joint Using Fractal Theory

2019 ◽  
Author(s):  
Jingjing Xu ◽  
Zhifeng Liu ◽  
Yongsheng Zhao ◽  
Qiang Cheng ◽  
Yanhu Pei ◽  
...  
Keyword(s):  
Prediction Accuracy ◽  
Fractal Theory ◽  
Great Influence ◽  
Joint Stiffness ◽  
Equilibrium Analysis ◽  
Torsional Stiffness ◽  
Tangential Stiffness ◽  
Proposed Model ◽  
Stiffness Model ◽  
Rv Reducer

Abstract It is known that mechanical connections have great influence on the dynamic characteristic of the assembly. In existing methods, the torsional stiffness of the robotic joint is calculated only considering the stiffness of components of the system, which largely reduces the prediction accuracy of the joint stiffness. In the paper, to predict the joint stiffness more accurately, a model is proposed considering influences of the stiffness of all connections existed in a joint system. The normal and tangential stiffness of the contact surface of each connection are calculated by combining the equilibrium analysis of the force and the fractal theory. Then the total stiffness of one robotic joint can be modelled by putting the torsional stiffness of all connections and that of the RV reducer and gear pair in parallel. To verify the proposed model, its simulation result is compared to the stiffness based on the previous technique without considering the influence of connections. The comparison result shows that the proposed model can improve the stiffness-prediction accuracy. This study can be extended to the stiffness modeling of other joint systems and provides a theoretical basis for the dynamic analysis of the robotic system.

Winkler load-transfer analysis for pipelines subjected to surface load

2019 ◽  
Vol 111 ◽  
pp. 147-156
Author(s):  
Chenrong Zhang ◽  
Jinru Zhu ◽  
Maosong Huang ◽  
Jian Yu
Keyword(s):  
Load Transfer ◽  
Surface Load ◽  
Load Transfer Analysis

Deformation and load transfer analysis of staggered composite-steel lap joints subjected to progressive damage

2020 ◽  
Vol 215 ◽  
pp. 110690 ◽  
Author(s):  
Alaa El-Din A. El-Sisi ◽  
Hesham M. El-Emam ◽  
Hani A. Salim ◽  
Hossam El-Din M. Sallam
Keyword(s):  
Load Transfer ◽  
Lap Joints ◽  
Progressive Damage ◽  
Load Transfer Analysis ◽  
Composite Steel
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