scholarly journals Effect of Material Stiffness Variation on Shakedown Solutions of Soils Under Moving Loads

2018 ◽  
pp. 73-82
Author(s):  
Shu Liu ◽  
Juan Wang ◽  
Dariusz Wanatowski ◽  
Hai-Sui Yu
Keyword(s):  
Moving Loads ◽  
Material Stiffness ◽  
Stiffness Variation

Material stiffness control of compliant tools by using electromagnetic suction

2019 ◽  
Vol 233 (13) ◽  
pp. 4719-4728 ◽  
Author(s):  
Ming Zeng ◽  
Yu-Jia Li ◽  
Tao Ren ◽  
Qing Tu
Keyword(s):  
Friction Force ◽  
Human Body ◽  
Rotational Stiffness ◽  
Variable Rigidity ◽  
Soft Robots ◽  
Suction Force ◽  
Material Stiffness ◽  
Stiffness Variation ◽  
Stiffness Control ◽  
Supply Current

Variable rigidity materials that are safe, controllable, reversible, and repeatable have potentially widespread implications in robotic technologies. This paper presents a method for controlling the stiffness of materials for compliant tools, such as grippers, soft robots, and endoscopes. The force of electromagnetic suction transforms two structures from their relaxed-state into a more rigid state. The system presented here has the ability of quickly increasing the stiffness with increased current in the coils that create electromagnetic suction, wherein the stiffness can be controlled by the variation of supply current. The process of controlling stiffness variation is reversible and repeatable under the safe voltage of human body. The system can lead to the production of tools that are small, flexible, dexterous, and safe. Suction force, friction force, and rotational stiffness were calculated to evaluate the performance of the system. Experiments were carried out to verify the proposed concept and the calculations.

Control of Vibrations due to Moving Loads on Suspension Bridges

2006 ◽  
Vol 11 (3) ◽  
pp. 293-318 ◽  
Author(s):  
M. Zribi ◽  
N. B. Almutairi ◽  
M. Abdel-Rohman
Keyword(s):  
Bridge Deck ◽  
Suspension Bridge ◽  
Lyapunov Theory ◽  
Dynamic Responses ◽  
Suspension Bridges ◽  
Control Force ◽  
Moving Loads ◽  
Hydraulic Actuator ◽  
Long Span ◽  
Suspended Cables

The flexibility and low damping of the long span suspended cables in suspension bridges makes them prone to vibrations due to wind and moving loads which affect the dynamic responses of the suspended cables and the bridge deck. This paper investigates the control of vibrations of a suspension bridge due to a vertical load moving on the bridge deck with a constant speed. A vertical cable between the bridge deck and the suspended cables is used to install a hydraulic actuator able to generate an active control force on the bridge deck. Two control schemes are proposed to generate the control force needed to reduce the vertical vibrations in the suspended cables and in the bridge deck. The proposed controllers, whose design is based on Lyapunov theory, guarantee the asymptotic stability of the system. The MATLAB software is used to simulate the performance of the controlled system. The simulation results indicate that the proposed controllers work well. In addition, the performance of the system with the proposed controllers is compared to the performance of the system controlled with a velocity feedback controller.

Assessment of Resonance Effects on Railway Bridges under Moving Loads

2017 ◽  
Vol 5 (4) ◽  
pp. 38
Author(s):  
Gharad A.M. ◽  
Sonparote R. S. ◽  
◽  
Keyword(s):  
Moving Loads ◽  
Railway Bridges ◽  
Resonance Effects

Application of the reciprocity theorem for the evaluation of vibrations generated by moving loads

2020 ◽  
pp. 33-40
Author(s):  
Nguyen Tron Tam ◽  
◽  
E.N. Kurbatsky ◽  
Nguyen Anh Tuan ◽  
◽  
...  
Keyword(s):  
Reciprocity Theorem ◽  
Moving Loads

scholarly journals Study of the Ultraviolet Effect and Thermal Analysis on Polypropylene Nonwoven Geotextile

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1080
Author(s):  
Clever Aparecido Valentin ◽  
Marcelo Kobelnik ◽  
Yara Barbosa Franco ◽  
Fernando Luiz Lavoie ◽  
Jefferson Lins da Silva ◽  
...  
Keyword(s):  
Uv Light ◽  
Polymeric Materials ◽  
Tensile Tests ◽  
Thermomechanical Analysis ◽  
Material Stiffness ◽  
Before And After ◽  
Electron Microscopy Analysis ◽  
Physical Tests ◽  
Nonwoven Geotextile

The use of polymeric materials such as geosynthetics in infrastructure works has been increasing over the last decades, as they bring down costs and provide long-term benefits. However, the aging of polymers raises the question of its long-term durability and for this reason researchers have been studying a sort of techniques to search for the required renewal time. This paper examined a commercial polypropylene (PP) nonwoven geotextile before and after 500 h and 1000 h exposure to ultraviolet (UV) light by performing laboratory accelerated ultraviolet-aging tests. The state of the polymeric material after UV exposure was studied through a wide set of tests, including mechanical and physical tests and thermoanalytical tests and scanning electron microscopy analysis. The calorimetric evaluations (DSC) showed distinct behaviors in sample melting points, attributed to the UV radiation effect on the aged samples. Furthermore, after exposure, the samples presented low thermal stability in the thermomechanical analysis (TMA), with a continuing decrease in their thicknesses. The tensile tests showed an increase in material stiffness after exposition. This study demonstrates that UV aging has effects on the properties of the polypropylene polymer.

scholarly journals Shakedown of Layered Pavements under Repeated Moving Loads

2014 ◽  
Author(s):  
Shu Liu ◽  
Juan Wang ◽  
Hai-Sui Yu ◽  
Dariusz Wanatowski
Keyword(s):  
Moving Loads
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