scholarly journals High-Velocity Shear and Soft Friction at the Nanometer Scale

2021 ◽  
Vol 7 ◽  
Author(s):  
Per-Anders Thorén ◽  
Riccardo Borgani ◽  
Daniel Forchheimer ◽  
David B. Haviland
Keyword(s):  
High Speed ◽  
Surface Deformation ◽  
Soft Materials ◽  
Lateral Force ◽  
Velocity Shear ◽  
Polymer Materials ◽  
Amplitude Dependence ◽  
Dynamic Force ◽  
Stick Slip ◽  
Soft Polymer

We study high-speed friction on soft polymer materials by measuring the amplitude dependence of cyclic lateral forces on the atomic force microscope (AFM) tip as it slides on the surface with fixed contact force. The resulting dynamic force quadrature curves separate the elastic and viscous contributions to the lateral force, revealing a transition from stick-slip to free-sliding motion as the velocity increases. We explain force quadratures and describe how they are measured, and we show results for a variety of soft materials. The results differ substantially from the measurements on hard materials, showing hysteresis in the force quadrature curves that we attribute to the finite relaxation time of viscoelastic surface deformation.

scholarly journals Influence of hinge length and distribution number on the camber and cornering properties of a non-pneumatic tire

2020 ◽  
Vol 12 (12) ◽  
pp. 168781402098468
Author(s):  
Xianbin Du ◽  
Youqun Zhao ◽  
Yijiang Ma ◽  
Hongxun Fu
Keyword(s):  
Neural Network ◽  
Network Model ◽  
Adaptive Learning ◽  
High Speed ◽  
Back Propagation ◽  
Lateral Force ◽  
Learning Ability ◽  
Vehicle Performance ◽  
Neural Network Theory ◽  
Bp Neural Network Model

The camber and cornering properties of the tire directly affect the handling stability of vehicles, especially in emergencies such as high-speed cornering and obstacle avoidance. The structural and load-bearing mode of non-pneumatic mechanical elastic (ME) wheel determine that the mechanical properties of ME wheel will change when different combinations of hinge length and distribution number are adopted. The camber and cornering properties of ME wheel with different hinge lengths and distributions were studied by combining finite element method (FEM) with neural network theory. A ME wheel back propagation (BP) neural network model was established, and the additional momentum method and adaptive learning rate method were utilized to improve BP algorithm. The learning ability and generalization ability of the network model were verified by comparing the output values with the actual input values. The camber and cornering properties of ME wheel were analyzed when the hinge length and distribution changed. The results showed the variation of lateral force and aligning torque of different wheel structures under the combined conditions, and also provided guidance for the matching of wheel and vehicle performance.

scholarly journals Soft Jumping Robot Using Soft Morphing and the Yield Point of Magnetic Force

2021 ◽  
Vol 11 (13) ◽  
pp. 5891
Author(s):  
Gang-Hyun Jeon ◽  
Yong-Jai Park
Keyword(s):  
Residual Stress ◽  
Polymer Materials ◽  
Rigid Base ◽  
Release Mechanism ◽  
Transfer Energy ◽  
Deformation Control ◽  
Energy Retention ◽  
Base Jumping ◽  
Jumping Robot ◽  
Soft Polymer

In this paper, soft-morphing, deformation control by fabric structures and soft-jumping mechanisms using magnetic yield points are studied. The durability and adaptability of existing rigid-base jumping mechanisms are improved by a soft-morphing process that employs the residual stress of a polymer. Although rigid body-based jumping mechanisms are used, they are driven by multiple components and complex structures. Therefore, they have drawbacks in terms of shock durability and fatigue accumulation. To improve these problems, soft-jumping mechanisms are designed using soft polymer materials and soft-morphing techniques with excellent shock resistance and environmental adaptability. To this end, a soft jumping mechanism is designed to store energy using the air pressure inside the structure, and the thickness of the polymer layer is adjusted based on the method applied for controlling the polymer freedom and residual stress deformation. The soft jumping mechanism can transfer energy more efficiently and stably using an energy storage and release mechanism and the rounded ankle structure designed using soft morphing. Therefore, the soft morphing and mechanisms of energy retention and release were applied to fabricate a soft robot prototype that can move in the desired direction and jump; the performance experiment was carried out.

Dynamic Force and Torque Analysis of Spherical Four Link Mechanisms

1983 ◽  
Vol 105 (3) ◽  
pp. 492-497 ◽  
Author(s):  
A. T. Yang ◽  
Sun Zhishang
Keyword(s):  
Dynamic Analysis ◽  
Optimum Design ◽  
Mass Distribution ◽  
High Speed ◽  
Dynamic Force ◽  
Arbitrary Mass ◽  
Link Mechanism ◽  
Torque Analysis ◽  
Analytical Expressions

In this paper we present a dynamic analysis of a general spherical four-link mechanism whose links have arbitrary mass distribution. Results, which are in explicit analytical expressions in terms of inertia-induced forces and moments in links, are useful for optimum design of the mechanism under high-speed operation.

2000 Macromolecular Science and Engineering Award LectureThe versatility of azobenzene polymers

2001 ◽  
Vol 79 (7) ◽  
pp. 1093-1100 ◽  
Author(s):  
Almeria Natansohn ◽  
Paul Rochon
Keyword(s):  
Liquid Crystalline ◽  
Surface Deformation ◽  
Polymer Structure ◽  
Light Polarization ◽  
Polymer Materials ◽  
Science And Engineering ◽  
Crystalline Polymers ◽  
The Third ◽  
Macroscopic Motion ◽  
Azobenzene Groups

The well-known trans–cis–trans photoisomerization of azobenzenes produces at least three different kinds of motion in the polymer materials to which the azobenzenes are bound. The first is a photoinduced motion of the azobenzene groups only, and they can align in a selected position with respect to the light polarization. The second is a macroscopic motion of huge amounts of polymeric material, producing surface deformation, and the third is a reorganization of smectic domains in liquid crystalline polymers. These motions and their consequences are briefly discussed in relation to the polymer structure and some possible photonic applications are mentioned.Key words: photoinduced orientation, azobenzene polymers, surface gratings, photonics, thermochromism, photochromism, photorefractivity, photoinduced chirality and switching.

Hypotheses about the Tools Origin of Textile Materials

2015 ◽  
Vol 1090 ◽  
pp. 18-21
Author(s):  
Yuan Tao ◽  
Wei Dong Yu
Keyword(s):  
Soft Materials ◽  
Stone Tools ◽  
Polymer Materials ◽  
Evidence Based ◽  
High Polymer ◽  
Origin Time ◽  
Textile Materials ◽  
Physical Evidence ◽  
Better Than

As high polymer materials, textile materials are easily to be carbonized and then disappear, so it is almost impossible to study the origin of it from physical evidence. Based on the objective historical facts, through analysis and inference, the paper believed that textile materials, as soft materials, are better than stone tools in the aspects of obtaining, making, functions and uses. Two hypotheses about the origin of textile materials are proposed. The first is that textile materials originate from tools, and the origin time of it is not later than stone tools. The second is that signs and clothing application of textile materials both evolve from its usage as tools, so the origin sequence of textile materials is tools, signs, and clothing.

scholarly journals SUBSIDENCE EVALUATION OF HIGH-SPEED RAILWAY IN SHENYANG BASED ON TIME-SERIES INSAR

2018 ◽  
Vol IV-3 ◽  
pp. 273-276
Author(s):  
Yun Zhang ◽  
Lianhuan Wei ◽  
Jiayu Li ◽  
Shanjun Liu ◽  
Yachun Mao ◽  
...  
Keyword(s):  
Time Series ◽  
High Speed ◽  
Cross Validation ◽  
Surface Deformation ◽  
Local Environment ◽  
Local Area ◽  
Safe Operation ◽  
High Speed Rail ◽  
High Speed Railway ◽  
Under Construction

More and more high-speed railway are under construction in China. The slow settlement along high-speed railway tracks and newly-built stations would lead to inhomogeneous deformation of local area, and the accumulation may be a threat to the safe operation of high-speed rail system. In this paper, surface deformation of the newly-built high-speed railway station as well as the railway lines in Shenyang region will be retrieved by time series InSAR analysis using multi-orbit COSMO-SkyMed images. This paper focuses on the non-uniform subsidence caused by the changing of local environment along the railway. The accuracy of the settlement results can be verified by cross validation of the results obtained from two different orbits during the same period.

scholarly journals The Reducing Approaches of Scattering Losses in Polymer Planar Optical Waveguides

2021 ◽  
Vol 7 (1) ◽  
pp. 31-40
Author(s):  
T. Radzievskaya ◽  
N. Ivanov ◽  
S. Tarasov
Keyword(s):  
Data Transmission ◽  
Optical Waveguides ◽  
Soft Lithography ◽  
High Speed ◽  
Polymeric Materials ◽  
Polymer Materials ◽  
Advantages And Disadvantages ◽  
High Speed Data ◽  
Scattering Losses ◽  
Planar Optical Waveguides

The article presents the development prospects of planar optical waveguides for high-speed data transmission systems optoelectronic buses by polymer materials. The advantages and disadvantages of using non-specialized polymeric materials for general use are revealed. The polymer planar optical waveguides fabrication technologies are proposed. The main losses types in planar optical waveguides, the reasons for their occurrence, as well as approaches to their reduction are determined. Using the example of PDMS polymer and soft lithography technology, the technological process critical stages of polymer planar optical waveguides production are noted, which contribute to an scattering losses increase. For each stage, algorithms are proposed to prevent an scattering losses increase. These algorithms were implemented in practice in the manufacture of layouts of polymer planar optical waveguides of the optical-electronic data transmission bus.

A Forced Response Analysis and Application of Impact Dampers to Rotordynamic Vibration Suppression in a Cryogenic Environment

1993 ◽  
Author(s):  
J. J. Moore ◽  
A. Palazzolo ◽  
R. Gadangi ◽  
T. A. Nale ◽  
S. A. Klusman ◽  
...  
Keyword(s):  
High Speed ◽  
Vibration Suppression ◽  
Forced Response ◽  
Optimum Operating ◽  
Response Analysis ◽  
Amplitude Dependence ◽  
Test Rig ◽  
Equivalent Viscous Damping ◽  
Impact Damper ◽  
The Impact

Abstract A high speed damper test rig has been assembled at Texas A&M University to develop rotordynamic dampers for rocket engine turbopumps that operate at cryogenic temperatures, such as those used in the Space Shuttle Main Engines (SSMEs). Damping is difficult to obtain in this class of turbomachinery due to the low temperature and viscosity of the operating fluid. An impact damper has been designed and tested as a means to obtain effective damping in a rotorbearing system. The performance and behavior of the impact damper is verified experimentally in a cryogenic test rig at Texas A&M. Analytical investigations indicate a strong amplitude dependence on the performance of the impact damper. An optimum operating amplitude exists and is determined both analytically and experimentally. In addition, the damper performance is characterized by an equivalent viscous damping coefficient. The test results prove the impact damper to be a viable means to suppress vibration in a cryogenic rotorbearing system.

Sign in / Sign up

Export Citation Format

Share Document