TwAS: treadmill with adjustable surface stiffness

2021 ◽  
pp. 199-240
Author(s):  
Amir Jafari ◽  
Nafiseh Ebrahimi
Keyword(s):  
Surface Stiffness

The growth and collapse of cavitation bubbles near composite surfaces

1989 ◽  
Vol 203 ◽  
pp. 199-214 ◽  
Author(s):  
A. Shima ◽  
Y. Tomita ◽  
D. C. Gibson ◽  
J. R. Blake
Keyword(s):  
Experimental Study ◽  
Bubble Size ◽  
The State ◽  
Bubble Collapse ◽  
Viscoelastic Materials ◽  
Effective Parameters ◽  
Composite Surface ◽  
Surface Stiffness ◽  
Cavitation Bubbles

An experimental study has been made of the growth and collapse of a bubble near a composite surface consisting of two viscoelastic materials. The migratory characteristics of the bubble are examined by means of streak photography. The bubble migration depends not only on the properties of the composite surface but also on bubble size and distance from the surface. Both the surface stiffness and surface inertia are considered to be effective parameters contributing to the bubble migration: the former seeming to be a particularly important factor. The state of neutral bubble collapse, with no migration towards or away from a surface, can be made to occur with an appropriate combination of the surface stiffness and inertia.

A Novel Treadmill That Can Bilaterally Adjust the Vertical Surface Stiffness

2018 ◽  
Vol 23 (5) ◽  
pp. 2338-2346
Author(s):  
Ernesto Hernandez ◽  
Christian Warhmund ◽  
Kyle Lamoureux ◽  
Essie Lee ◽  
Isaac Sanchez ◽  
...  
Keyword(s):  
Vertical Surface ◽  
Surface Stiffness

scholarly journals Peak Vertical Ground Reaction Force during Two-Leg Landing: A Systematic Review and Mathematical Modeling

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Wenxin Niu ◽  
Tienan Feng ◽  
Chenghua Jiang ◽  
Ming Zhang
Keyword(s):  
Mathematical Modeling ◽  
Systematic Review ◽  
Mathematical Model ◽  
Ground Reaction Force ◽  
Reaction Force ◽  
Influence Factors ◽  
Vertical Ground Reaction Force ◽  
Surface Stiffness ◽  
Drop Landing ◽  
Vertical Ground

Objectives. (1) To systematically review peak vertical ground reaction force (PvGRF) during two-leg drop landing from specific drop height (DH), (2) to construct a mathematical model describing correlations between PvGRF and DH, and (3) to analyze the effects of some factors on the pooled PvGRF regardless of DH.Methods. A computerized bibliographical search was conducted to extract PvGRF data on a single foot when participants landed with both feet from various DHs. An innovative mathematical model was constructed to analyze effects of gender, landing type, shoes, ankle stabilizers, surface stiffness and sample frequency on PvGRF based on the pooled data.Results. Pooled PvGRF and DH data of 26 articles showed that the square root function fits their relationship well. An experimental validation was also done on the regression equation for the medicum frequency. The PvGRF was not significantly affected by surface stiffness, but was significantly higher in men than women, the platform than suspended landing, the barefoot than shod condition, and ankle stabilizer than control condition, and higher than lower frequencies.Conclusions. The PvGRF and root DH showed a linear relationship. The mathematical modeling method with systematic review is helpful to analyze the influence factors during landing movement without considering DH.

scholarly journals Effects of Running Surface Stiffness on Three-Segment Foot Kinematics Responses with Different Shod Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Noor Arifah Azwani Abdul Yamin ◽  
Khairul Salleh Basaruddin ◽  
Ahmad Faizal Salleh ◽  
Mohammad Shahril Salim ◽  
Wan Zuki Azman Wan Muhamad
Keyword(s):  
Plantar Fascia ◽  
Joint Rotation ◽  
Foot Kinematics ◽  
Surface Stiffness ◽  
Flat Base ◽  
Running Shoes ◽  
Stance Time ◽  
Biomechanical Responses ◽  
Artificial Grass ◽  
Male Subjects

Objective. The aim of this study was to investigate the effects of surface stiffness on multisegment foot kinematics and temporal parameters during running. Methods. Eighteen male subjects ran on three different surfaces (i.e., concrete, artificial grass, and rubber) in both heeled running shoes (HS) and minimal running shoes (MS). Both these shoes had dissimilar sole profiles. The heeled shoes had a higher sole at the heel, a thick base, and arch support, whereas the minimal shoes had a flat base sole. Indeed, the studied biomechanical parameters responded differently in the different footwear during running. Subjects ran in recreational mode speed while 3D foot kinematics (i.e., joint rotation and peak medial longitudinal arch (MLA) angle) were determined using a motion capture system (Qualysis, Gothenburg, Sweden). Information on stance time and plantar fascia strain (PFS) was also collected. Results. Running on different surface stiffness was found to significantly affect the peak MLA angles and stance times for both HS and MS conditions. However, the results showed that the joint rotation angles were not sensitive to surface stiffness. Also, PFS showed no relationship with surface stiffness, as the results were varied as the surface stiffness was changed. Conclusion. The surface stiffness significantly contributed towards the effects of peak MLA angle and stance time. These findings may enhance the understanding of biomechanical responses on various running surfaces stiffness in different shoe conditions.

scholarly journals A Penetrometer for Quantifying the Surface Stiffness of Sport Sand Surfaces

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 64 ◽  
Author(s):  
David V. Thiel ◽  
Matthew T. O. Worsey ◽  
Florian Klodzinski ◽  
Nicholas Emerson ◽  
Hugo G. Espinosa
Keyword(s):  
Soft Tissue Injuries ◽  
Beach Sand ◽  
Depth Of Penetration ◽  
Future Studies ◽  
Novel Technique ◽  
Sand Box ◽  
Surface Stiffness ◽  
Fitness Training ◽  
The Relationship

Sand sports include running, volleyball, soccer, beach flags, ironman, and fitness training. An increased amount of soft tissue injuries have been widely reported. A novel technique of determining the surface stiffness of beach sand in-situ used a simple drop-test penetrometer. The relationship between drop height and the depth of penetration squared was linear (Pearson’s correlation coefficient r2 > 0.92). The stiffness ratio between the soft dry sand and ocean-saturated wet sand compacted by eight hours of coastal water exposure was approximately seven, which was similar to previously reported stiffness measurements in a sand box. However, the absolute stiffness values were much smaller. While this technique was manually operated, an automatic system is postulated for future studies.

Modulation of surface stiffness and cell patterning on polymer films using micropatterns

2017 ◽  
Vol 106 (3) ◽  
pp. 976-985 ◽  
Author(s):  
Hiroshi Sunami ◽  
Yusuke Shimizu ◽  
Junko Denda ◽  
Ikuko Yokota ◽  
Tomokazu Yoshizawa ◽  
...  
Keyword(s):  
Polymer Films ◽  
Cell Patterning ◽  
Surface Stiffness

scholarly journals Calculation of Surface Properties of Cubic and Hexagonal Crystals through Molecular Statics Simulations

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 329 ◽  
Author(s):  
Zihan Tang ◽  
Yue Chen ◽  
Wei Ye
Keyword(s):  
Surface Properties ◽  
Surface Stress ◽  
Critical Role ◽  
Constitutive Law ◽  
Face Centered Cubic ◽  
Hexagonal Close Packed ◽  
Surface Stiffness ◽  
Pure Metals ◽  
Face Centered ◽  
Hexagonal Crystals

Surface property is an important factor that is widely considered in crystal growth and design. It is also found to play a critical role in changing the constitutive law seen in the classical elasticity theory for nanomaterials. Through molecular static simulations, this work presents the calculation of surface properties (surface energy density, surface stress and surface stiffness) of some typical cubic and hexagonal crystals: face-centered-cubic (FCC) pure metals (Cu, Ni, Pd and Ag), body-centered-cubic (BCC) pure metals (Mo and W), diamond Si, zincblende GaAs and GaN, hexagonal-close-packed (HCP) pure metals (Mg, Zr and Ti), and wurzite GaN. Sound agreements of the bulk and surface properties between this work and the literature are found. New results are first reported for the surface stiffness of BCC pure metals, surface stress and surface stiffness of HCP pure metals, Si, GaAs and GaN. Comparative studies of the surface properties are carried out to uncover trends in their behaviors. The results in this work could be helpful to the investigation of material properties and structure performances of crystals.

scholarly journals Stiffness Calculation Method and Stiffness Characteristic Analysis of Bolted Connectors

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Shi-kun Lu ◽  
Deng-xin Hua ◽  
Yan Li ◽  
Fang-yuan Cui ◽  
Peng-yang Li
Keyword(s):  
Surface Roughness ◽  
Bolted Joints ◽  
Joint Surface ◽  
Characteristic Analysis ◽  
Surface Stiffness ◽  
Stiffness Characteristic ◽  
Calculation Results ◽  
Bolt Connection ◽  
The Relationship ◽  
Effect Of Surface

At present, few scholars have studied the effect of surface roughness on assembly stiffness. The influence of the joint surface stiffness on the overall stiffness is neglected. In this paper, a new method for calculating the stiffness of bolted joints is presented. The effect of joint surface stiffness on the overall stiffness is considered. Firstly, the relationship between load and displacement between cylinder and cylinder (including the joint surface with certain roughness) is studied, and the stiffness characteristic expression of the joint surface is obtained; the results are compared with the traditional stiffness calculation theory, and then, the influence of bolt connection surface on bolt connection is studied and compared with the stiffness calculation results of traditional bolt connection. The results show that the theoretical model presented in this paper is more practical.

Sign in / Sign up

Export Citation Format

Share Document