scholarly journals The role of gravity or pressure and contact stiffness in granular rheology

2015 ◽  
Vol 17 (4) ◽  
pp. 043028 ◽  
Author(s):  
Abhinendra Singh ◽  
Vanessa Magnanimo ◽  
Kuniyasu Saitoh ◽  
Stefan Luding
Keyword(s):  
Contact Stiffness ◽  
Granular Rheology

scholarly journals Nonlocal granular rheology: Role of pressure and anisotropy

2014 ◽  
Vol 105 (2) ◽  
pp. 24002 ◽  
Author(s):  
Elie Wandersman ◽  
Martin van Hecke
Keyword(s):  
Granular Rheology

Nano Scale Creep and the Role of Defects

1996 ◽  
Vol 436 ◽  
Author(s):  
S. A. Syed Asif ◽  
J. B. Pethica
Keyword(s):  
Room Temperature ◽  
Contact Stiffness ◽  
Surface Films ◽  
Force Method ◽  
Before And After ◽  
Long Time ◽  
Reverse Creep ◽  
Temperature Strain ◽  
Accurate Observation

AbstractThe modulating force method in nanoindentation gives a direct measure of contact stiffness, and being insensitive to drift, allows the accurate observation of creep in small indents to be carried out over long time periods. We present results for a range of metals at room temperature. Strain rate indices similar to those for macroscopic creep are found. Reverse creep occurs for step unloading greater than about half the starting load. For electropolished tungsten, we find quite different behaviour before and after the sudden pop-in. Afterwards, creep is as in other metals, but beforehand, it is essentially zero. The slight changes of stiffness observed at the very smallest loads are due to diffusion of adsorbed surface films into the contact zone. Our results show that the dislocations nucleated and multiplied at pop-in provide the mechanism of creep.

scholarly journals On the Role of Contact and System Stiffness in the Measurement of Principal Variables in Fretting Wear Testing

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4152 ◽  
Author(s):  
Diego Infante-García ◽  
Miguel Marco ◽  
Alaitz Zabala ◽  
Farshad Abbasi ◽  
Eugenio Giner ◽  
...  
Keyword(s):  
Contact Stiffness ◽  
Fretting Wear ◽  
Displacement Sensor ◽  
Wear Testing ◽  
Sensor Calibration ◽  
Tangential Contact ◽  
Contact Configuration ◽  
Wear Tests ◽  
Flat Contact

In this work, the role of the contact stiffness in the measurement of principal variables in fretting wear tests is assessed. Several fretting wear tribometers found in the literature, including one developed by the authors, are analysed and modelled using numerical methods. The results show the importance of the tribosystem stiffness and tangential contact stiffness in the displacement sensor calibration and in the correct numerical modelling of fretting wear tests, especially for flat-to-flat contact configuration. The study highlights that, in most cases, direct comparisons between fretting results with severe wear obtained with different tribometers cannot be performed if the contact stiffness is not properly considered during the development of the experiments.

scholarly journals Depletion of glycosaminoglycans decreases contact stiffness of single collagen I fibrils in aqueous solution

2020 ◽  
Author(s):  
Jonathan Roth ◽  
Cody L. Hoop ◽  
Jonathan K. Williams ◽  
Robert Hayes ◽  
Jean Baum
Keyword(s):  
Aqueous Solution ◽  
Contact Stiffness ◽  
Collagen Fibrils ◽  
Structural Motif ◽  
Indentation Modulus ◽  
Connective Tissues ◽  
Force Microscopy ◽  
Atomic Force ◽  
Nanoscale Topography

AbstractCollagen fibrils serve as the molecular scaffolding for connective tissues throughout the human body and are the most abundant protein building block in the extracellular matrix (ECM). Glycosaminoglycans (GAGs) are an important class of polysaccharides in the ECM that mediate collagen fibril development, cell adhesion and motility, wound healing, inter alia. Depletion or mis-regulation of GAGs has been shown to be intimately related to diseases such as cancer, hyperglycemia, and glaucoma. However, the molecular-level coordination between collagen fibrils and GAGs to regulate ECM mechanobiology is unclear. Here, high resolution atomic force microscopy experiments are used to assess perturbations to nanoscale topography and mechanical properties of single collagen fibrils upon GAG depletion in aqueous solution. Fast force maps show that GAG depletion lowers indentation modulus by about half compared to native fibrils while retaining a key structural motif (D-banding). These results shed new light on the functional role of GAGs and may aid in strategies to treat diseases that impair ECM mechanobiology.

The Role of Surface Structure in Normal Contact Stiffness

2015 ◽  
Vol 56 (3) ◽  
pp. 359-368 ◽  
Author(s):  
C. Zhai ◽  
Y. Gan ◽  
D. Hanaor ◽  
G. Proust ◽  
D. Retraint
Keyword(s):  
Surface Structure ◽  
Contact Stiffness ◽  
Normal Contact ◽  
Normal Contact Stiffness

Bouncing Vibration and Complete Tracking Conditions of a Contact Recording Slider Model on a Harmonic Wavy Disk Surface

1997 ◽  
Vol 119 (4) ◽  
pp. 720-725 ◽  
Author(s):  
Kyosuke Ono ◽  
Kan Takahashi
Keyword(s):  
Contact Stiffness ◽  
Contact Point ◽  
Dynamic Contact ◽  
Disk Surface ◽  
Stiffness And Damping ◽  
Parameter Values ◽  
The Relationship ◽  
Contact Recording ◽  
Bounce Height

An extended study of the general characteristics of the bouncing vibrations of a contact recording head slider was done for a single-degree-of-freedom slider model bouncing on a harmonic wavy disk surface with linear contact stiffness and damping. The relationship between bounce height and waviness frequency and the role of a top contact point necessary for stable bouncing vibrations are discussed. Since the dynamic contact force increases to ten times the static slider load even when the bounce height is only one nanometer, the importance of complete tracking without separation is discussed. Then the complete tracking conditions of disk surface waviness under disturbances of ten nanometer bounce height are calculated for various design parameter values, including the waviness phase. It is also shown that a collision model can predict almost the same complete tracking zones as an elastic contact model.

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor

Role of the allergist in diagnosis and management of patients with uveitis

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre
Keyword(s):  
Diagnosis And Management

The power of norms to sway fused group members

2018 ◽  
Vol 41 ◽  
Author(s):  
Winnifred R. Louis ◽  
Craig McGarty ◽  
Emma F. Thomas ◽  
Catherine E. Amiot ◽  
Fathali M. Moghaddam
Keyword(s):  
Evolutionary Anthropology ◽  
Normative Systems ◽  
Violent Extremism ◽  
Identity Fusion ◽  
Group Members

AbstractWhitehouse adapts insights from evolutionary anthropology to interpret extreme self-sacrifice through the concept of identity fusion. The model neglects the role of normative systems in shaping behaviors, especially in relation to violent extremism. In peaceful groups, increasing fusion will actually decrease extremism. Groups collectively appraise threats and opportunities, actively debate action options, and rarely choose violence toward self or others.

Elaborating the role of reflection and individual differences in the study of folk-economic beliefs

2018 ◽  
Vol 41 ◽  
Author(s):  
Kevin Arceneaux
Keyword(s):  
Decision Making ◽  
Individual Differences ◽  
Cognitive Processes ◽  
Evolutionary History ◽  
Behavioral Responses ◽  
History Of ◽  
Economic Beliefs

AbstractIntuitions guide decision-making, and looking to the evolutionary history of humans illuminates why some behavioral responses are more intuitive than others. Yet a place remains for cognitive processes to second-guess intuitive responses – that is, to be reflective – and individual differences abound in automatic, intuitive processing as well.

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