Analysis of Resistible Force of Soft Material Fingertip focused on Change in Contact Area under External Loads

2019 ◽  
Vol 2019 (0) ◽  
pp. 2P1-G10
Author(s):  
Yoshinori FUJIHIRA ◽  
Yanfeng YANG ◽  
Naohiko HANAJIMA ◽  
Masato MIZUKAMI ◽  
Tetsuyou WATANABE
Keyword(s):  
Contact Area ◽  
Soft Material ◽  
External Loads

scholarly journals The effect of flexible joint-like elements on the adhesive performance of nature-inspired bent mushroom-like fibers

2018 ◽  
Vol 9 ◽  
pp. 2893-2905 ◽  
Author(s):  
Elliot Geikowsky ◽  
Serdar Gorumlu ◽  
Burak Aksak
Keyword(s):  
Elastic Modulus ◽  
Contact Area ◽  
Unit Area ◽  
Soft Material ◽  
Soft Or ◽  
Fiber Density ◽  
Adhesion Properties ◽  
Flexible Joint ◽  
Ladybird Beetles ◽  
Stiff Joint

Many organisms rely on densely packed, tilted and curved fibers of various dimensions to attach to surfaces. While the high elastic modulus of these fibers enables an extremely large number of fibers per unit area, where each fiber stands freely without sticking to its neighbors, the tilt/curvature provides them with the compliance and the directional adhesion properties to attach strongly and efficiently to a surface. Recent studies have revealed that many of such organisms also feature materials with a graded elastic modulus that is tailored towards improving the contact area without sacrificing the fiber density. In particular, for male ladybird beetles, research has shown that the adhesive setae feature a material gradient such that the elastic modulus of the material at the junction between the stalk and the divergent distal end is close to minimum. This soft material acts like a flexible joint, improving the bending compliance of the tip. Here, we mimic this feature using tilted, mushroom-like, stiff fibers comprised of a stiff stalk of elastic modulus 126 MPa, a softer tip of elastic modulus 8.89 MPa, and a joint-like element of elastic modulus 0.45 MPa (very soft), 8.89 MPa (soft), or 126 MPa (stiff) in between. The results from load–drag–pull (LDP) experiments performed along (gripping) and against (releasing) the tilt direction indicate that the soft and the very soft joint fibers performed superior to the stiff joint fibers and maintained directionally dependent performance. The soft joint fibers achieved up to 22 kPa in shear and 110 kPa in pull-off stress in the gripping direction, which are twice and ten times higher than that in the releasing direction, respectively. A model to optimize the elastic modulus of the joint-like elements to enable sliding without peeling of the tips has been proposed.

Nanomechanical Effects

2021 ◽  
pp. 253-272
Author(s):  
C. Julian Chen
Keyword(s):  
Barrier Height ◽  
Contact Area ◽  
Soft Materials ◽  
Sample Surface ◽  
Soft Material ◽  
Measurable Effect ◽  
Tunneling Barrier ◽  
Hard Materials ◽  
Small Force ◽  
The Stability

This chapter discusses the effect of force and deformation of the tip apex and the sample surface in the operation and imaging mechanism of STM and AFM. Because the contact area is of atomic dimension, a very small force and deformation would generate a large measurable effect. Three effects are discussed. First is the stability of the STM junction, which depends on the rigidity of the material. For soft materials, hysterisis is more likely. For rigid materials, the approaching and retraction cycles are continuous and reproducible. Second is the effect of force and deformation to the STM imaging mechanism. For soft material such as graphite, force and deformation can amplify the observed corrugation. For hard materials as most metals, force and deformation can decrease the observed corrugation. Finally, the effect of force and deformation on tunneling barrier height measurements is discussed.

Experimental Investigation of Effect of Change in Contact Area by Deformation of Soft Material Fingertip on Resistible Force

2018 ◽  
Vol 2018 (0) ◽  
pp. 1P2-G18
Author(s):  
Yoshinori FUJIHIRA ◽  
Ryuji NAKAZAWA ◽  
Naohiko HANAJIMA ◽  
Masato MIZUKAMI ◽  
Tetsuyou WATANABE
Keyword(s):  
Experimental Investigation ◽  
Contact Area ◽  
Soft Material

The Contract Problem for an Elastic Layer Supported by Two Elastic Quarter Planes

1974 ◽  
Vol 41 (3) ◽  
pp. 673-678 ◽  
Author(s):  
F. Erdogan ◽  
M. Ratwani
Keyword(s):  
Contact Pressure ◽  
Contact Area ◽  
Elastic Layer ◽  
Applied Load ◽  
Stress Singularity ◽  
Cauchy Kernel ◽  
Relative Distribution ◽  
Space Problem ◽  
Frictionless Contact ◽  
External Loads

The frictionless contact problem for an elastic layer supported by two elastic quarter planes is considered. It is shown that as in the layer-half-space problem, the width of the contact area is dependent on the relative distribution of the applied load and is independent of its amplitude. At the corner of the support the contact pressure has an integrable singularity with its power α (0 < α < 0.5) depending on a single bielastic constant. The problem is reduced to a singular integral equation with a generalized Cauchy kernel and with the unknown contact pressure as the density function. The calculated results include the power and the strength of the stress singularity, the width of the contact area, and the contact pressure for various geometries, external loads, and material combinations.

Load-Bearing in the Ovine Medial Tibial Condyle: Effect of Meniscectomy

1993 ◽  
Vol 06 (02) ◽  
pp. 100-104 ◽  
Author(s):  
D. M. Pickles ◽  
C. R. Bellenger
Keyword(s):  
Knee Joint ◽  
Contact Area ◽  
Mammalian Species ◽  
Total Removal ◽  
Load Bearing ◽  
Human Knee ◽  
Biochemical Effects ◽  
Pressure Sensitive ◽  
Medial Meniscectomy ◽  
Tibial Condyle

SummaryTotal removal of a knee joint meniscus is followed by osteoarthritis in many mammalian species. Altered load-bearing has been observed in the human knee following meniscectomy but less is known about biochemical effects of meniscectomy in other species. Using pressure sensitive paper in sheep knee (stifle) joints it was found that, for comparable loads, the load-bearing area on the medial tibial condyle was significantly reduced following medial meniscectomy. Also, for loads of between 50 N and 500 N applied to the whole joint, the slope of the regression of contact area against load was much smaller. Following medial meniscectomy, the ability to increase contact area as load increased was markedly reduced.The load bearing area on the medial tibial condyle was reduced following meniscectomy.

Thickness Estimation Method of a Hard Object Located in a Soft Material using a Grasping Forceps with Sensors for Tumor Detection

2016 ◽  
Vol 136 (9) ◽  
pp. 377-383
Author(s):  
Kai Saito ◽  
Akihito Nakai ◽  
Ken Masamune ◽  
Takeyoshi Dohi ◽  
Kenta Kuwana
Keyword(s):  
Estimation Method ◽  
Tumor Detection ◽  
Soft Material ◽  
Thickness Estimation

An Analytical Thermodynamic Approach to Friction of Rubber on Ice

2012 ◽  
Vol 40 (2) ◽  
pp. 124-150
Author(s):  
Klaus Wiese ◽  
Thiemo M. Kessel ◽  
Reinhard Mundl ◽  
Burkhard Wies
Keyword(s):  
Coefficient Of Friction ◽  
Liquid Layer ◽  
Contact Area ◽  
Leading Edge ◽  
Viscous Friction ◽  
Analytical Approximation ◽  
Real Contact Area ◽  
Length Scales ◽  
Real Contact ◽  
Ice Surface

ABSTRACT The presented investigation is motivated by the need for performance improvement in winter tires, based on the idea of innovative “functional” surfaces. Current tread design features focus on macroscopic length scales. The potential of microscopic surface effects for friction on wintery roads has not been considered extensively yet. We limit our considerations to length scales for which rubber is rough, in contrast to a perfectly smooth ice surface. Therefore we assume that the only source of frictional forces is the viscosity of a sheared intermediate thin liquid layer of melted ice. Rubber hysteresis and adhesion effects are considered to be negligible. The height of the liquid layer is driven by an equilibrium between the heat built up by viscous friction, energy consumption for phase transition between ice and water, and heat flow into the cold underlying ice. In addition, the microscopic “squeeze-out” phenomena of melted water resulting from rubber asperities are also taken into consideration. The size and microscopic real contact area of these asperities are derived from roughness parameters of the free rubber surface using Greenwood-Williamson contact theory and compared with the measured real contact area. The derived one-dimensional differential equation for the height of an averaged liquid layer is solved for stationary sliding by a piecewise analytical approximation. The frictional shear forces are deduced and integrated over the whole macroscopic contact area to result in a global coefficient of friction. The boundary condition at the leading edge of the contact area is prescribed by the height of a “quasi-liquid layer,” which already exists on the “free” ice surface. It turns out that this approach meets the measured coefficient of friction in the laboratory. More precisely, the calculated dependencies of the friction coefficient on ice temperature, sliding speed, and contact pressure are confirmed by measurements of a simple rubber block sample on artificial ice in the laboratory.

Measurement and Visualization of the Contact Pressure Distribution of Rubber Disks and Tires

1995 ◽  
Vol 23 (4) ◽  
pp. 238-255 ◽  
Author(s):  
E. H. Sakai
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Contact Area ◽  
Light Absorption ◽  
Lateral Force ◽  
Contact Pressure Distribution ◽  
High Definition ◽  
The Road ◽  
Close Relationship ◽  
Processing Techniques

Abstract The contact conditions of a tire with the road surface have a close relationship to various properties of the tire and are among the most important characteristics in evaluating the performance of the tire. In this research, a new measurement device was developed that allows the contact stress distribution to be quantified and visualized. The measuring principle of this device is that the light absorption at the interface between an optical prism and an evenly ground or worn rubber surface is a function of contact pressure. The light absorption can be measured at a number of points on the surface to obtain the pressure distribution. Using this device, the contact pressure distribution of a rubber disk loaded against a plate was measured. It was found that the pressure distribution was not flat but varied greatly depending upon the height and diameter of the rubber disk. The variation can be explained by a “spring” effect, a “liquid” effect, and an “edge” effect of the rubber disk. Next, the measurement and image processing techniques were applied to a loaded tire. A very high definition image was obtained that displayed the true contact area, the shape of the area, and the pressure distribution from which irregular wear was easily detected. Finally, the deformation of the contact area and changes in the pressure distribution in the tread rubber block were measured when a lateral force was applied to the loaded tire.

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