The Strain Generated on a Rubber Surface in the Course of Pattern Abrasion

2000 ◽  
Vol 28 (2) ◽  
pp. 96-105 ◽  
Author(s):  
T. Iwai ◽  
Y. Uchiyama
Keyword(s):  
Contact Area ◽  
Applied Load ◽  
Crack Surface ◽  
Optical Microscope ◽  
Surface Strain ◽  
Front Part ◽  
Breaking Strain ◽  
Outermost Surface ◽  
Rubber Surface ◽  
Isoprene Rubber

Abstract The surface strain on a rubbing rubber surface was examined in the course of pattern abrasion. Rubbing experiments between the outermost surface of a rotating isoprene rubber wheel and a cylindrical lens were conducted. Observations of the contact area were made through the lens. Markers were put on the rubbing rubber surface to measure strain. The maximum strains at the inclined rubber surface between the ridges were from around 40% to 100%. In order to measure the strain at the crack-propagating area, a marker was put on the lower front part of the ridge. It was found that the strain necessary for crack propagation underneath the ridge was 750%, which was almost equivalent to its breaking strain, irrespective of the applied load. At that moment, newly generated crack surface was confirmed. However, no visible crack was observed through an optical microscope when the strain was measure at 200% to 400%.

How Does Rubber Slide?

1971 ◽  
Vol 44 (5) ◽  
pp. 1147-1158 ◽  
Author(s):  
A. Schallamach
Keyword(s):  
Tangential Stress ◽  
Relative Motion ◽  
Contact Area ◽  
Driving Force ◽  
High Speed ◽  
Stress Gradient ◽  
Compressive Stresses ◽  
Rubber Surface ◽  
The Waves ◽  
Soft Rubber

Abstract Visual observations of contact areas between soft rubber sliders and hard tracks, and between hard sliders and soft rubber tracks, show that relative motion between the two frictional members is often only due to “waves of detachment” crossing the contact area at high speed from front to rear. Adhesion appears to be complete between these waves which are moving folds in the rubber surface, almost certainly produced by buckling. Buckling is attributed to tangential compressive stresses, predicted by a simple theory and qualitatively confirmed by experiment. The driving force for the waves of detachment is a tangential stress gradient, also theoretically predicted.

scholarly journals Mechanical Properties of Electrospun, Blended Fibrinogen: PCL Nanofibers

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1843
Author(s):  
Jacquelyn M. Sharpe ◽  
Hyunsu Lee ◽  
Adam R. Hall ◽  
Keith Bonin ◽  
Martin Guthold
Keyword(s):  
Mechanical Properties ◽  
Strain Softening ◽  
Electrospun Nanofibers ◽  
High Energy ◽  
Optical Microscope ◽  
Ductile Material ◽  
Breaking Strain ◽  
Atomic Force ◽  
Microscope Technique ◽  
Afm Probe

Electrospun nanofibers manufactured from biocompatible materials are used in numerous bioengineering applications, such as tissue engineering, creating organoids or dressings, and drug delivery. In many of these applications, the morphological and mechanical properties of the single fiber affect their function. We used a combined atomic force microscope (AFM)/optical microscope technique to determine the mechanical properties of nanofibers that were electrospun from a 50:50 fibrinogen:PCL (poly-ε-caprolactone) blend. Both of these materials are widely available and biocompatible. Fibers were spun onto a striated substrate with 6 μm wide grooves, anchored with epoxy on the ridges and pulled with the AFM probe. The fibers showed significant strain softening, as the modulus decreased from an initial value of 1700 MPa (5–10% strain) to 110 MPa (>40% strain). Despite this extreme strain softening, these fibers were very extensible, with a breaking strain of 100%. The fibers exhibited high energy loss (up to 70%) and strains larger than 5% permanently deformed the fibers. These fibers displayed the stress–strain curves of a ductile material. We provide a comparison of the mechanical properties of these blended fibers with other electrospun and natural nanofibers. This work expands a growing library of mechanically characterized, electrospun materials for biomedical applications.

The influence of screw torque in the application of bone plates

2001 ◽  
Vol 14 (02) ◽  
pp. 78-83 ◽  
Author(s):  
T.C. Hearn ◽  
T.D. Woodside ◽  
J.R. Field
Keyword(s):  
Contact Area ◽  
Plate Fixation ◽  
Clinical Situation ◽  
Surface Strain ◽  
Bone Plates ◽  
Bone Plate ◽  
Clinical Criteria ◽  
Axial Tension ◽  
Interface Contact ◽  
Plate Reconstruction

SummaryThe applied level of screw torque has a significant impact on both the mechanical and vascular environment in bone following the application of a bone plate. The amount of torque applied dictates the resultant level of axial tension generated in the screw and the compressive forces between the plate and underlying bone. The interface contact area between the plate and underlying bone is also affected. As a consequence, screw torque can be implicated in the pathogenesis of implant induced osteopenia and other pathological occurrences that follow bone plate fixation.The work performed was designed to evaluate the effect of the applied level of screw torque. The construction stiffness (rigidity) and bone surface strain was quantitated in response to variable levels of screw torque. This was performed utilizing intact and osteotomized cadaveric bone.The current level of screw torque applied in the clinical situation, for 4.5 mm cortical screws, is approximately 5 Newton metres (Nm). It appears from the work presented herein, that lowering the level of applied screw torque does not adversely affect the rigidity of the final construction. This fact may serve to ameliorate the pathological consequences of applying screws and plates using current clinical criteria.The amount of torque applied to screws in the application of bone plates has a profound effect on a number of elements, namely the interface contact area and force. The work presented examines the effect of screw torque on the rigidity and bone strain distribution of fractured bone following bone plate reconstruction. It appears that the use of lower levels of screw torque, than currently used in clinical practice, does not adversely effect the rigidity of the final construction. These findings support the notion that the level of screw torque applied may have a role in ameliorating the pathogenic response that occur following bone plate application, namely osteopaenia.

scholarly journals Effect of Pin Size on Reciprocating Sliding Wear Test of Ti-6Al-4V

2015 ◽  
Vol 773-774 ◽  
pp. 237-241
Author(s):  
Nurarina Ahmad Nurdin ◽  
D.A. Harun ◽  
Abdul Latif Mohd Tobi ◽  
R. Md. Nasir
Keyword(s):  
Contact Pressure ◽  
Contact Area ◽  
Vickers Hardness ◽  
Sliding Wear ◽  
Flat Surface ◽  
Wear Test ◽  
Optical Microscope ◽  
Reciprocating Sliding ◽  
Sliding Test ◽  
Reciprocating Sliding Wear

Ti-6Al-4V is material that has the special characterisation and widely used in tribology studies. In this study reciprocating sliding test between Ti-6Al-4V pin on Ti-6Al-4V flat surface was conclude and focussed on the different contact area of pin size. The testing is run using tribometer pin-on-flat machine where the parameter set on the computer. The sample profilometry than analysed using 3D optical microscope (OM) and value of hardness get from Vickers hardness (HV) test. Due to the experiment, the contact pressure for 6.5 mm is higher than the 12 mm pin size, that brings the higher depth of wear.

scholarly journals Surface strain measurements of fingertip skin under shearing

2016 ◽  
Vol 13 (115) ◽  
pp. 20150874 ◽  
Author(s):  
Benoit Delhaye ◽  
Allan Barrea ◽  
Benoni B. Edin ◽  
Philippe Lefèvre ◽  
Jean-Louis Thonnard
Keyword(s):  
Contact Area ◽  
Normal Force ◽  
Complex Geometry ◽  
Tangential Direction ◽  
Surface Strain ◽  
Haptic Interfaces ◽  
Dexterous Manipulation ◽  
Strain Waves ◽  
Theoretical Predictions ◽  
High Resolution Images

The temporal evolution of surface strain, resulting from a combination of normal and tangential loading forces on the fingerpad, was calculated from high-resolution images. A customized robotic device loaded the fingertip with varying normal force, tangential direction and tangential speed. We observed strain waves that propagated from the periphery to the centre of the contact area. Consequently, different regions of the contact area were subject to varying degrees of compression, stretch and shear. The spatial distribution of both the strains and the strain energy densities depended on the stimulus direction. Additionally, the strains varied with the normal force level and were substantial, e.g. peak strains of 50% with a normal force of 5 N, i.e. at force levels well within the range of common dexterous manipulation tasks. While these observations were consistent with some theoretical predictions from contact mechanics, we also observed substantial deviations as expected given the complex geometry and mechanics of fingertips. Specifically, from in-depth analyses, we conclude that some of these deviations depend on local fingerprint patterns. Our data provide useful information for models of tactile afferent responses and background for the design of novel haptic interfaces.

Effect of Cryogenic Treatment on Creep Resistance of Cu-11.74Al-0.38Ni Alloy

2014 ◽  
Vol 508 ◽  
pp. 102-105
Author(s):  
Rong Hua Zhang ◽  
Biao Wu ◽  
Xiao Ping Zheng
Keyword(s):  
Creep Deformation ◽  
Creep Resistance ◽  
Room Temperature ◽  
Applied Load ◽  
Cryogenic Treatment ◽  
Optical Microscope ◽  
Temperature Creep ◽  
Before And After ◽  
Room Temperature Creep

In order to explore the effect of cryogenic treatment on creep resistance of Cu-11.74Al-0.38Ni alloy at room temperature, the room temperature creep deformation of Cu-11.74Al-0.38Ni alloy before and after cryogenic treatment at different applied load and time were measured by nanoindention technique, and the products were also characterized by optical microscope. The results show that cryogenic treatment can refine the grains, and reduce creep deformation of the alloy, which can improve the creep resistant properties of Cu-11.74Al-0.38Ni alloy effectively.

Model for a Sphere–Flat Elastic–Plastic Adhesion Contact

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Zhi Qian Wang ◽  
Jin Feng Wang
Keyword(s):  
Contact Area ◽  
Applied Load ◽  
Dissipated Energy ◽  
Polynomial Functions ◽  
Elastic Plastic ◽  
Adhesion Contact ◽  
Cubic Model ◽  
Cubic Polynomial ◽  
Plastic Displacement ◽  
Work Done

This paper presents a cubic model for the sphere–flat elastic–plastic contact without adhesion. In the cubic model, the applied load and the contact area are described by the cubic polynomial functions of the displacement to the power of 1/2 during loading and unloading, and the applied load is also expressed as the cubic polynomial function of the contact area to the power of 1/3 during loading. Utilizing these cubic polynomial functions, the elastic–plastic load (EPL) index, which is defined by the ratio between the dissipated energy due to plastic deformations and the work done to deform the sphere during loading, is calculated analytically. The calculated EPL index is just the ratio between the residue displacement after unloading and the maximum elastic–plastic displacement after loading. Using the cubic model, this paper extends the Johnson–Kendall–Roberts (JKR) model from the elastic regime to the elastic–plastic regime. Introducing the Derjaguin–Muller–Toporov (DMT) adhesion, the unified elastic–plastic adhesion model is obtained and compared with the simplified analytical model (SAM) and Kogut–Etsion (KE) model.

Influence of Forming on the Properties of Alloy Based on the Matrix of FeAl Intermetallic Phase

2013 ◽  
Vol 212 ◽  
pp. 49-52 ◽  
Author(s):  
Janusz Cebulski ◽  
Katarzyna Basa ◽  
Dorota Pasek
Keyword(s):  
Tensile Test ◽  
Crack Surface ◽  
Intermetallic Phase ◽  
Optical Microscope ◽  
Forming Process ◽  
Process Measures ◽  
Matrix Microstructure ◽  
Static Tensile Test ◽  
The Matrix ◽  
Static Tensile

Presented article describes results of studies concerning on influence of forming processes on alloy characteristics based on the FeAl intermetallic phase matrix. Microstructure of the alloy was evaluated with optical microscope after crystallization and forming process. Measures of hardness were taken using Vickers method. Static tensile test was used to set limitation of malleability and ultimate tensile strength. Crack surface after static tensile test was observed using scanning electron microscope.

The effects of contact area and applied load on the morphology of in vitro worn ultra-high molecular weight knee prostheses: a micro-Raman and gravimetric study

2014 ◽  
Vol 45 (9) ◽  
pp. 781-787 ◽  
Author(s):  
Silvia Tozzi ◽  
Enrico Modena ◽  
Stefano Falcioni ◽  
Alessandra Sudanese ◽  
Saverio Affatato ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Contact Area ◽  
Applied Load ◽  
Knee Prostheses ◽  
Ultra High Molecular Weight
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