scholarly journals Understanding Friction and Wear Behaviours of Smooth Resilient Surfaces: Application for Pedestrian Fall Safety Improvements

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
In-Ju Kim
Keyword(s):  
Friction And Wear ◽  
Recent Literature ◽  
Initial Surface ◽  
Slip Resistance ◽  
Wear And Tear ◽  
Surface Profiles ◽  
Safety Assessments ◽  
Resistance Performance ◽  
Test Outcomes ◽  
Flooring Materials

The recent literature identified that certain types of smooth floors and flooring materials showed good slip-resistance performance under moderately contaminated situations such as water wet and soapsuds-covered conditions. However, topographic structures of such flat floor/walkway surfaces are significantly changed by wear and tear developments with continuous ambulation. A number of reasons seem to be involved in flooring wear developments, but such changes may result in substantial losses of slip resistance (or traction) functions. Even though the importance of this issue is wide, it is scarce to find any systematic investigations on tribophysical characteristics of smooth floors (<10 µm in Ra roughness) and their wear impacts on traction performance. Moreover, it is difficult to find studies on wear progress of floors and its impacts on pedestrian fall safety assessments. This study focuses on exploring wear activities of smooth resilient floors and disclosing wear consequences on traction properties. To measure slip-resistance features and investigate wear advances of smooth resilient floors, dynamic friction tests were carried out amongst purposely arranged 4 flat specimens (polymethyl methacrylate: PMMA) and 3 shoes. Wear formations and progressions of the PMMA surfaces were methodically evaluated by observing surface profiles during the tests. The test outcomes evidently presented that initial surface features of the PMMA specimens were significantly modified by primary-, secondary-, and shared-wear mechanisms and significantly influenced traction performance. This study may have design applications for the safety enhancements of smooth floors/footpaths to preclude pedestrian fall incidents.

scholarly journals How surface stress transforms surface profiles and adhesion of rough elastic bodies

2020 ◽  
Vol 476 (2243) ◽  
pp. 20200477
Author(s):  
Chung-Yuen Hui ◽  
Zezhou Liu ◽  
Nicolas Bain ◽  
Anand Jagota ◽  
Eric R. Dufresne ◽  
...  
Keyword(s):  
Surface Stress ◽  
Periodic Structures ◽  
Surface Profile ◽  
Initial Surface ◽  
One Dimensional ◽  
Patterned Substrate ◽  
Soft Solids ◽  
Elastic Bodies ◽  
Surface Profiles ◽  
Qualitative Changes

The surface of soft solids carries a surface stress that tends to flatten surface profiles. For example, surface features on a soft solid, fabricated by moulding against a stiff-patterned substrate, tend to flatten upon removal from the mould. In this work, we derive a transfer function in an explicit form that, given any initial surface profile, shows how to compute the shape of the corresponding flattened profile. We provide analytical results for several applications including flattening of one-dimensional and two-dimensional periodic structures, qualitative changes to the surface roughness spectrum, and how that strongly influences adhesion.

Numerical Simulation of Fretting Wear at the Dimple/Gimbal Interface

2013 ◽  
Author(s):  
Zhengqiang Tang ◽  
Youyi Fu ◽  
Frank E. Talke
Keyword(s):  
Friction And Wear ◽  
Disk Drive ◽  
Fretting Wear ◽  
Von Mises Stress ◽  
Experimental Measurements ◽  
Contact Interface ◽  
Surface Profiles ◽  
Von Mises ◽  
Worn Surface ◽  
Interface Geometry

A numerical model for the simulation of fretting wear at the dimple/gimbal interface of a hard disk drive suspension has been developed. The friction and wear coefficients used in the model are determined from experimental measurements. Archard’s wear equation is implemented numerically and the contact interface geometry is updated incrementally. The von Mises stress distribution and the worn surface profiles are determined.

Analysis of Handling Stresses in Thin Solar Silicon Wafers Generated by a Rigid Vacuum Gripper

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Hao Wu ◽  
Shreyes N. Melkote
Keyword(s):  
Stress Distribution ◽  
Dominant Role ◽  
High Stress ◽  
Surface Profile ◽  
Silicon Wafers ◽  
Wafer Surface ◽  
Initial Surface ◽  
Fe Modeling ◽  
Solar Silicon ◽  
Surface Profiles

Breakage of thin solar silicon wafers during handling and transport depends on the stresses imposed on the wafer by the handling/transport device. In this paper, the stresses generated in solar silicon wafers by a rigid vacuum gripper are analyzed via a combination of experiments and numerical modeling. Specifically, stresses produced in monocrystalline (Cz) and multicrystalline (Cast) silicon wafers of different thicknesses when handled by a vacuum gripper are analyzed using the finite element (FE) method. With the measured surface profiles of the wafer and the gripper as input, the handling process is simulated using FE modeling and the stress distribution obtained. The FE modeling results are validated by experimental data of wafer surface profile during handling. The results show that while the vacuum level does not have significant impact on the stress distribution, the initial surface profiles of the thin wafer and gripper play a dominant role in producing regions of high stress in the wafer.

Self Adapting Mechanical Step Bearings for Variations in Load

Tribology ◽  
2005 ◽  
Author(s):  
Robert L. Jackson
Keyword(s):  
Friction And Wear ◽  
Multiple Scales ◽  
The Self ◽  
Dynamic Responses ◽  
External Control ◽  
Small Scale ◽  
Precision Control ◽  
Surface Profiles ◽  
Bearing Design ◽  
And Behavior

As the application of small-scale and precision technologies increases, the need will grow for bearings which are able to provide precision control of their location. At the micro and nano-scale there is a need for new bearing technologies to reduce friction and wear, and provide precision control of bearing motion. This control can be provided by electronically controlled actuators and sensors, but then the system is dependant on the reliability of the electronics. This work uses numerical methods to research the design and behavior of self adapting smart step bearings. These step bearings are designed to change their surface profiles to achieve an optimal or controlled behavior, without the use electronics or external control. The bearing changes its profile to control the film height of the bearing to a near constant value for different loads. The result is a self adapting step bearing design that may be applied at multiple scales for use in a wide variety of machine components. The numerical simulation shows that the self adapting step bearing is able to autonomously adapt in real time to dynamic loads and maintain a desired film thickness with a relatively small amount of deviation. The self adapting step bearing also exhibits smaller dynamic responses to transient loads in comparison to a conventional static geometry step bearing.

Review of Self-Healing Polymers as Propituous Biomaterials

2020 ◽  
Vol 05 ◽  
Author(s):  
Smita Nayak ◽  
Bhaskar Vaidhun ◽  
Kiran Kedar
Keyword(s):  
Recent Literature ◽  
Polymeric Materials ◽  
Research Trends ◽  
Self Healing ◽  
4D Printing ◽  
Regulatory Requirements ◽  
Pharmaceutical Drug ◽  
Polymeric Biomaterials ◽  
Supportive Role ◽  
Wear And Tear

In the last few decades, as understanding of polymers grew, their applications in healthcare gained prominence. However, their widespread use was limited due to inevitable ageing, unavoidable degradation and excessive wear and tear. In order to overcome this drawback, researchers took inspiration from the capability of the human body to heal itself. Sci-entific curiosity and focussed efforts in this direction have laid the foundation for successful conceptualization of self-healing polymeric biomaterials and their commercial utilization for ancillary purposes. This review familiarizes the readers with recent literature in self-healing polymers, their fabrication techniques as well as applications in medical and pharma-ceutical arenas. It is heartening to note that these polymeric materials have overcome the disadvantages of conventional polymers and shown immense promise in breakthrough technologies such as tissue engineering, anti-biofouling as well as 3D and 4D printing. Self -healing polymers are poised to become critical supporting biomaterials in traditional disciplines such as orthopaedics, dentistry and pharmaceutical drug delivery. Efforts are on to design novel self-healing materials that meet the regulatory requirements of safety and biocompatibility. Research trends indicate that self-healing polymers may play a pivotal supportive role in furthering advances in therapeutics. The authors have, through this review, attempted to spark interest and stimulate creative minds to work in this domain.

Influence of Surface Roughness and Oil Ageing on Various Ceramic-Steel Contacts under Boundary Lubrication

1995 ◽  
Vol 209 (3) ◽  
pp. 173-182 ◽  
Author(s):  
J Denape ◽  
T Masri ◽  
J-A Petit
Keyword(s):  
Silicon Nitride ◽  
Boundary Lubrication ◽  
Friction And Wear ◽  
Tetragonal Zirconia ◽  
Degradation Process ◽  
Wear Behaviour ◽  
Fracture Mechanisms ◽  
Initial Surface ◽  
Tribological Behaviour ◽  
Used Oil

The friction and wear behaviour of four structural ceramics (two aluminium oxides of different purity, a silicon nitride and a tetragonal zirconia polycrystal) have been investigated under boundary lubrication against a 100C6 hard steel (52100 steel). The effect of three initial surface roughnesses of the ceramics is studied. Lubrication is by a commercial oil used ‘as received’ (new oil) and ‘aged’ (used oil). Tests are performed on an alternating ‘pin-on-plate’ tribometer. The friction and wear responses are analysed in terms of three main parameters depending on the mechanical preparation mode of the ceramics surface: the roughness magnitude, the morphology of the asperities (sharps or blunts) and the mechanical strength of the asperities. The evolution of these parameters during sliding leads to significant changes of tribological behaviour and contact pressure. The friction and wear transitions result from changes of the lubrication mode where roughness and oil have a competitive action. The wear processes of the ceramic surfaces include fracture mechanisms of the asperities and/or polishing by the mechanochemical action of the lubricant and submicronic ceramic wear debris. The worn surfaces of steel exhibit either abrasion grooves or a continuous metallic layer covering the steel. A running-in effect is observed on both silicon nitride and zirconia but does not occur on aluminas. The stronger running-in effect is observed with used oil. The used oil can lead to a very smooth sliding surface on the ceramic and allows particularly low friction coefficients and steel wear, but only after a more severe initial degradation process ESCA analyses on steel reveal the occurrence of a reaction film generated through chemical reactions with the oil.

Friction and Wear Behaviors of Three Ceramic Composite

2006 ◽  
Vol 315-316 ◽  
pp. 94-97 ◽  
Author(s):  
Xue Feng Yang ◽  
Jian Xin Deng ◽  
Jun Zhou ◽  
S.Q. Yao ◽  
C. Li
Keyword(s):  
Fracture Toughness ◽  
Wear Resistance ◽  
High Speed ◽  
Friction And Wear ◽  
Ceramic Composite ◽  
Cutting Tools ◽  
Test Machine ◽  
Flexure Strength ◽  
Wear And Tear ◽  
Hot Pressing Sintering

Three ceramic composite were prepared by hot pressing sintering. The friction and wear behaviors of the composite were experimented at the high speed wear and tear test machine. Results show that the three ceramic composite have strong fracture toughness and flexure strength. The wear mechanisms of three ceramic composite are mainly brittleness peel off and furrow. Al2O3/(W, Ti)C and Al2O3/SiCw ceramic composite have great capabilities in wear resistance; they are excellent materials of cutting tools and dies.

TRIBOLOGICAL CHARACTERISTICS OF POLYURETHANES USED FOR THE SOLES OF FOOTWEAR

Tribologia ◽  
2021 ◽  
Vol 294 (6) ◽  
pp. 71-75
Author(s):  
Jacek Przepiórka ◽  
Marian Szczerek ◽  
Marian W. Sułek
Keyword(s):  
Coefficient Of Friction ◽  
Friction And Wear ◽  
Base Material ◽  
Operating Conditions ◽  
Test Results ◽  
Footwear Industry ◽  
Wear And Tear ◽  
Variable Friction ◽  
The Coefficient Of Friction ◽  
Shoe Soles

The inability to take into account the type of base material (floor, pavement, soil), as well as the inability to take into account the variable friction conditions – load, intermediary medium (water, loose abrasive, sand or other soil particles), sliding velocity, and ambient temperature – is a significant limitation the use of friction methods and devices used so far in the footwear industry to precisely anticipate the behavior of the bottom materials in the actual operating conditions of the footwear. These limitations prompted the authors to adapt a tribological tester for this purpose, used in the area of construction and operation of machines and material engineering. A research methodology was developed and, in order to verify it, measurements of the coefficient of friction and wear of polyurethane used for shoe soles in combination with a raw and varnished wooden substrate were carried out. The obtained test results are characterized by diversity, which proves the high research resolution of the developed method. It allows determining the coefficient of friction of associations influencing the slip of the footwear and the wear and tear that determines the length of use of the footwear.

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