scholarly journals Understanding the influence of silicone elastomer properties on wedge-shaped microstructured dry adhesives loaded in shear

2018 ◽  
Vol 15 (146) ◽  
pp. 20180551 ◽  
Author(s):  
Aiva Simaite ◽  
Brigitte Temple ◽  
Mohammad Amin Karimi ◽  
Vahid Alizadehyazdi ◽  
Matthew Spenko
Keyword(s):  
Elastic Modulus ◽  
Interfacial Adhesion ◽  
Biomedical Applications ◽  
Normal Direction ◽  
Stick Slip ◽  
Flat Surfaces ◽  
Work Of Separation ◽  
Dry Adhesives ◽  
Normal Adhesion ◽  
Interfacial Adhesion Strength

Anisotropic, gecko-inspired, microstructured adhesives are one of the most promising solutions for many applications in robotics and biomedical applications that require controllable adhesives to grip flat surfaces. In such adhesives, normal adhesion is negligible when loaded solely in the normal direction, but becomes available when the adhesive is loaded in shear first. However, much remains to be learned regarding the friction and failure mechanisms of microstructures loaded in shear. In response, we analysed the load–displacement profiles of wedge-shaped microstructured adhesives comprised of nine different silicone elastomers and their mixtures loaded in shear. The results show that the friction profile depends on at least three factors related to material properties: interfacial adhesion strength in the normal direction (work of separation), elastic modulus and the sample's imperfections (e.g. contamination, misalignment and moulding errors). Moreover, the work of separation influences the maximum friction load such that for materials with the same elastic modulus, the strongest interfacial adhesion yields the lowest friction force. To explain this, we suggest that strongly adhering materials will lead to a macroscopic frictional sliding of the array rather than previously reported stick-slip behaviour.

Elastic-Modulus-Dependent Macroscopic Supramolecular Assembly of Poly(dimethylsiloxane) for Understanding Fast Interfacial Adhesion

Langmuir ◽  
2021 ◽  
Author(s):  
Yingzhi Sun ◽  
Xinghuan Wang ◽  
Menglin Xiao ◽  
Shanshan Lv ◽  
Mengjiao Cheng ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Interfacial Adhesion ◽  
Supramolecular Assembly

Development and Characterization of New Ti-25Ta-Zr Alloys for Biomedical Applications

2021 ◽  
Vol 1016 ◽  
pp. 137-144
Author(s):  
Pedro Akira Bazaglia Kuroda ◽  
Fernanda de Freitas Quadros ◽  
Mycaela Vieira Nascimento ◽  
Carlos Roberto Grandini
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Elastic Modulus ◽  
Biomedical Applications ◽  
Solution Heat Treatment ◽  
High Hardness ◽  
Microstructural Characterization ◽  
Β Phase ◽  
Cp Ti ◽  
Microscopy Techniques

This paper deals with the study of the development, structural and microstructural characterization and, selected mechanical properties of Ti-25Ta-50Zr alloy for biomedical applications. The alloy was melted in an arc furnace and various solution heat treatments were performed to analyze the influence of the temperature and time on the structure, microstructure, microhardness and elastic modulus of the samples. The structural and microstructural results, obtained by X-ray diffraction and microscopy techniques, showed that the solution heat treatment performed at high temperatures induces the formation of the β phase, while solution heat treatment performed at low temperatures induces the formation of the α” and ω metastable phases. Regarding the effect of time, samples subjected to heat treatment for 6 hours have only the β phase, indicating that lengthy treatments suppress the α” phase. Regarding the hardness and elastic modulus, the alloy with the α” and ω phases, after treatment performed at a temperature of 500 °C, has a high hardness value and elastic modulus due to the presence of the ω phase that hardens and weakens alloys. The titanium alloys developed in this study have excellent mechanical properties results for use in the orthopedic area, better than many commercial materials such as cp-Ti, stainless steel and Co-Cr alloys.

Characteristics of the Transfer Film and Tribological Properties of Oxide/PTFE Composites

2013 ◽  
Vol 631-632 ◽  
pp. 172-175 ◽  
Author(s):  
Ting Xie ◽  
Zheng Hua Zhou ◽  
Zhen Xing Xu ◽  
Jian Wei Yu ◽  
Ming Hua Jiao
Keyword(s):  
Adhesion Strength ◽  
Tribological Properties ◽  
Interfacial Adhesion ◽  
Measured Data ◽  
Transfer Film ◽  
Micro Hardness ◽  
Transfer Films ◽  
Ptfe Composites ◽  
Interfacial Adhesion Strength ◽  
Better Than

The formed transfer film on the counterpart surface and tribological properties of PTFE composites filled with Al2O3 or SiO2 were investigated in this paper. The results indicated that under the same friction conditions, the friction coefficients of SiO2/PTFE and Al2O3/PTFE are very close to each other, but the wear resistance of SiO2/PTFE is superior to that of Al2O3/PTFE. According to the measured data, the micro-hardness and elastic modulus of the transfer film for SiO2/PTFE are much better than those of Al2O3/PTFE. In addition, the interfacial adhesion strength between the transfer film of SiO2/PTFE and the counterface is higher. It can be proved that the mechanical properties of transfer films for PTFE composites vary with different fillers and the friction transfer film with better adhesion strength and mechanical property is useful to improve the tribological properties of the composite.

Three-Dimensional Mechanical Modeling of Magnet-Controlled Transfer Printing

2019 ◽  
Vol 11 (05) ◽  
pp. 1950042 ◽  
Author(s):  
Xiaofei Zhang ◽  
Changhong Linghu ◽  
Jizhou Song
Keyword(s):  
Adhesion Strength ◽  
Interfacial Adhesion ◽  
Scaling Law ◽  
Three Dimensional ◽  
Magnetic Pressure ◽  
Work Of Adhesion ◽  
Engineering Systems ◽  
Transfer Printing ◽  
Dimensional Parameters ◽  
Interfacial Adhesion Strength

The recently developed magnet-controlled transfer printing is valuable to develop advanced engineering systems due to its ability to tune the interfacial adhesion strength continuously and rapidly. A three-dimensional analytical model based on the energy method is developed for the magnet-controlled transfer printing. The predicted interfacial adhesion strengths agree well with experiments. A scaling law is established for the normalized interfacial adhesion strength, which depends on only four non-dimensional parameters: the normalized stamp size, the normalized stamp height, the normalized work of adhesion, and the normalized magnetic pressure. The influences of the non-dimensional parameters on the adhesion strength are fully investigated. This study provides a theory to guide the design of stamp and selection of the magnetic pressure to enable a successful magnet-controlled transfer printing.

scholarly journals Open Porous α + β Titanium Alloy by Liquid Metal Dealloying for Biomedical Applications

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1450 ◽  
Author(s):  
Stefan Alexander Berger ◽  
Ilya Vladimirovich Okulov
Keyword(s):  
Titanium Alloy ◽  
Elastic Modulus ◽  
Liquid Metal ◽  
Yield Strength ◽  
Biomedical Applications ◽  
High Yield ◽  
High Yield Strength ◽  
Open Porous Structure ◽  
Micrometer Scale ◽  
High Deformability

Open porous dendrite-reinforced TiMo alloy was synthesized by liquid metal dealloying of the precursor Ti47.5Mo2.5Cu50 (at.%) alloy in liquid magnesium (Mg). The porous TiMo alloy consists of α-titanium and β-titanium phases and possesses a complex microstructure. The microstructure consists of micrometer scale β-titanium dendrites surrounded by submicrometer scale α-titanium ligaments. Due to the dendrite-reinforced microstructure, the porous TiMo alloy possesses relatively high yield strength value of up to 180 MPa combined with high deformability probed under compression loading. At the same time, the elastic modulus of the porous TiMo alloy (below 10 GPa) is in the range of that found for human bone. This mechanical behavior along with the open porous structure is attractive for biomedical applications and suggests opportunities for using the porous TiMo alloy in implant applications.

Microwedge Machining for the Manufacture of Directional Dry Adhesives

2013 ◽  
Vol 1 (1) ◽  
Author(s):  
Paul Day ◽  
Eric V. Eason ◽  
Noe Esparza ◽  
David Christensen ◽  
Mark Cutkosky
Keyword(s):  
Flat Glass ◽  
Shear Loading ◽  
Mold Material ◽  
Preferred Direction ◽  
Process Characterization ◽  
Feature Geometry ◽  
Dry Adhesives ◽  
Tool Trajectory ◽  
Normal Adhesion ◽  
The Relationship

Directional dry adhesives are inspired by animals such as geckos and are a particularly useful technology for climbing applications. Previously, they have generally been manufactured using photolithographic processes. This paper presents a micromachining process that involves making cuts in a soft material using a sharp, lubricated tool to create closely spaced negative cavities of a desired shape. The machined material becomes a mold into which an elastomer is cast to create the directional adhesive. The trajectory of the tool can be varied to avoid plastic flow of the mold material that may adversely affect adjacent cavities. The relationship between tool trajectory and resulting cavity shape is established through modeling and process characterization experiments. This micromachining process is much less expensive than previous photolithographic processes used to create similar features and allows greater flexibility with respect to the microscale feature geometry, mold size, and mold material. The micromachining process produces controllable, directional adhesives, where the normal adhesion increases with shear loading in a preferred direction. This is verified by multi-axis force testing on a flat glass substrate. Upon application of a post-treatment to decrease the roughness of the engaging surfaces of the features after casting, the adhesives significantly outperform comparable directional adhesives made from a photolithographic mold.

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