Assessment of experimental friction parameters and contact property of pipe string for the estimation and verification of a solution for pipe stuck in the China's first rock pipe jacking

The paper presents experimental data on the study of the friction parameters of hard alloys in sliding friction units, including the heating temperature, surface roughness, wear and friction coefficient, depending on the duration of the test and the friction path.

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Test of Friction Parameters in Bulk Metal Forming Based on Forward Extrusion Processes

Journal of Shanghai Jiaotong University (Science) ◽

10.1007/s12204-020-2162-7 ◽

2020 ◽

Vol 25 (3) ◽

pp. 333-339

Author(s):

Xia Chen ◽

Tong Wen ◽

Kefan Liu ◽

Yifei Hong

Keyword(s):

Metal Forming ◽

Bulk Metal ◽

Bulk Metal Forming ◽

Forward Extrusion ◽

Friction Parameters

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The influence of shallow buried double-line parallel rectangular pipe jacking construction on ground settlement deformation

Alexandria Engineering Journal ◽

10.1016/j.aej.2020.11.038 ◽

2021 ◽

Vol 60 (1) ◽

pp. 1911-1916

Author(s):

Shiju Ma ◽

Mingyu Li ◽

Junwei Jin ◽

Kun Bai

Keyword(s):

Ground Settlement ◽

Double Line ◽

Line Parallel ◽

Pipe Jacking

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Asymmetric and chaotic responses of dry friction oscillators with different static and kinetic coefficients of friction

Meccanica ◽

10.1007/s11012-021-01382-8 ◽

2021 ◽

Author(s):

Gábor Csernák ◽

Gábor Licskó

Keyword(s):

Dry Friction ◽

Continuation Method ◽

Friction Model ◽

Lugre Friction Model ◽

Kinetic Coefficients ◽

Friction Oscillator ◽

Lugre Friction ◽

Friction Parameters ◽

Two Parameter ◽

Parameter Bifurcation

AbstractThe responses of a simple harmonically excited dry friction oscillator are analysed in the case when the coefficients of static and kinetic coefficients of friction are different. One- and two-parameter bifurcation curves are determined at suitable parameters by continuation method and the largest Lyapunov exponents of the obtained solutions are estimated. It is shown that chaotic solutions can occur in broad parameter domains—even at realistic friction parameters—that are tightly enclosed by well-defined two-parameter bifurcation curves. The performed analysis also reveals that chaotic trajectories are bifurcating from special asymmetric solutions. To check the robustness of the qualitative results, characteristic bifurcation branches of two slightly modified oscillators are also determined: one with a higher harmonic in the excitation, and another one where Coulomb friction is exchanged by a corresponding LuGre friction model. The qualitative agreement of the diagrams supports the validity of the results.

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Ultrasonic Characterization of Nanoparticle-Based Ceramics Fabricated by Spark-Plasma Sintering

Ceramics ◽

10.3390/ceramics4020012 ◽

2021 ◽

Vol 4 (2) ◽

pp. 135-147

Author(s):

Hanuš Seiner ◽

Michaela Janovská ◽

Martin Koller ◽

Petr Sedlák ◽

Kateřina Seinerová ◽

...

Keyword(s):

Activation Energy ◽

Boron Nitride ◽

Internal Friction ◽

Elastic Constants ◽

Carbon Nitride ◽

Plasma Sintering ◽

Spark Plasma ◽

Friction Parameters ◽

Boron Carbon Nitride ◽

Boron Carbon

Resonant ultrasound spectroscopy was used to determine elastic constants and internal friction parameters of bulk nanoparticle-based ceramic materials compacted by spark plasma sintering. Boron nitride-based and boron carbon nitride-based materials were studied, and the results were compared with similar bulk materials prepared from graphene nanoplatelets. The results showed that such nanoparticle-based materials can be strongly anisotropic, and can have very different elastic constants depending on the nanoparticles used. From the temperature dependence of the internal friction parameters, the activation energy for sliding of the individual monolayers along each other was determined for each material. Very similar values of the activation energy were obtained for boron nitride, boron carbon nitride, and graphene, ranging from 15 to 17 kJ/mol.

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