Transversely isotropic viscoelastic materials: Contact mechanics and friction

et al. 2021

Preprint

The evaluation of slope deformation and stability under freeze-thaw cycles is an important research direction and a challenge for geotechnical engineering in cold regions. However, most previous studies only considered the influence of the number of freeze-thaw cycles, but ignored the anisotropic characteristics of layered rock slopes. Meanwhile, the number of freeze-thaw cycles and the bedding dip are rarely considered in previous numerical simulations. Based on this background, the carbonaceous slate of the Pulang copper mine in China was used as the sample material to perform uniaxial compression tests on seven types of carbonaceous slate with different bedding dip angles after completing six different times of freeze-thaw cycles. The test results are applied to the numerical simulation analysis of the deformation characteristics and stability of the layered rock slope of the copper mine. The results show that freezing and thawing will cause layered rock degradation effects, thereby reducing rock mechanical parameters, and the influence is most obvious when the bedding dip is approximately 45°. In the numerical simulation, it is found that the deformation characteristics and stability change trend of the layered rock slope are similar to the above-mentioned experiments. In addition, it is necessary to consider the number of freeze-thaw cycles and the bedding dip to avoid too much difference for the maximum horizontal displacement of a layered rock slope. This study provides a feasible evaluation plan for the deformation characteristics and stability of the layered rock slope in Pulang area of China.

Section: Introductionmentioning

confidence: 99%

Investigation of Anisotropy on Deterioration of Mechanical Parameters of Layered Rock Under Freeze-thaw Cycles

Zhang

Wu²,

et al. 2021

Preprint

“…Therefore, AFM has been widely applied for measurement of sample morphology and atomic forces, especially longitudinal forces. While friction force and frictional properties of samples were previously measured by other methods, AFM was commonly used to characterize thickness, morphology [ 15 , 16 , 17 ], roughness [ 15 , 18 , 19 , 20 ] and surface characterization. As a useful tool, AFM is increasingly being used to measure the interaction forces between samples and recognition events between proteins at the single molecule level.…”

Section: Introductionmentioning

confidence: 99%

Friction Determination by Atomic Force Microscopy in Field of Biochemical Science

2018

Micromachines

Atomic force microscopy (AFM) is an analytical nanotechnology in friction determination between microscale and nanoscale surfaces. AFM has advantages in mechanical measurement, including high sensitivity, resolution, accuracy, and simplicity of operation. This paper will introduce the principles of mechanical measurement by using AFM and reviewing the progress of AFM methods in determining frictions in the field of biochemical science over the past decade. While three friction measurement assays—friction morphology, friction curve and friction process in experimental cases—are mainly introduced, important advances of technology, facilitating future development of AFM are also discussed. In addition to the principles and advances, the authors also give an overview of the shortcomings and restrictions of current AFM methods, and propose potential directions of AFM techniques by combining it with other well-established characterization techniques. AFM methods are expected to see an increase in development and attract wide attention in scientific research.

“…Due to the disadvantage of low fracture toughness and brittleness of piezoelectric materials, there has been growing interest concerned about their contact behavior. For the two-dimensional (2D) contact of homogeneous piezoelectric materials, we can refer to the frictionless contact (Wang et al, 2008; Zhou and Lee, 2012), sliding frictional contact (Mokhtari et al, 2016; Zhou and Lee, 2014), adhesive contact (Guo and Jin, 2009), and fretting contact (Li et al, 2016). For the axisymmetric contact of homogeneous piezoelectric materials, extensive works can be found by Giannakopoulos and Suresh (1999), Chen (2000), Giannakopoulos and Parmaklis (2007), Yang (2008), and Berndt and Sevostianov (2016) for the frictionless contact problem; Xiong et al (2005) for the Reissner–Sagoci problem; Chen and Yu (2008) for the partial slip contact problem; and Chen and Yu (2005) and Rogowski and Kalinński (2007) for the adhesive contact problem.…”

Section: Introductionmentioning

confidence: 99%

Axisymmetric partial slip contact of a functionally graded piezoelectric coating under a conducting punch

Journal of Intelligent Material Systems and Structures

2016

This article considered the axisymmetric partial slip contact problem of a functionally graded piezoelectric coated half-space indented by a rigid spherical punch subjected to a normal load. It is assumed that the punch within the contact region is a perfect conductor with a constant electric potential. The electro-mechanical properties of the functionally graded piezoelectric materials vary exponentially along the thickness direction. The whole contact region consists of an inner circular stick region surrounded by an outer annular slip region obeying Coulomb’s law of friction. The problem is reduced to a set of coupled Cauchy singular integral equations by employing the Hankel integral transform. An iterative method is used to determine the unknown stick/slip region, normal contact pressure, electric charge, and radial tangential traction. The effects of the resultant electric charge, friction coefficient, and gradient index on the surface electro-mechanical fields are presented in detail.