An Electrically Permeable Mode-Iii Nano-Elliptical Hole Embedded In One-Dimensional Hexagonal Piezoelectric Quasicrystals With Surface Effect

2021 ◽  
Author(s):  
Zhi-na Zhao ◽  
Jun-hong Guo ◽  
Jing Yu
Keyword(s):  
Surface Effect ◽  
Elliptical Hole ◽  
Mode Iii ◽  
One Dimensional

scholarly journals Surface effects on a mode-III reinforced nano-elliptical hole embedded in one-dimensional hexagonal piezoelectric quasicrystals

2021 ◽  
Vol 42 (5) ◽  
pp. 625-640
Author(s):  
Zhina Zhao ◽  
Junhong Guo
Keyword(s):  
Surface Layer ◽  
Boundary Conditions ◽  
Field Intensity ◽  
Surface Effect ◽  
Crack Tip ◽  
Elliptical Hole ◽  
Engineering Practice ◽  
Intensity Factors ◽  
One Dimensional ◽  
Field Intensity Factors

AbstractTo effectively reduce the field concentration around a hole or crack, an anti-plane shear problem of a nano-elliptical hole or a nano-crack pasting a reinforcement layer in a one-dimensional (1D) hexagonal piezoelectric quasicrystal (PQC) is investigated subject to remotely mechanical and electrical loadings. The surface effect and dielectric characteristics inside the hole are considered for actuality. By utilizing the technique of conformal mapping and the complex variable method, the phonon stresses, phason stresses, and electric displacements in the matrix and reinforcement layer are exactly derived under both electrically permeable and impermeable boundary conditions. Three size-dependent field intensity factors near the nano-crack tip are further obtained when the nano-elliptical hole is reduced to the nano-crack. Numerical examples are illustrated to show the effects of material properties of the surface layer and reinforced layer, the aspect ratio of the hole, and the thickness of the reinforcing layer on the field concentration of the nano-elliptical hole and the field intensity factors near the nano-crack tip. The results indicate that the properties of the surface layer and reinforcement layer and the electrical boundary conditions have great effects on the field concentration of the nano-hole and nano-crack, which are useful for optimizing and designing the microdevices by PQC nanocomposites in engineering practice.

Surface effect on deformation around an elliptical hole by surface energy density theory

2019 ◽  
Vol 25 (2) ◽  
pp. 337-347
Author(s):  
Liyuan Wang
Keyword(s):  
Energy Density ◽  
Surface Energy ◽  
Hoop Stress ◽  
Surface Effect ◽  
Plane Deformation ◽  
Surface Elasticity ◽  
Closed Form Solution ◽  
Elliptical Hole ◽  
External Loading ◽  
Surface Energy Density

The finite plane deformation of nanomaterial surrounding an elliptical hole subjected to remote loading is systematically investigated using a recently developed continuum theory. A complex variable formulation is utilized to obtain a closed-form solution for the hoop stress along the edge of the hole. The results show that when the size of the hole reduces to the same order as the ratio of the surface energy density to the applied remote stress, the influence of the surface energy density plays an even more significant role, and the shape of the hole coupled with surface energy density has a significant effect on the elastic state around the hole. Surprisingly, in the absence of any external loading, the hoop stress induced solely by surface effects is identical to that for a hole with surface energy in a linearly elastic solid derived by the Gurtin–Murdoch surface elasticity model. The results in this paper should be useful for the precise design of nanodevices and helpful for the reasonable assessment of test results of nano-instruments.

scholarly journals Antiplane Fracture Problem of Three Nanocracks Emanating from an Electrically Permeable Hexagonal Nanohole in One-Dimensional Hexagonal Piezoelectric Quasicrystals

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Dongsheng Yang ◽  
Guanting Liu
Keyword(s):  
Stress Intensity ◽  
Intensity Factor ◽  
Boundary Conditions ◽  
Energy Release Rate ◽  
Release Rate ◽  
Surface Effect ◽  
Electric Displacement ◽  
One Dimensional ◽  
Phonon Field ◽  
Electric Displacement Intensity Factor

Based on the Gurtin-Murdoch surface/interface model and complex potential theory, by constructing a new conformal mapping, the electrically permeable boundary condition with surface effect is established, and the antiplane fracture problem of three nanocracks emanating from a hexagonal nanohole in one-dimensional hexagonal piezoelectric quasicrystals with surface effect is studied. The exact solutions of the stress intensity factor of the phonon field and the phason field, the electric displacement intensity factor, and the energy release rate are obtained under the two electrically permeable and the electrically impermeable boundary conditions. The numerical examples show the influence of surface effect on the stress intensity factors of the phonon field and the phason field, the electric displacement intensity factor, and the energy release rate under the two boundary conditions. It can be seen that the surface effect leads to the coupling of the phonon field, phason field, and electric field, and with the decrease of cavity size, the influence of surface effect is more obvious.

New experimental techniques for fracture testing of highly deformable materials

2015 ◽  
Author(s):  
E. Dall’Asta ◽  
V. Ghizzardi ◽  
R. Brighenti ◽  
E. Romeo ◽  
R. Roncella ◽  
...  
Keyword(s):  
Elliptical Hole ◽  
Solution Space ◽  
Image Correlation ◽  
Thermoplastic Composites ◽  
Mixed Mode Fracture ◽  
Full Field ◽  
One Dimensional ◽  
Notched Specimens ◽  
Global Matching ◽  
Deformable Materials

A new experimental method for measuring strain fields in highly deformable materials has been developed. This technique is based on an in-house developed Digital Image Correlation (DIC) system capable of accurately capturing localized or non-uniform strain distributions. Thanks to the implemented algorithm based on a Semi-Global Matching (SGM) approach, it is possible to constraint the regularity of the displacement field in order to significantly improve the reliability of the evaluated strains, especially in highly deformable materials. Being originally introduced for Digital Surface Modelling from stereo pairs, SGM is conceived for performing a one-dimensional search of displacements between images, but here a novel implementation for 2D displacement solution space is introduced. SGM approach is compared with the previously in-house developed implementation based on a local Least Squares Matching (LSM) approach. A comparison with the open source code Ncorr and with some FEM results is also presented. The investigation using the present DIC method focuses on 2D full-field strain maps of plain and notched specimens under tensile loading made of two different highly deformable materials: hot mix asphalt and thermoplastic composites for 3D-printing applications. In the latter specimens, an elliptical hole is introduced to assess the potentiality of the method in experimentally capturing high strain gradients in mixed-mode fracture situations.

scholarly journals New experimental techniques for fracture testing of highly deformable materials

2015 ◽  
Vol 10 (35) ◽  
pp. 161-171
Author(s):  
E. Dall’Asta ◽  
V. Ghizzardi ◽  
R. Brighenti ◽  
E. Romeo ◽  
R. Roncella ◽  
...  
Keyword(s):  
Elliptical Hole ◽  
Solution Space ◽  
Image Correlation ◽  
Thermoplastic Composites ◽  
Mixed Mode Fracture ◽  
Full Field ◽  
One Dimensional ◽  
Notched Specimens ◽  
Global Matching ◽  
Deformable Materials

A new experimental method for measuring strain fields in highly deformable materials has been developed. This technique is based on an in-house developed Digital Image Correlation (DIC) system capable of accurately capturing localized or non-uniform strain distributions. Thanks to the implemented algorithm based on a Semi-Global Matching (SGM) approach, it is possible to constraint the regularity of the displacement field in order to significantly improve the reliability of the evaluated strains, especially in highly deformable materials. Being originally introduced for Digital Surface Modelling from stereo pairs, SGM is conceived for performing a one-dimensional search of displacements between images, but here a novel implementation for 2D displacement solution space is introduced. SGM approach is compared with the previously in-house developed implementation based on a local Least Squares Matching (LSM) approach. A comparison with the open source code Ncorr and with some FEM results is also presented. The investigation using the present DIC method focuses on 2D full-field strain maps of plain and notched specimens under tensile loading made of two different highly deformable materials: hot mix asphalt and thermoplastic composites for 3D-printing applications. In the latter specimens, an elliptical hole is introduced to assess the potentiality of the method in experimentally capturing high strain gradients in mixed-mode fracture situations.

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