1993 Fiscal Year Final Research Report Summary
Theoretical Study on Electric Fracture Mechanics of Piezoelectric Ceramics
| Project/Area Number |
03650070
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
材料力学
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
SHINDO Yasuhide Tohoku University, Faculty of Engineering Materials Processing Professor, 工学部, 教授 (90111252)
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| Project Period (FY) |
1991 – 1993
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| Keywords | Theory of Electroelasticity / Electric Fracture Mechanics / Crack / Stress Intensity Factor / Energy Release Rate / Piezoelectric Ceramics / Theory of Plates / Integral Equation |
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| Research Abstract |
Piezoelectric effects are extensively utilized in electromechanical devices. Piezoelectric ceramics such as lead zirconate (PZT) are currently under study as candidate materials for piezoelectric actuators. For the reliable service lifetime predictions of the components, an electric fracture mechanics approach has to be considered. The stress intensity factor approach of linear elastic fracture mechanics has proven to be very successful in prediction the unstable fracture of brittle solids. When electromechanical loads are applied to piezoelectric members, the same approach is expected to apply, at least as far as the initiation of the crack motion is concerned. However, the problem is more difficult than the purely elastic case because the electroelastic interaction effect must be accounted for.
In this research project, the electric fracture mechanics analysis of piezoelectric materials with the symmetry of a hexagonal class (6mm) is investigated.
1.Electroelastic Analysis of Piezoelec
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tric Ceramic Plates
Following the theory of linear piezoelectricity, the electroelastic analysis is presented for the bending problems of piezoelectric ceramic plates, which are polarized in transverse direction.
2.Electroelastic Fracture Mechanics Analysis of Piezoelectric Ceramic strips
We consider the electroelastic problem of a finite crack in an orthotropic piezoelectric ceramic strip under longitudinal shear. The crack is situated symmetrically and oriented in a direction parallel to the edges of the strip. Numerical calculations are carried out, and the stress intensity factor and the energy release rate are shown graphically for piezoelectric ceramics. We also study the antiplane electroelastic problem of an orthotropic piezoelectric ceramic strip with a finite crack, which is situated symmetrically and oriented in a direction normal to the edges of the strip.
3.Dynamic Longitudinal Shearing of a Cracked Piezoelectric Ceramic
We consider the scattering of a horizontally polarized shear wave by a finite crack in an orthotropic piezoelectric ceramic. The path-independent J-integral, generalized to take an inertial effect into account, is extended to include piezoelectric effects, and is evaluated at the crack tip to obtain the dynamic energy release rate. Numerical values on the dynamic stress intensity factor and the dynamic energy release rate for some piezoelectric ceramics are obtained and the results are graphed to display the electroelastic interactions. Less
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