| Budget Amount *help |
¥13,700,000 (Direct Cost: ¥13,700,000)
Fiscal Year 2001: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2000: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1999: ¥10,200,000 (Direct Cost: ¥10,200,000)
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| Research Abstract |
In most of the applications as sensors and actuators in ffie field of smart structures and devices, piezoelectric materials are subjected to both high mechanical stresses and intense electric fields, hence, it is important for reliability and durability to investigate the fracture and deformation behavior of piezoelectric materials under mechanical and electrical loads. In this research project, the electric fracture and deformation behavior of advanced piezoelectric material systems is investigated. From the theoretical considerations and experimental data for piezoelectric material systems, the following results can be obtained :
1. We analyze the linear electroelastic problems for cracked piezoelectric ceramics. The effects of electroelastic interactions and piezoelectric properties on the fracture mechanics parameters (stress intensity factor, energy release rate, energy density, fatigue crack growth rate) are calculated. We also discuss the electrical boundary condition along the c
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rack faces.
2. (a) We consider the multiple scatterlng of antiplane shear waves in a piezoelectric fibrous composite with slip at interfaces. Numerical calculations for some piezoelectric fibrous composites are obtained and the effects of interfacial slippages and electroelastic interactions on the phase velocity and attenuation of coherent plane wave, and the effective piezoelectrically stiffened elastic constant are discussed. We also analyze the dynamic electroelastic problem for a piezoelectric ceramic having a circular piezoelectric inclusion. Numerical results for the dynamic stress and electric field concentrations are computed, and they are plotted in terms of the piezoelectric material constants, frequency, and applied electric field. (b) We consider the problem of horizontally polarized shear waves scattered from arc-shaped interface cracks between a circular piezoelectric fiber and its surrounding elastic matrix. Numerical values on the dynamic stress intensity factor, dynamic energy release rate, scattering cross section and electrical signal are obtained and the results are presented graphically to display the electroelastic interactions.
3. We perform the indentation fracture (IF) and single-edge precracked beam (SEPB) tests on piezoelectric ceramics, and examine the influence of applied electric field on the fracture and deformation properties. We also employ the finite element analyses to calculate the stress intensity factor and energy release rate. The numerical findings are then correlated with the experimental results.
4. We perform the modified small punch (MSP) tests on piezoelectric ceramics, and obtain the fracture initiation loads under different electric fields. We also model the electromechanical response of piezoelectric ceramics under mechanical and electric fields using a finite element approach, and calculate the deflection and critical MSP energy. Attempts are made to compare the results of finite element analysis with experimental observations. Less
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