1995 Fiscal Year Final Research Report Summary
Development of Polar Nonhomogeneous thermoelastic theory and its Application to Thermal Stress Analysis of Porous Functionally Graded Materials
| Project/Area Number |
06650079
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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 |
Materials/Mechanics of materials
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| Research Institution | Iwate University |
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Principal Investigator |
SUGANO Yoshihiro Iwate Univ., Faculty of Engng., Dept.of Mech.Engng., Professor, 工学部, 教授 (90089160)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Nonhomogeneous Thermoelasticity / Nonhomogeneous Heat Conduction / Thermal Stress / Functionally Graded Materials / Reduction of Thermal Stress / Temperature Field / Material Tailoring |
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| Research Abstract |
Based on an inference that reduction of thermal stress due to pores in functionally graded materials (FGMs) is produced by the presence of couple stress, a plane-strain thermoelastic problem with couple-stress was formulated for nonhomogeneous bodies using Mindlin's couple-stress theory. But analytical solutions to the governing differential equations were not obtained because of arbitrary nonhomogeneities with respect to thermal and mechanical properties of functionally graded materials and complexity of couple-stress theory. Then, in the present research, because of consideration on initiation of vertical cracks of ceramics 100% layr and spallation caused by linking-up of verticalcracks, an approximate three-dimensional analysis method was proposed for thermal stresses related to the initiation and linking-up of vertical cracks in a functionally graded material plate with temperature variation and nonhomogeneous properties only in the thickness direction. It was revealedthrough the a
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nalysis and numerical calculation for PSZ/SUS304 functionally graded plate that the reduction of tensile thermal stresses in the ceramic 100% layr on the heated surface is significantly dependent on composional distribution, and that ceramics-rich compositional distribution is very effective for the thermal stress recuction. Secondary, analytical solutions was obtained for temprature and thermal stresses in a functionally graded plate subjected to intermittent heating on its surface. The transient temperature field was derived from the solution for a transient heat conduction problem in the same functionally graded plate heated continually on its surface that is analyzed by Vodicka's method. Thermal stresses were analyzed based on Rogers and Spencer's solutions which were expressed in terms of the solution to the approximate, two-dimensional, thin-plate, governing equations for an equivalent homogeneous plate. Numerical calculations for the transient temperature and thermal stress distributions in PSZ/SUS304/PSZ functionally graded plate revealed effectiveness of ceramics-rich compositional distribution for the tensile thermal stress reduction on the heated surface during thermal-cycle loading. Less
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