Micromechanical Modeling and Analysis of Intelligent Materials

1999 Fiscal Year Final Research Report Summary

• Project/Area Number: 10650087
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Materials/Mechanics of materials
• Research Institution: KYOTO INSTITUTE OF TECHNOLOGY
• Principal Investigator: ARAKI Shigetoshi Faculty of Engineering and Design, Kyoto Institute of Technology, Associate Professor, 工芸学部・機械システム工学科, 助教授 (60222741)
• Project Period (FY): 1998 – 1999
• Keywords: Micromechanics / Intelligent materials / Inclusion / Eigenstrain / Shape memory alloy / Shape memory polymer / Toughness / Stiffness

Research Abstract

Micromechanical modeling of a intelligent material containing TiNi fibers is performed by taking into consideration of the existence of fibers with transformation strain which corresponds to the total amount of shrinkage of the fiber. In modeling, thermal expansion strain due to the mismatch of thermal expansion coefficients between TiNi fiber and matrix is also considered. The total potential energy can be obtained, hence, the stress intensity factor K at the crack tip in the material and the overall elastic modulus of the material can be expressed successfully in terms of the transformation strain of fibers and the thermal expansion strain occurred in the material. We can see that the K value decreases with increasing in the shrink strain of fibers. The change in K with temperature is consistent with the experimental result and the change in macroscopic elastic modulus with temperature and transformation strain can be also obtained. Moreover, micromechanical modeling of a intelligent material containing shape memory polymer particles is also performed by considering that the values of glass transition temperature of particles in the material, TィイD2gィエD2, is various and then overall elastic modulus of the material is formulated as a function of the probability distribution of TィイD2gィエD2 of particles. When the distribution of TィイD2gィエD2 is a Bi-modal type, we can see that the overall elastic modulus of the material is constant irrespective of temperature within the temperature range between both values of TィイD2gィエD2 and whose value depends only upon the ratio between two probability densities of TィイD2gィエD2 of particles in the material. For a uniform type of TィイD2gィエD2 distribution, overall elastic modulus of the material decreases with increasing in temperature and whose decreasing rate becomes more large as the difference between maximum value and minimum one of TィイD2gィエD2 becomes small.