Micromechanical Analysis of Macroscopic Stiffness of a SMP Intelligent Composite Material

2008-05-07T10:49:41Z

2008-05-07T10:49:41Z

2005-03-31

A shape memory polymer (SMP) is a functional material with a property of shape fixity effect. By this property, SMP material deformed in the rubber state cannot restore the shape to the original one if the material is cooled to be in the glass state with having maintained the deformed state. From this, when SMP reinforcements in the rubber state are embedded in a matrix material, the shape of reinforcements may be unchanged due to the constraint from the matrix surrounding reinforcements, even if the material is cooled till the reinforcements becomes the glass state. Therefore, the macroscopic stiffness of the composite material after cooling depends upon the shape of SMP reinforcements in the rubber state. If the shape of SMP reinforcements is a spheroid or a cylinder, the macroscopic stiffness of the composite in the longitudinal direction of the reinforcement differs from that in its lateral direction. Namely, the property of the material on the stiffness shows anisotropy. In this study, by taking into consideration shape fixity effect of the SMP reinforcement, micromechanical modeling and analysis are performed for an intelligent composite material containing SMP reinforcements and the change in degree of anisotropy of the material on the stiffness is examined. The macroscopic elastic modulus of the material is formulated as a function of the aspect ratio of the reinforcement. By using the expression obtained above, the value of the macroscopic elastic modulus can be obtained by changing the aspect ratio of the reinforcement. Especially, for the spheroidal reinforcement, we find that there are two aspect ratios that values of the macroscopic elastic modulus in the longitudinal direction of the reinforcement are same each other, and values of the macroscopic elastic modulus in the lateral direction of the reinforcement obtained from these aspect ratios are different from each other. As the result, we can suggest that it is possible to change degree of anisotropy of the material on the stiffness by utilizing the shape fixity effect of the SMP reinforcement.

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京都工芸繊維大学　工芸学部研究報告　第５３巻　理工・欧文(2004) pp.1-18

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http://hdl.handle.net/10212/1708

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Journal Article

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