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Physical Aging in Long Term Creep of Polymeric Composite Laminates

Published online by Cambridge University Press:  05 May 2011

H. W. Hu
H. W. Hu*
Affiliation:
Composite Materials and Lightweight Structures Laboratory, Department of Vehicle Engineering, National Pingtung University of Science and Technology, Pingtung, Taiwan 91201, R.O.C.
*
*Associate Professor
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Abstract

This paper presents a complete approach to characterize physical aging in long term creep of composite laminates using short term creep test. Carbon/epoxy composite IM7/977−3 was use to make the coupon specimens of unidirectional fiber orientation and symmetrical laminates. Creep tests were conducted on the specimens to obtain momentary compliances at isothermal conditions. Physical aging in elastic and in creep compliances were modeled respectively. Momentary creep compliances in various aging times were shifted to superpose a reference curve by introducing shift factors for both relaxation time and shape factor of a power law model. Linear relations between shift factors and aging time in log-log scale were found and defined as shift rates. By using reference curve associated with the shift rates, momentary creep compliance in any given aging time can be predicted. By introducing a time dependent shift factor, momentary creep compliance can be modified and turned into an effective time model, which can successfully predict the long term creep of composite laminates at isothermal aging. This approach only requires the test data of momentary creep, and no material properties in each lamina are needed.

Keywords

A. Polymer-matrix composites (PMCs)B. Physical agingB. CreepC. Analytical modeling.
Type
Articles
Information
Journal of Mechanics , Volume 23 , Issue 3 , September 2007 , pp. 245 - 252
Copyright
Copyright © The Society of Theoretical and Applied Mechanics, R.O.C. 2007

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