19554894-Abaqusumat-Program-Example

19554894-Abaqusumat-Program-Example - ABAQUS IMPLEMENTATION...

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Unformatted text preview: ABAQUS IMPLEMENTATION OF CREEP FAILURE IN POLYMER MATRIX COMPOSITES WITH TRANSVERSE ISOTROP Y A Thesis Presented to The Graduate Faculty of The University of Akron In Partial Fulfillment of the Requirements for the Degree Master of Science Fengxia Ouyang December, 2005 ii ABAQUS IMPLEMENTATION OF CREEP FAILURE IN POLYMER MATRIX COMPOSITES WITH TRANSVERSE ISOTROPY Fengxia Ouyang Thesis Approved: Accepted ________________________________ _______________________________ Advisor Dean of the College Wieslaw Binienda George K. Haritos ________________________________ ______________________________ Faculty Reader Dean of the Graduate School Pizhong Qiao George R. Newkome ________________________________ ______________________________ Department of Chair Date Wieslaw Binienda iii ABSTRACT Polymer Matrix Composites (PMC) are increasingly favored in structural applications for their light weight and durability. However, the numerical modeling of these materials poses several challenges. This is primarily due to the highly anisotropic nature of the creep exhibited by these materials above the glass transition temperature. Also, the damage and failure of the material is of particular interest to designers using the PMCs. Recently, a sustained effort has been to provide the designer with large computer codes containing comprehensive constitutive equations, often equipped with large number of internal variables and with the most general mathematical forms, for use in structural design analysis. Although elegant and useful, such constitutive laws are often expensive in implementation. Specially for early stages of the design, a quicker way of estimating complicated PMC behavior is needed. In this work, the constitutive material law by Robinson and Binienda (2001) [1,2] is utilized for such an approach. The model is successful in describing polymer matrix composite (PMC) materials having long or continuous reinforcement fibers embedded in a polymer matrix. Although the material law includes a single scalar parameter to describe the damage, it retains the essential material behavior. The material law is implemented computationally as a user defined subroutine (UMAT) in a commercially available FEA code (ABAQUS). The material parameters iv are obtained from experiments of thin-walled tubular specimens reinforced with unidirectional, helical fibers at an angle θ = 90 o , 60 o and 45 o under tensile and shear loading . The model correctly predicts the relation between logarithmic creep rate and logarithmic stress. The user subroutine has robust convergence properties. The creep strain rate and the effect of damage on the creep strain rate are presented for the benchmark problem of a square plate with a circular hole at the center and pressure vessel. The effect of fiber orientation on the durability of the square plate and pressure vessel under damaging loads, is studied....
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This note was uploaded on 01/27/2012 for the course ECON 101 taught by Professor Abba during the Spring '11 term at Dominican School of Philosophy and Theology.

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19554894-Abaqusumat-Program-Example - ABAQUS IMPLEMENTATION...

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