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Dynamic tensile strength of polyurea

Published online by Cambridge University Press:  13 December 2011

George Youssef  and
Vijay Gupta
George Youssef
Affiliation:
Department of Mechanical Engineering, University of California Los Angeles, Los Angeles, California 90095
Vijay Gupta*
Affiliation:
Department of Mechanical Engineering, University of California Los Angeles, Los Angeles, California 90095
*
a)Address all correspondence to this author. e-mail: vgupta@ucla.edu
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Abstract

Dynamic tensile strength of polyurea is measured at an ultrahigh strain rate of 1.67 × 107 s−1 by generating spall failures inside thick polyurea coatings bonded to steel plates using laser-generated stress waves of several nanoseconds in duration. Specifically, thick polyurea films were cast on a steel plate whose backside was provided with water glass–covered Al film. The Al film was melted by focusing a high-energy Nd:YAG laser pulse over 3-mm-diameter area. Exfoliation of the Al generated a compressive stress wave toward the polyurea coating, which turned tensile upon reflection from the free surface. At a threshold laser energy, the amplitude of the returning tensile stress wave exceeded the dynamic tensile strength of polyurea. The stress wave profile inside the steel plate was interferometrically recorded at the threshold laser fluence and was used in a wave mechanics simulation to calculate the peak tensile stress. The polyurea was modeled as a viscoelastic solid.

Keywords

StrengthViscoelasticityShock loading
Type
Articles
Information
Journal of Materials Research , Volume 27 , Issue 2 , 28 January 2012 , pp. 494 - 499
Copyright
Copyright © Materials Research Society 2011

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