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MODELING STRUCTURAL POLYMERIC FOAMS UNDER COMBINED CYCLIC COMPRESSION-SHEAR LOADING

Alkhtany, Moshabab Mobarek, H
http://rave.ohiolink.edu/etdc/view?acc_num=akron1469532064

Abstract Details

2016, Doctor of Philosophy, University of Akron, Mechanical Engineering.
The objective of this research was to investigate the mechanical behavior of Divinycell PVC H100 foam under combined cyclic compression-shear loading, and to develop material constitutive models to predict response of the foam under these conditions. Structural polymeric foams are used for the core of sandwich structures in aerospace, marine, transportation, and other industries. They are valued for enabling high specific stiffness and strength as well as energy absorption and impact resistance of sandwich structures. This research addresses energy absorption of the foam due to plastic collapse, damage and hysteresis. Experiments were done to obtain out-of-plane mechanical properties of Divinycell PVC H100 foam under cyclic compression-shear loading. Stress-strain curves for the Divinycell PVC H100 foam under various combinations of compression-shear deformation and deformation rates were obtained. Rate-dependent behavior was observed before and after foam yielding. Yielding and damage in the foam occurred simultaneously. Foam yielding was associated with permanent change in cell micro-structure either by buckling cell walls when the foam is under compression or by bending and stretching cell walls when they were under shear. The Tsai-Wu failure criterion was shown to be a good predictor of yielding and damage initiation. The foam produced hysteresis either due to viscoelasticity and/or viscoplasticity if it was allowed to undergo reverse yielding during unloading and reloading. A phenomenological model was developed to describe the behavior of PVC H100 foam. This model consisted of a standard linear material model for viscoelastic response before yielding/damage initiation. After yielding/damage initiation, combined plastic flow and damage was modeled by modifying the viscoelastic properties of the standard linear model with damage properties and adding a viscoplastic element in series with it in order to control the plastic flow stress. Tsai-Wu plasticity and a specialized hardening function to account for different hardening rates in compression and shear were used to capture plastic flow behavior of the foam under combined compression and shear. The constitutive model was programmed in an ABAQUS user-material subroutine and finite element analysis was used to simulate the tests. Good agreement was found between the predicted and test results, except for specimens which appeared to fail during the tests due to stress concentration effects.
Michelle Hoo Fatt (Advisor)
Gregory Morscher (Committee Member)
Kwek-Tze Tan (Committee Member)
Anil Patnaik (Committee Member)
Kevin Kreider (Committee Member)
Mechanical Engineering
Divinycell PVC H100 foam; polymeric foams; combined cyclic compression-shear tests; hysteresis; viscoelasticity; viscoplasticity; Mullins effect; viscoelastic damage; constitutive modeling; Tsai-Wu yield criterion

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Citations

  • Alkhtany, H, M. M. (2016). MODELING STRUCTURAL POLYMERIC FOAMS UNDER COMBINED CYCLIC COMPRESSION-SHEAR LOADING [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1469532064

    APA Style (7th edition)

  • Alkhtany, H, Moshabab. MODELING STRUCTURAL POLYMERIC FOAMS UNDER COMBINED CYCLIC COMPRESSION-SHEAR LOADING . 2016. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1469532064.

    MLA Style (8th edition)

  • Alkhtany, H, Moshabab. "MODELING STRUCTURAL POLYMERIC FOAMS UNDER COMBINED CYCLIC COMPRESSION-SHEAR LOADING ." Doctoral dissertation, University of Akron, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1469532064

    Chicago Manual of Style (17th edition)

akron1469532064
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This open access ETD is published by University of Akron and OhioLINK.