Roberts-Tompkins, Altramese L. (2009-12). Viscoelastic Analysis of Sandwich Beams Having Aluminum and Fiber-reinforced Polymer Skins with a Polystyrene Foam Core. Master's Thesis. Thesis uri icon

abstract

  • Sandwich beams are composite systems having high stiffness-to-weight and strength-to-weight ratios and are used as light weight load bearing components. The use of thin, strong skin sheets adhered to thicker, lightweight core materials has allowed industry to build strong, stiff, light, and durable structures. Due to the use of viscoelastic polymer constituents, sandwich beams can exhibit time-dependent behavior. This study examines and predicts the time-dependent behavior of sandwich beams driven by the viscoelastic foam core. Governing equations of the deformation of viscoelastic materials are often represented in differential form or hereditary integral form. A single integral constitutive equation is used to model linear viscoelastic materials by means of the Boltzmann superposition principle. Based on the strength of materials approach, the analytical solution for the deformation in a viscoelastic sandwich beam is determined based on the application of the Correspondence Principle and Laplace transform. Finite element (FE) method is used to analyze the overall transient responses of the sandwich systems subject to a concentrated point load at the midspan of the beam. A 2D plane strain element is used to generate meshes of the three-point bending beam. User material (UMAT) subroutine in ABAQUS FE code is utilized to incorporate the viscoelastic constitutive model for the foam core. Analytical models and experimental data available in the literature are used to verify the results obtained from the FE analysis. The stress, strain, and deformation fields during creep responses are analyzed. Parameters such as the viscosity of the foam core, the ratio of the skin and core thicknesses, the ratio of the skin and core moduli, and adhesive layers are varied and their effect on the timedependent behavior of the sandwich system is examined.
  • Sandwich beams are composite systems having high stiffness-to-weight and
    strength-to-weight ratios and are used as light weight load bearing components. The use
    of thin, strong skin sheets adhered to thicker, lightweight core materials has allowed
    industry to build strong, stiff, light, and durable structures. Due to the use of viscoelastic
    polymer constituents, sandwich beams can exhibit time-dependent behavior. This study
    examines and predicts the time-dependent behavior of sandwich beams driven by the
    viscoelastic foam core. Governing equations of the deformation of viscoelastic materials
    are often represented in differential form or hereditary integral form. A single integral
    constitutive equation is used to model linear viscoelastic materials by means of the
    Boltzmann superposition principle. Based on the strength of materials approach, the
    analytical solution for the deformation in a viscoelastic sandwich beam is determined
    based on the application of the Correspondence Principle and Laplace transform. Finite
    element (FE) method is used to analyze the overall transient responses of the sandwich
    systems subject to a concentrated point load at the midspan of the beam. A 2D plane
    strain element is used to generate meshes of the three-point bending beam. User material (UMAT) subroutine in ABAQUS FE code is utilized to incorporate the viscoelastic
    constitutive model for the foam core. Analytical models and experimental data available
    in the literature are used to verify the results obtained from the FE analysis. The stress,
    strain, and deformation fields during creep responses are analyzed. Parameters such as
    the viscosity of the foam core, the ratio of the skin and core thicknesses, the ratio of the
    skin and core moduli, and adhesive layers are varied and their effect on the timedependent
    behavior of the sandwich system is examined.

publication date

  • December 2009