Abstract: This paper describes analysis of low velocity transverse impact on fully backed sandwich beams with composite faces from Eglass/epoxy and cores from Polyurethane or PVC. Indentation on sandwich beams has been analyzed with the existing theories and modeled with the FE code ABAQUS, also loadings have been done experimentally to verify theoretical results. Impact on fully backed has been modeled in two cases of impactor energy with SDOF model (single-degree-of-freedom) and indentation stiffness: lower energy for elastic indentation of sandwich beams and higher energy for plastic area in indentation. Impacts have been modeled by ABAQUS. Impact results can describe response of beam in terms of core and faces thicknesses, core material, indentor energy and energy absorbed. The foam core is modeled using the crushable foam material model and response of the foam core is experimentally characterized in uniaxial compression with higher velocity loading to define quasi impact behaviour.
Abstract: In the study of honeycomb crushing under quasistatic loading, two parameters are important, the mean crushing stress and the wavelength of the folding mode. The previous theoretical models did not consider the true cylindrical curvature effects and the flow stress in the folding mode of honeycomb material. The present paper introduces a modification on Wierzbicki-s model based on considering two above mentioned parameters in estimating the mean crushing stress and the wavelength through implementation of the energy method. Comparison of the results obtained by the new model and Wierzbicki-s model with existing experimental data shows better prediction by the model presented in this paper.
Abstract: This paper deals with analysis of flexural stiffness,
indentation and their energies in three point loading of sandwich
beams with composite faces from Eglass/epoxy and cores from
Polyurethane or PVC. Energy is consumed in three stages of
indentation in laminated beam, indentation of sandwich beam and
bending of sandwich beam. Theory of elasticity is chosen to present
equations for indentation of laminated beam, then these equations
have been corrected to offer better results. An analytical model has
been used assuming an elastic-perfectly plastic compressive behavior
of the foam core. Classical theory of beam is used to describe three
point bending. Finite element (FE) analysis of static indentation
sandwich beams is performed using the FE code ABAQUS. The
foam core is modeled using the crushable foam material model and
response of the foam core is experimentally characterized in uniaxial
compression.
Three point bending and indentation have been done
experimentally in two cases of low velocity and higher velocity
(quasi-impact) of loading. Results can describe response of beam in
terms of core and faces thicknesses, core material, indentor diameter,
energy absorbed, and length of plastic area in the testing. The
experimental results are in good agreement with the analytical and
FE analyses. These results can be used as an introduction for impact
loading and energy absorbing of sandwich structures.