TY - GEN
T1 - Failure of Foam Core Sandwiches
T2 - ASME 2000 International Mechanical Engineering Congress and Exposition, IMECE 2000
AU - Bazant, Zdenek P.
AU - Brocca, Michele
N1 - Funding Information:
The following are the conclusions drawn from the above investigation • A new co-injection resin infusion molding technique is introduced to fabricate foam-core sandwich panels. • Sandwich with higher density foam demonstrates higher buckling load than the ones with lower density foams having similar face sheet constructions. However, if the core densities are low, the variation in their failure loads is seen to be minimal. • Presence of core-skin disbonds slightly reduces the buckling load, initiates extensive delamination, and significantly changes the post-buckling behavior. • Implanted teflon also reduces the amount of core shear as part of the input energy is presumably expended to continue the delamination growth. • Higher density foam arrests core-skin delamination and core-shear phenomena almost entirely during buckling. • The correlation between experimental, analytical and FEM results are excellent in case of sandwiches without implants. However, modification of the FE model, and formulations of analytical equations in case of panels with teflon will be required for more accurate predictions. Acknowledgements The authors would like to appreciate the Office of Naval Research (ONR) to support this grant through grant No. N00014-90-J-11995. Dr. Y. D. S. Rajapakse is the Technical Monitor.
Publisher Copyright:
© 2000 by ASME.
PY - 2000
Y1 - 2000
N2 - The paper presents a new constitutive model for closed-cell polymeric foams. The model is of the microplane type. In this model, the constitutive law is characterized in terms of vectors rather then tensors. The conceptual simplicity of this 'first-principles' approach makes it possible to base the model more directly on the physical phenomena occurring in the microstructure, in this case the elastic bending of the cells idealized as spheres in contact. The model is then employed in a finite element analysis of three point bending tests of sandwich beams failing by core indentation. Good agreement of the numerical results with the experimental observations is achieved. The softening and size effect engendered by the reduction of tangential bending stiffness due to the geometrically nonlinear effect of core indentation is discussed.
AB - The paper presents a new constitutive model for closed-cell polymeric foams. The model is of the microplane type. In this model, the constitutive law is characterized in terms of vectors rather then tensors. The conceptual simplicity of this 'first-principles' approach makes it possible to base the model more directly on the physical phenomena occurring in the microstructure, in this case the elastic bending of the cells idealized as spheres in contact. The model is then employed in a finite element analysis of three point bending tests of sandwich beams failing by core indentation. Good agreement of the numerical results with the experimental observations is achieved. The softening and size effect engendered by the reduction of tangential bending stiffness due to the geometrically nonlinear effect of core indentation is discussed.
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U2 - 10.1115/IMECE2000-2032
DO - 10.1115/IMECE2000-2032
M3 - Conference contribution
AN - SCOPUS:85119841674
T3 - ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)
SP - 51
EP - 67
BT - Mechanics of Sandwich Structures
PB - American Society of Mechanical Engineers (ASME)
Y2 - 5 November 2000 through 10 November 2000
ER -