Bending of Curved Sandwich Panels with a Transversely Flexible Core-Closed-Form High-Order Theory

The bending behavior of a curved sandwich panel with a transversely flexible core, i.e., "soft" in the out of plane direction is derived. It is formulated using a rigorous systematic closed-form approach based on variational principles. The effects of the transversely flexible core are incorporated resulting in non-linear patterns, denoted also as high-order effects, for the inplane and the transverse deformations through the height of the core. The governing equations along with the associated boundary and continuity conditions for a general type of sandwich panel, i.e,. unidentical skins, composite laminated or metallic and a "soft" core are derived. General type of boundary conditions, including spring conditions, as well as different conditions at upper and lower skins at the same section, are implemented and the effects of "stiff' edge inserts, denoted as global boundary conditions, along with the induced localized effects are considered. Localized effects at support regions with or without edge stiffeners, with movable and immovable supports, and in the vicinity of concentrated loads are studied. The effects are described in terms of the internal resultants and displacements of each skin, peeling (transversely normal) stresses and shear stresses at the skin-core interfaces, and stress and displacement fields in the core through its height. Numerical results of a typical curved panel used in a test setup and comparisons with experimental data are presented. The analytical results are in good agreement with the experimental ones. The effects of global boundary conditions, such as a "stiff' edge beam, and similar local boundary conditions on the localized effects are presented and discussed. The stress concentration involved in the case of a concentrated load especially in its near vicinity is described.

[1]  H.-R. Meyer-Piening,et al.  Buckling analysis of FRP faced cylindrical sandwich panel under combined loading , 1990 .

[2]  A. Kühhorn,et al.  A nonlinear theory for sandwich shells including the wrinkling phenomenon , 1992 .

[3]  M. Stein,et al.  Nonlinear theory for plates and shells including the effects of transverse shearing , 1986 .

[4]  Ahmed K. Noor,et al.  Computational Models for Sandwich Panels and Shells , 1996 .

[5]  A. Noor,et al.  Assessment of computational models for sandwich panels and shells , 1995 .

[6]  E. Carrera,et al.  STATIC BUCKLING OF MODERATELY THICK, ANISOTROPIC, LAMINATED AND SANDWICH CYLINDRICAL SHELL PANELS , 1990 .

[7]  K. M. Rao.  Buckling Analysis of FRP-Faced Anisotropic Cylindrical Sandwich Panel , 1985 .

[8]  Ahmed K. Noor,et al.  Hierarchical adaptive modeling of structural sandwiches and multilayered composite panels , 1994 .

[9]  Yeoshua Frostig,et al.  Bending of Nonsymmetric Sandwich Beams with Transversely Flexible Core , 1991 .

[10]  Y. Frostig,et al.  High-order bending of sandwich beams with a transversely flexible core and unsymmetrical laminated composite skins , 1995 .

[11]  M. Di Sciuva,et al.  An Improved Shear-Deformation Theory for Moderately Thick Multilayered Anisotropic Shells and Plates , 1987 .

[12]  Yeoshua Frostig,et al.  Free Vibrations Of Sandwich Beams With A Transversely Flexible Core: A High Order Approach , 1994 .

[13]  J. Whitney,et al.  Shear Deformation in Heterogeneous Anisotropic Plates , 1970 .

[14]  M. Baruch,et al.  HIGH-ORDER BUCKLING ANALYSIS OF SANDWICH BEAMS WITH TRANSVERSELY FLEXIBLE CORE , 1993 .

[15]  Göran Tolf.  Stresses in a curved laminated beam , 1983 .

[16]  B. C. Nakra,et al.  Vibration and damping analysis of curved sandwich beams with a visoelastic core , 1988 .

[17]  J. Hutchinson,et al.  An introduction to the elastic stability of structures , 1976 .

[18]  Yeoshua Frostig.  On stress concentration in the bending of sandwich beams with transversely flexible core , 1993 .

[19]  Wang Ying-jiang,et al.  Nonlinear stability analysis of a sandwich shallow cylindrical panel with orthotropic surfaces , 1989 .

[20]  J. Reddy.  A Simple Higher-Order Theory for Laminated Composite Plates , 1984 .

[21]  Buckling of Generally Anisotropic Shallow Sandwich Shells , 1990 .

[22]  J. N. Reddy,et al.  Exact Solutions of Moderately Thick Laminated Shells , 1984 .

[23]  Ahmed K. Noor,et al.  Assessment of computational models for multilayered anisotropic plates , 1990 .

[24]  Sture Smidt,et al.  Bending of curved sandwich beams , 1995 .

[25]  Yeoshua Frostig,et al.  Behavior of delaminated sandwich beam with transversely flexible core — high order theory , 1992 .

[26]  Yeoshua Frostig,et al.  Bending of sandwich beams with transversely flexible core , 1990 .

[27]  Y. Frostig,et al.  HIGH-ORDER BENDING OF SANDWICH BEAMS WITH TRANSVERSELY FLEXIBLE CORE AND NONPARALLEL SKINS , 1994 .

[28]  R. Christensen,et al.  A High-Order Theory of Plate Deformation—Part 2: Laminated Plates , 1977 .

[29]  T. Kant,et al.  Geometrically Non-Linear Analysis of Doubly Curved Laminated and Sandwich Fibre Reinforced Composite Shells with a Higher Order Theory and C° Finite Elements , 1992 .