A Holistic Approach to Static Design of Sandwich Beams with Foam Cores

ABSTRACT: Sandwich panels with strong and stiff face sheets separated by light weight core are increasingly being used in aero-space, marine, automobile, and electronic packaging industries due to their low mass coupled with other attractive properties like corrosion resistance, thermal insulation, and acoustic damping. Most of the design methodology for the sandwich constructions is based on stiffness and core shear stress and the methodologies do not bring out clearly the loading situations under which sandwich panels would work. In this work, a holistic approach has been made to identify the applicability of sandwich construction based on a step-by-step procedure combining the stiffness requirement, allowable core shear stress, interface bond strength, allowable face compressive strength derived from failure modes. Further, weight optimization exercise is also included as a part of design procedure. A computer algorithm is developed and is illustrated with an example on sandwich beam with epoxy-resin impregnated bi-woven glass cloth as face sheets and polyurethane foam as core material with densities varying from 100 to 400 kg/m3. KEY WORDS: sandwich beam, static design, stiffness, core allowable shear stress, interface bond strength, failure modes, polyurethane (PU)