Sandwich theory | EPFL Graph Search

Sandwich theory describes the behaviour of a beam, plate, or shell which consists of three layers—two facesheets and one core. The most commonly used sandwich theory is linear and is an extension of first-order beam theory. The linear sandwich theory is of importance for the design and analysis of sandwich panels, which are of use in building construction, vehicle construction, airplane construction and refrigeration engineering. Some advantages of sandwich construction are: Sandwich cross sections are composite. They usually consist of a low to moderate stiffness core which is connected with two stiff exterior facesheets. The composite has a considerably higher shear stiffness to weight ratio than an equivalent beam made of only the core material or the facesheet material. The composite also has a high tensile strength to weight ratio. The high stiffness of the facesheet leads to a high bending stiffness to weight ratio for the composite. The behavior of a beam with sandwich cross-section under a load differs from a beam with a constant elastic cross section. If the radius of curvature during bending is large compared to the thickness of the sandwich beam and the strains in the component materials are small, the deformation of a sandwich composite beam can be separated into two parts deformations due to bending moments or bending deformation, and deformations due to transverse forces, also called shear deformation. Sandwich beam, plate, and shell theories usually assume that the reference stress state is one of zero stress. However, during curing, differences of temperature between the facesheets persist because of the thermal separation by the core material. These temperature differences, coupled with different linear expansions of the facesheets, can lead to a bending of the sandwich beam in the direction of the warmer facesheet. If the bending is constrained during the manufacturing process, residual stresses can develop in the components of a sandwich composite.

Proposed Panel Zone Model for Beam-To-Column Joints in Steel Moment Resisting Frames

Dimitrios Lignos, Andronikos Skiadopoulos, Ahmed Mohamed Ahmed Elkady

In capacity designed steel moment resisting frames (MRFs), beam-to-column joints (i.e., panel zones) are designed to remain elastic. To potentially exploit the beneficial aspects of the stable panel zone hysteretic response in shear, a robust panel zone mo ...

2023

Origami-inspired carbon fiber-reinforced composite sandwich materials - Fabrication and mechanical behavior

Thomas Keller, Yuntong Du

A folding fabrication method inspired by origami for carbon fiber-reinforced composites to fabricate three-dimensional structures is presented. PMI foams serve as substrates, making it possible to manufacture this kind of origami-inspired composite sandwic ...

ELSEVIER SCI LTD2021