Indentation Of Sandwich Beams Research Articles

Indentation of sandwich beams: Comparison of Vlasov, Winkler, and shear theories with composite surfaces reinforced by CNTs and ANN model

The use of sandwich structures has spread to a wide range of fields today. As a result of their thin top and low stiffness, sandwich beams are very susceptible to local loads. One practical solution to increase the sandwich structure's indentation resistance is to add bending strength to the top. The structural properties of carbon nanotubes make them well-suited for use in polymer matrixes; their addition improves the attributes of polymers. Experimental and theoretical investigations of the sandwich structure's indentation behavior are presented in this article. As well, simulations of sandwich structures are conducted using Abaqus software. A tensile test of composite samples and Mori Tanaka's theory were used to determine the elastic modulus of epoxy resin reinforced with carbon nanotubes at different mass percentages. The elastic modulus of composites can be improved by adding carbon nanotubes up to 0.3 % by mass while the mechanical properties are reduced when more than 0.3 % of carbon nanotubes were added. Finally, the analytical solution and Abaqus modeling results for the indentation of the sandwich structure were compared with the results obtained from the experimental tests. A machine learning model is proposed for prediction of sandwich beams deflection. The results of the predictions were phenomenal, with MAE of less than 2 %. The computational costs have been compared with the experimental results, and the machine learning method is very efficient.

Quasi-Static and Low-Velocity Impact Response of Fully Backed or Simply Supported Sandwich Beams

The present paper describes analysis of low-velocity transverse impact on sandwich beam, with composite faces from Eglass/epoxy and cores from Polyurethane or PVC. Boundary conditions are fully backed rigid or simply supported. This research is based on a step by step study to generate more reliable impact results. Indentation of laminated beam, indentation of sandwich beams, and three-point loading have been analyzed with existing theories and modeled with the FE code ABAQUS, also their results are compared with experimental results. In quasi-static three-point bending, energy is consumed through three mechanisms: indentation of laminated beam, indentation of sandwich beam, and bending of sandwich beam. Impact on fully backed specimen is modeled in two cases of impactor energies using mass spring model of SDOF (single-degree-of-freedom) and indentation stiffness, lower energy of impactor for elastic indentation of sandwich beams, and higher energy for indentation in plastic area. TDOF (two-degree-of-freedom) with flexural and contact stiffnesses are used for impact on simply supported beams. Impacts are simulated by ABAQUS, as well. Results can describe response of beam and impactor displacements in terms of core and faces thicknesses, core material, and impactor energies for static and impact results. The experimental results are in good agreement with the analytical and FE analyses.

A Study of Indentation Energy in Three Points Bending of Sandwich beams with Composite Laminated Faces and Foam Core

INTRODUCTION 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, and then these equations have been corrected to offer better results. An analytical model has been used assuming an elasticperfectly 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 tests have been done in two cases of quasi-static loading low velocity and higher velocity. 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 in sandwich structures

Indentation of composite sandwich beams

Indentation of a sandwich beam is analysed as linear elastic bending of the top skin on a rigid-perfectly plastic foundation (the core). The theoretical predictions of fracture load from this simple theory are shown to be in good agreement with experimental results from indentation tests on strips of sandwich panel, with glass-fibre-reinforced plastic skins and foam core, supported on a rigid base.