Flexural testing and analysis of full-strain-fields in sandwich composites

Abstract

The objective of this work was to characterize the full-field flexural behavior of composite sandwich beams. Finite element analysis was used to estimate the behavior of sandwich beams under three- and four-point-bending tests and were compared with experimental results obtained via digital image correlation and strain-gauges. Two different polyurethane core thicknesses and two different sandwich lengths were used to simulate short- and long-beam. Two distinct sandwich beams were used by means of two different faces: aluminum and basalt fiber reinforced polymer composite. Full-strain-fields and flexural displacements results were obtained showing that BFRP sandwiches exhibited higher flexibility and higher capacity of absorption energy than the aluminum specimens however with a higher prospect of core shear failure. For both face materials short-beams present higher strains than the long-beams and 4PB test specimens showed negative strain distribution in the upper side of the specimen and positive in the underside contrary to 3PB that presents positive strain distribution along the fulfilled. Moreover, results show that the strain distribution in not symmetric. Obtained experimental results are in good agreement with estimations; the digital image technique attested to be a complementary method to strain gages measurements in experimental full-strain-fields analysis.

Keywords

• Composite sandwich beams
• strain-fields
• FEM
• DIC
• VIC
• strain-gages