Study Of Manufacturing Process And Flexural Properties Of A Box-section Beam With Foam-core Sandwich Walls

Box-section composite beams with foam-core sandwich walls not only have high strength with lightweight due to its sandwich structure, but also have excellent flexural stiffness and torsional stiffness due to its box-section configuration. The box-section composite beams with foam-core sandwich walls may find very good potential applications in aerospace vehicles and airplanes.Research on the design of structures, manufacturing process and flexural properties of the box-section composite beams with foam-core sandwich walls were conducted in this paper. A new integral manufacturing process was proposed and developed to fabricate the the box-section composite beams with foam-core sandwich walls. A water-soluble core module and fabric cloth winding process were adopted in the manufacturing process.The box-section beam usually has a hollow configuration, therefore it is very difficult to fabricate the structures integrally. Generally, the beam structures were fabricated by bonded with simple parts, which usually caused some problems to the loading capability of the structures due to weak bonding strength of the parts. In order to evaluate the mechanical properties of the box-section composite beams with foam-core sandwich walls fabricated by the integral process developed by the authors, specimen fabricated by bonded with simple parts were also used in the testing. A square-section beam was taken as an example to show the manufacturing process of bonded with simple parts. According to the square-section beam, three configurations, such as I-section, U-section and L-section were chosen to assemble the box-section beam. The three foam-core sandwich parts were fabricated by module process with vacuum assistent.A 3-point bending test was conducted to evaluate the strength to mass ratio and flexural stiffness to mass ratio of the box-section composite beams with foam-core sandwich walls by integral process and bonded with simple parts process, respectively. The experimental results show that the the strength to mass ratio and flexural stiffness to mass ratio of the box-section composite beams with foam-core sandwich walls by integral process were increased by130.9% and 105.3%, respectively, compared with that of the specimen by the bonded with simple parts process. Among of the results of the specimen by the bonded with simple parts process, U-section and L-section beam structures have higher specific flexural strength and stiffness than that of the I-section beam. All I-section, U-section and L-section beams show anisotropic behaviors to the loading direction due to its unsymmetric section configuration and joint ways.