Study On The Preparation And Molding Process Of Foam-sandwich Structural Acoustic Composites

Foam-sandwich structural composite is an advanced structural composite composed of fiber reinforced resin matrix composite with high strength as skin and light foam material as core material.Foam-sandwich structure has many advantages,such as small specific gravity,large stiffness,heat insulation,sound insulation and so on.Moreover,the structure can selectively control the properties of the composites by selecting the materials of the skin and core materials to meet the specific application conditions.Because of its excellent properties,foam-sandwich structural composites have been widely used in aerospace,ship yachts,rail transit and wind power generation.Recent studies have shown that the foam-sandwich structural composite has both outstanding mechanical properties and excellent acoustic properties compared with the traditional noise-reduction materials.In this paper,we apply this structural composite to the field of acoustic materials,and the effects of skin,core material and molding process on the acoustic properties of composites are discussed:Firstly,the surface density of the glass fiber cloth was taken as a single variable.The composite material is made of glass fiber cloth with three different areal densities as reinforcing material and epoxy resin 2040-2042 as a matrix.The loss factor is used as the evaluation standard for damping properties of composite materials.Interlaminar shear strength,in-plane tensile strength and in-plane shear strength are used as the evaluation criteria for mechanical properties.Next,a polymethacrylimide(PMI)foam was selected as the core material.The PMI foam does not have sound absorbing properties,so the PMI foam is apertured according to the principle of Helmholtz resonator to improve its sound absorption performance.The opening number,opening depth and opening diameter were studied as variables.After sample preparation,the test was carried out through a standing wave tube to explore the factors that affect the sound absorption performance of the PMI foam.The foam sandwich composite is composed of open-cell PMI foam as the core material and composite material as skin.The sound insulation performance of the composite was tested by standing wave tube,and it was studied how the open-cell PMI foam as core material affected the sound insulation performance of the sandwich composite.Finally,PMI foam as the core material,carbon fiber and glass fiber reinforced resin-based composite material as the skin,combined with vacuum infusion process method and the hand lay-up molding method,through the early stage,a lot of foam-sandwich structure acoustic composite parts are formed.Exploring,a large special-shaped component of acoustic composite with foam-sandwich structural were successfully fabricated,which laid a solid foundation for the practical application of such composite materials.