Research Of Fabrication And Mechanical Properties Of Sandwich Structure With S-type Foldcore Made Of GFRP

Structural light-weighting is one of the popular issues in the field of engineering technology at home and abroad.As a new type of sandwich structure,the sandwich structure with foldcore has a broad application prospect in the structural light-weighting technology.As a new type of sandwich structure,there are many kinds of configurations about sandwich structure with foldcore such as V-type,M-type,S-type,and so on.Among them,sandwich structure with S-type foldcore has obvious advantages,but the research on its mechanical properties is still scarce.In this thesis,based on the literature review about the design of configuration,fabrication process and mechanical properties of sandwich structure with foldcore at home and abroad,the unique advantages of the composite sandwich structure with S-type foldcore are analyzed and studies are carried out as follows:First of all,the configuration characteristics of S-type foldcore and its mechanism of superior compression performance are briefly analyzed.Given the defects of the traditional hot-pressing mold for the foldcore of composite materials,a new hot pressing mold is designed,which is easy to operate and ensures the forming quality of the foldcore,and two kinds of composite sandwich structure with foldcore are successfully manufactured.Secondly,the flatwise compression experiments were carried out on the composite sandwich structure with S-type foldcore and the effects of foldcore wall thickness on the flatwise compression performance and failure characteristics of the structure are compared and analyzed.Besides,the low-velocity impact experiments under various working conditions are carried out.The effects of impact energy,the shape and size of the impactor,impact position,and areal-density of the structure on the low-velocity impact performance and impact damage mode of the structure are obtained.Finally,according to the Hashin failure criterion and Yeh interlaminar failure criterion based on strain-description,a numerical simulation model of the low-velocity impact of the composite sandwich structure with S-type foldcore which can describe progressive damage and stiffness degradation was established,and the simulation results are compared with the experimental results,which provides a reference for the expansion research of composite sandwich structure with foldcore.