Mechanical Behavior And Application Technology Of FRP Curved Sandwich Panels

This thesis proposes and studies an innovative FRP(fibre-reinforced polymer)component,which is the FRP curved sandwich panels based on rapid prototype technology.Such panel is composed of FRP face sheets and foam core,whose appearance can be obtained with parametric design method and then precisely manufactured with rapid prototype technology,such as CNC(computer numerical control)machining and 3D printing technology.In this way,the multi-functions,including heat preservation and insulation,solar energy power generation,and self-sensing,are realized in the structural member of such panel,which make it to be a new component integrating building functions and structure.The reliable mechanical behavior is the basis to ensure the multi-functions normally working,and the advanced manufacturing technology is the key issue to gurantee its engineering application.This thesis focuses on FRP curved sandwich panels,and conducts a series of studies about the mechanical experiments,computational and analytical theory,engineering design method for freeform shaped panels,advanced manufacturing technology and the practical engineering application.The main research content and achievements of this thesis includes:(1)The mechanical experiments were conducted for typical FRP curved sandwich panels.12 specimens of cylindrically curved FRP sandwich panels with different design parameters were flexurally tested to study the influences of the foam density,inclined degree,sandwich thickness and the face sheets' stacking sequences on the capacity and failure modes.FEA(finite element analysis)and parameter study were conducted to simulate the experiments and find the failure mechanism.It was shown that the FRP curved sandwich panels had the similar failure modes compared to the flat panles,but had more complicated failure mechanism.(2)A high-order sandwich panel theory was developed to analyze the cylindrically curved FRP sandwich panels with foam core.Such method was accurate enough and much faster when used to analyze the local effects and interface stress distributions compared to the FEA results.The parameter study was further conducted to study the key issues which influenced the local effects and stress concentration.(3)The structural design method was put forward for freeform shaped FRP sandwich panels.A simplified design method was built to calculate the resultants and deformation for the cylindrically curved FRP sandwich panels.The parametric modelling technique and engineering design method were further proposed for the freeform shaped FRP sandwich panels.(4)The state-of-art of the advanced manufacturing technology for FRP curved sandwich panels was studied.A novel manufacturing method,3D printing technology,was explored to make FRP curved sandwich panels.The mechanical experiments of components manufactured with different 3D printing techiniques were conducted to study the feasibility when constructing such panels.It was shown that the anisotropy needed to be considered when manufactured with 3D printing technology.(5)Based on the above study achievements,an integrating design method was developed for such panels.Finally,a practical engineering application,the enclosure system of a large bridge made of FRP curved sandwich pane with foam core,were designed and optimized.