Study On Instability Mechanism Of Medium - Pressure Bar In Carbon Fiber Dome

Based on the background of new carbon fiber cable dome, the instability mechanism and failure mode of compressed carbon fiber composite pipe with elastic support are investigated in this paper.According to practical engineering application, filament winding and pultruded CFRP circular tube under axial compression are studied in this paper as the research object, the influence of diameter-thickness ratio, slenderness ratio, boundary conditions and elastic constraint conditions on failure modes of these two CFRP tubes is analyzed. The influence of ply sequences are additionally investigated for filament winding CFRP circular tube under compression. Through finite element analysis, the following conclusions are drawn:(1)For filament winding CFRP tube with the ply sequence being [0n-x/90x], increasing toroidal layers is conducive to improving the ability of resisting local failure of the pipe. An appropriate proportion of toroidal vertical layer ratio can keep the bearing capacity of the pipe in a relatively stable value,while more toroidal may be counterproductive.(2)The influence of diameter-thickness ratio and slenderness ratio on two different molding processed CFRP tubes are basically the same.With different diameter-thick ratios, CFRP tube shows a sudden damage and an obvious brittle failure in a small slenderness. While for large slenderness, damage occurs very slowly.(3)After studying the critical slenderness ratio between local buckling and bending buckling of CFRP circular tube under compression in simple boundary conditions, it is found that for filament winding CFRP tube with the same diameter-thick ratio and toroidal vertical layer ratio but different thickness, the critical slenderness ratio between local buckling and bending buckling is very close. For pultruded CFRP tube with same diameter-thick ratio but different thickness, the critical slenderness ratio between local buckling and bending buckling is also very close in the same boundary conditions.(4)For the two kinds of CFRP tubes with no lateral elastic support condition, it is shown that with smaller and larger end constraints, the change of the constraint degree has little effect on the critical length between local buckling and bending buckling. While for a moderate constraint between them, the change of the constraint degree has a large effect on the critical length.(5)For the two kinds of CFRP tube with lateral elastic support condition, results indicate that critical lateral stiffness between lateral buckling and no lateral buckling is related to both the length of the component and the rotational stiffness of both end.(6) After summarizing the material failure rules of two different kinds of CFRP tubes, the following conclusions were discovered:for filament winding CFRP tube, matrix fiber shear failure is most likely to occur, and for pultruded CFRP tube the matrix tensile failure.Elastic support bearings were also designed in this paper. And the results of finite element analysis shows that, the designed bearings in this paper can provide elastic restraint for the component.