Stability Analysis Of Hat-stiffened Composite Panels

Composite materials has high specific strength,high specific modulus,and its characteristics could be designed easily.Used composite materials in the structure can reduce the structural weight effectively,while the requirements have to be ensured.Because of these excellent performances,composite materials has becoming a favorite material sector fastly.Whether the composite materials widely used in the aircraft structure has becoming an important indicator to measure the nature of the aircraft.Composite hat-stiffened panels structure as an important representative of the aircraft,when under axial compression loads,the main failure mode is caused by buckling.In order to ensure safety using of the aircraft structure,the needing for stability analysis of such structures is becoming more and more important.In order to save cost and time calculation in the Engineering,linear buckling load always be recognized as the design load.This simplification is usually reasonable.But for the structure which has higher requirements of aerodynamic shape,there allows a certain degree of buckling.In this case,we should examine the post-buckling equilibrium path of the structure.So we can provide a basis for the further design in reducing the structural's weight.In this paper,we will study on the hat-stiffened composite panels,which based on ABAQUS finite element analysis software,and study its stability under axial compressive loads.The paper mainly content of the following aspects:(1)Firstly,the paper studied on the linear stability analysis of composite laminates.According to the buckling modes,we designed the rib's position preliminary.Take out the modes and the buckling eigenvalue of its linear stability analysis,then calculate the buckling load.(2)Secondly,put the first order buckling mode which multiplied by the thickness of 1%as the initial injury substitution in the post-buckling analysis.Observing the post-buckling equilibrium path.When considering the debonding between rips and plates,the post-buckling load is about 1.4 times than the buckling load.Compared with the no-debonding mode,adhesive layer not working is likely to be the important limitation.(3)Explored the influence of the hat-stiffened composite panels parameters on the buckling and post-buckling.The parameters include gradient angle,rib height,flange width,ribs density,and the ribs location.Obtained the results that for this article laminates involved,on which two symmetrically arranged relative distance 170mm,gradient angle of 68.2~?,a height of 35mm cap-type ribs can reach better stability.(4)Finally,studied on the influence of laminates laying angle to the buckling load,and drawing a diagonal direction,when the laying angle and the load are in the same direction,the structure can achieve better stability.