Strength Research On Composite Structural Similarity Scaled Model Of Wing With Debonding Damage

Aircraft wind tunnel experiment has a crucial role in its performance parameters designing,such as flight performance,load distribution,strength check,structure layout and so on.For the restriction of domestic wind tunnel size,wind tunnel experiment only uses scale model.The scale model need simulate the aero-dynamic response accurately,so its design should be based on similarity theory to make sure achieve geometric,dynamic similarity with the original aircraft.It is difficult to use a traditional medal-skeleton model to simulate the aerodynamic response of the high-speed modern airplane due to issues like the overweight ratio is too high. Composite structure-similarity scale model is an advanced wind tunnel experimental model,which could significantly increase the structure efficiency, reduce the structure weight effectively,and achieve geometric,dynamic similarity and structure similarity with the original aircraft..Because of similar theoretical requirement,the design and manufacture of ComSSM adopt bonding form instead of mechanical way.So this model become a thin-walled bonding structure.It may occur buckling instability to reduce the strength.Scale model contain some fine structures,such as beam flange.If the width of flange is too short,it may degrade the bonding strength.And the model may contain some bonding defects in the manufacturing process,such as air bubble.Bonding interface also occur in the wind tunnel experiment.These defects and micro-cracks will have bad effect on the structure strength.Lack of strength,the model will break ahed of time.It means experiment fail and damage the wind tunnel to cause serious economic loss.A strength analysis method based on wing-box structure was presented to study composite wing scale model. Firstly, according to the material characteristic, different failure criteria were adopted to identify damage onset of the components. And a stiffness degradation rule,which contain continuum damage status variables, was presented. Secondly, the interface element was employed between the beam flange and the skin to discuss the influence of bonding strength on the ultimate load carrying capacity. The failure modes of wing-box structure, which subjected to bending and torsion loads, were studied by using the nonlinear finite element method. The numerical results agree well with experimental result.It indicate that the failure process can be stimulated effectively by considering the bonding strength. Finally, the effect of flange width and bonding defects on the model strength was discussed based on the strength prediction method. The consequence will contribute to the model strength prediction and the manufacturing process optimization and its structure safety assessment in wind tunnel experiment.