Research On The Mechanical Behavior Of Stitched Stiffened Laminates Subjected To Compression After Impact Damage

Stiffened composite panels are one of the most typical composite structure of modern plane and aerospace aircraft, it maintains the composite laminates' advantages of high specific strength, high specific stiffness, while stringers greatly improve the bearing capacity of the structure. Composite laminates have the shortcomings of weak inter-lamina mechanical properties and impact resistance; Stitched composite material not only improves inter-laminar toughness, suppresses delamination expansion, but also improves compressive characteristics after impact by introducing stitched lines in the thickness direction. The stitching process is relatively simple, low cost and has good prospects. At present, there are much relevant research about basic mechanical properties of stitched composite materials, but less research about residual compressive strength of stitched composite laminates after low-velocity impact, and much less research about residual compressive strength of stitched composite stiffened panel. Therefore, carrying out research about residual compressive strength of stitched composite stiffened panel after impact has important significance and application value.This paper is focused on factors including stringer, density, size, type which affects residual compressive strength of stitched composite stiffened panel after impact. Based on ABAQUS software platform, A finite element model was established to predict the progressive damage of stitched laminates, in which the laminate was simulated by three dimensional brick element, the interface was simulated by cohesive element and the stitch was modeled by bar element. And write user subroutine which simulates damage evolution process of composite laminates under compression after impact damage. The model agrees well with the experimental results, so that the model and calculation method are rational and valid. Then, using the same modeling and computational methods explore stringers, density, size and type of the influence of residual compressive strength in details. Some conclusions and laws with reference value are obtained, and the current work laid the foundation for further study about stitched composite stiffened panel of residual compressive strength after impact damage.