Streamline stiffener path optimization (SSPO) for embedded stiffener layout design of non-uniform curved grid-stiffened composite (NCGC) structures

Fabrication and testing of composite hierarchical Isogrid stiffened cylinder

Sensitivity analysis for optimization design of non-uniform curved grid-stiffened composite (NCGC) structures

Adopting filament winding and co-curing technique, carbon fiber reinforced composite (CFRC) Isogrid stiffened cylinders (ISCs) were designed and manufactured. Revealed by experiments, CFRC ISC has multi-failure modes, including material failure, global instability, local buckling, rib crippling and end delamination. Failure criteria for the first four failure modes were proposed and applied to predict the failure load of specific ISC. Skin thickness, cell dimension, rib height, rib thickness and end strengthening scheme jointly decide the failure pattern and failure load of the ISC. Failure maps were deduced to figure out the optimizing route for lightweight design of ISC. Wrapped ends were suggested to restrict the end delamination failure mode which results in rather low and uncertain load carrying capacity.

Multi-failure analysis of composite Isogrid stiffened cylinders

https://researchrepository.ucd.ie/bitstream/10197/10499/2/OptimizationCompositeOffshoreTower.pdf

Optimization of composite material tower for offshore wind turbine structures

Grid stiffened panels promise increased damage tolerance with reduced weight. Recent progress in automated manufacturing of composites has made it possible to produce such panels at low cost and thus has made them a competitive alternative to traditional skin-stiffened or sandwich panels. Fuselage skin panels typical of a 150 passenger aircraft were designed using an iterative process combining finite element models and local special purpose analysis methods. 40 cm by 30 cm panels, representing the final design, were fabricated using vacuum assisted resin transfer moulding. Pristine and impact damaged panels were tested in compression to failure. A progressive failure model was used to predict the extent and type of damage during impact. It was then combined with the global finite element model to obtain residual strength predictions. Analytical predictions were very close to test results. The fabrication method showed good quality and consistency and, when automated, can be used for production.

Ertan Acar

Papers

Design, analysis, fabrication, and testing of composite grid-stiffened panels for aircraft structures