Evaluation of Reduction of Strain Concentration around a Circular Hole in Composite Laminates by Fiber Steering Placement Technique

RoboticAutomated FiberPlacement (AFP)andAutomaticTapeLay-up (ATL)techniquearewell-developedandappliedtopracticalproducing processforenhancing productivityand reducing costs.Theroboticprocessenablessteering fiberorprepreg tape,whichmakesit possible toproducestructureswithoutfiberendsattheedgeofopenholesorcut-outs.Itcanreducethestress concentration and prevent failurefrom thefiberends located at theholesurfaces.Thestrengthof thestructurecan significantlyimprovewith thepresenceofcut-outsand open holes.In this study, asimplifiedmodelofalaminatecomprising steeredlayerswithacircularholeisproposedthatcan beproduced byemploying thesteering technique.Thethickness distribution and theelasticpropertiesweretheoreticallyderivedonthebasisofageometricalconsiderationandaclassicallamination theory. The stress and strain distributions of axisymmetric laminated plates were semianalytically derived for an axisymmetric load and a uniaxial uniform load to understand the mechanism and to evaluatethedegreeofreduction in stress concentration.