Modified shear lag emodel for fibers and fillers with irregular cross-sectional shapes

摘要

For fibers with irregular cross sectons such as ultrahigh modulus polyetheylene(UHMPE) fibers and ribbon-like carbon fibers,the orginal shear lag model would not provide accurate calcualtons for interfacial shear stress because it assumes a cricular fiber cross section.In this study,a modified shear lag model is projposed to calcualte the interfacial shear stress that reflects the change of fiber cross-sectonal shape.Microbond test on a UHMPE fiber/epoxy system was used for verification of the model.The difference between theitnerfaacilal shear strength (IFSS) calculatedusign the modified model and that usign the original model assuming an equivalent fiber diameter was foudn to be as high as 15% and it leinearly increased as the irreegularity of the cross-sectional shape increased.whe n the iregularity costant exceeds 1.12,the error in IFSS involvedin using th eoriginal shear lag model and an equivalent fiber dimaneter is greater than 10%.