A NOVEL FINITE-ELEMENT INVESTIGATION OF THE EFFECTS OF WASHER FRICTION IN COMPOSITE PLATES WITH BOLT-FILLED HOLES

A novel two-dimensional finite element model has been developed in ord er to satisfactorily represent the effects of washer-plate friction du e to bolt torque on the response of bolted CFRP laminated plates loade d in uniaxial tension. A carbon fibre-epoxy laminate of quasi-isotropi c lay-up configuration [(+/-45 degrees/90 degrees/0 degrees)(2)](5) wa s investigated. The bolt was assumed to be of perfect fit and bolt and washers were assumed to be rigid. A constant in-plane uniaxial tensil e stress was applied to the laminate. The degree of lateral clamping p ressure, applied normal to the laminate via the washers, was varied fr om zero to high pressures. In all investigations this lateral clamping pressure was assumed to be uniform over the washer area. Through-thic kness effects and interlaminar phenomena were necessarily ignored give n the nature of the model. Friction between the plate and the bolt cor e was also ignored. Results obtained highlight the appreciable effects of washer friction on the laminate's response and likely mode of fail ure, affecting both the magnitude and location of the plate's in-plane peak global strain components.