Load Bearing Behaviour of Thermoplastic Composite/Metal Hollow Structures with Multiscale Form Closure

Abstract

AbstractJoining systems with a multi-scale form closure function enable to pass very high loads into rod- and tube-shaped fibre reinforced structures and achieve high degrees of material utilization for the composite part. The multi-scale load application is based on a combination of macro and meso form closure with adaptation to the fibre angle of the braided preform. The design of the form closure elements on different scales determines the joint failure mode, which can be cohesive or adhesive failure. This paper presents the investigation of the influence of a multi-scale form closure on the load bearing capability of hybrid joints made of carbon fibre reinforced thermoplastic and aluminium under static tension load. Using structurally relevant combinations of meso structures and macro contours, numerical sensitivity analyses are used to determine the relationships between geometric parameters of the form closure elements, the transmittable forces and the failure behaviour. Experimental investigations of the joint strength of meso, macro and combined-structured tubular specimens show the beneficial effect of multi-scale structuring to increase the joint strength and match with the numerical simulations. Concluding advises for the contour joints design are given.KeywordsMultiscale form closureContour jointsJoint strengthFailure behaviourNumerical analysesFriction-based contactPull-out test