Lattice structures as interface design of additively manufactured composite components

Additive manufacturing (AM) offers new freedoms in product design. Combination of multiple materials in a single component without additional process steps makes AM well suited for integration of functions and development of novel component designs, but combination of multiple materials is accompanied by reduced adhesion, impeding high strength designs. The size of manufacturing machines as well as the build orientation additionally restrict the design of AM components. In order to manufacture parts that exceed the build size or in order to combine conventional manufacturing processes and AM, bonding processes become necessary. Depending on materials and adhesive, these compounds can show a similar problem of diminished adhesion. By utilizing the geometric freedom of AM and producing interlocking structures, this problem can largely be alleviated. This thesis shows the feasibility of using lattice structures manufactured by material extrusion (MEX) as interlocking bonds in multi-material and conventional bonding. Due to the 3D-interlock, transmission of force occurs mainly through a positive fit and diminished adhesion becomes largely irrelevant. While curing of adhesive inside the pores of a lattice can produce interlocks in almost all circumstances, producing multi-material AM interlocks requires joint processability of the two materials. Hence, different influences on multi-material MEX are highlighted and means of facilitating processing of incompatible materials are demonstrated. Different influences on the strength of such structures are identified by demonstrating design freedoms of lattice structures and implementation in a CAD environment. In order to separate the influences test specimens are developed and a systematic investigation is conducted. The results are formalized in design guidelines to increase accessibility to product developers. These guidelines are applied to a prototypical component in order to demonstrate their effectiveness.