Flexible Materialien für die additive Fertigung: hyperelastische, viskoelastische Eigenschaften und der Einfluss unsicherer Materialparameter

Additive manufacturing, commonly called 3D printing, has become an established method in many fields of production. It is a preferred method to produce small series or individual parts of
components. If such printed parts shall replace traditionally produced parts, the mechanical properties have to be at least comparable. Even enhanced properties are desirable.
This works addresses the hyperelastic and viscoelastic properties of different flexible materials in additive manufacturing. Additional an investigation of the influence of material uncertainties, e.g. by voids, is presented.
In particular two different printing methods are examined: on the one hand fused deposition modeling (FDM) and on the other hand stereolithography (SLA). While FDM technique uses a meltable plastic as the basic material, the SLA method is based on the hardening of a photopolymeric resin material.
To investigate the hyperelastic material properties, uniaxial tensile tests are performed until rupture. For the used specimens, different printing parameters are varied. Uniaxial stress relaxation tests serve to determine the viscoelastic properties. Parameters of different hyper- and viscoelastic material models are identified by a conditional nonlinear regression. The gained parameters are verified in a FEM-simulation.
In conclusion the influence of uncertain parameters on different material properties is investigated. One the one hand the size distribution of spherical voids in closed-cell materials is determined, followed by a statistical analysis of the void radii distribution. On the other hand the influence of uncertain material parameters on an output parameter is studied on the example of an Euler-Bernoulli-beam.