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3D-Printing of Curing Polymers

3D-Printing of Curing Polymers

Leitung:  Christian Weißenfels, Peter Wriggers
Team:  M.Sc. Philipp Hartmann
Jahr:  2016
Förderung:  DFG (Graduiertenkolleg 1627)

In the health care industry  Additive Manufacturing (AM) of patient specific implants is desirable to improve their functionality and patient outcomes. This requires the extrusion of fluid like medical grade silicone and a subsequent high speed curing by an infrared laser. Within the AM process, the output power of the laser, nozzle diameter, the extrusion rate as well as the translational velocity of the extruder are the crucial processing parameters. So far, their influences have only been examined by experimental studies, which include a feasibility study of different parameter combinations. However, the material behaviour during the printing and laser induced curing is not fully understood. Therefore, complex multiphysics simulations are required. Additionally, the virtual AM enables the possibility to predict results before time-consuming experimental tests are performed and opens up possibilities for computational process optimizations.     
 
In this project, a thermodynamically consistent finite strain curing model is developed within the classical continuum mechanical framework. Since the material extrusion involves extremely large deformations, a classical mesh-based numerical solution scheme such as the Finite Element Method is not applicable and a meshfree scheme is necessary. In contrast to classical continuum mechanics a state based Peridynamics framework is applied. The key differentiator between classical continuum mechanics and Peridynamics is the solution of integral instead of partial differential equations. The transition from a classical continuum mechanical material model to the peridynamical framework is performed via the non-local deformation gradient. From this idea a specialised  in-house three dimensional Peridynamics code is developed.
This enables the AM process to be simulated on the basis of the finite strain curing model and its implementation within a Peridynamics framework.