A polyolefin with certified biocompatibility according to USP class VI was used by our group as feedstock for filament-based 3D printing to meet the highest medical standards in order to print personal protective equipment for our university hospital during the ongoing pandemic. Besides the chemical resistance and durability, as well as the ability to withstand steam sterilization, this polypropylene (PP) copolymer is characterized by its high purity, as achieved by highly efficient and selective catalytic polymerization. As the PP copolymer is suited to be printed with all common printers in fused filament fabrication (FFF), it offers an eco-friendly cost–benefit ratio, even for large-scale production. In addition, a digital workflow was established focusing on common desktop FFF printers in the medical sector. It comprises the simulation-based optimization of personalized print objects, considering the inherent material properties such as warping tendency, through to validation of the process chain by 3D scanning, sterilization, and biocompatibility analysis of the printed part. This combination of digital data processing and 3D printing with a sustainable and medically certified material showed great promise in establishing decentralized additive manufacturing in everyday hospital life to meet peaks in demand, supply bottlenecks, and enhanced personalized patient treatment.

Interactive criteria describe the failure of a material as a function of the stress or strain tensor components, which are combined into a functional that denotes material failure when a threshold level is reached. Although no indication is given of the failure mode, these criteria are definitely interesting since they can be easily implemented in a Finite Element code, which is the established numerical technique for crash simulation. In this paper, we explore the applicability of these criteria to short glass fibre reinforced polypropylene, which is widespread in structural applications. For this class of materials, a compression-sensitive, strain-rate and orientation-dependent implementation is proposed, which is needed due to the characteristics of the polymeric matrix. In particular, the criteria of Tsai–Hill and Tsai–Wu are here investigated and validated in an application to an industrial part, as a bumper stiffener beam, for which a dedicated set of impact tests has been carried out. Notwithstanding the limitations of the approximate material laws here used, which is suitable for an early stage design, the prediction of the part failure proved to be more accurate than what can be achieved with simpler criteria based on maximum admissible strain.

An approach to the simulation of foamed injection molded Polypropylene parts subjected to impact loading is presented in this paper. The proposed method, which considers strain-rate-dependent material properties and the possible occurrence of fracture, is, in particular, suitable for parts manufactured with core-back technology. The method was developed to be used within the functionality of a commercial Finite Element solver using a shell-type element mesh. The material model is based on a three-layer structure, with two compact skin layers and a foamed core layer made of expanded material. The properties of the foamed material are assumed as those of the compact grade scaled by a suitable factor, which is identified via inverse engineering on a set of bending tests executed on specimens having different foam densities. The fracture of the material is then predicted using a damage model which considers the effects of triaxiality. The approach is then validated on industrial parts from the automotive sector, subjected to impact in a component test. Despite the simplicity of the presented approach, which makes this method suitable for industrial applications and especially for early-stage design, the validation shows a sufficiently accurate simulation of part behavior under the impact, with a reasonable prediction of damage and fracture.