The Essential Work of Fracture Parameters for 3D printed polymer sheets

TL;DR

This paper investigates the fracture resistance of 3D printed polymer sheets using the Essential Work of Fracture method, highlighting the impact of fibre reinforcement and proposing a cost-effective small punch test for characterization.

Contribution

It introduces a novel application of the EWF method to additively manufactured polymers and proposes a miniature DDEN-SP test for efficient fracture property measurement.

Findings

Fibre reinforcement significantly increases fracture resistance.

Onyx exhibits an order of magnitude higher fracture energy than non-reinforced polymers.

The DDEN-SP test aligns well with traditional methods, offering a cost-effective alternative.

Abstract

Additive manufacturing is becoming increasingly popular in academia and industry. Accordingly, there has been a growing interest in characterizing 3D printed samples to determine their structural integrity behaviour. We employ the Essential Work of Fracture (EWF) to investigate the mechanical response of polymer sheets obtained through additive manufacturing. Our goal is twofold; first, we aim at gaining insight into the role of fibre reinforcement on the fracture resistance of additively manufactured polymer sheets. Deeply double-edge notched tensile (DDEN-T) tests are conducted on four different polymers: Onyx, a crystalline, nylon-reinforced polymer, and three standard polymers used in additive manufacturing - PLA, PP and ABS. Results show that fibre-reinforcement translates into a notable increase in fracture resistance, with the fracture energy of Onyx being an order of magnitude higher than that reported for non-reinforced polymers. On the other hand, we propose the use of a miniature test specimen, the deeply double-edge notched small punch specimens (DDEN-SP), to characterize the mechanical response using a limited amount of material. The results obtained exhibit good alignment with the DDEN-T data, suggesting the suitability of the DDEN-SP test for measuring fracture properties of additively manufactured polymers in a cost-effective manner.