Strain Release Behaviour during Crack Growth of a Polymeric Beam under Elastic Loads for Self-Healing

Abstract

The response of polymeric beams made of Acrylonitrile butadiene styrene (ABS) and thermoplastic polyurethane (TPU) in the form of 3D printed beams is investigated to test their elastic and plastic responses under different bending loads. Two types of 3D printed beams were designed to test their elastic and plastic responses under different bending loads. These responses were used to develop an origami capsule-based novel self-healing mechanism that can be triggered by crack propagation due to strain release in a structure. Origami capsules of TPU in the form of a cross with four small beams, either folded or elastically deformed, were embedded in a simple ABS beam. Crack propagation in the ABS beam released the strain, and the TPU capsule unfolded with the arms of the cross in the direction of the crack path, and this increased the crack resistance of the ABS beam. This increase in the crack resistance was validated in a delamination test of a double cantilever specimen under quasi-static load conditions. Repeated test results demonstrated the effect of self-healing on structural crack growth. The results show the potential of the proposed self-healing mechanism as a novel contribution to existing practices which are primarily based on external healing agents.

Analysis of the Self-Healing Capability of Thermoplastic Elastomer Capsules in a Polymeric Beam Structure Based on Strain Energy Release Behaviour during Crack Growth

“…Furthermore, from the experimental results, it is observed that the modulus value of the TPE "cross" origami capsule increases with the strain rate. The experimental results correlate with the material properties that define TPE as a flexible material with more flexible filaments than ABS and TPU [42]. The TPE is less hard than ABS and TPU, due to which the beam surface had a more rubbery texture [43].…”

“…TPE is characterised using the study’s extended research work and scope. The analytical process was similar to that of ABS and TPU [ 41 , 42 ], which involves the capsule deflection at different thicknesses, which is 1–3 mm in our case. From the analysis of 3D curves, as indicated in Figure 10 , it is evident that the plastic regime achieves the maximum value of the applied load at 2 mm and 3 mm.…”