Crack propagation and arrests in gelatin hydrogels are linked to tip curvatures

Shrivastava, A and Supreeth, M and Gundiah, N (2023) Crack propagation and arrests in gelatin hydrogels are linked to tip curvatures. In: Soft Matter, 19 (36). pp. 6911-6919.

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Abstract

Gelatin hydrogels are attractive scaffold materials for tissue engineering applications as they provide motifs for cell attachment, undergo large deformations, and are tunable. Low toughness and brittle fractures however limit their use in load bearing applications. An investigation of crack tip processes and mechanisms of crack propagation is warranted to link fracture properties with material microstructure. We cross-linked gelatin using glutaraldehyde to obtain low cross-linked control hydrogels and used an additional cross-linker, methylglyoxal, to fabricate MGO hydrogels with higher cross-links. We quantified fractures in the gelatin hydrogels from both groups using pure shear notch tests and characterized strain fields near the crack tip using 2-D digital image correlation. We used a numerical method based on Taylor's series expansion to measure the crack tip curvatures in the hydrogels. This method captures tip curvatures better than the parabolic method routinely used in studies. Results from our study show that cracks in gelatin hydrogels underwent frequent arrests during propagation through the specimen width in both groups. MGO hydrogels had 85 enhanced fracture toughness and a significantly higher number of stalls compared to the control group. Crack initiations following stalls in the sample correlated with low tip curvatures in both hydrogel groups. We also show that mechanical stretching blunts the crack tip before crack propagation; the degree of blunting was independent of the cross-link density and elastic modulus of the gelatin hydrogels. These results show a link between crack growth and the tip curvature in cross-linked gelatin hydrogels, and offer potential insights for the development of tougher hydrogels. © 2023 The Royal Society of Chemistry.

Item Type:	Journal Article
Publication:	Soft Matter
Publisher:	Royal Society of Chemistry
Additional Information:	The copyright for this article belongs to the Royal Society of Chemistry.
Keywords:	Brittle fracture; Cell engineering; Crack propagation; Crack tips; Ductile fracture; Fracture toughness; Magnesia; Numerical methods; Scaffolds (biology), Cell attachments; Crack propagation and arrest; Cracks propagation; Cross-linked gelatins; Gelatin hydrogels; Larger deformations; Load-bearing; Scaffold materials; Tissue engineering applications; Tunables, Hydrogels
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	23 Nov 2023 06:53
Last Modified:	23 Nov 2023 06:53
URI:	https://eprints.iisc.ac.in/id/eprint/83217

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