2023 APS March Meeting
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session G09: Friction, Fracture, and Adhesion in Soft Materials I
11:30 AM–2:30 PM,
Tuesday, March 7, 2023
Room: Room 132
Sponsoring
Unit:
DSOFT
Chair: Xin Yong, Binghamton University
Abstract: G09.00001 : Toughening of brittle materials through crack tip complexity*
11:30 AM–12:06 PM
Abstract
Presenter:
John M Kolinski
(Ecole Polytechnique Federale de Lausanne)
Author:
John M Kolinski
(Ecole Polytechnique Federale de Lausanne)
Brittle fracture is characterized by a direct relationship between the strain energy that drives the crack on the one hand, and the fracture energy on the other hand, in the form of energy balance. This leaves little room to augment toughness without modifying the material by introducing inclusions, as is common practice for composite solids. However, this raises an important question: can anything be done to enhance the toughness of a brittle solid without modifying the material? We suggest that any means by which the crack front can be made more complex may enhance effective fracture toughness, in a manner consistent with energy balance. Crack tip complexity emerges when a crack breaks its planar symmetry, and the crack tip loading conditions become fully 3D. As a consequence of the geometric complexity of the crack tip, more fracture surface is generated when the crack advances, requiring additional strain energy for the crack to progress. Here, we study the toughness enhancement of a brittle solid through crack tip complexity, realized in an otherwise `ideally brittle' hydrogel. Using optical sectioning microscopy methods, we can directly measure the crack tip complexity, and simultaneously measure the far-field, effective fracture energy using the crack tip opening displacement (CTOD). We find that the effective fracture energy increases with the length of the 3D space-curve traced out by the crack tip. This result directly demonstrates an effective toughness enhancement of neat, brittle solids based entirely on crack tip complexity. The 3D loading conditions realized at the tip of such complex cracks raise significant challenges for the physics and engineering science community centered on crack tip stability. Our detailed in-situ measurements might be used to motivate the development of a theory for 3D fracture that could allow for facile interpretation of effective fracture energy of brittle solids with complex crack tips when the crack front geometry is known.
*SNSF project grant No. 200021_192102