Understanding interfacial fracture behavior between microinterlocked soft layers using physics-based cohesive zone modeling

Opposite moving detachment waves mediate stick-slip friction at soft interfaces

“…In such cases, the primary recourse to accurately determine the cut-off stress and process zone size is via molecular dynaimcs simulations [44] and physically motivated cohesive zone models [45]. For compressible materials such as rubbery polymers, this is not so; infinite tensile stresses at the edges of contact are in fact common with adhesion problems in soft materials [37].…”

Rational design of bioinspired tissue adhesives

“…Further, our computational simulation showed a significant influence of muscle contraction, which tends to relax the compressive stress around the connecting surface for easy release. In a follow‐up study, 10 we biomimicked lizard tail autotomy and related muscle contraction using soft microinterlocking structures 7 that can be actuated on‐demand via subsurface soft patch, showing high‐end tunable adhesion. Here too, the computer modelling identified C‐G and L‐T as the inherent toughening mechanisms.…”

Biomimetic fracture model of lizard tail autotomy

“…3, C to H and I to N (summarized in table S1), show that adhesion energy and peak force significantly decreased in peel mode (see experimental details in supplementary text 5), demonstrating the fracture’s mode-dependent vulnerability. The difference in mode-dependent results can be explained by the equal load sharing of the micropillars ( 5 ), which was quantified by comparing the associated characteristic stress decay lengths ( 6 , 7 ). We recorded a 17-fold difference between the modes (see the “Equal load sharing calculation” section in supplementary text 5).…”

“…The hierarchical toughening can be explained as follows. First, the nanoporous-assisted contact on top of the micropillars exerts a crack-arresting effect that can be explained by the crack initiation at multiple discontinuities plus the coplanar Cook-Gordon mechanism ( 7 , 8 ) that imparted repulsive stress interactions between the vicinal coplanar cracks ( 8 , 9 ) during propagation. This greatly contributed toward the intrinsic ( 10 ) fracture toughening mechanism at the interface.…”

“…To analyze and compare the toughening mechanism at the nanoscale and microscale levels, we also performed cohesive zone modeling and submodeling ( 7 ). The contour plots in Fig.…”