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Crack Propagation

All articles tagged with #crack propagation

Simple Liquids Can Crack: New Breakthrough in Fluid Fracture
science21 hours ago

Simple Liquids Can Crack: New Breakthrough in Fluid Fracture

Drexel researchers, led by Thamires Lima, found that even simple, nonelastic liquids can fracture under high tearing stress, showing brittle-crack-like failure with crack speeds of roughly 500–1,500 m/s and a critical stress near 2 MPa—challenging the notion that only elastic or viscoelastic fluids crack. The cracks form rapidly after nucleation, aided by cavitation and lacking elastic energy dissipation, unlike slower cracks in complex fluids. Using extensional rheology and high-speed imaging, the team demonstrated that simple fluids can fracture, with potential implications for propellers, inkjet printing, soft robotics, and more; they also suggest that a deeper mechanism—perhaps cohesive energy—is at play and that faster testing could reveal cracking in even less viscous liquids.

Tape Screech Demystified: Tiny Sonic Booms From Adhesive Cracks
science4 months ago

Tape Screech Demystified: Tiny Sonic Booms From Adhesive Cracks

Physicists explain Scotch tape’s open‑air screech as a sequence of tiny, sideways cracks in the adhesive that form as you peel. These cracks open nanoscopic gaps between tape and surface; air can’t rush in fast enough to fill them, so a pressure pulse travels with each crack to the tape’s edge and collapses into the surrounding air, producing the audible screech. High‑speed cameras and synchronized microphones linked each pulse to a crack reaching the edge. The same team noted earlier vacuum experiments can emit X‑rays with tape flown in a perfect vacuum, but the in‑air screech comes from the crack‑driven pressure pulses.