Drexel Finds Simple Liquids Can Fracture Like Solids
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- Drexel University researchers reported in Physical Review Letters that simple liquids can fracture like solids when stretched past a critical stress point, with the discovery happening accidentally during ExxonMobil Technology & Engineering Company–funded rheology tests.
- Thamires Lima, Ph.D., assistant research professor at Drexel's College of Engineering, said the finding "fundamentally changes our understanding of fluid dynamics" and likely applies to all simple liquids, including common ones like water and oil.
- Tar-like hydrocarbon blends fractured under a critical stress of roughly 2 megaPascals—comparable to the tension from a laundry bag of 10 bricks snagging on a fingernail—producing a loud snapping noise that Lima initially mistook for the machine breaking.
- Styrene oligomer tested at the same viscosity fractured at the same stretching rate, and both simple liquids and their polymer counterparts broke at the same critical stress, suggesting elasticity is not required for fracture and that the phenomenon may be chemistry-independent.
- The fracture was captured on a high-speed camera, showing the same sudden break typical of brittle fracture in solid metals, and was reproduced at multiple temperatures, each producing a unique stretching rate that induced fracturing proportional to the 2 megaPascal threshold.
- Early clues point to cavitation—the formation and rapid collapse of vapor bubbles sending shockwaves through the liquid—as a possible physical mechanism driving the solid-like fracture behavior.
- The team plans further research into why the phenomenon occurs and how it manifests in other liquids, with potential applications in fiber spinning and other processes that stretch viscous liquids under tension.
Why it matters: The researchers explicitly say the finding raises new possibilities for manipulating liquids in hydraulics, 3D printing, and even blood vessel applications, because the assumption that liquids flow rather than break no longer holds under sufficient force. The 2 megaPascal critical stress threshold—reproduced across two different liquids and multiple temperatures—means engineering systems that stretch viscous liquids may need to account for a previously unrecognized fracture limit. The accidental nature of the discovery also underscores how little the field understood about what happens at the boundary between flow and failure in simple fluids.
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