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Tunable solidification of cornstarch under impact: How to make someone walking on cornstarch sink.

ABSTRACT: Hundreds of YouTube videos show people running on cornstarch suspensions demonstrating that dense shear thickening suspensions solidify under impact. Such processes are mimicked by impacting and pulling out a plate from the surface of a thickening cornstarch suspension. Here, using both experiments and simulations, we show that applying fast oscillatory shear transverse to the primary impact or extension directions tunes the degree of solidification. The forces acting on the impacting surface are modified by varying the dimensionless ratio of the orthogonal shear to the compression and extension flow rate. Simulations show varying this parameter changes the number of particle contacts governing solidification. To demonstrate this strategy in an untethered context, we show the sinking speed of a cylinder dropped onto the suspension varies markedly by changing this dimensionless ratio. These results suggest applying orthogonal shear while people are running on cornstarch would de-solidify the suspension and cause them to sink.

SUBMITTER: Niu R

PROVIDER: S-EPMC7209985 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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Tunable solidification of cornstarch under impact: How to make someone walking on cornstarch sink.

Niu Ran R Ramaswamy Meera M Ness Christopher C Shetty Abhishek A Cohen Itai I

Science advances 20200508 19

Hundreds of YouTube videos show people running on cornstarch suspensions demonstrating that dense shear thickening suspensions solidify under impact. Such processes are mimicked by impacting and pulling out a plate from the surface of a thickening cornstarch suspension. Here, using both experiments and simulations, we show that applying fast oscillatory shear transverse to the primary impact or extension directions tunes the degree of solidification. The forces acting on the impacting surface ar ...[more]

PMID: 32494699

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Tunable solidification of cornstarch under impact: How to make someone walking on cornstarch sink.

Publications

Tunable solidification of cornstarch under impact: How to make someone walking on cornstarch sink.

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