"Long before it's in the papers"
November 03, 2015

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Physicists study how balloons burst

Nov. 2, 2015
Courtesy of the National Center 
for Scientific Research, Paris
and World Science staff

A mod­er­ately in­flat­ed rub­ber bal­loon pricked with a nee­dle bursts in­to two large pieces—but if you in­flate it un­til it ex­plodes on its own, you get doz­ens of shreds.

Those are among the find­ings of two phys­i­cists at the Un­ivers­ity of Par­is Di­de­rot, which they pub­lished Oct. 30 in the jour­nal Phys­i­cal Re­view Let­ters.

Two explosion mechanisms of a rub­ber bal­loon. Im­ages are shown 0.3 milli­sec­onds apart. Top: a mod­erate­ly in­flated bal­loon. A crack propa­gates across the mem­brane, finally split­ting it into two. Bot­tom: a highly tensed bal­loon bursts into many long shreds. (© Sébastien Moulinet)


While the re­search ap­pears just in time for the holi­day sea­son, the au­thors see a se­rious pur­pose be­hind it.

“Un­der­stand­ing the phys­ics of frag­menta­t­ion is im­por­tant in a wide range of in­dus­t­ri­al and geo­phys­i­cal ap­plica­t­ions,” write the au­thors, from the Lab­o­r­a­to­ry of Sta­tis­ti­cal Phys­ics at the uni­vers­ity.

They added that they wanted to shed light on the frag­menta­t­ion pro­cesses in ma­te­ri­als sub­jected to im­pacts or ex­plo­sions.

The au­thors of the pa­per, en­ti­tled “Pop­ping Bal­loons: A Case Study of Dy­nam­i­cal Frag­menta­t­ion,” stud­ied de­tailed frame-by-frame im­ages of burst­ing bal­loons and of­fered an ex­plana­t­ion of the phe­nom­e­na.

“Us­ing rub­ber mem­branes, we de­vel­op an ex­pe­ri­men­tal anal­y­sis that en­ables us to track the frag­menta­t­ion pro­cess” in time and space, wrote the au­thors, Séb­as­tien Mou­linet and Mokh­tar Ad­da-Be­dia.

When a crack spread­ing across a bal­loon reaches a crit­i­cal speed, they ex­plained, the crack be­comes un­sta­ble and splits in­to two new cracks. This is be­cause at this speed, “tip split­ting be­comes the sole avail­a­ble mech­an­ism of re­leas­ing the stored elas­tic en­er­gy,” they wrote.

“Burst­ing a highly stretched mem­brane,” they not­ed, “yields a tree­like frag­menta­t­ion net­work that orig­i­nates at a sin­gle seed crack, fol­lowed by suc­ces­sive crack tip-split­ting events.” Thus the bal­loon bursts in­to shreds.


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A moderately inflated rubber balloon pricked with a needle bursts into two large pieces—but if you inflate it until it explodes on its own, you get dozens of shreds. Those are among the findings of two physicists at the University of Paris Diderot, which they publish in a new paper in the journal Physical Review Letters. “Understanding the physics of fragmentation is important in a wide range of industrial and geophysical applications,” write the authors, from the Laboratory of Statistical Physics at the university. The researchers said they wanted to shed light on the fragmentation processes in materials subjected to impacts or explosions. The authors of the paper, entitled “Popping Balloons: A Case Study of Dynamical Fragmentation,” studied detailed frame-by-frame images of bursting balloons and offered an explanation of the phenomena. “Using rubber membranes, we develop an experimental analysis that enables us to track the fragmentation process” in time and space, wrote the authors, Sébastien Moulinet and Mokhtar Adda-Bedia. When a crack spreading across a balloon reaches a critical speed, they explained, the crack becomes unstable and splits into two new cracks. This is because at this speed, “tip splitting becomes the sole available mechanism of releasing the stored elastic energy,” they wrote. “Bursting a highly stretched membrane,” they noted, “yields a treelike fragmentation network that originates at a single seed crack, followed by successive crack tip-splitting events.” Thus the balloon bursts into shreds.