Crack Paths 2009

Figure 4. Width of tears as a function experim nts: film thickness is 50 (r gh 0.025 and 0.1. The crack id

of the distance from their tips for two sets o

f

en

film thickness is 50 (right) or 90 µ m(left); the ratio

varies beetwe

0.025 and 0.1. The crack free length was kept at d=2.6 cm. 2

p:

Figure 5. Schematic of a top view of th horizontal ut cross the hang ng verti The opening angle of region 3 at th cra of th torn film is β, w ile m ic e experimental setup: the red rectangle show t r c l part of he film, wit a magnified thicknes ws a

with a magnified thickness.

region 3 at the crack tip is α, the bevel angle across the thickn el ess

i

he

while θ is the angle between the hanging part and the axes of t

cylinders.

W eused image analysis to measure the three-dimensional shape of the film as explaiined

hereafter. W enote that the curvature in the cu vature i he y-direction, so that w e the x-direction is very small in comparison w di ect n, e neglect it. To visualize the film curvature, r ith

ualize the film curvature, we

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