Why do windscreens crack in a zig-zag? © iStock

Why do windscreens crack in a zig-zag?

Windscreen glass can break in unexpected patterns.

Asked by: Lee Hatfield, Boston

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‘How do materials crack and break?’ is one of the hottest research areas in modern materials science. Even for a simple sheet of glass we are far from knowing the full answer.

Windscreen cracking is complicated, because windscreens are laminated, with two sheets of glass held together by a glue layer. The ‘give’ in the glue slows the cracking by taking up some of its energy, and allows more time for changes of direction due to imperfections in the glass.


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