A.
A uniform substance doesn’t cope well with knocks because only a small proportion of the material is actually (8) . All the energy from the blow goes towards breaking the material in one or two places, but often the pieces left (9) are pristine (未经破坏的).
B.
But instead of the energy being concentrated in one place, the holes provide many weak spots that all absorb energy as they break, says Vincent. "You are controlling the places (10) the wood breaks, and it can then absorb more (11) , more safely. "
C.
The researchers believe the principle could be applied to any material- (12) example, to manufacture lighter and more protective packaging. It could (13) be used in car bumpers, crash barriers and arm our for military vehicles, says Ulrike Wegst, (14) the Max Plank Institute for Mental Research in Stuttgart. But she emphasizes that you (15) to design the substance with the direction of force in mind. "The direction of loading is crucial," she says.