Shock absorption based on woodpeckers

Edit Hook

Researchers Sang-Hee Yoon and Sungmin Park at the University of California, Berkeley, have designed a bio-inspired shock-absorbing system to protect commercial micromachined devices from unwanted high-g and high-frequency mechanical excitations. The new shock-absorbing system consists of close-packed microglasses within two metal enclosures and a viscoelastic layer fastened by steel bolts.

Key Differentiators

According to the paper referenced below, "this bio-inspired shock-absorbing system shows a failure rate of 0.7% for the commercial micromachined devices at 60 000 g, whereas a conventional hard-resin method yields a failure rate of 26.4%, thus verifying remarkable improvement in the g-force tolerance of the commercial micromachined devices."

Biomimicry Story

When a woodpecker is establishing its territory, it pounds its beak into an often hollow tree to create a knocking sound that carries a long distance. According to the article referenced below, "A woodpecker is known to drum the hard woody surface of a tree at a rate of 18 to 22 times per second with a deceleration of 1200 g, yet with no sign of blackout or brain damage." The researchers studied what happens to a woodpecker during drumming, and what protects its brain. They concluded that "the woodpecker dissipates the mechanical excitations generated from drumming with its unique endoskeletal structures such as its beak, hyoid, spongy bone, and skull bone." This information led them to mimic the qualities of those structures to create their shock-absorbing system: "The shock-absorbing mechanism of the woodpecker suggests that the g-force tolerance of micromachined devices can be improved by: (i) an external layer with high strength which protects the micromachined devices from physical damage (e.g. deformation, fracture, etc) like the woodpecker’s beak; (ii) a viscoelastic layer which evenly distributes incident mechanical excitations like the hyoid; (iii) a porous structure with resilience rigidity which suppresses high-frequency mechanical excitations and prevents transmitted ones from being concentrated into the micromachined devices like the spongy bone; (iv) another high-strength layer which contains a porous structure like the skull bone."Reference article: Yoon S-H; Park S. 2011. A mechanical analysis of woodpecker drumming and its application to shock-absorbing systems. Bioinspiration and Biomimetics. 6: 1-12.

Challenges Solved

A mechanical shock is known to seriously deteriorate the linear operation of any spring–mass-type micromachined device and even to physically damage the micromachined device. Yoon and Park sought an alternative to current shock-absorbing systems. Shock attenuators have either been too bulky, don't work at high temperatures, or won't work for micromachined devices.

Edit Summary