How spider webs achieve their strength

The silk that spiders use to build their webs, trap their prey and dangle from your ceiling is one of the strongest materials known.

Photo: Francesco Tomasinelli and Emanuele Biggi

But it turns out it's not simply the material's exceptional strength that makes spider webs so resilient; it's the material's unusual combination of strength and stretchiness - silk's characteristic way of first softening and then stiffening when pulled. These properties, scientists have found, vary depending on the forces applied, as well as on the overall design of the web.

Markus Buehler, an associate professor of civil and environmental engineering (CEE) at MIT, has previously analysed the complex, hierarchical structure of spider silk and its amazing strength - on a pound-for-pound basis, it's stronger than steel.

Now, Buehler and his colleagues have applied their analysis to the structure of the webs themselves, finding evidence of the key properties that make webs so resilient and relating those properties back to the molecular structure of silk fibers.

The lessons learned from this work, Buehler says, could not only help develop more damage-resistant synthetic materials, but could also provide design principles that might apply to networked systems such as the Internet or the electric grid.

A paper describing the new findings has been published this week in Nature. In addition to Buehler, the study was carried out by CEE graduate students Steven Cranford and Anna Tarakanova, and Nicola Pugno of the Politecnico di Torino in Italy.