With new understandings of how bones maintain strength, one day we may see bone-inspired materials for more durable products, such as aircraft wings. In addition, these findings may lead to better treatment for diseases such as osteoporosis.
The grid-shaped internal structure of the bone is usually composed of a vertical network of slab-shaped pillars and a thinhorizontal rod-like network of pillars that extends between them. When a bone is all under a single heavy load at a time, much depends on the density of the vertical pillar to determine whether it will break. Previously, it was thought that horizontal pillars had little effect on bone strength.
However, using computer models, researchers at Cornell University recently found that the higher the density of horizontal pillars, the more smaller load cycles the bones bear over time before they break – that is, their long fatigue life.
“If you consider how many low amplitude loads something can withstand, these small transverse tilt pillars are important,” said lead scientist Christopher J. Hernandez. As people age, they first lose these horizontal pillars, increasing the likelihood that the bones will break due to multiple periodic loads. “
To physically test the computer model data, the researchers printed samples of various bone-inspired polyurethane polymer materials in 3D and then repeatedly loaded them through the process. It has been found that by increasing the thickness of the horizontal pillars, the fatigue life of the material can be increased by up to 100 times.
Now the team hopes their findings will inspire artificial materials that are better able to withstand multiple loads throughout their life. Hernandez points out that aerospace materials are a good example, saying: “The wings of an aircraft can withstand thousands of loads in each flight. “
The study was described in a recent paper published in the Proceedings of the National Academy of Sciences. The study could also help guide the development of treatments for degenerative bone disease.