Cancellous bone inspires engineering strategies for prolonging material life.
A recent discovery of how cancellous bones bounce back after breaking could lead to new materials that continue to perform after suffering damage.
With a sponge-like exterior and brittle interior, cancellous bones near joints and in the vertebrae have material heterogeneity. Cornell engineers have determined that this property is what allows bones to recover after a break, an ability artificial materials lack.
Cancellous bone directs cracks to other locations to preserve its structure and recover its shape after a break. By studying this type of healing, the engineers were inspired to devise strategies capable of extending the life of defective materials.
Once a break occurs, materials tend to fall apart and lose their functionality. Surface treatments have been developed by engineers to protect car and aircraft parts from cracks and eventual product failure. However, implementing restructuring techniques based on cancellous bone opens the possibility for materials that can maintain their structural integrity despite cracks.
“We used to think that we had cancellous bone for the same reasons that we use foams in engineering, to absorb energy or make the structure more lightweight,” said Chris Hernandez, associate professor of mechanical and aerospace engineering. “But it turns out that cancellous bone does something different. The way cancellous bone breaks actually makes it heal better.”
Bones undergo microscopic fractures just from everyday movements. As a result, they are in a constant state of repair. This was thought to explain why the elderly have an increased risk of broken bones from falling. However, the Hernandez group determined that the material heterogeneity of cancellous bones is what limits crack propagation and eventual failure.
Engineering Applications and Beyond
In addition to car and aircraft parts, this discovery can be applied to skids in chemical processes. Common failures are present in pump parts, valves, pipes, and even the totes from forklift damage.
According to researcher Johnathan Matheny, the insights gained from this research can also be applied in medicine, “to help us identify people at risk for an osteoporosis-related fracture and prescribe drug treatment.”
The research is published under the title “Material heterogeneity in cancellous bone promotes deformation recovery after mechanical failure” in the Proceedings of the National Academy of Sciences.
