Posted October 5th, 2010
The National Science Foundation’s (NSF) web site posted an article today about Dr. Nikhil Gupta’s NSF-supported research “that reveals surprising insights about the effect of compression on bones, and about the limitations of the foams used for protection in helmets and armor.”
Dr. Gupta is an NYU-Poly materials scientist and mechanical engineer. Paulo Coelho, a New York University College of Dentistry materials scientist, is his collaborator on the research.
Below is an excerpt from the article. To read it in full, go to NSF.gov.
Gupta and Coelho found that bone injuries differ dramatically depending on the speed at which the bone is compressed. At high compression rates — like a shock wave from a bomb blast or a hard hit in a football scrimmage — bones show widespread micro-cracks so small they can only be detected by a scanning electron microscope.
When bones are compressed slowly, as when jogging or falling, fewer cracks occur, but they tend to be larger and easily spotted. The experiments were conducted on rabbit femur bones, though the scientists believe similar findings would apply to a range of human bones.
"We were surprised to find that not only did the nature of the bone fractures change depending on the speed of compression, but that bones crack in different directions based on speed," Coelho said. Learning that bones need to be reinforced from multiple angles to prevent injury brought Gupta back to the initial impetus for his research — improving the foams used in protective military gear.