last may This was revealed by researchers from the US Naval Research Laboratory in Washington, DC elastic reaction and designed gradient materials can be combined to make extremely effective acoustic metamaterials, According to Physics today.
What are acoustic metamaterials? They are advanced materials that can effectively block sound using only their geometry. The question is, can they do it without disrupting the airflow?
In March 2019, researchers from Boston University, Xin Zhang, a professor at the College of Engineering, and Reza Ghaffarivardavagh, Ph.D. student in the Department of Mechanical Engineering, present a document demonstrating an acoustic metamaterial that can effectively cut out sounds while maintaining airflow.
“Today’s sound barriers are literally thick heavy walls,” Gafarivardava said at the time. The researcher decided that there should be a better, more efficient way of suppressing noise than materials and continued to design it.
This new method is especially useful in situations where thick heavy walls cannot be used as a jet engine outlet. A jet engine barricade is not an option, so the crew around it wears earplugs to protect their hearing from the powerful roar.
But what if there was a way to allow the airflow of the jet engine while blocking the sound? Zhang and Gafarivardava invented an acoustic metamaterial that could do just that.
They used 3D printing to materialize an open structure made of plastic and continued to test it with a speaker. The attempt was a hit, as the speaker exploded at an annoyingly high noise level, but nothing was heard at all! The noise-canceling acoustic metamaterial worked.
Zhang’s team said they were delighted with the success of their test. “We’ve seen similar results in our computer modeling for months – but it’s one thing to see simulated computer sound pressure levels, it’s another to hear its effects yourself,” said Jakob Nikolajczyk, co-author of the study and a former student researcher in the laboratory. Zhang.
Further research by the team showed that they could block 94 percent of the noise of absolutely everything. The new development has many applications from aircraft to drones to construction. The study was published in the journal Physical examination B.
For more examples of acoustic metamaterials be sure to read our article on the topic.