October 24, 2013
Researchers Develop Bomb Detection System Using Sound Waves
Lee Rannals for redOrbit.com - Your Universe Online
Researchers at the American Society of Mechanical Engineers Dynamic Systems and Control Conference have developed a remote bomb detection system that can identify whether a bomb contains low-yield or high-yield explosives.The device is the first remote bomb detection that is able to discern between these two parameters. Existing methods require the user to get really close to the suspicious object, but the latest device is a remote acoustic detection system, allowing the operator to stay farther away.
“The idea behind our project is to develop a system that will work from a distance to provide an additional degree of safety,” Douglas Adams, a Distinguished Professor of Civil and Environmental Engineering at Vanderbilt University, said in a statement.
The researchers are developing the acoustic detection system as part of a major Office of Naval Research grant. The new system consists of a phased acoustic array that focuses an intense sonic beam at a suspected improvised explosive device.
One instrument known as a laser vibrometer is aimed at a suspicious object’s casing and records how the casing is vibrating in response. The nature of the vibrations detected can reveal a number of things about what is inside the container.
“We are applying techniques of laser vibrometry that have been developed for non-destructive inspection of materials and structures to the problem of bomb detection and they are working quite well,” Adams said.
For current experiments, the team used an inert material in a target that simulates the physical properties of low-yield explosives. Another target was made from a simulant of high-yield explosives. Both targets were fastened to acrylic caps to simulate plastic containers, and mechanical actuators substituted for the acoustic array to supply the sonic vibrations.
Tests showed differences in the vibration patterns of the two caps that allowed the team to distinguish between the two materials.
Another test showed that the remote acoustic detection system can differentiate between an empty container and one filled with water or a clay-like substance. The test used a one-gallon plastic milk container, and acoustic waves were produced by a device called an air driver. The empty jug had the largest vibrations, while the jug with the clay-like material had the smallest.
The team has established that the best way to detect suspicious devices made of rigid material like metal is to use short ultrasonic waves. Longer subsonic and infrasonic waves can be used to penetrate softer materials like plastics. The team will be continuing their study to determine which frequencies better penetrate cloth materials.