Before naval equipment is installed on ships, it needs to be tested to ensure it can withstand years of wear and violent shock. Just an hour north of the College, Hi-Test is one of only two private companies in the U.S. that has the machines and equipment needed to perform this testing on some of the largest units that eventually end up on our warships. The company has the largest vibration table of its kind in the country, and it has the barges, quarry holes, craftsmen, and engineers needed for a wide range of explosive shock testing.
As test engineer Matt Dolan explained during the tour, shock and vibration testing are performed on computers, antennae, engines, rocket mounts—almost every piece of equipment that is installed on U.S. Navy ships and submarines. Government contractors build the equipment according to government standards and then send it to Hi-Test for rigorous trials to test its structural and operational integrity. Ships’ propellers cause vibrations at various frequencies, some of which may cause equipment to break or stop functioning, and warships need to continue operating even if mines, torpedoes, depth charges, or other forces send shockwaves through the hulls.
Hi-Test performs heavyweight shock testing in old slate quarries that have filled with water. The extreme depth of the quarry holes is ideal for testing, as the initial shockwaves and their reflections from the bottoms of the holes are easily distinguishable on monitoring equipment. Units are bolted to fixtures and large steel decks, which are lowered by crane into custom-fabricated barges. The barges are then pulled out into the middle of the quarry holes, where High Blast Explosive (HBX) charges are set at varying depths and distances from the barge. Accelerometers are attached to the equipment and fixtures to monitor g-forces.
Students also viewed the large vibration table, essentially a 29,000-lb. aluminum box that rests on four stout airbags. An internal steel axle with hanging adjustable weights rotates at different speeds to create various frequencies of vibration.
Other discussions on the tour included instructional reviews of torque, potential energy, kinetic energy, as well as in-depth examinations and demonstrations of medium-weight and lightweight shock machines. Some students may explore possible summer internships at Hi-Test to gain a better perspective on their future careers in engineering or Defense Department testing.