YPG becomes shock testing site for U.S. Navy

  Yuma Proving Ground may be located in the middle of desert, but now has a new, if unlikely, moniker: certified naval test site.

  The U.S. Navy has added YPG to its list of approved testing facilities. Earlier this year, a guided munition designed for use at sea was subjected to shock testing on YPG's new lightweight shock machine built by HiTest Laboratories of Arvonia, Va.

  All machinery and structures on military vessels undergo shock testing to simulate the vibration caused by underwater explosions encountered in naval combat.

  A large shock can cause sudden catastrophic damage to a piece of equipment, and numerous lower-level shocks can cause incremental fatigue failure that reduces the service life of an item.

  Military requirements mandate that equipment used on naval vessels be able to withstand multiple shocks of 25 Gs. YPG's shock machine can deliver shocks in excess of 100 Gs.

  The U.S. Marine Corps' desire to co-locate this capability with other munitions testing prompted the construction of the shock testing machine.

  Typically, a tested projectile is destroyed after completion of a test. The Marine Corps, however, wished to confirm the effectiveness of rounds after being exposed to shock.  

  It was deemed cost-effective by the Navy to construct a lightweight shock testing machine at YPG, then fire the tested projectile on site. The proving ground boasts the longest overland artillery firing range in the nation.

  The lightweight shock testing machine was originally developed in Great Britain in 1939 and first constructed in the United States by General Electric a year later.

  The apparatus is 13 feet high and uses a falling weight and swinging pendulum to strike an anvil plate with a 450-pound hammer traversing an angle from a height of one, three or five feet. 

  The anvil plate can accommodate payloads (including fixtures) that weigh up to 550 pounds, though typical payloads are 250-300 pounds. An electric solenoid triggers the hammer's drop from an adjacent control panel when nonexplosive items are being tested.

  If ordnance is being tested, testers trigger the drop from a bunker 1,800 feet away.

  The steel trailer used for this is protected by an armor-plated structure surrounded by a concrete wall and an earthen berm. In this instance, testers view the drops via television monitors.  The standard test requires that the tested item be subjected to the shock of nine drops of the 450-pound hammer. 

  YPG officials were first approached about the possibility of bringing a lightweight shock testing machine to the proving ground early last year. The frame and steel reinforcements for the machine's concrete foundation arrived during the 2007 summer months, and concrete was poured by October. 

  The presence of sophisticated test infrastructure, including the ability to precondition ammunition to temperatures ranging from below 65 degrees Fahrenheit to 145 degrees Fahrenheit, made coming to YPG a cost-effective decision, Navy officials said.

  YPG anticipates additional funding in the near future will enable several upgrades to the site, including fiber optic cable for the control room and a structure to better control test temperatures. Sufficient demand will allow the proving ground to acquire a medium-weight shock machine that uses a 2,000-pound hammer to shock palletized loads or other objects weighing several tons.

  "We're on the West Coast. We have more resources than anybody in the private sector at our fingertips," said Dominick Salafia, lead engineer for the Metrology and Simulation Division at YPG. "We offer the testing community many unique capabilities and a great deal of expertise in testing munitions and unusual items."

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This story previously appeared in The Outpost, the newspaper of Yuma Proving Ground.