Explosive atmospheres, extreme temperature fluctuations and powerful vibrations are just some of the punishing environmental conditions military communications equipment must endure on the battlefield or in the sky.
Field survivability tests are an effective means to test the equipment’s functionality and ensure Soldier safety, but Army and industry developers also use environmental test labs as a viable alternative to real-life testing.
“Using a lab to replicate the harshest environmental conditions expedites the testing process at a fraction of the cost,” said Christopher Manning, Command Power and Integration, or CP&I, Directorate’s Prototype Integration and Testing Division chief, under the Army’s Communications-Electronics Research, Development and Engineering Center, or CERDEC.
Most importantly, an Army program of record’s test is its final exam; therefore, it makes sense to take a few practice tests in a lab first, Manning said.
The Environmental Test Facility is located in CERDEC’s Command, Control, Communications, Computers, Intelligence, Surveillance and Reconnaissance Prototype Integration Facility, or C4ISR PIF. The facility provides customers with a wide range of capabilities to test design integrity, ensure equipment adheres to military specifications and troubleshoot design prototypes to ensure the most comprehensive equipment reaches the warfighter.
Environmental testing is one component of CERDEC’s testing capabilities designed to help inform requirements that advance Soldier communications capabilities for overall situational awareness.
The most requested environmental test is the vibration test, performed using the electrodynamic shaker to determine how equipment responds to various vibration frequencies.
Project Manager Warfighter Information System, or WIN-T, recently engaged the Environmental Test Facility to test prototyped brackets, which were attached to transit cases and designed to hold communications and network equipment in place onboard a C-17 aircraft during flight.
The brackets remained intact despite enduring violent airborne vibration simulations, but when the engineers switched the profile to simulate ground-based vehicles driving over worst-case rough terrain, some of the brackets cracked.
“The original manufacturer designed the case that the brackets mount to for air transport and certain vehicular vibrations,” said Michael Panko, CERDEC CP&I engineer. “However, the transit cases will be transported by ground vehicle to the aircraft, so it was imperative that they withstood more rigorous vibrations.”
This quick test took very little effort compared to the time and expense WIN-T could have incurred if the brackets had been deployed and then pulled back for redesign, Panko said.
CERDEC CP&I Power Division also required vibration testing for its Enhanced Modular Universal Battery Charger, which provides brigade combat teams with a man-portable and vehicle-mounted capability to charge multiple battery types simultaneously.
“PIF engineers were extremely professional and provided detailed testing expertise in all phases of military environmental standard testing,” said Anthony DeAnni, CERDEC CP&I team leader. “Within weeks, we were able to schedule time in the lab, run the tests and obtain detailed results to validate the charger will meet mission needs.”
High/low temperature and altitude
The Army’s high-tech systems must also contend with fluctuating harsh climates; therefore, high and low temperature and humidity testing is also requested on a regular basis.
These tests expose equipment to temperatures between -130 to 392 degrees Fahrenheit (-90 to 200 degrees Celsius) and can also include altitude testing for up to 100,000 feet. The tests take place in a wide range of chamber sizes to allow testing on the equipment “as is” or integrated into a military wheeled vehicle.
Engineers from CERDEC’s Space and Terrestrial Communications Directorate, or S&TCD, have relied on the Environmental Test Facility for several tests, including a recent high and low temperature test on a signal processing device known as a band reject filter used on a mine-resistant, ambush- protected vehicle, or MRAP.
“Environmental data for this particular filter did not exist, so we were unsure if the filter could perform in extreme temperatures on the vehicle,” said Jerson Zuniga, S&TCD engineer. “After we tested the filter in the chamber, our project manager customer was able to make an informed decision regarding the hardware’s implementation, which ultimately lead to its successful fielding.”
The Environmental Test Facility can also test for a variety of explosive atmosphere conditions. For example, lithium batteries can rupture and vent off gas if they become overcharged, damaged or reach the end of their lifecycle. The violent battery vent simulation test, based on a calculation developed by the Communications-Electronics Command Safety Directorate, quickly releases pressure into an apparatus that holds the battery. Engineers monitor the response to see how fast that box releases the pressure, with the goal of safely releasing the pressure without the box blowing apart or rupturing, creating a dangerous projectile situation.
Explosive atmospheres can also occur mid-flight when fuel fumes inside a cargo or transport aircraft and an effective ignition source are present.
“Something as simple as turning on a radio could create a small spark, and combined with the fumes, could potentially become an explosive mid-air disaster in an instant,” Panko said. “If you are inside a vehicle, taking one or two breaths of those fumes until you can safely exit the vehicle is certainly preferable to being hit with a large piece of shrapnel.”
Engineers conduct this atmospheric explosive test by placing communications equipment into a special chamber, then simulating an explosive atmosphere. If the equipment does not ignite after it is remotely turned on and operated then it passes the test.
In some instances though, customers want to test the equipment’s durability should it be exposed to a blast in an enclosed area. The engineers can intentionally light the atmosphere then safely vent the chamber at the test’s conclusion.
Salt corrosion, high voltage
Salt fog testing is another popular and critical test in the Environmental Test Facility because some metals can begin to corrode after only a few hours of salt-water exposure.
PM WIN-T recently had Environmental Test Facility engineers test the seals and connectors that were part of a new cable design used to deliver power to the Satellite Terminal Transportable system. After placing the cable in the salt fog cabinet for a standard 48-hour test, including intermittent drying times, engineers determined that the surface coating on the connectors was slightly deteriorated in appearance. However, the cable itself remained watertight and testers determined it would not adversely affect the function or electrical characteristics of the connectors.
High voltage testing, also known as high potential testing, ensures cables and equipment remain properly insulated if exposed to over-voltage situations – especially those caused by human error while in use in a dynamic field environment, Panko said.
This process is done in a controlled environment by intentionally exposing the cable to an extremely high electrical voltage – typically five to 15 times the normal operating voltage.
Test process, safety
Department of Defense and industry customers partner with the Environmental Test Facility to test military-built and ruggedized commercial-off-the-shelf products.
“The process to test military or commercial equipment is straightforward,” said Tom Stezar, a PI&T Division branch chief under CERDEC CP&I. “We can schedule and perform tests on short notice because we do not have the typical backlog associated with field-based testing on vehicles and weapons system.”
The Environmental Test Facility capabilities adhere to strict MIL-STD-810 and ISO 9001 mission reliability and quality standards and all measurement equipment is calibrated to the National Institute and Standards Technology traceable standards. NIST standards ensure each piece of communications equipment tested in the lab performs as designed in the most predictable – and the most unlikely — scenarios.
“Deploying equipment that fails on the battlefield can be a dangerous, frustrating and expensive problem,” Panko said. “Investing in a test upfront can save a lot of money in the long run, but most importantly, it can save soldier lives.”