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Feature - 19 November 2007 (SPG ArmyTech)

Tough Talking Modern warfare requires more technology in the field than ever – and it needs to be mobile as well as rugged. Fleur Doidge reports.

Ruggedised notebooks are the latest products intended to not just meet, but exceed, personnel expectations out in the field. Notebook computers for consumer and business use are at best 'durable' or 'semi-rugged' rather than fully rugged – what this means is that they're slightly less fragile than the non-durable versions. Conversely, truly rugged notebooks are expected to meet a variety of international standards and specifications, the most common being MIL-STD-810F and IP54. MIL-STD-810F is a 539-page US military standard of rating aerospace and ground-deployed equipment for use in battle conditions, according to the item's ability to withstand such factors as vibration, shock and extremes of humidity and temperature. No more than five units of a particular model being tested may be submitted to complete the tests in order to pass MIL-STD-810F. This means that four out of five units may fail any one test for the model and still be awarded the standard. Nevertheless, MIL-STD-810F is the accepted standard and imposes conditions way beyond the capabilities of your average laptop. The tests include spraying water at 50kPa–150kPa at a rate of 10l a minute from 30cm to 50cm away from the unit for one hour, dropping the unit 90cm onto a plywood surface (on a total of 26 different edges, corners or surfaces) and shaking the unit at 20Hz–1,000Hz in different axes for one hour, to simulate the vibrations induced during in-vehicle travel. Also, the units must be dusted with 2kg of talcum per cubic metre at 15°C–30°C and 25%–75% humidity for eight hours, do five operation cycles at -10°C–50°C for 24 hours, and 72 hours non-operational at -35°C–75°C. As if that wasn't enough, for their final trick testers place the units in temperatures moving between 20°C and 60°C with relative humidity of 95% for five 48-hour cycles, repeated every 24 hours. IP54 is about how well the enclosure is protected. A 1mm body must not be able to penetrate the enclosure and dust must not be able to enter in sufficient quantities for the equipment to stop operating safely and satisfactorily. BUILT FOR A LICKING

Some of the rugged laptops that meet both standards and are considered suitable for military use. Keyboards are sealed and protected against water, while the screen itself has a secondary protection layer in front of the LCD. Many also feature a magnesium alloy shell and a case of acrylonitrile butadiene styrene (ABS) compound that's 20 times stronger than traditional notebook plastics. ABS is an oil-based polymer that exhibits strength, rigidity and toughness at -25°C–60°C. Certain grades, with more polybutadiene, have higher impact resistance. It can be attacked by some strong chemicals, including acetone and concentrated sulphuric or nitric acids, and is about twice as expensive as the more commonly used polystyrene. Instead of having a rigid connector for the daughter board or hard drive, some have a flexible one that better absorbs impact. And the case is honeycombed to provide greater strength, with components insulated from each other as much as possible. Rugged notebook vendors also try to incorporate fewer moving parts – such as solid-state drives and special heatsink mesh for cooling, instead of relying on fragile fans that also let dust and dirt inside. Rubber corners and covers . . .


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