ABERDEEN PROVING GROUND, Md. — The future of the Army's land vehicles is taking shape on a cement slab on a grassy field at Aberdeen Proving Ground, where a medium-caliber gun blasts away at point-blank range at an aluminum hull hung with pads of exotic new armor plate.

After the murderous fire pierces, bends and shreds the protective materials, Army engineers study the damage and draw lessons for the next try.

It's all part of a high-stakes effort to develop lightweight composites that outperform traditional steel.

The research is intended to help create vehicles that are light and mobile enough for 21st-century battlefields, yet can adapt to diverse and changing threats, said Thomas Killion, deputy assistant Army secretary for research and technology and the Army's head scientist.

"You could put really heavy armor on a vehicle that would protect it against all threats, but if you can't move, the vehicle becomes rather dysfunctional," Killion said.

One analyst applauded the Army's approach.

"The basic approach is a sound one, particularly in terms of designing a vehicle that you can swap armor on as the threat environment changes," said Thomas Donnelly, a defense and security policy analyst at the American Enterprise Institute, a Washington think tank.

Army Research Laboratory engineers at the sprawling base on the Chesapeake Bay created the battle-tested composite used in the Army's Frag Kit 6 that protects some Mine Resistant Ambush Protected vehicles. Defense News, a sister publication of Army Times, was granted unprecedented access to the facilities.

The engineers are creating and testing hundreds of new combinations of lightweight materials in search of the next generations of armor plate.

The new armor derives its strength not just from the materials' properties, but also by the way they are blended. Some of the materials — such as fiber, fiberglass and ceramics — are woven together.

"Fibers flex and give elasticity," said Ernest Chin, Army Research Laboratory's chief of survivability materials branch. "They stretch and weave so they can catch projectiles."

Others — ultra-high-molecular-weight polyethylene, silicon carbide, resin and epoxies — are melted in an oven to make a single solid substance.

Metals may be joined by a new procedure called friction stir welding, which heats up panels' border areas and promises to eliminate seams.

"This can give us the desired platform and weight in the vehicle, better blast protection and a nice smooth surface," Chin said.

The Army plans to develop three generations of composite armor that will culminate in the panels that will protect the 27-ton Manned Ground Vehicle when it arrives in 2015.