Lansmont Corp. engineers have developed the active impact surface design technology for several test machines currently installed at the Army Research Laboratory in Adelphi, Maryland and the Air Force Research Laboratory (AFRL) located at Valparaiso, Florida’s Eglin Air Force Base.

The 91HITS (Horizontal Impact Test System) simulates an explosion occurring from the side of a vehicle.
Penetrator bombs experience incredible amounts of accel- eration amplitude upon impact. After impact, as the weapon descends through floors of a building or a bunker structure, the intelligent fuse mounted near the rear of the structure determines the exact moment and location when the penetra- tor bomb will detonate.

To begin intelligent fuse laboratory simulations, the AFRL contracted Lansmont to design a fast, vertical shock system that produced extremely high acceleration shock pulses. Lansmont’s HSX20 Shock System has a maximum velocity change capability of 150 feet per second, which simulates con- trollable, programmable impacts at high speeds.

The Lansmont system incorporates an “active” seismic base design, a large steel mass that serves as the impact surface during a shock test. Unlike stationary seis- mic bases, the impact surface is attached to a nitrogen-charged piston and is accelerated towards the falling table dur- ing the shock test. The shock table and impact surface accelerating toward one another significantly boosts the impact energy level.

In addition to the HSX20, the Army Research Laboratory also needed a hor- izontal impact test system which could simulate the energy associated with IED explosions in a controlled laboratory environment. The test system would then be used to design protection sys- tems, including seat structure and restraint systems.

Lansmont’s technology, the 91HITS (Horizontal Impact Test System), simu- lates an explosion occurring from the side of a vehicle, instead of directly underneath. A seated crash test dummy, or device under test (DUT), is mounted to a stationary, floating test sled. Instead of firing the test sled into a rigid mass, the Army required the test sled to remain stationary during test- ing. This eliminates any chances of bias- ing results with high pre-acceleration levels linked to the initial “firing” of the test sled and DUT.

The 91HITS has one bullet and one test sled. The bullet is pneumatically fired into the test sled achieving impact velocity changes as high as 34 mph (15 m/s) and accelerations upwards of 500g. The test takes place within a 20 ft. end-to-end operating envelope, and the event occurs in less than a half-second. After the desired impact, the table and specimen are decelerated by a pneumatic braking system. Each of these violent events is controlled by Lansmont’s TTSII (TouchTest Shock version II) controls, including all sled and DUT shock pulse data.

Finally, Lansmont also created the VITS (Vertical Impact Test System), which Adelphi’s ARL laboratory refers to as the Crew Seating Blast Effects Simulator (CSBES). The system repli- cates and studies the effects of explosive shocks experienced by soldiers inside combat vehicles. A 1200-pound alu- minum “bullet,” fired by a pneumatic piston, impacts the VITS stationary table. In addition, the VITS replicates an initial impact to the feet of the dummy, simulating floor deformation and an ensuing “after shock” coming from the vehicle’s landing, known as “slam down.” The sequence is also controlled using Lansmont’s TTSII controls.

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Defense Tech Briefs Magazine

This article first appeared in the August, 2011 issue of Defense Tech Briefs Magazine.

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