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Remote Test Site

aerial view of the CHES facility
Aerial view of SRI's remote test site.

Experiments in areas such as weapons effects, evaluating hazards and safety issues, and basic science are conducted at SRI's Corral Hollow Experiment Site (CHES) remote test facility by experienced Poulter Laboratory engineering and analytical support staff.

The site is available for use on commercial, foreign government, and U.S. government contracts. Five separate explosive firing areas are active year-round and supported by long-term staff.

The test site receives additional support from SRI headquarters in Menlo Park, California. Consulting physicists, engineers, and technicians from Poulter Laboratory and other R&D groups visit regularly to collaborate with and guide staff in achieving experimental goals.

Experiments performed at the site vary widely. Simple experiments can be conceived, designed, and conducted in a day to obtain urgent information for a client, or complex experiments can be designed, fabricated, and conducted over months. Some experiments may entail participants from a team of agencies and contractors, using many instrument channels and test articles that are custom-built at SRI or elsewhere. The most common experiment is a precision test to validate computer codes by obtaining reliable data under well-defined conditions. Experiments are also conducted to evaluate specific client systems and provide expert guidance for overall system optimization.

The 480-acre site is fully developed, with permanent buildings, roads, and utilities, including commercial electrical power, running water, and telephone lines. On-site support for experiments is provided by these resources:

  • Machine shop
  • Welding shop
  • Carpenter shop
  • Earth-moving equipment
  • Large inventory of hardware, equipment, and material

Accommodations include temperature-controlled office space, meeting rooms, a kitchen, and showers.

drop tower facility
SRI's precision-impact drop tower facility

Precision Impact Drop Tower Facility

SRI has constructed a 28-m-tall drop tower facility that provides precision impact testing. The drop tower is ideal for evaluating the impact damage to vehicles, aircraft, and helicopters and for determining the severity of injuries to passengers through the use of instrumented crash dummies. The drop tower can also be used to evaluate damage to inert ordnance casings and other packaging systems.

The facility consists of a vertical guide rail that supports a specially designed sled attached to the test article. The combined guide rail and sled maintain a precise test article drop orientation to produce an impact orientation within 1 degree of the desired value. Depending on the required rigging to lift the test article into position, the facility can accommodate a drop height of up to 25 m with a test article weighing 10,000 lb. To achieve higher impact velocities associated with higher desired drop heights, commercial off-the-shelf (COTS) rocket motors are added to the test article to increase its downward acceleration. Associated with the drop tower facility are a wide variety of instrumentation capabilities, including acceleration, strain, and stress. The impact event is recorded with up to four Phantom high-speed video cameras.

Explosive Shock Tube Facility

SRI operates one of the largest explosively driven shock tube testing facilities in the United States. The 8-ft-diameter, 257-ft-long shock tube can be used with up to 100 lb of explosive strands distributed in the driver end to simulate typical long-duration airblast environments produced by large explosion sources such as nuclear explosions or vehicle-borne improvised explosive devices (VBIEDs).

shock tube facility
SRI's shock tube facility

Explosive charges can also be tailored to produce airblast loads that simulate a vapor cloud explosion (VCE) or situations in which the time histories of both static and dynamic pressures, including the negative phase, have to be matched simultaneously. Longer pulse duration and weaker negative phase can be achieved by closing the driver end of the shock tube.

In its current configuration, the shock tube can produce airblast environments ranging from 100 psi peak pressure and 30 ms positive phase duration to 3 psi peak pressure and 200 ms duration. Expansion of the shock tube diameter to 12 ft is planned to make it ideal for testing full-size windows, blast panels, and anthropomorphic test devices (ATDs) as well as scaled models of larger structural systems.

The facility is supported by an experienced engineering and technical staff, who use dynamic instrumentation equipment to measure the free-field static and stagnation pressures as well as the force, stress, strain, and acceleration experienced by structures exposed to the airblast. Four high-speed video cameras are available to capture the overall target response and enable measurement of the speed and size of fragments produced by failing and disintegrating structures. The relative amplitudes of static and dynamic pressures can be controlled by introducing gases other than air in longitudinal sections separated by thin foils between the driver and the test point. Validated hydrocode computations are performed to design the explosive driver and the length and density of various gas mixtures that must be used to achieve simultaneous matching of static and dynamic pressures at a prespecified test point.