Square tube, square hole

摘要

The TTMA-100 Trailer Truck Mounted Attenuator from Gregory Industries is an innovative and affordable addition to work-zone safety. It is a hitch-mounted NCHRP Test Level 3 trailer that can be equipped to any vehicle in your fleet 10,000 GVW or greater. The ease of use allows the ITMA-100 to be equipped to just about any vehicle in your fleet, thus eliminating the need for dedicated vehicles. Designed for safety and protection in work-zone areas, the TTMA-100 provides a simplified and low-cost alternative to bulky truck-mounted attenuators.The TTMA-100 uses a patented tube-bursting technology to safely dissipate the energy of an impacting vehicle. The concept is simple in design. A tapered mandrel with a square cross section is forced into a square tube with smaller inside dimensions. The mandrel pushes against the inside of the tube, creating outward forces on the inside of the tube, concentrating stresses in the comers and creating a controlled cracking of the steel. As the mandrel proceeds forward through the impact area, the tubes are split into four flat straps of metal that are curled outward by the flared portion of the mandrel. This bursting process dissipates the energy of the impacting vehicle, thus creating a controlled ride down during an impacting event and bringing the impacting vehicle to a slowed stopping point.