Development of a New Braking System for a Horizontal Sled Used in Crash Tests with an Imposed Deceleration

In crashworthiness, experimental tests with an imposed deceleration are customary. At LAST Crash Labs, Politecnico di Milano, Italia, an oleopneumatic braking system is currently used to arrest with a prescribed deceleration profile a trolley running on a horizontal sled. Unfortunately, this system is rather costly, difficult to regulate and complicated time profiles are out of reach. In effort to overcome these drawbacks, a different braking system is under development. The basic idea is to arrest the trolley by means of a number of irons bars (here called deceleration beams) with different lengths and placed at different distances the ones from the others. The concept is rather simple, but difficult to realise. Core of the system is the constraint system meant to slow down the trolley by deforming the deceleration beams. Static and dynamic tests initially carried out to develop the new braking system were also used to validate a numerical model that was eventually used to perfect the braking system. A numerical scheme was worked out so that, fixed an arbitrary deceleration profile, it were possible to decide the test set-up that guarantees a deceleration close to the fixed one.