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For many years, turned-down guardrail terminals have been constructed as a safety treatment for W-beam guardrails. This terminal is designed to drop down and allow vehicles impacting the end of the barrier to slowly ride up onto the guardrail and come to a controlled stop. However, testing has indicated that the rail element does not always release properly, thereby causing mini-size vehicles to rollover. This research study involved the development of several retrofit concepts for the turned-down guardrail terminal. The primary focus of this effort involved the development of a mechanism that allows the W-beam rail element to release at a lower force and thereby improve its performance during small car impacts. The major focus of this paper is to share the complicated modeling effort required for successful simulation of the vehicle-guardrail impact and its' redesign.

Full scale testing of a vehicle to assess its side impact crashworthiness is often difficult since it requires the use of sleds or moving barriers to simulate the impact. This work describes a method developed in which the vehicle is dropped sideways from any given height onto any type of object in order to simulate a side impact. Results indicate that the drop test methodology is acceptable for determining if an automobile provides adequate crush resistance and whether or not if protruding objects will injure the occupants of the vehicle. Energy analysis of the drop side impact revealed that the weight of the car increased the work done by crushing by about 16%. By varying test parameters, such as drop height, impact angle and barrier type, different real world conditions can be effectively simulated.

Past studies have shown the applicability of advanced numerical methods for crashworthiness simulation. Lumped parameter (LP) modeling and finite element (FE) modeling have been demonstrated as two useful methodologies for achieving this endeavor. Experimental tests and analytical modeling using LP and FE techniques were performed on an experimental vehicle in order to evaluate the compatibility and interrelationship of the two numerical methods for crashworthiness simulation. The objective of the numerical analysis was to simulate the vehicle crashworthiness in a 0 degree, 48.6 KPH frontal impact. Additionally, a single commercial software, LS-DYNA3D, was used for both the LP and FE analysis.