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Development of a new energy-absorbing roadside/median barrier system with restorable elastomer cartridges

Jennifer D Schmidt, University of Nebraska - Lincoln

Abstract

A Manual for Assessing Safety Hardware (MASH) Test Level 4 (TL-4) energy-absorbing, urban roadside/median barrier was developed to reduce lateral vehicle accelerations below those observed during similar crashes into permanent concrete barriers. Several types of energy absorbers were evaluated for use in this barrier. Elastic polymers, or elastomers, have superior restorability, reusability, compressibility, and resistance to environmental effects. Although many shapes were explored, conical-shaped, cylindrical-shaped, and shear fender elastomers were found to be the most efficient in terms of size, weight, ease of use, and energy absorption. Finite element analysis simulations were used to further study the energy absorption and deflection of the elastomer shapes. One point nodal pressure tetrahedron solid elements accurately modeled the deformation of rubber. The best elastomer material models in LS-DYNA were the Simplified Rubber/Foam and the Blatz-Ko Rubber models, which were validated through component tests. Component tests were conducted at 5 mph on (1) an 80-durometer, 2-in. thick cylinder, (2) a 60-durometer, 2-in. thick cylinder, and (3) an 80-durometer, 1-in. thick cylinder. Components tests were also conducted at speeds varying from 5 mph to 15 mph on a 16-in. high, 14-in. wide, and 22-in. long marine shear fender. ^ The final design consisted of an open concrete rail with shear fender rubber posts that are anchored to a concrete foundation. The precast concrete beams measured 22 in. wide, 20 in. tall, and 20 ft long and were spliced on top of 16-in. high, 14-in. wide, and 22-in. long shear fender posts, which were spaced at 10 ft on center. Finite element analysis simulations also demonstrated that lateral vehicle accelerations were reduced by up to 33 percent for a MASH TL-4 small car impact and up to 29 percent for a MASH TL-4 pickup truck impact into the new barrier as compared to a rigid concrete barrier. Simulations also demonstrated that the new barrier had adequate capacity to contain the MASH TL-4 single-unit truck. The cost of the barrier was estimated to be $175/ft. The barrier should be further evaluated using finite element simulations and full-scale crash testing.^

Subject Area

Engineering, Civil

Recommended Citation

Schmidt, Jennifer D, "Development of a new energy-absorbing roadside/median barrier system with restorable elastomer cartridges" (2012). ETD collection for University of Nebraska - Lincoln. AAI3546814.
http://digitalcommons.unl.edu/dissertations/AAI3546814

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