Modeling Crushable Foam for the SAFER Racetrack Barrier

Roadside Safety at theUniversity of NebraskaKarla LechtenbergResearch Associate Engineer

Midwest Roadside Safety FacilityUniversity of Nebraska Lincoln

October 31, 2015

Midwest Roadside Safety Facility

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Midwest Roadside Safety FacilityStarted in the late 1980s at UNLPurpose Improve safety along our nations roadwaysDesign, simulation, and testingClientsState DOTs, FHWA, private industry, and motorsports organizations

Midwest Roadside Safety Facility

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Roadside Safety in a NutshellTest systems to protect vehicles departing the roadDevelop new systems to meet performance standardsUpdate and improve existing systemsDetermine where DOTs should use safety hardware

Midwest Roadside Safety Facility

Our job is to make sure that when you get in the vehicle, you can be safe even when you get in an accident. That means that whenever you see something on the side of the road, if it was designed and tested by MwRSF or another performance testing agency, that device or system has been tested to make sure that it meets the qualifications of testing recommendations, and when it is hit at travel speeds, you will be protected.

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Why Roadside Safety?

Midwest Roadside Safety Facility

Why Roadside Safety?

Midwest Roadside Safety Facility

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Why Roadside Safety?Approximately 30,000 vehicle accident fatalities per year30% of these involve run off road accidentsEstimated cost have reached well over $50 billion annually

Midwest Roadside Safety Facility

Roadside Safety is Working

Midwest Roadside Safety Facility

Roadside Barrier Test StandardsSmall car and pickup trucks62 mph25 impact angleSingle unit trucks (U-Haul)56 mph15 impact angleTractor-trailer (Semis)56 mph15 impact angle

Midwest Roadside Safety Facility

But we dont get to test all of it to our own standards. We follow the government recommendations for what a barrier system should do. The small car and pickup tests are done with little Kia cars or Dodge Ram pickups, usually. But the single unit trucks and semi trucks are the big crashes.8

Roadside Safety DevicesTypes of DevicesEnd terminals and crash cushionsFlexible barriersSemi-rigid barriersRigid barriers (i.e. concrete bridge rails)Portable and permanent signsPolesRace track safety

Midwest Roadside Safety Facility

Evaluation CriteriaStructural adequacyVehicle must be contained or redirected back toward roadwayVehicle trajectoryVehicle cannot go through the barrierVehicle cannot touch ground behind barrierVehicle must remain upright (no rollover)Occupant safety requirementsOccupant deceleration limitsOccupant compartment integrity

Midwest Roadside Safety Facility

Before we show you the tests, wed like to show you how we evaluate the safety performance of the system. Basically, it comes down to this: if the vehicle breaks through the barrier, rolls over, or stops too fast, it fails. As long as it stays on its wheels and the barrier system doesnt stop the vehicle too fast or let it through, then the test is a pass!

Now, use your new test evaluating skills to guess pass or fail on a single-unit truck test.10

Structural Adequacy

Midwest Roadside Safety Facility

Vehicle Trajectory

Midwest Roadside Safety Facility

Vehicle Trajectory

Midwest Roadside Safety Facility

Occupant Safety

Midwest Roadside Safety Facility

Occupant Safety

Midwest Roadside Safety Facility

Vehicles pulled by tow-trucks with either 2:1 or 6:1 pulley system

Midwest Roadside Safety Facility

We pull the cars using duelie trucks. We can either pull with a 6:1 or 2:1 mechanical advantages, which means that the pulling vehicles either go 1/6 or the speed of the pulled vehicle. This one is an IRL car with a 6:1 advantage.16

Bullnose Guardrail

Midwest Roadside Safety Facility

Design Requires Patience ...

Midwest Roadside Safety Facility

The Payoff

Midwest Roadside Safety Facility

Real World

Midwest Roadside Safety Facility

W-beam Guardrail

Midwest Roadside Safety Facility

Midwest Guardrail System

Midwest Roadside Safety Facility

Guardrail over Curb

Standard guardrail over 4 curb Midwest Guardrail System (MGS) over 6 curb

Midwest Roadside Safety Facility

MGS Bridge Rail

Midwest Roadside Safety Facility

Guardrail to PCB Transition25Guardrail and PCB often connected to form work zonesNo crashworthy connection existsDevelop MASH TL-3 transition between W-beam guardrail and F-shape PCBs

Midwest Roadside Safety Facility

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LS-DYNA No Transition26

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Simulation of Concepts27Evaluate conceptsCaptureSnagStabilityPocketingModify until transition meets MASH TL-3Evaluate CIP

Midwest Roadside Safety Facility

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Guardrail to PCB Transition

Midwest Roadside Safety Facility

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MGSPCB-129

Test no. 3-21Evaluate snag and pocketingCenterline of 5th guardrail post from end-shoe

5 4 3 2 1

Midwest Roadside Safety Facility

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MGSPCB-2Test no. 3-20Evaluate vehicle extension under rail and combined loading on guardrail

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Midwest Roadside Safety Facility

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MGSPCB-231

Midwest Roadside Safety Facility

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MGSPCB-232

Midwest Roadside Safety Facility

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MGSPCB-333

Test no. 3-21 ReverseEvaluate stability, capture, and reverse snag

Midwest Roadside Safety Facility

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Questions???

Midwest Roadside Safety Facility