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Technical Summary

NCAC 2007-T-006 December 2007

NCAC Vehicle Model Development Update Pick-up Truck Modeling

In March 2007, NCAC took delivery of a 2007 Chevy Silverado Quad-Cab pick-up truck. This vehicle is being reverse engineered by the NCAC staff to meet future research and evaluation needs of both NHTSA and FHWA. NHTSA is very interested in studying the different Secondary Energy Absorbing Systems (SEAS) and will use the resultant model in continued vehicle-to-vehicle compatibility analysis. The FHWAs interest stems from the fact that this vehicle conforms to the large vehicle for the proposed update to the NCHRP 350 roadside hardware crashworthiness criteria.

The new Chevy Silverado model meet the requirements for the proposed AASHTO MASH 08 criteria, although it differs somewhat from the specifications cited in the NCHRP 22-14(2) report which was the basis for MASH 08. The specifications for the two NCAC pick-up truck models and the comparative data from the NCHRP report are provided in Table 1. The Silverado model is heavier than the 2270 kg requirements, but has the appropriate body style and center of gravity. The Ford F250 model represents a heavier vehicle by almost 1300 pounds. It is useful to note that the 2007 Silverado weighs less than the 2002 Dodge Ram 1500 which was the basis for the proposed criteria. Changes in the weight of vehicle models are common between model years.

For the first time, the Chevy Silverado was sent for inertial testing at a commercial lab prior to teardown to provide a new set of data for use in validating and calibrating the FE model that will result from the reverse engineering. The decision to incur the additional costs for the inertial testing was made to support efforts to develop procedures to increase the confidence in FE modeling and crash simulation. The basic results form this testing are provided in Table 2.

Table 1 Comparison of Pickup Truck Specifications

NCAC FE Models Chevy Silverado

Ford F-250

Model Year 2007 2006 Body Type 4 door crew

cab Extended cab

Weight, kg (lbs)

2337 (5152) 2910 (6415)

Wheelbase, in 144 142 CG, in 27.96

NCHRP Project 22-14(2) Report Ford F-250 Dodge Ram 1500

Model Year 2002 2002 Body Type Regular cab Quad cab Weight, kg (lbs)

2286 (5035) 2452 (5356)

Wheelbase, in 137 160 CG, in 28.4 27.4

Table 2 Inertial Testing Results 2007 Chevy Silverado, Inertia test results

Pitch inertia, ft-lb-sec2 4542 Yaw inertia, ft-lb-sec2 4763 Roll inertia, ft-lb-sec2 776

Vehicle CG, in 27.96

NCAC also conducted non-destructive testing of the Chevy Silverado for use in the validation of the model. A series of low speed bump tests were con-ducted at FOIL to gather data for suspension validation. Standard 10x2 speed bump made of recycled plastic was used with an additional 2 support as shown in the Figure 1. The front and rear suspensions were instrumented with accelerometers and string pot potentiometers to measure the rate of suspension deflection. The vehicle was run over these bumps at various speeds for one- and both-side bump positions and the data from the various instruments recorded.

Figure 1 Standard bump for suspension response

tests

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Figure 2 Bump tests for Chevy Silverado

Similar tests were conducted using a Geo

Metro to allow comparisons for small and large vehicles.

Currently, the vehicle is being systematically disassembled and digitized using both traditional taping methods and a laser scanning device to generate surface geometry of the vehicle. The laser device has considerably

reduced the time required to digitize parts. It is expected that the finite element model will include over 900,000 elements. The reverse engineering and frontal impact validation process is expected to be completed by May 2008. Computer images of the cab and frame resulting from these efforts are shown in Figure 3. Small Vehicle

There is a plan to start building a new small car model in late 2008. The current NCAC Dodge Neon small car model is over ten years old and it is out of production. NHTSA has a need for the small car for additional vehicle -to-vehicle compatibility evaluation. Further, the proposed update to NCHRP 350 also calls for a small car in the 1100 kg range. Table 3 below indicates the specifications data that has been gathered for the small compact car segment (from Edmonds website). It can be noted that all but one of the small cars noted meet the 1100 +/-25 kg weight requirement in the proposed update. NHTSA has expressed interest in the Honda Civic to better understand the Advanced Compatibility Engineering (ACE) structure that Honda has introduced in its fleet. The Kia Rio has, however, been the vehicle used in the early crash tests under the proposed update to NCXHRP 350. A final decision on which vehicle will become the next NCAC is pending while these differences are resolved.

Figure 3 Computer images of the cab and frame components of the Chevy Silverado.

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me

ill

act

igid

lt in ifferent post barrier impact behaviors.

Figure 4 Mercedes Smart Fortwo microcar.

Figure 5 Structure of the Mercedes Smart Fortwo

micro car.

Interm

e

sider rrently on the

arket as shown in Table 4.

ediate Vehicle

The NCAC recently completed the validation of a 2001 Ford Taurus. Since there arsuggestions that some crashworthiness testing involve a mid-sized vehicle, it is useful to conthe characteristics of those cu

With Congress is calling for an increasean average fuel economy of 35 mpg by 2020 new vehicle types have been proposed and soare even appearing in the market place. New micro-cars (subcompacts) are expected to gain traction in the U.S. due to their improved stylingand superior fuel economy. The Smart Fortwo car from Mercedes which weighs only 750 kg wstart selling in the US in 2008 (see Figure 4). With the growing number of small sub-compcars entering the US fleet, the compatibility between these vehicles and roadside hardware needs to be addressed. Further, these microcarsare expected to rely on a significantly more rstructure (see Figure 5) which may resu

m

d

Figure 6 Views of the NCAC Ford Taurus Model

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Table 3 Summary of small car specifications for current models.

Make & Model Model

Year Curb Weight Kg

Wheelbase, in

Length, in Width, in Engine

Kia Rio 2008 1090 98 167 67 1.6 L 4 cyl Honda Fit 2008 1140 97 157 66 1.5 L 4 cyl Toyota Yaris 2008 1055 100 169 67 1.5 L 4 cyl Mini Cooper 2008 1155 97 146 66 1.6 L 4 cyl Chevrolet Aveo 2008 1148 98 170 67 1.6 L 4 cyl Scion Xb 2008 1400 102 167 69 2.4 L 4 cyl Honda Civic 2008 1220 106 177 69 1.8 L 4 cyl Ford Focus 2007 1196 103 175 67 2.0 L 4 cyl Toyota Corolla 2008 1177 102 178 67 1.8L 4 cyl Smart Fortwo 2008 750 74 106 61 1.0L 3 cyl

Table 3 Summary of mid-sized car specifications for current models

Make & Model Year Curb Weight (kg)

Wheelbase (in)

Length (in)

Width (in)

Ford Taurus 2001 1521 109 198 73 Honda Accord 2008 1492 110 194 73 Toyota Camry 2008 1500 109 189 72 Ford Fusion 2008 1443 107 190 72 Chevy Malibu 2008 NA 112 192 70 Kia Optima 2008 1442 107 186 71 Nissan Altima 2008 1418 109 190 71 Mits. Galant 2008 1555 108 191 72 Pontiac G6 2008 1499 112 189 71

For More Information: See the NCAC Website (www.ncac@gwu.edu) for more information including: A PowerPoint file providing the trace plots and

animations is available for downloading. Information on other NCAC efforts Or, contact: FHWA Roadside Safety Team Dr. Ken Opiela, PE (Team Leader) 202-493-3371 kenneth.opiela@fhwa.dot.gov

NCAC Staff Dr. Steve Kan, Director 703-726-8511 cdkan@ncac.gwu.edu Dr. Dhafer Marzougui 703-726-8532 dmarzoug@ncac.gwu.edu This Technical Summary was produced under Cooperative Agreement DTFH61-02-X-00076 Operation & Maintenance of the FHWA/NHTSA National Crash Analysis Center between FHWA and George Washington University.