The National Crash Analysis Center The George Washington University Un-Constrained Models Comparison For Elastic Roof – Production Roof – Strong Pillars Properties; Roadbed Weights & Speeds Jan 27, 2011 Prepared by: Fadi Tahan (703)

Slide 2 Study Overview  FE Model  Model Validation to Static Tests (NHTSA test number C0139 & C0140)  Un-Constrained Model Set up  Different Roof Property Simulations  Different Roadbed Weight Simulation  Deformable Roof  Elastic Roof  Different Roadbed Speed Simulation  145° Initial Roll Angle  180° Initial Roll Angle 5/17/2015

Slide 3 5/17/2015 FEA Model  The Finite Element model of a 2003 Ford Explorer was used  The suspensions, drivetrain and engine were removed to reduce the model (shown in yellow)  The weight and inertia of these parts were replaced by adding concentrated mass and inertia elements at six points on the ladder frame (shown in red) Full Model Reduced Model

Slide 4 Model Validation - Based on FMVSS 216 Tests 5/17/2015 Validation to NHTSA test number C0139 Validation to NHTSA test number C0140 5° Pitch; 25° Roll10° Pitch; 45° Roll

Slide 5 5/17/2015 Roof Material Properties Effect On Un-Constrained Model (Elastic Roof – Production Roof – Strong Pillars Properties)

Slide 6 3 Different Roof Models – Material Change 5/17/2015  Elastic Roof Model; SWR is measured to be 3.9 Components shown in blue have pure elastic properties (Properties shown in next slide)  Production Roof Model; (No material change) SWR =  Strong Pillars & Production Roof Rails Model; SWR = Components shown in green are made from DF140T (Properties shown in next slide) E= 200GPa With No Yielding Strong Roof & Production Roof Rails Materials E= 200GPa; Yield at ~775 MPa

Slide 7 Material Characteristics 5/17/2015 Yield (True) Stress: ~ 775 Mpa Maximum Plastic Strain: ~ 13.3% E= 200GPa Yield (True) Stress: N/A Plastic Strain: N/A E= 200GPa Based on Arcelor-Mittal Steels What SWR?

Slide 8 5/17/2015 U-C Model – Setup Front View Side View ISO View

Slide 9 Model Setup - Roadbed Dimension 5/17/ mm (~ 180 in – 15 ft) 2800 mm (~ 110 in – 9 ft) The roadbed weight is 3183 kg (7000 lbs) Vehicle weight is 2255 kg ( 4971 lbs) The roadbed surface is made of wood of 25.4 mm (1 in) thick

Slide 10 U-C – Roadbed Normal Force Vs Roll Angle 5/17/2015 Roof Material Variation Production Elastic Strong

Slide 11 U-C – Roll Rate Vs Roll Angle 5/17/2015 Filtered Curves (SAE 060) Roof Material Variation Production Elastic Strong

Slide 12 U-C – Passenger & Driver Intrusion Characteristics 5/17/ m m Roof Material Variation Production Elastic Strong

Slide 13 U-C – Passenger & Driver Intrusion Characteristics 5/17/2015 Roof Material Variation Production Elastic Strong

Slide 14 U-C Animation – Elastic Roof Vs. Strong Pillars 5/17/2015

Slide 15 U-C – Elastic Roof Vs. Strong Pillars Overlay 5/17/2015 Elastic Roof Model & Strong Pillars Model Overlaid on top of each other (t = 0 s) Roof Crush at ~ 195° Roll Angle (t = 0.2 s) Roof Crush at ~ 215° Roll Angle (t = 0.3 s)

Slide 16 Conclusion For Different Roof Properties It is assumed that using an elastic roof model can be used for simplification for the rollover parametric study since: The roadbed normal force for the strong pillars model follows similar pattern as the elastic model  The roof crush mode is attributed to the location of the buckling at the structure or excessive elasticity for elastic model  The driver side intrusion for the strong pillar model is only 21% more than the elastic model 5/17/2015

Slide 17 5/17/2015 Roadbed Weight Effect On Un-Constrained Model (4 Different Weights)

Slide 18 5/17/2015 U-C Model – Setup Front View Side View ISO View

Slide 19 Model Setup - Roadbed Dimension 5/17/ mm (~ 180 in – 15 ft) 2800 mm (~ 110 in – 9 ft) Four different roadbed weights were investigated: 2255 kg (4971 lbs) Similar weight of the vehicle with initial roadbed speed of 6.7 m/s 3183 kg (7000 lbs) Baseline analysis with initial roadbed speed of 6.7 m/s 4183 kg (9222 lbs) 1 ton more than the baseline model with initial roadbed speed of 6.7 m/s 3183 kg (7000 lbs) with constant roadbed speed (assumption made to cover heavy roadbed weight)

Slide 20 Roadbed Force, Roll Angle & Intrusion Characteristics Comparisons Deformable Roof Roadbed Force, Roll Angle & Intrusion Characteristics Comparisons Deformable Roof 5/17/2015

Slide 21 U-C – Roadbed Normal Force Vs Roll Angle 5/17/2015 Deformable Roof Variations in Roadbed Weight 2255 kg 3183 kg 4183 kg 3183 kg

Slide 22 U-C – Roll Rate Vs Roll Angle 5/17/2015 Filtered Curves (SAE 060) Deformable Roof Variations in Roadbed Weight 2255 kg 3183 kg 4183 kg 3183 kg

Slide 23 U-C – Passenger & Driver Intrusion Characteristics 5/17/2015 Deformable Roof Passenger Driver Passenger Driver Variations in Roadbed Weight 2255 kg 3183 kg 4183 kg 3183 kg

Slide 24 U-C – Roadbed Speed (Deformable Roof) 5/17/2015 Deformable Roof at 350 ms

Slide 25 Roadbed Force, Roll Angle & Intrusion Characteristics Comparisons Elastic Roof Roadbed Force, Roll Angle & Intrusion Characteristics Comparisons Elastic Roof 5/17/2015

Slide 26 Strong Roof Assumption - Elastic Model 5/17/2015 E= 200GPa With No Yielding  Representative of future vehicles that are going to meet the new FMVSS 216 requirements  All roof components were switched to linear elastic  The Strength to Weight Ratio (SWR) is measured to be 3.9 Elastic Roof

Slide 27 U-C – Roadbed Normal Force Vs Roll Angle 5/17/2015 Elastic Roof Variations in Roadbed Weight 2255 kg 3183 kg 4183 kg 3183 kg

Slide 28 U-C – Roll Rate Vs Roll Angle 5/17/2015 Filtered Curves (SAE 060) Elastic Roof Variations in Roadbed Weight 2255 kg 3183 kg 4183 kg 3183 kg

Slide 29 U-C – Passenger & Driver Intrusion Characteristics 5/17/2015 Elastic Roof Passenger Driver Passenger Driver Variations in Roadbed Weight 2255 kg 3183 kg 4183 kg 3183 kg

Slide 30 U-C – Roadbed Speed (Elastic Roof) 5/17/2015 at 350 ms Elastic Roof

Slide 31 Conclusion For Different Roadbed Weights 5/17/2015 Elastic Roof The normal roadbed force, the roll rate and the intrusion characteristics were similar for both the Deformable and Elastic roof models. When the roadbed weight increased, the difference between the initial and final roadbed speeds decreased. The percentage decrease for the Deformable model was greater than for the Elastic model. * The heavy roadbed weight is assumed by applying a constant speed

Slide 32 Conclusions Roadbed Weight  What difference does it make on the test?  What weight to I need?

Slide 33 5/17/2015 Roadbed Speed Effect On Un-Constrained Model (6 Different Speeds)

Slide 34 Strong Roof Assumption - Elastic Model 5/17/2015 E= 200GPa With No Yielding  Representative of future vehicles that are going to meet the new FMVSS 216 requirements  All roof components were switched to linear elastic  The Strength to Weight Ratio (SWR) is measured to be 3.9 Elastic Roof

Slide 35 5/17/2015 Baseline Model – Setup ISO View Side View Front View

Slide 36 Different Roadbed Speeds Roadbed Force, Roll Angle & Intrusion Characteristics 5/17/2015

Slide 37 Baseline Simulation – Elastic Model 5/17/2015 Simulation tracked at the C.G.

Slide 38 Roadbed Normal Force Vs Roll Angle 5/17/2015 Variations in Roadbed Speed 0 kph 09 kph 18 kph 24 kph 30 kph 36 kph

Slide 39 Roll Rate Vs Roll Angle 5/17/2015 Filtered Curves (SAE 060) Variations in Roadbed Speed 0 kph 09 kph 18 kph 24 kph 30 kph 36 kph

Slide 40 Passenger & Driver Intrusion Characteristics 5/17/2015 Passenger (near) Side Driver (far) Side

Slide 41 Different Roadbed Speeds Roadbed Force, Roll Angle & Intrusion Characteristics 5/17/2015

Slide 42 Model Setup & Initial Conditions 5/17/2015 Initial conditionValue Rotational Speed190 0/s Vertical Drop Distance10 cm Roadbed Speed24.2 km/h Roll Angle at Impact Pitch Angle 5050 Yaw Angle10 0 Front View Side View Same set up as previous model with initial roll angle of 180° Roadbed

Slide 43 Baseline Simulation – Elastic Model 5/17/2015 Simulation tracked at the C.G.

Slide 44 Roadbed Normal Force Vs Roll Angle 5/17/2015 Variations in Roadbed Speed 180 o Roll Angle 09 kph 18 kph 24 kph 30 kph 36 kph

Slide 45 Roll Rate Vs Roll Angle 5/17/2015 Filtered Curves (SAE 060) Variations in Roadbed Speed 180 o Roll Angle 09 kph 18 kph 24 kph 30 kph 36 kph

Slide 46 Driver Intrusion Characteristics 5/17/2015

Slide 47 Intrusion Characteristics Comparison (180° & 145°) 5/17/2015 Dynamic Intrusion Intrusion Rate Driver (far) Side

Slide 48 Conclusion For Different Roadbed Speeds  The minimum roadbed speeds necessary to obtain 3 quarter turns rollover is of 24 km/h (14.9 mph) (Have you tried 20 and 22?)  The roadbed normal forces follow the same pattern for roadbed speeds between 24 and 36 km/h ( mph) for initial roll angle of 145°  When the roadbed speed increases, the roll rate after initial contact increases for speeds above 18 km/h (11.2 mph)  For different roadbed speeds and the baseline initial conditions, the dynamic intrusion and the intrusion rate for initial roll angle of 145° are higher than for 180° initial roll angle 5/17/2015

Slide 49 5/17/2015 QUESTIONS?