ROBUST PROJECT TRL Limited WP5 - Computational Mechanics B1 (ESP-N2) Barrier – Steel N2 MAIN REPORT Volume 1 of 1

December 2005 Doc. No.: ROBUST-5-014c – Rev. 0

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Main Report

Report title: WP5 - Computational Mechanics Client: TRL Limited

Doc. no.: Document no ROBUST-5-014c- Rev. 0

TRL Project no.: ROBUST EC/HA 11106787/11106788

Reporter(s): M McGrath and G Williams

Abstract: The Robust Project aims to improve scientific and technical knowledge on the main issues still open in the new European standards on the road restraint system EN1317. The knowledge acquired will form the basis of updated standards for EN 1317 and lead to more advanced road restraint systems and improve road-users safety. This report is part of the deliverables from Work Package 5 – Computational Mechanics. This report documents the simulations performed on the B1 (ESP-N2) barrier. The simulations were performed by TRL Limited. Keywords:

Restricted Internal

Free distribution Ref. allowed

Rev. no. Date Prepared by Checked by Approved by Reason for revision

0

08-12-05

M McGrath

G Williams

Issued for Comment

28

6-2-

1-no

-en

ROBUST project Page iSimulation company TRL Limited ROBUST-5-014c – Rev. 0.WP5 - Computational Mechanics B1 ESP-N2 Barrier MAIN REPORT

CONTENTS 1 INTRODUCTION ...................................................................................................1 2 SUMMARY AND CONCLUSIONS ........................................................................2

2.1 Summary ...............................................................................................................2 2.2 Conclusions ...........................................................................................................2

3 SIMULATION OF BARRIER B5 – CASE 3............................................................3 3.1 General ..................................................................................................................3 3.2 Additional data .......................................................................................................3 3.3 Input data...............................................................................................................3 3.3.1 Test item ................................................................................................................3 3.3.2 Test procedure.......................................................................................................4 3.3.3 Analysis data .........................................................................................................4 3.4 Analysis results......................................................................................................6

4 REFERENCES ....................................................................................................13

ROBUST project Page 1Simulation company TRL Limited ROBUST-5-014c – Rev. 0.WP5 - Computational Mechanics B1 ESP-N2 Barrier MAIN REPORT

1 INTRODUCTION

The Robust project aims to improve scientific and technical knowledge on the main issues still open in the new European standards on road restraint systems EN 1317.

The knowledge acquired will form the basis of updated standards for EN1317 and lead to more advanced road restraint systems and improved road-users’ safety.

This report is part of the deliverables from Work Package 5 – Computational Mechanics.

The objective of WP5 is:

Evaluation and enhancement of the use of computational mechanics to complement experimental activity

Criteria and procedures for the validation of computational mechanics results through comparison with test results

Reconstruction of real life accidents

Identification of the activity needed for further enhancement of the use of computational mechanics.

This report documents the simulations performed on the B1 (ESP-N2) barrier. The simulations were performed by TRL Limited as part of the ROBUST project and were run with version 970 revision 5434a of LS-DYNA with the data output at 1.0E-5 from the THF and NODOUT files.

ROBUST project Page 2Simulation company TRL Limited ROBUST-5-014c – Rev. 0.WP5 - Computational Mechanics B1 ESP-N2 Barrier MAIN REPORT

2 SUMMARY AND CONCLUSIONS

2.1 Summary

The following simulation has been performed with the B1 barrier:

Barrier Test Name id. Chapter

B1 – case 3

Post fixed 200mm below ground level. The ends of profile are fixed.

TB11 GM_R4_Vehicle-B1_ESP-N2_barrier

Chapter 3

The main results are summarised in Table 2-1 below.

Table 2-1 Results from simulation with the B1 barrier

Case ASI [-] THIV [km/h]

PHD [g]

Working Width [mm]

Exit speed [km/h]

Exit angle [deg]

Trajectory Detailed description

3 0.80 23.70 12.86 748 81.49 7.57 OK Chapter 3

2.2 Conclusions NA

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3 SIMULATION OF BARRIER B1 – CASE 3

3.1 General This chapter gives a brief description of the results obtained from a simulation of a small car (GM_R4) hitting the B1 barrier with a velocity of 100 km/h and at an angle of 20 degrees. The B1 barrier is an ESP-N2 barrier, which consists of sigma posts and N2 steel profile.

The characteristics specific to this simulation are:

The sigma posts are fixed 200 mm below ground level

All posts are modelled as non-linear

The ends of the w-profile are fixed

No friction between barrier and vehicle

Friction between the ground and tyres was set to 0.7

3.2 Additional data The following data and files supplement the result presentation of the simulation as presented in this chapter.

Excel worksheet file: GM_R4_Vehicle-ESP-N2_barrier.xls

Rawdata file: GM_R4_Vehicle-ESP-N2_barrier_Rawdata.zip

Animations:

- front view GM_R4_Vehicle-ESP-N2_barrier_Front_view.mpg *

- side view GM_R4_Vehicle-ESP-N2_barrier_Side_view.mpg *

- top view GM_R4_Vehicle-ESP-N2_barrier_Top_view.mpg *

- perspective GM_R4_Vehicle-ESP-N2_barrier_Perspective_view.mpg *

*AVI format of the animation is available on request (approximately 130MB each)

3.3 Input data

3.3.1 Test item

Test item: ESP-N2 Vehicle: GeoMetro GM_R4

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3.3.2 Test procedure

1) Test type – TB11 Impact speed: 100 km/h Impact angle: 20 degrees Impact point About 25.6 metres from the beginning of the VRS Spinning wheels: Yes Inertial vehicle test mass: 893 kg

2) VRS model

Barrier type: ESP-N2

Number of posts: 37 (including 2 x 3 posts at the end slopes)

Spacing: 2 m

Total length: 76 m

Element formulation/type: Shell elements used for all sections

Connection/Joints: Bolt connections are modelled using spot-welds with failure (between the posts and profile).

Foundation: Modelled

End anchoring: W-profile is fixed at the ends

Soil (type and formulation): NA

Roadway: Modelled as rigid walls

Plot of FE-Model Table 3.1

Material Data Table 3.2

3) Vehicle model The model of the GeoMetro, version GM_R4 was used in the simulation. The mass of the vehicle includes the mass of the GEBOD dummy model.

3.3.3 Analysis data Timestep: 1.29E-6

Precision: Single

Friction barrier/vehicle (static coefficient): 0.0

Friction barrier/vehicle (dynamic coefficient) 0.0

Friction wheel/ground (static coefficient) 0.7

Friction wheel/ground (dynamic coefficient) NA

Accelerometer location (mounting block) from COG (mm)

As supplied with model

ROBUST project Page 5Simulation company TRL Limited ROBUST-5-014c – Rev. 0.WP5 - Computational Mechanics B1 ESP-N2 Barrier MAIN REPORT

Sampling rate 1.0E-5 for THF and NODOUT data

Friction other: NA

Table 3-1 Model description. VRS for roads Vehicle restraint system Computer model,

Model description Nodes Shell elements / Brick elements Spot welds Materials

60786 56379/0 37 7 Other

The VRS was modelled using shell elements for all sections. The bolt connections were modelled using spot-welds (between the posts and profile). There is no friction between the car and the VRS. The road was modelled in the FE-model. The posts were extended below the road.

Table 3-2 Material characteristic – Steel and plastic sections. Vehicle restraint system

Part E-Module [MPa] Density [kg/m3] Yield Stress [MPa] Ultimate Stress [MPa]

Failure Strain [-] Comments

Sigma Posts 210000 7850 300.0 450.0 0.3 Non-linear

W-profile 210000 7850 300.0 450.0 0.3 Non-linear

Brackets 210000 7850 300.0 450.0 0.3 Non-linear Strain Rate Stress vs. strain values STRAIN -- STRESS

NA 0.0 – 300 MPa 0.3 – 450 MPa

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3.4 Analysis results

1) VRS Maximum global dynamic deflection: 666 mm Working width: 748 mm Maximum global permanent deflection: Unable to calculate because the barrier

was still moving at the end of the run at 500 ms.

Length of contact: 5.9 m approximately Major parts fractured or detached: No Description of damage to test items: Limited Ground anchorage’s meets design levels: NA Plot of test items: Table 3-3 - Table 3-6

2) Vehicle Image of the vehicle at the time when the exit angle and speed were calculated at

365ms

Exit speed: 81.49 km/h Exit angle: 7.57 degrees Rebound distance: NA Vehicle breaches barrier: No Vehicle passes over the barrier: No Vehicle within CEN “box”: Simulation was not run for a long enough

period to make the assessment. Vehicle rolls over after impact: No Damage to test vehicle: Table 3-7

ROBUST project Page 7Simulation company TRL Limited ROBUST-5-014c – Rev. 0.WP5 - Computational Mechanics B1 ESP-N2 Barrier MAIN REPORT

3) General description of vehicle trajectory: The vehicle hits the VRS at a velocity of 100 km/h and at an angle of 20 degrees. The vehicle leaves the VRS at an angle of 7.57 degrees. The trajectory is good in the simulation.

Vehicle damage TAD: NA Vehicle damage VDI: NA Vehicle cockpit def. index VCDI: NA Major parts of vehicle detached: No Plots of the vehicle: Table 3-7

4) Assessment of the impact severity Post-processing procedure Accelerometer data used in Diadem Acceleration severity index, ASI: 0.80 Acceleration graphs: No THIV: 23.7 km/h Time of flight: NA Post-impact head deceleration, PHD: 12.86 g Flail space: 0.6 x 0.3 m

5) General statement Based on the above it can be concluded that the crash protection system fulfils the requirements of the CEN standard

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Table 3-3 Vehicle - Front view.

Time 0.00 Time 0.08

Time 0.16 Time 0.24

Time 0.35 Time 0.45

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Table 3-4 Vehicle – Side view. Time 0.00 Time 0.08

Time 0.16 Time 0.24

Time 0.35 Time 0.45

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Table 3-5 Vehicle - Top view Time 0.00 Time 0.08

Time 0.16 Time 0.24

Time 0.35 Time 0.45

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Table 3-6 Vehicle – Iso View Time 0.00 Time 0.08

Time 0.16 Time 0.24

Time 0.35 Time 0.45

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Table 3-7 Vehicle damage. Top view Bottom view

Side view Side view

View View

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4 REFERENCES

Ref. 1: EN 1317-1: Road restraint systems – Part 1: Terminology and general criteria for test methods. European Committee for Standardization, April 1998.

Ref. 2: EN 1317-2: Road restraint systems – Part 2: Performance classes, impact test acceptance criteria and test methods for safety barriers. European Committee for Standardization, April 1998.