DIFFERENT BUSSES -COMPARISON-

Transcription

1 DIFFERENT BUSSES -COMPARISON-

2 Current Work It starts from a real road accident happen to a bus on Nitsund bridge in 1998 Main Tasks: understanding of Nitsund parapet limitation (first structure built in 1964 and uploaded in 1998) comparison of existing bus-models first simulation has been based on standard test according to EN 1317: If the results were unacceptable the impact angle was decreased by 5 degrees until good results were archived (lower limit was 10 degrees) If the results were still unacceptable the velocity was degreased by step of 10 km/h until good results were archived

3 Nitsund Old Parapet (1964) Nr Test vehicle Bus (13 ton) Bus (13 ton) Test parapet IPE 140 Test type Velocity [km/h] Impact Angle [deg] Acceptable Results TB No IPE 140 NA Yes Bus (13 ton) IPE 140 NA Yes Handrail: diameter 60 mm Post: IPE mm 450 mm Absorbed Energy: 74 KJ Guardrail: a double wave shape with reinforce elements (100 mm) directly bolted to the post Rigidly fixed to the ground

4 Nitsund New Parapet (1998) Nr Test vehicle 4 Bus (13 ton) 5 Handrail: tree pipes of diameter 60 mm (250, 900, 1050 mm from the ground) Post: HE 100 A Test parapet HE 100 A Test type 600 mm 450 mm Velocity [km/h] Impact Angle [deg] Acceptable Results TB Yes Bus (13 ton) HE 100 A NA No Absorbed Energy: 287 KJ Guardrail: a double wave shape connected to an absorb element (W shape) bolt to the posts Rigidly fixed to the ground

5 IMPORTANCE OF SPINNING WHEELS AND STEERING SYSTEM

6 City bus * * Original-city-bus (green) presents neither spinning wheels nor steering system For city-bus (red) added: 6 spinning wheels (2 front, 4 rear) front steering wheels comprised of: one spring elements for stopper compression one shock absorber a stabilizer bar 13 ton City bus respect all the characteristic requested from EN-1317 Nr Test parapet Test type Velocity [km/h] Impact Angle [deg] 2 IPE 140 NA HE100 A TB

7 Test 2 Test parapets Velocity Impact angle Nitsund Old 70 km/h 10 deg city bus O-city bus L contact L contact θ θ City bus Original city bus Working Width 0.72 m 0.99 m Permanent Defl m 0.46 m Dynamic Defl m 0.54 m Exit Speed 63.8 km/h 44.5 km/h Exit Angle 6.9 deg 10.9 deg

8 Test 4 Test parapets Velocity Impact angle Nitsund New 70 km/h 20 deg city bus O-city bus L contact L contact θ θ City bus Original city bus Working Width 0.95 m m Permanent Defl. 0.32* m 0.98* m Dynamic Defl m 1.16 m Exit Speed 43.3 km/h 32.2 km/h Exit Angle 3.1 deg 13.9 deg

9 Remark A: Spin W. and steering S. The simulations performed permit to: Show the influence on the bus behavior of the added elements Obtained different recorded value and behavior for all tests performed For city bus with the spinning wheels and the steering system: decreasing in angle exit decreasing in velocity exit lighter impact in the rear bus part because of a smaller angular velocity around vertical axis Smaller barrier post impact deformation

10 CITY BUS Vs CONVENTIONAL BUS

11 Conventional Bus The design of this conventional bus started at NPRA in 2006 The conventional bus can be used from all cm-e experts that contributed at the study and the evolution of the model Now-a-day the model is not complete and suffer of a lack of some essential elements in the frontal structure To improve the performance, some beam elements have been introduced to increase the structure stiffness. This solution better reproduces the structure behavior during the impact

12 Bus Models City bus Conventional bus DETAILS Vehicle Length: L [m] City L WB Conventional W Standar H Vehicle Width: W [m] Vehicle Height: H [m] Vehicle Weight [Kg] Xcg [m] Vehicle CG: Zcg [m] Wheel Base: WB [m] Wheel Radius: r [m] ± ±0.975 ±0.08

13 Test 2 Test parapets Velocity Impact angle Nitsund Old 70 km/h 10 deg city bus Conv. bus L contact L contact θ θ City bus Conventional bus Working Width 0.72 m 0.90 m Permanent Defl m 0.37 m Dynamic Defl m 0.46 m Exit Speed 63.8 km/h 61.3 km/h Exit Angle 6.9 deg 9.6 deg

14 Test 4 Test parapets Velocity Impact angle Nitsund New 70 km/h 20 deg city bus Conv. bus L contact L contact SIMULA TION OF EXISTIN G PARAPE TS θ θ City bus Conventional bus Working Width 0.95 m 0.78 m Permanent Defl m 0.45 m Dynamic Defl m 0.53 m Exit Speed 43.3 km/h 45.5 km/h Exit Angle 3.1 deg 5.3 deg

15 Remark B: Comparison city Vs Conventional bus Bus type Working Width [m] Permanent Defl. [m] Dynamic Defl- [m] City Nitsund Old 70km 10 deg O-City Conv City Nitsund New 70km 20 deg O-City Conv Exit Speed [km/h] Exit Angle [deg] The recorded values for conventional bus could be consistent compared with city bus whit spinning wheels and steering system

16 Future Development Continue to evaluate the influence of steering system and spinning wheels Analyzing city bus behavior against rigid wall Comparing simulated bus data whit real full-scale crash test Modify the conventional bus on the base of new drawing Chassis Sigma post frontal structure 55 mm using a the ESP (additional guardrail) restraint system: 100 mm Double wave guardrail 150 mm 200 mm 310 mm Ground level 1200 mm 1900 mm

17 DIFFERENT BUSSES -COMPARISON- THANK YOU...