CAE-Companion-2018-2019

Engineering WISSEN CAE

Functional Development: Pedestrian Protection - Lower Leg Impact

Requirements/Critical Target Values: „ „ UN R127: Impactor:

Flex PLI Legform Impactor (valid from 9/2017) 40 km/h (11.1 m/s), 0°, 75 mm over ground

Test Conditions:

Criteria: Tibia Bending Moment

< 340 Nm (up to 264 mm: 380 Nm)

MCL Elongation

< 22 mm < 13 mm

ACL/PCL Elongation

„ „ Euro NCAP Impactor:

Flex PLI Legform Impactor

Test Conditions:

40 km/h (11.1 m/s), 0°, 75 mm over ground

Criteria:

maximum Score

0 Points

Tibia Bending Moment

< 282 Nm < 19 mm < 10 mm

≥ 340 Nm ≥ 22 mm ≥ 10 mm

MCL Elongation

ACL/PCL Elongation

Procedures: „ „ Use of full vehicle models (impact area: detailed models of all components; motor package can be rigid) „ „ High detailing for bumper, radiator, grill, optional accessories (head light cleaning system, parking sensors etc.) „ „ Proper material characterization for plastic parts is required incl. failure definition „ „ Connection modeling is highly significant (clips, sliding components) „ „ Use of validated impactor model „ „ Typical simulation duration: 40 ms (up tp complete rebound→ legform impactor completely separated from vehicle) Critical Modeling Parameters: „ „ Strain rate dependency of materials in the impact area „ „ Details of spatial discretization Evaluation Criteria: „ „ Tibia Bending Moment „ „ MCL Elongation „ „ ACL/PCL Elongation „ „ For the optimization: Plot the above criteria vs. displacement to identify jamming Main Influencing Factors: „ „ Geometry of vehicle front (impact points, impact behavior) „ „ Material stiffness at impact point (potential for optimization) „ „ Stiffness of geometrical package „ „ Clearance between outer bumper shell and bumper beam (minimum 80 mm, filled with energy-absorbing foam or deformation elements) „ „ No jamming elements (e.g. parking sensors) should be placed directly in front of the bumper beam „ „ Homogeneous support of the impactor along the full vehicle width is required. „ „ Sharp stiffness gradient should be avoided.

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