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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