FE-based simulation and validation of a pedestrian impact detection system
Ladda ner
Publicerad
Författare
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
According to the European Commission, pedestrians accounted for 18.4% of road
traffic fatalities in the EU in 2023 [5]. Modern vehicles integrate systems such as
the Active Hood Lift System (AHLS), which lifts the bonnet to reduce head trauma
during pedestrian collisions[3]. A key component enabling AHLS is the pressuresensitive
sensor tube, which detects frontal impacts and triggers hood deployment
within milliseconds. To support the deployment of AHLS, this project aimed to
develop and validate a Finite Element (FE) model of an air-filled pressure sensor
tube for use in pedestrian impact detection. The model was implemented in LSDYNA
and evaluated against physical impact tests conducted at three velocities.
Waveform correlation between simulated and measured pressure signals was assessed
using the Waveform Index Factor (WIFac) to quantify model accuracy.
The model was assessed under varying configurations to evaluate its predictive accuracy.
Foam material properties and fixation methods were systematically tested.
Among them, the calibrated foam material model generally yielded the highest waveform
correlation with physical test results, achieving WIFac values typically above
70% across the tested velocities. By contrast, plastic strap fixation and alternative
foam models resulted in lower WIFac values, often below 60%. A nonlinear
inverse relationship was observed between the tube’s Young’s modulus and the resulting
peak pressure, with 0.001 GPa providing the closest match for the advanced
dynamic test. This is physically consistent, as lower stiffness allows for greater deformation
and a more gradual pressure increase. Sensitivity analysis was performed
by introducing small perturbations in initial velocity and impactor position to evaluate
the model’s robustness. Results showed that the waveform structure remained
stable under moderate variations, supporting the model’s reliability within expected
test tolerances. Therefore, the calibrated foam model is recommended as the reference
configuration for simulation-based evaluations of AHLS pressure tube systems.
To explore the model’s applicability in more complex scenarios, additional simulations
were conducted using the PDI-2 full-leg impactor. These simulations exhibited
increased signal deviations, indicating that further refinement is necessary for integration
into biomechanical assemblies. Future work should focus on experimental
validation of material parameters and extension to full-vehicle implementations.
Beskrivning
Ämne/nyckelord
FE, FEM, Pressure tube, AHLS, WIFac, PDI-2