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MODEL VALIDATION AND FE ANALYSIS OF THE HEAD BONNET IMPACT
Injury and Forensic Biomechanics
Poster P-82
S455
MODEL VALIDATION AND FE ANALYSIS OF THE HEAD BONNET IMPACT Massimiliano Salaorno, Bruno Puglisi, Alberto L. Audenino [email protected]
Department of Industrial and Mechanical Engineering University of Catania, Catania, Italy
Introduction
Methods In the first part, a FE model (HEXA8) of adult headform impactor has been developed, using MSC.Dytran®: the outer layer of the headform has been simulated by Mooney-Rivlin formulation (silicon rubber). The inner core and the guided certification impactor have been simulated by linear elastic material (aluminium). (Fig.1).
Figure 1: certification impactor (left) and pedestrian headform (right) FE model
Figure. 3: FE models of simplified and real car bonnet To reduce the acceleration, maximum plasticization of inner structure has been achieved by modifying shape, number and thickness of the beams.
Results The Mooney-Rivlin parameters have been obtained by experimental tests on silicon rubber at different strain rate (C10=1.74 MPa; C01=0.50 MPa). The peak acceleration value (3800ms-2) of headform impactor during certification, is between the directive limits (3311 ÷ 4046 ms-2, fig. 4). The difference between FE and lumped model is 4%.
Acceleration [m/s2]
The directive 2003/102/CE intends to reduce the injuries of the pedestrians during frontal impact with passenger cars. The directive describes the device that must be employed to simulate pedestrian head: HIC is used to evaluate the severity of the impact. This work has two goals: to realize a FE model of pedestrian headform impactor; to optimize the car bonnet structure in order to reduce the accelerations and consequently the HIC (Head Injury Criteria) [Schmitt,2007].
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To validate the FE procedure, a non linear lumped parameter model (Fig.2) has been developed [Deb, 2006].
Figure 2: lumped parameter model model: m1 is impactor mass, m2 is headform mass, keq is non linear stiffness between certification impactor and headform calculated by non linear FE model, using MSC.Marc® In the second part, the validated headform model has been used to study real bonnet impact. Some FE models of different bonnet have been realized (Fig.3). Shell elements (steel, following JohnsonCook formulation) have been used to optimize [Kerkeling, 2005] the car bonnet.
16th ESB Congress, Posters
Figure 4: lumped parameter model (red curve); FE result (blue curve) The reduction of HIC and displacement have been found on simplified bonnet (7% and 2% respectively, fig. 3 left) and real bonnet (15% and 2% respectively, fig. 3 right).
Discussion In the first part a reliable FE model of the headform has been developed; in the second part, some example of optimization of inner structure of bonnet has been presented.
References Deb et al, Int J Impact Eng, 30:521-539, 2006. Kerkeling et al, 19th ESV Conference, 2005 Schmitt et al, Trauma Biomechanics, Springer,2007
Journal of Biomechanics 41(S1)
Poster P-82
S455
MODEL VALIDATION AND FE ANALYSIS OF THE HEAD BONNET IMPACT Massimiliano Salaorno, Bruno Puglisi, Alberto L. Audenino [email protected]
Department of Industrial and Mechanical Engineering University of Catania, Catania, Italy
Introduction
Methods In the first part, a FE model (HEXA8) of adult headform impactor has been developed, using MSC.Dytran®: the outer layer of the headform has been simulated by Mooney-Rivlin formulation (silicon rubber). The inner core and the guided certification impactor have been simulated by linear elastic material (aluminium). (Fig.1).
Figure 1: certification impactor (left) and pedestrian headform (right) FE model
Figure. 3: FE models of simplified and real car bonnet To reduce the acceleration, maximum plasticization of inner structure has been achieved by modifying shape, number and thickness of the beams.
Results The Mooney-Rivlin parameters have been obtained by experimental tests on silicon rubber at different strain rate (C10=1.74 MPa; C01=0.50 MPa). The peak acceleration value (3800ms-2) of headform impactor during certification, is between the directive limits (3311 ÷ 4046 ms-2, fig. 4). The difference between FE and lumped model is 4%.
Acceleration [m/s2]
The directive 2003/102/CE intends to reduce the injuries of the pedestrians during frontal impact with passenger cars. The directive describes the device that must be employed to simulate pedestrian head: HIC is used to evaluate the severity of the impact. This work has two goals: to realize a FE model of pedestrian headform impactor; to optimize the car bonnet structure in order to reduce the accelerations and consequently the HIC (Head Injury Criteria) [Schmitt,2007].
4000 3000 2000 1000 0 -1000
0
1
2
3
4
Time [ms]
To validate the FE procedure, a non linear lumped parameter model (Fig.2) has been developed [Deb, 2006].
Figure 2: lumped parameter model model: m1 is impactor mass, m2 is headform mass, keq is non linear stiffness between certification impactor and headform calculated by non linear FE model, using MSC.Marc® In the second part, the validated headform model has been used to study real bonnet impact. Some FE models of different bonnet have been realized (Fig.3). Shell elements (steel, following JohnsonCook formulation) have been used to optimize [Kerkeling, 2005] the car bonnet.
16th ESB Congress, Posters
Figure 4: lumped parameter model (red curve); FE result (blue curve) The reduction of HIC and displacement have been found on simplified bonnet (7% and 2% respectively, fig. 3 left) and real bonnet (15% and 2% respectively, fig. 3 right).
Discussion In the first part a reliable FE model of the headform has been developed; in the second part, some example of optimization of inner structure of bonnet has been presented.
References Deb et al, Int J Impact Eng, 30:521-539, 2006. Kerkeling et al, 19th ESV Conference, 2005 Schmitt et al, Trauma Biomechanics, Springer,2007
Journal of Biomechanics 41(S1)