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cross section crash boxes

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CHAPTER 5<br />

SIMULATION AND OPTIMIZATION OF EMPTY AND<br />

PARTIALLY ALUMINUM FOAM FILLED CRASH<br />

5.1. Material Modeling<br />

5.1.1. 1050H14 Base Material<br />

BOXES<br />

Three material models are widely used in the simulations of the mechanical<br />

response of the <strong>crash</strong> box base materials. These models include the plastic kinematic<br />

model, Mat 3 in LS-DYNA (Mamalis, et al. 2003c, Wang, et al. 2005), the piece-wise<br />

linear plasticity model, Mat 24 in LS-DYNA (Mamalis, et al. 2003b, Meguid, et al.<br />

2004b) and the anisotropic plasticity model, Mat103 in LS-DYNA (Fyllingen, et al.<br />

2007). It was previously shown by Lademo et al. (Lademo, et al. 2008) that the<br />

processing history and anisotropy of box materials had negligible effects on the<br />

predicted load values and the deformation characteristics of the <strong>crash</strong> <strong>boxes</strong> subjected to<br />

frontal impact. Hence, it was suggested that the use of the simple piece wise or plastic<br />

kinematic model could sufficiently resemble the real crushing behavior of metallic <strong>crash</strong><br />

<strong>boxes</strong>. In the present thesis, two material models, Mat3 and Mat24, were initially<br />

considered for the simulating of the crushing behavior of 1050H14 Al <strong>crash</strong> box. The<br />

material properties of 1050H14 Al alloy were determined from the uniaxial tension<br />

stress-strain curve of the base material.<br />

In plastic kinematic material model, the mechanical properties are characterized<br />

by the material flow stress (y), Young’s modulus (E) and tangent modulus (Et) as<br />

depicted in Figure 5.1., (Hallquist 2006)<br />

81

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