The Significance of the Production Process of FRP Parts for the Performance in Crashworthiness
As there is a trend in the automotive industry towards using FRP composites for reducing the weight of vehicles, adequate simulation tools to effectively and accurately predict the structural response of composite structures in crashworthiness are needed. Due to the manufacturing induced fiber orientation, which is particularly for short fiber reinforced composites locally varying, the pointwise mechanical behavior of (S)FRP is a priori unknown and accordingly the prediction of the mechanical behavior of FRP-components is challenging. A promising approach is an analysis that covers the complete process chain from the molding process to the crashworthiness modelling: fiber orientation are determined by process simulation and transferred to the structural analysis model through a data-mapper. Using this information, the local anisotropic material behavior can be determined by means of a homogenization procedure and used for the structural analysis. In this paper two recently implemented possibilities for LS-DYNA ® are presented. For the first approach, the data-mapper “DYNAmap” transfers the fiber orientation tensor, which is evaluated in a MoldFlow ® simulation, to the structural analysis model. Using a recently developed constitutive model, pointwise effective anisotropic material properties for this composite are automatically determined and used for the structural simulation. This calculation of homogenized macroscopic properties is done in two steps: At first, effective properties of an associated “pseudo uni-directional” composite are determined by analytical homogenization (see Dvorak [2013]). In a second step an orientation averaging of these uni-directional properties in accordance with the mapped local fiber orientation is carried out; see Advani & Tucker [1987]. While for elasticity the determination of effective properties is done only once in a preprocessing step, for considering inelastic behavior, an update of the material properties during the simulation is necessary from time to time. Alternatively, DYNAmap provides the possibility to perform a homogenization for evaluating the pointwise effective anisotropic elastic stiffness parameters and to transfer the resulting local stiffness values to *MAT_ANISOTROPIC_ELASTIC_PLASTIC. This approach can be extended to an anisotropic elasto-plasticity model with rate dependent hardening. For this purpose, the user has to provide the appropriate Lankford-coefficients and hardening curves, while the mapper provides the dominant fiber orientation pointwise. Damage and failure can be added through *MAT_ADD_EROSION. Within the presentation applications of both approaches will be discussed and compared.
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The Significance of the Production Process of FRP Parts for the Performance in Crashworthiness
As there is a trend in the automotive industry towards using FRP composites for reducing the weight of vehicles, adequate simulation tools to effectively and accurately predict the structural response of composite structures in crashworthiness are needed. Due to the manufacturing induced fiber orientation, which is particularly for short fiber reinforced composites locally varying, the pointwise mechanical behavior of (S)FRP is a priori unknown and accordingly the prediction of the mechanical behavior of FRP-components is challenging. A promising approach is an analysis that covers the complete process chain from the molding process to the crashworthiness modelling: fiber orientation are determined by process simulation and transferred to the structural analysis model through a data-mapper. Using this information, the local anisotropic material behavior can be determined by means of a homogenization procedure and used for the structural analysis. In this paper two recently implemented possibilities for LS-DYNA ® are presented. For the first approach, the data-mapper “DYNAmap” transfers the fiber orientation tensor, which is evaluated in a MoldFlow ® simulation, to the structural analysis model. Using a recently developed constitutive model, pointwise effective anisotropic material properties for this composite are automatically determined and used for the structural simulation. This calculation of homogenized macroscopic properties is done in two steps: At first, effective properties of an associated “pseudo uni-directional” composite are determined by analytical homogenization (see Dvorak [2013]). In a second step an orientation averaging of these uni-directional properties in accordance with the mapped local fiber orientation is carried out; see Advani & Tucker [1987]. While for elasticity the determination of effective properties is done only once in a preprocessing step, for considering inelastic behavior, an update of the material properties during the simulation is necessary from time to time. Alternatively, DYNAmap provides the possibility to perform a homogenization for evaluating the pointwise effective anisotropic elastic stiffness parameters and to transfer the resulting local stiffness values to *MAT_ANISOTROPIC_ELASTIC_PLASTIC. This approach can be extended to an anisotropic elasto-plasticity model with rate dependent hardening. For this purpose, the user has to provide the appropriate Lankford-coefficients and hardening curves, while the mapper provides the dominant fiber orientation pointwise. Damage and failure can be added through *MAT_ADD_EROSION. Within the presentation applications of both approaches will be discussed and compared.
12-B_Simulation_093.pdf
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