Generation of representative volume elements for CoDiCoFRP with curvature control
Topic(s) : Special Sessions
Co-authors :
Celine LAUFF (GERMANY), Matti SCHNEIDER , Thomas BÖHLKEAbstract :
Combining continuous (Co) and discontinuous (DiCo) fiber-reinforced phases leads to a material system (CoDiCoFRP) with a high specific stiffness and an elevated design freedom of the manufactured components. To exploit their inherent lightweight potential, their anisotropic mechanical properties need to be determined. These properties are conveniently obtained by computational homogenization methods operating on representative volume elements (RVEs). These volume elements, however, need to be provided upfront.
Investigating the constituents of CoDiCoFRP with micro-CT imaging on the microscale reveals that the composites are mainly characterized by the fiber volume fraction, the fiber length and orientation distribution as well as the fiber curvature [1]. Especially for long fiber-reinforced thermoplastics (LFTs) as constituents for the discontinuous phase, the observed fiber bending is significant [2] and needs to be accounted for by modelling the fibers as flexible structures. For given geometrical descriptors, it is rather challenging to obtain suitable RVEs matching the prescribed criteria by micro-CT only. Therefore, computational algorithms for generating microstructures come in handy as suitable tools for this purpose. Moreover, the generated microstructures can be arranged to be periodic, which is well-known to be reduce the required RVE size.
We present a microstructure generation strategy for CoDiCoFRP with LFT as constituent for the DiCo phase. The generated microstructures feature a layered structure consisting of Co and DiCo phases with periodized geometrical description. To account for the fiber bending within the DiCo phase, we model each fiber as a polygonal chain with straight cylindrical segments. Without controlling the angles between adjacent segments of the polygonal chains, unrealistically high angles may occur. To overcome this limitation with respect to the representativity, we introduce a number of mechanisms to realize desired fiber curvature states, e.g., a maximum angle between two adjacent fiber segments, and investigate their ramifications.
Investigating the constituents of CoDiCoFRP with micro-CT imaging on the microscale reveals that the composites are mainly characterized by the fiber volume fraction, the fiber length and orientation distribution as well as the fiber curvature [1]. Especially for long fiber-reinforced thermoplastics (LFTs) as constituents for the discontinuous phase, the observed fiber bending is significant [2] and needs to be accounted for by modelling the fibers as flexible structures. For given geometrical descriptors, it is rather challenging to obtain suitable RVEs matching the prescribed criteria by micro-CT only. Therefore, computational algorithms for generating microstructures come in handy as suitable tools for this purpose. Moreover, the generated microstructures can be arranged to be periodic, which is well-known to be reduce the required RVE size.
We present a microstructure generation strategy for CoDiCoFRP with LFT as constituent for the DiCo phase. The generated microstructures feature a layered structure consisting of Co and DiCo phases with periodized geometrical description. To account for the fiber bending within the DiCo phase, we model each fiber as a polygonal chain with straight cylindrical segments. Without controlling the angles between adjacent segments of the polygonal chains, unrealistically high angles may occur. To overcome this limitation with respect to the representativity, we introduce a number of mechanisms to realize desired fiber curvature states, e.g., a maximum angle between two adjacent fiber segments, and investigate their ramifications.