Virtual process chain of sheet molding compound: Development, validation and perspectives

Görthofer, Johannes; Meyer, Nils; Pallicity, Tarkes Dora; Schöttl, Ludwig; Trauth, Anna; Schemmann, Malte; Hohberg, Martin; Pinter, Pascal; Elsner, Peter; Henning, Frank; Hrymak, Andrew N.; Seelig, Thomas; Weidenmann, Kay André; Kärger, Luise; Böhlke, Thomas

doi:10.1016/j.compositesb.2019.04.001

Cited by 80 publications

(45 citation statements)

References 52 publications

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“…However, these properties are difficult to determine after molding, and predicting these properties in the early development process can reduce expensive corrections of mold design. Additionally, utilization of process induced fiber orientations improves the predictive quality of structural simulations [1].…”

Section: Introductionmentioning

confidence: 99%

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Direct Bundle Simulation approach for the compression molding process of Sheet Molding Compound

Meyer

Schöttl

Bretz

et al. 2020

Composites Part A: Applied Science and Manufacturing

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The manufacturing process of Sheet Molding Compounds (SMC) induces a reorientation of fibers during the flow, which influences local properties and is of interest for structural computations. Typically, the reorientation is described with an evolution equation for the second order fiber orientation tensor, which requires a closure approximation and multiple empirical parameters to describe long fibers. However, CT scans of SMC microstructures show that fiber bundles stay mostly intact during molding. Treating hundreds of fibers in such a bundle as one instance enables direct simulation on component scale. This work proposes a direct simulation approach, in which bundle segments experience Stokes' drag forces and opposing forces are applied to the fluid field. The method is applied to specimens with a double-curved geometry and compared to CT scans. The Direct Bundle Simulation provides increased accuracy of fiber orientations and enables prediction of fiber-matrix separation with affordable computational effort at component scale.

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Section: Introductionmentioning

confidence: 99%

“…Fiber reorientation is typically modeled based on fiber orientation tensors in-troduced by Advani and Tucker [8] as A = S p ⊗ p Ψ(p) dp (1) and…”

Section: Introductionmentioning

confidence: 99%

Direct Bundle Simulation approach for the compression molding process of Sheet Molding Compound

Meyer

Schöttl

Bretz

et al. 2020

Composites Part A: Applied Science and Manufacturing

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“…The low tooling costs (compared to steel processing) and fast cycle times make compression molding a cost-efficient method to manufacture large DFC parts in a one-shot high volume production process, enabling DFC parts to replace automotive metal components for mass-reduction purposes [6,7]. As this material class and manufacturing method allow a high freedom of design [5], part integration (e.g., fasteners or inserts) [7], and can be used to mold complex three-dimensional (3D) shaped structural and non-structural components with corrugations, ribs and domes, it is widely used among the automotive industry and a key aspect for the endeavor to reduce the vehicle weight as much as possible [5,8]. Among this type of DFC, carbon fiber sheet molding compounds (CF-SMC) have been extensively used for interior and exterior, structural and non-structural composite applications in the automotive and aerospace industry [7,[9][10][11][12].…”

Section: Motivation and Materialsmentioning

confidence: 99%

Direct Fiber Simulation of a Compression Molded Ribbed Structure Made of a Sheet Molding Compound with Randomly Oriented Carbon/Epoxy Prepreg Strands—A Comparison of Predicted Fiber Orientations with Computed Tomography Analyses

2020

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Discontinuous fiber composites (DFC) such as carbon fiber sheet molding compounds (CF-SMC) are increasingly used in the automotive industry for manufacturing lightweight parts. Due to the flow conditions during compression molding of complex geometries, a locally varying fiber orientation evolves. Knowing these process-induced fiber orientations is key to a proper part design since the mechanical properties of the final part highly depend on its local microstructure. Local fiber orientations can be measured and analyzed by means of micro-computed tomography (µCT) and digital image processing, or predicted by process simulation. This paper presents a detailed comparison of numerical and experimental analyses of compression molded ribbed hat profile parts made of CF-SMC with 50 mm long randomly oriented strands (ROS) of chopped unidirectional (UD) carbon/epoxy prepreg tape. X-ray µCT scans of three entire CF-SMC parts are analyzed to compare determined orientation tensors with those coming from a direct fiber simulation (DFS) tool featuring a novel strand generation approach, realistically mimicking the initial ROS charge mesostructure. The DFS results show an overall good agreement of predicted local fiber orientations with µCT measurements, and are therefore precious information that can be used in subsequent integrative simulations to determine the part’s mesostructure-related anisotropic behavior under mechanical loads.

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“…Connected to this is the issue of predicting the mechanical properties of the finalized SMC parts. This will not be discussed in detail in this paper, but the approach of Görthofer et al [27] allowed the mapping between results of compression molding simulations into structural models with good accuracy regarding predictions of structural properties. Until new models for the fiber orientation have been developed a possible route forward is to use commercial software as those presented in the introduction and calibrate them with experiments.…”

Section: Possible Areas Of Future Researchmentioning

confidence: 99%

“…Some more recent efforts include Li et al [3], Oter et al [24], Song et al [25], and Motaghi [26]. Several relatively new studies have also concerned the modeling of the entire process chain [27,28], concerning both process modeling [29,30] and mechanical modeling [31,32].…”

Section: Introductionmentioning

confidence: 99%

Review of the Numerical Modeling of Compression Molding of Sheet Molding Compound

et al. 2020

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A review of the numerical modeling of the compression molding of the sheet molding compound (SMC) is presented. The focus of this review is the practical difficulties of modeling cases with high fiber content, an area in which there is relatively little documented work. In these cases, the prediction of the flows become intricate due to several reasons, mainly the complex rheology of the compound and large temperature gradients, but also the orientation of fibers and the micromechanics of the interactions between the fluid and the fibers play major roles. The details of this during moldings are discussed. Special attention is given to the impact on viscosity from the high fiber volume fraction, and the various models for this. One additional area of interest is the modeling of the fiber orientation.

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Virtual process chain of sheet molding compound: Development, validation and perspectives

Cited by 80 publications

References 52 publications

Direct Bundle Simulation approach for the compression molding process of Sheet Molding Compound

Direct Bundle Simulation approach for the compression molding process of Sheet Molding Compound

Direct Fiber Simulation of a Compression Molded Ribbed Structure Made of a Sheet Molding Compound with Randomly Oriented Carbon/Epoxy Prepreg Strands—A Comparison of Predicted Fiber Orientations with Computed Tomography Analyses

Review of the Numerical Modeling of Compression Molding of Sheet Molding Compound

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