Cost, Draping, Material and Partitioning Optimization of a Composite Rail Vehicle Structure

This study proposes a novel methodology to combine topology optimization and ply draping simulation to partition composite structures, improve structural performance, select materials, and enable more accurate representations of cost- and weight-efficient manufacturable designs. The proposed methodology is applied to a structure as a case study to verify that the methodology is effective. One design concept is created by subjecting the structure to a kinematic ply draping simulation to inform the partitioning of the structure, improve drapability and performance, and reduce structural defects. A second design concept is created that assumes that plies are draped over the entire structural geometry, forming an integral design. The two design concepts’ topologies are subsequently optimized to specify ideal material and ply geometries to minimize mass and reduce costs. The results indicate that the partitioned structure has a 19% lower mass and 15% lower material costs than the integral design. The two designs produced with the new methodology are also compared against two control designs created to emulate previously published methodologies that have not incorporated ply draping simulations. This demonstrates that neglecting the effects of ply draping produces topology optimization solutions that under-predict the mass of a structure by 26% and costs by 38%.

Material description for textile draping simulation: data structure, open data exchange formats and system for automatic analysis of experimental series

The simulative development of clothing and other textile products requires a complete set of material parameters to be provided. Currently, different simulation software providers users with different values and formats for these parameters. This paper provides an overview about the most important values and proposed structures for storing both the raw data and the extracted parameters. The structure is implemented in both JSON and XML formats, allowing integration in proven formats for three-dimensional worlds such as gltf and x3d. Finally, a structure for organization of the raw data of the testing devices is described. Following this structure allows automatic processing, normalization and extraction of the parameters in short time. The goal of the paper is to simplify and unify the exchange of material parameters for textile fabrics.

Variable-thickness design of CFRP B-pillar reinforcement considering draping

An integrated optimization method that comprehensively considers draping factors such as fiber reorientations and cutting of layers is proposed for designing CFRP B-pillar reinforcement with a variable thickness. A laminate parameterization scheme, the local shared layer parameterization scheme (LSL-PS), is developed to parameterize the physical composition of laminates with variable-thickness. Kinematic draping simulations and preform designs are introduced to evaluate fiber reorientations and eliminate manufacturing defects. The optimization design of the B-pillar reinforcement is integrated with a LSL-PS, draping-simulation and preform-design, a RBF surrogate model and GA. At the same time, a comparative optimization without the consideration of draping factors is performed in parallel. The comparison results show that considering draping not only helps designers eliminate manufacturing defects but also helps to obtain a further weight reduction of 13.33% because fiber reorientations are fully utilized to improve the structural performance.

Mesoscale draping simulation of carbon fiber mat for arbitrary weave architecture

We perform a mesoscale draping simulation using a woven carbon fiber mat model consisting of fiber bundles. The deformation of various types of fabrics during draping is predicted using fiber bundle data; no fabric experiments are necessary. First, bending experiments and simulations are performed to determine the material constants of the fiber bundle. To confirm the validity of the mesoscale model, we compare the experimental and simulation results of bias-extension tests. The simulated test shows that the simulation reproduces the deformation behavior of the carbon fiber mat under tensile force. The draping of a plain-weave or twill-weave carbon fiber mat on a hemispheric mold is simulated using the proposed mesoscale model and investigated experimentally. The results confirm that the simulation reproduces the deformation of the fabric using only the fiber bundle data.

Experimental and Numerical Determination of the Local Fiber Volume Content of Unidirectional Non-Crimp Fabrics with Forming Effects

Detailed knowledge of the local fiber orientation and the local fiber volume content within composite parts provides an opportunity to predict the structural behavior more reliably. Utilizing forming simulation methods of dry or pre-impregnated fabrics allows for predicting the local fiber orientation. Additionally, during the forming process, so-called draping effects like waviness, gapping or shear-induced transverse compression change the local fiber volume content. To reproduce and investigate such draping effects, different manufacturing tools have been developed in this work. The tools are used to create fabric samples with pre-defined deformation states, representing the different draping effects. The samples are evaluated regarding the resulting fiber volume content. The experimental results are compared with the predictions of an analytical solution and of a numerical solution based on draping simulation results. Furthermore, the interaction of the draping effects at arbitrary strain states is discussed regarding the resulting fiber volume content.