Ticona Engineering Polymers has announced the global availability of "integrative simulation" technology that can help customers design cost-effective complex glass fiber reinforced parts. "As a solution provider, Ticona recognizes that successful new components rely on the speed and quality of computer-aided engineering (CAE) predictions," said Ulrich Mohr-Matuschek, Ticona global part design/CAE leader. "Customers today expect working solutions based on detailed structural response predictions and optimized mold design."

Since 2009, Mohr-Matuschek and his team have worked with e-Xstream engineering DIGIMAT material and structure modeling tools to link Autodesk Moldflow plastic injection molding simulation tools with ANSYS Inc. structural analysis to improve the accuracy of computing fiber reinforced components under load. Labeled integrative simulation, because it integrates processing simulation data in the computation of the component, this technology can be used in designing complex parts that use both short and long fiber reinforced thermoplastics.

"By systematically comparing simulation and experimental results, we have shown this procedure can move simulation forecasts a lot closer to the actual experimental gradients," Mohr-Matuschek said. "Thus, the non-linear and anisotropic simulation of a sunroof mount made with a glass fiber reinforced Celanex thermoplastic polyester (PBT) matches the experimental values a lot better than the results of other computation models."

Fiber Flow Orientation Key to Success

The field of application for fiber reinforced thermoplastic polymers is constantly increasing, especially in parts exposed to high loads. Cost and time factors are issues that have played a significant role in increasing the relevance of CAE in part design. Standard procedures, based on the finite-element (FE) method are frequently used. Numeric methods provide information on the component's behavior under load assuming uniform mechanical properties of the molded material. However, mechanical properties of fiber reinforced thermoplastics vary depending upon the orientation of the fibers. During the mold filling phase of the injection molding process the fibers typically are oriented in different directions within the part as a function of the melt flow. The influence of this local fiber orientation is substantial and not taken into account in the common numerical methods, a factor which plays a significant role for components subject to high or extreme loads.

Unlike standard FE calculation methods, integrative simulation takes into account the influence of the local fiber orientation in the component as well as the elastic-plastic behavior of the matrix materials. Non-linear anisotropic material models are used for this method. Models are based on stress/strain curves that are determined on specimens of the specified material in the main orientation direction of the glass fibers, at a 45-degree angle and perpendicular to the main direction. The results for the fiber directions are transferred after the mold filling simulation via so-called "mapping" to the structural analysis.

Very Good Approximation of Gradient

Ticona applied the integrative simulation for the design of a glass fiber reinforced sunroof mount made of Celanex 2300 GV1/30 PBT and examined the results in terms of accuracy in comparison to experimentally determined values. "This is a great example of an effective joint project with one of our customers, Roland Peter, manager simulation & analysis, Roof Systems, Inteva Products in Germany," Mohr-Matuschek added.

The systematic comparison of this non-linear anisotropic simulation displays a considerably improved compliance with experimentally determined values. The resulting simulation for the sunroof mount illustrates that the integrative simulation provides more accurate results than common linear isotropic calculations methods. "Our integrative simulation is an effective technology for the optimal design of a fiber reinforced component and offers major advantages in material savings and cost in complex parts," said Mohr-Matuschek. "Integrative simulation demonstrates the tools Ticona can deliver in helping customers to design components and underscores its position as a solutions provider in the field of material, component design and processing."