Experimental data

An understanding of microstructural state is key to defining reliable material cards. CT-scanning techniques are well suited to this, and the post-treatment of the large files which are generated are done with VGSTUDIO MAX software. The fiber orientation of test samples can be visualized, analyzed, and reduced to fiber orientation tensors, the mathematical object describing the microstructure which can then be used in material modeling.

Experimental data is the foundation of good material modeling. The MaterialCenter database is capable of managing huge amounts of measurement results while preserving all traceability of the data. Material, test conditions, operator, laboratory, and more traceability data is stored to ensure the best data reliability. Furthermore, data sharing and searching is made simple across the organization, with access rights carefully managed to preserve data security and avoid data leaks.

The availability of experimental data is key to Industry 4.0 and virtual prototypes. Materials Connect and Materials Enrich are bridging the gap between engineers eager to get more material data in all conditions, and material suppliers having to compromise between customer demands and costs. The physics-based modeling capabilities are associated with the power of data science to grow the experimental database without spending time and resources in labs.

Virtual data

The anisotropy of fiber-reinforced plastics has always been an obstacle to achieving the accuracy of calculations. By connecting processing to mechanical simulation, material modeling is the solution. Material cards are now included in the service offer of many material suppliers. It is easy to find the right material card in the Digimat-MX database for accurate simulation.

Alternatively, creating your own material card is possible in two ways. Quantitative material cards - the best quality for predictive simulation - can be generated from CT scans and some tensile measurements at various angles versus fiber direction. Those results are used in a reverse engineering process within Digimat-MX. A faster possibility is to generate intermediate-quality semi-quantitative material cards, which can be done in minutes, by reusing an existing tensile test curve. Unlike for quantitative material cards, some necessary assumptions are made on the microstructural state and on failure at other angles to compensate for the reduced amount of experimental information provided.

On top of material cards for static simulation, which have an elasto-plastic behavior with failure, customers can either create or find in Digimat-MX material cards for other types of material behavior that are more suitable for specific application cases:

In applications where temperature is a driver, Thermo-Elastics material cards predict the right material stiffness as a function of temperature for parts submitted to vibration and having heterogeneous temperature fields. This helps capture the right resonance frequencies because thermoplastics have a strong temperature sensitivity. When parts are submitted to high mechanical loads, Thermo-Elasto-Plastic material models with failure are more appropriate.

For the accuracy of crash simulations, it is highly recommended to account for the strain rate dependency of materials. Such Strain Rate Elasto-Plastic models are available to ensure better correlation with the results of physical tests.

Over longer periods of time, Strain Rate Elasto-Plastic models can also describe the creep of plastics under constant loading, or relaxation under constant deformation.

The strain rate dependency matters in the field of NVH where the damping and stiffness are frequency dependent. This is particularly useful for acoustic management of electric vehicles.

Whereas cars are dimensioned in crash, heavy vehicles like trucks are dimensioned in fatigue. For those who must manage this type of complex behavior, Digimat can also deliver an answer with specific fatigue material cards, provided by material suppliers. The longer the experimental test (fatigue, creep), the more value the material cards have.

In Summary

This solution provides material modeling to accurately design fiber-reinforced plastic parts right the first time, saving both unnecessary time and cost caused by multiple design iterations.