COOPERATE: High-strength, low-carbon components made from fiber-reinforced biopolymers

Methods for Sustainable Design: Understanding Materials, Developing Models, Optimizing Components

To design sustainable plastic components, materials and components must always be considered in conjunction with one another. Especially for components subjected to dynamic loads, the design determines their reliability and service life. In the “COOPERATE” project, we developed a comprehensive methodology to precisely characterize bio-based, sustainable materials, translate them into realistic material models, and thereby design durable, low-carbon components.

Material Characterization Beyond Standardized Assumptions

The bio-based polyamides used in the project differ from petrochemical reference materials in terms of mechanical behavior, processability, and service life. To ensure these materials could be used reliably under load, it was therefore necessary to record their behavior in detail through extensive tensile, vibration, and temperature tests.

Experts from Fraunhofer LBF developed advanced material models to represent material properties in structural simulation, including adapted nonlinear hardening models and anisotropic descriptions that incorporate fiber orientation from the injection molding simulation. These models replicate the actual behavior of short-fiber-reinforced biopolyamides under operating conditions and provide the basis for reliable component design.

Simulation and Design: Sustainability Through Intelligent Engineering

Based on the modeled material properties, the research team was able to virtually optimize the suspension linkage. Instead of relying on high raw material stiffness, the validated models enabled a targeted geometric design, improved load distribution, and the consideration of process and fiber orientation effects.

The result was a design that achieves a comparable service life despite varying material properties - without requiring significantly more material. In this way, “COOPERATE” demonstrates that the development of sustainable components depends primarily on methodological expertise and precise design, rather than on perfect material properties.

Validation on the Demonstrator: Bio-based and Durable

The optimized connecting rods were tested quasi-statically and dynamically at Fraunhofer LBF and within the consortium. The results show that the combination of comprehensive characterization, model-based design, and structural adaptation enables performance close to that of production parts, even with bio-based materials. The new design proved to be particularly robust under dynamic loading and met the defined service life criteria.

Sustainability Assessment and Outlook

In the life cycle assessment, the developed material COP1 demonstrated a reduced CO₂ footprint compared to the reference polyamide. The methodology we developed will make it possible in the future to select materials not only based on technical parameters but also on sustainability criteria, and then to optimize them specifically through simulation and design.

This approach can be applied to other injection-molded parts subjected to dynamic loads. – and strengthens the Fraunhofer LBF’s role as a development partner for cross-material, sustainable lightweight construction solutions.

Funding organizations and Partners:

Project Partners:

• BOGE Elastmetall GmbH
• TECNARO GmbH
• Technical University of Munich

Project Management: Fraunhofer Institute for Structural Durability and System Reliability LBF

Funding Agency: German Federal Ministry for Economic Affairs and Climate Action (BMWK)