Cross-sectional variable pultrusion for sustainable high-performance composites

The European research project OPTIPUL is developing the first pultrusion technology capable of continuously producing profile structures with variable cross-sections.

The project thus addresses a key challenge facing modern lightweight structures: until now, pultrusion has only allowed for constant geometries – a major limiting factor for efficient components and customized material utilization.

Fraunhofer IWU is playing a key role in OPTIPUL in the development and demonstration of the new manufacturing process. Based on the sustainable, reactively processable thermoplastic system ELIUM®, we are developing a completely new tool and process concept that enables targeted, active modification of the profile cross-section during the ongoing process. At the heart of our approach is a movable pin system that controls the profile geometry in conjunction with a pre-manufactured variable foam core. We design, engineer, and build both the test tools and the final demonstrator tool. In extensive test series, we determine the process windows, limits, and control variables – from heat transfer and curing to fibre reorientation, pull-off forces, and fibre volume contents. The ultimate goal is to produce a functional, sustainable leaf spring demonstrator that showcases the performance of the new technology. At the same time, material data and simulation results from project partners LIST and MERGE are incorporated into tool and process optimization. Ford Otosan ultimately validates the industrial relevance in the automotive application environment.

The technology offers great potential for many industries, such as mobility, mechanical engineering, energy, and infrastructure, wherever lightweight, material‑efficient, and adaptable structures are required.