DLR and its partners in the NATURE project are using very thin plies of carbon fiber-reinforced LMPAEK for thin-walled aerostructures. Source | DLR

Making the next generation of composite structures for space and aviation lighter and more efficient requires rethinking not only the structure, but also the material itself. The German Aerospace Center (DLR) Institute of Structures and Design (Stuttgart) and the associated DLR Centre for Lightweight Production Technology (Augsburg) have recently completed a major milestone with excellent results in the project NATURE, using automated fiber placement (AFP) to manufacture laminates from very thin plies of carbon fiber-reinforced prepreg made with LMPAEK thermoplastic polymer (Victrex, Clevelys, U.K.).

The prepreg, produced by Fukuvi Chemical Industry Co. Ltd. (Fukui, Japan), features a fiber areal weight (FAW) of only 36 grams per square meter (gsm) and is only 45 microns thick — so thin that each layer of the laminate has as few as seven fibers in the vertical direction. This is approximately a third of standard carbon fiber/LMPAEK material, meaning three times the design flexibility in deciding how fibers are oriented to achieve maximum performance.

NATURE project to reduce CO? emissions in aviation

Funded by the German Federal Ministry for Economic Affairs and Energy (BMWE), this project runs from 2023 to 2026 and focuses on the production of new lightweight helicopter structures and the holistic reduction of CO? emissions across the entire life cycle.

Fraunhofer IGCV highlights

Sources | Fraunhofer, LiezDesign - Adobe Stock

Project partners — including Airbus Helicopters, Fraunhofer IGCV and Technische Universität Dresden (TU Dresden) — are considering all phases from material production and manufacturing technologies to construction methods, operation and end-of-life processes. This cradle-to-grave approach avoids conflicting effects that could arise from optimizing individual process steps in isolation. The goal is to establish sustainable design principles and manufacturing processes that contribute to a significant reduction in the ecological footprint.

Thin-walled surface structures, innovative joining technologies

The production of modern carbon fiber-reinforced polymer (CFRP) components for the aerospace industry involves several energy-intensive process steps, particularly in the drilling and joining of different materials such as metals and adhesives. The resulting structural weight depends heavily on the properties and thickness of the prepreg.

Within the framework of NATURE, the consortium of experts in design, materials science, process engineering and the specific implementation scenario in helicopters are developing an innovative construction method based on thin-walled shell structures with pseudo hollow-profile stiffeners. This design enables significant mass savings without compromising the mechanical integrity of the structure.

Laboratory test bench for continuous ultrasonic welding of high-performance TPC at the DLR ZLP in  Augsburg. Source | DLR

The other key focus is further development of thermoplastic composite (TPC) manufacturing technologies to make laying and joining processes more efficient. The TPC tape laying process is being adapted to enable reliable production of thin, double-curved geometries. In addition, existing TPC joining processes are being evaluated for bio-based and recycled materials.

Process automation, material efficiency via SMC

Hot press at the DLR ZLP in Augsburg is used for SMC processing (left) and SMC test plate for analyzing mold filling behavior (right). Source | DLR

Another research area within the NATURE project is the automated manufacturing of sheet molding compound (SMC) structures, specifically using process simulations to significantly reduce process finding time and energy consumption. SMC technology enables the cost-effective production of complex structural components that were historically manufactured from metal. The SMC process is fully automatable and characterized by a high potential for functional integration. This opens new possibilities for lightweight construction, offering both ecological and economic advantages.