ÂÌñÏ×ÆÞ

As aircraft and spacecraft manufacturers advance toward next-generation technologies including large thermoplastic composite primary structures, reduced carbon-emissions propulsion including hydrogen power, and multifunctional structures, there is a lot of materials testing and validation work required before qualification and commercialization are possible.

CW had the chance to recently catch up with (FIBRE, Germany), a legally independent research institute operating in four sites with about 60 employees, focused on research of fiber-reinforced polymer composites and fibers for technical applications with a large focus on supporting next-generation aircraft and spacecraft technologies.

In what capacity? “Our DNA is materials testing,” explains Professor David May, FIBRE director. In fact, the institute started as a spin-off in the 1950s from the Bremen Cotton Exchange, conducting quality testing on cotton materials for use in textiles. By the late 1980s, the organization had evolved into an independent institute and, partnered with the local University of Bremen, its work began to transition from quality testing to more advanced research on a variety of fibers including cotton, wool and plant fibers, followed later by synthetic fibers and processing technologies. Over the past 25 years, composites were gradually added into the mix and expanded, and today composite materials comprise about 75% of FIBRE’s research. In particular, thermoplastic composites (TPC) are a strong focus.

“We say materials testing is our DNA because we characterize fibers, polymers and composites all the way from single fiber tests to yarn tests to coupon-level composite testing. Beyond that, we have activities related to development of manufacturing processes, process simulation, monitoring and quality assurance, and part design,” May says.

FIBRE receives about 10% of its funding from the government of Bremen and 90% from third-party funds. Since 2012, the institute has been involved in more than 100 publicly funded research projects, as well as numerous industry-funded R&D initiatives.

The institute currently runs sites at the University of Bremen campus, the (Center for Eco-Efficient Materials & Technologies) research & technology center, and the Bremen Cotton Exchange, as well as the Technology Center in Stade.

Beyond research itself, FIBRE is also involved in teaching and student research programs through its partnership with the university, and in developing the technical program for the , a TPC conference held every other year in Bremen for the past 15 years. “It’s the only conference in Europe really focusing on high-performance TPC,” May says. “I love this conference, because all participants work on thermoplastics and are experts who are genuinely interested in advancing the field, and so the quality of the presentations is top-notch.”

Earlier this year, CW had the chance to visit FIBRE’s ECOMAT site, and to catch up more recently with May, who stepped into the director role in August 2024 and also teaches at the University of Bremen and serves as Airbus Endowed Chair for Rivet-Free Assembly Technologies.

ECOMAT itself opened in 2019, and is a joint research facility run by the Free Hanseatic City of Bremen along with Airbus and other partners, with the goal of advancing technologies that will enable climate-neutral aviation. With more than 500 total researchers on site, ECOMAT houses a variety of tenants — including FIBRE, Airbus, Testia GmbH, the German Aerospace Center (DLR) .

Located within Bremen’s airport center, where it is neighbored by Airbus, ArianeGroup, MT Aerospace and others in the space and aviation fields, FIBRE’s ECOMAT site naturally emphasizes research projects related to aerospace applications. “Bremen is the city of aerospace, including spacecraft,” May adds.

Within this focus, the site’s research has a variety of branches, including cryogenic hydrogen, lightweight design and manufacturing technologies, 3D printing, virtual testing and approval procedures (more on some of these research areas below).

As part of ECOMAT, there is also a deep focus on technologies related to sustainability. “Indirectly, basically everything we’re doing is contributing to sustainability,” May says. “For example, we’re doing cryogenic testing so that Airbus can develop tanks for hydrogen-powered aircraft. Thermoplastics allow for more energy-efficient processes. We’re doing research on bio-based polymers and fibers, and recycled carbon fibers. It’s all about sustainability in some way.”

Capabilities: Cryolab, pultrusion, TFP, automated layup and more

In the last 6 years since opening the ECOMAT site, FIBRE has gradually added staff and capabilities into the facility. Today, the 1,500-square-meter space employs about 30 researchers plus graduate and undergraduate students from the local university.

FIBRE’s on-site’s capabilities and research areas include:

• Cryogenic testing
• Pultrusion and winding
• Automated fiber placement (AFP)
• Welding and patch repair
• Tailored fiber placement (TFP)
• Thermoforming
• Injection molding and overmolding
• Walk-in radiation shielding cabin for X-ray development and analysis, and more.

The newest and most prominent area seen on CW’s visit was the cryolab.

Cryogenic testing to support hydrogen storage, future aircraft

Airbus may have pushed back its timeline for launching its ZEROe hydrogen-powered aircraft into the 2040s, but the company is still committed to the program — and, notably, multiple partnerships and projects related to hydrogen-powered aircraft were announced by Airbus and others at this year’s Paris Air Show in June 2025.

On FIBRE’s end, the postponement doesn’t affect the research being done, May explains. “We’re focusing on coupon-level testing, so no matter what the timeline is on the commercial side, we have to start now to investigate how materials behave under cryogenic conditions.”

To support this work, in 2024, FIBRE’s ECOMAT site installed a laboratory for cryogenic material testing (cryolab), built and maintained in part with collaboration from Airbus. 

Currently, the lab features a machine capable of performing tensile and bending tests on material coupons immersed in liquid nitrogen at temperatures as low as -196°C and up to 100 kilonewtons (kN) pressure, either in quasistatic or dynamic testing. The lab is also installing a test machine for testing samples in gaseous helium as well, at temperatures as low as -250°C and up to 100-kN loads. This machine is capable of not only static tests but dynamic thermal cycling — “to investigate thermal- and mechanical-induced crack initiation and propagation,” May explains. In situ permeation testing is currently under construction. Airbus also has a dynamic helium system in the lab allowing for temperature cycling of samples.

The lab is currently focused on thermoset composite and TPC tests, but also characterizes other materials such as metals or adhesives.

In addition to mechanical behavior, the researchers can also use the test machines to measure properties such as coefficients of thermal expansion from 4K to 200°C  — which enables for research of permeation, potential cracking in the materials and component design.

These machines serve as a first step toward ultimately testing material behavior while subjected to cryogenic hydrogen. “The first step is figuring out how to do the tests,” May adds. “You have to rethink your testing equipment when you’re suddenly working with a sample that is submerged in a cryogenic liquid nitrogen tank. How do you measure the elongation? How do you measure acoustic emissions? Everything is new.” FIBRE researchers have developed new approaches for acoustic emissions testing using microphones capable of picking up sound travel through the immersion tank.

He adds, “Helium allows you to cover a very large temperature range, and it’s much easier to handle than the liquid nitrogen or even hydrogen. Of course, we are not sure yet as an industry whether the tests done in helium is transferrable to hydrogen, so that’s the first thing we will have to investigate.”

In addition to FIBRE’s cryolab, ECOMAT also has plans to construct a nearby ECOMAT Hydrogen Center (EHC) within the next few years, May explains, which will house research facilities involving Airbus and others studying the use of hydrogen propulsion in aircraft.

Ultimately, all of these efforts aim to support and enable infrastructure such as storage systems and pipes for transporting cryogenic hydrogen, and FIBRE plans to install capabilities for testing samples in liquid cryogenic hydrogen in the EHC. “This set of testing machines will enable us to investigate not only the mechanical behavior under cryogenic conditions, but also to evaluate transferability — for example, between the easier and cheaper helium tests and the more complex but closer-to-the-application hydrogen tests,” May says.

Thermoplastic composites research: Manufacturing, joining, repair

The largest lab space in FIBRE’s ECOMAT site houses areas for pultrusion, TFP and AFP systems, and current research projects are focused largely on optimizing manufacture, welding and repair processes using TPC, in addition to some bio-based materials.

“TPC in particular are very attractive for aircraft OEMs because you can do it quite a bit faster than with thermosets to meet the production rate increases that they are wanting. But it’s an area that really needs research, because [redesigning a part in TPC] also means you have to rethink everything, from manufacturing to joining to repair,” May says.

FIBRE’s TPC research at ECOMAT includes:

• Understanding the bond strengths and internal stressors on overmolded TPC, in order to optimize both part design and manufacturing process
• Resistance and ultrasonic welding to enable rivet-free aerospace assembly
• Part repair using inductive heating, and more.

Regarding repair, one technology FIBRE is working on starts with the manufacture of a carbon fiber/polyphenylene sulfide (PPS) patch manufactured using FIBRE’s robotic, AFP system (supplied by Conbility, Herzogenrath, Germany). This system enables fabrication of highly tailored, curved patches that closely match the performance of the original part.

This patch is welded to the scarfed damage area using msquare GmbH’s (Stuttgart, Germany) induction-based mats. “You pull a vacuum, put the mat inside, and can use it to do in situ consolidation or repair of TPC parts,” May says. FIBRE is working toward induction-based consolidation of curved TPC parts laid up using its ATP machine.

Regarding joining, FIBRE is investigating various welding techniques using TPC. “Applying conventional bonding strategies to TPC is more complex than bonding thermoset composites. So, there’s a lot of potential for welding, and large demonstrators like the MFFD [Multifunctional Fuselage Demonstrator] that have been set up to show this potential, but there is a lot of work that still needs to be done, and understanding at the material level that still needs to happen. That’s where research institutes come in,” May says.

Process monitoring for TFP

FIBRE operates a ZSK (Krefeld, Germany) TFP system for researching the fabrication of highly tailored preforms currently focusing on and mainly using carbon fibers and hybrid carbon fiber/thermoplastic yarns. Recent work has included the study of process monitoring methods for detecting defects in the preform and capabilities for adjusting the process in real time.

“It’s not always clear when you’re programming a stitch profile on the computer how the fiber and roving in the end will be exactly on your preform,” explains Marius Möller, research associate at FIBRE.

The team has installed a 3D laser-based monitoring system that scans the preform while it is being stitched, measuring and reporting height data to help the user determine whether there are any defects such as cracks or creases in the fabric. This is combined with a high-contrast camera that supplies images and width measurements for detecting potential gaps in the fibers.

“We use this data to predict what the final preform will look and can make adjustments,” Möller says. The goal is to work with an industry partner to translate this into a machine learning software system. “This would help to adjust your stitching profile automatically while you’re going, so you don’t have to do it in an iterative process.”

Optimizing natural fiber composites pultrusion

While aerospace is a strong focus for the ECOMAT site, it’s worth noting that FIBRE’s location in Bremen lends itself to other industrial research areas as well. “Besides space and aeronautics, the city of Bremen is also well-known as a trading city with shipbuilding yards,” May says. This led to a collaboration with nearby Bremen-based , a flax fiber composites specialist that got its start in boatbuilding with its Greenboats brand.

The BMWE-funded (Federal Ministry for Economic Affairs and Energy) BioPul project began officially in August 2024 as a 2-year initiative aimed at optimizing the pultrusion process for use with natural fibers.

Circular Structures has specialized in flax fiber/bio-epoxy infusion — originally for the manufacture of boats and ultimately diversifying into applications like wind blade nacelles and recreational vehicles. “However, infusion can be expensive and labor-intensive, so we’ve been investigating lower-cost options like pultrusion,” explains Paul Riesen, head of R&D at Circular Structures.

In the BioPul project, Circular Structures works with FIBRE and pultruder Thomas Technik (Bremervoerde, Germany) on material selection and design for the trial profiles, basing the prototypes on real load cases.

Using FIBRE’s in-house Thomas Technik pultrusion machine, “we started with a really small profile to see if it’s even possible,” explains Simon Boysen, research associate for structural design and manufacturing technologies at FIBRE. “Compared to typical glass fibers, natural fibers have short lengths —  as short as 20 centimeters — which leads to a lot of issues when it comes to pultrusion. Not the least of which is the distance between the die to the pulling units.” It took a trial-and-error process to adjust and optimize the pultrusion system for natural fibers.

An additional challenge is that natural fibers in general take in more moisture and humidity than synthetic fibers, necessitating the installation of an oven as the first step after the rovings are pulled off the creels. “Part of what we’ve been working on is evaluating the process parameters for the pre-drying, and our current process is about a 10-minute pre-drying process for optimal moisture content going into pultrusion,” Boysen says.

The researchers began by pultruding flat profiles to perfect the pre-drying and pultrusion process using unidirectional (UD) flax rovings impregnated with liquid epoxy. Next, they started integrating a layer of biaxial twill flax fabrics as a middle layer within the pultruded profile — acting as a sort of core.

Why do this? “We want to be able to improve and control the mechanical properties not just in the 0° direction like in a conventional pultruded profile, but +/- 45° and 90° as well,” Boysen explains. “We know how to achieve UD pultruded profiles, including, now, using flax fiber. The goal here is to use these materials for applications requiring more flexible arrangement of the fibers and textiles.”

There were challenges with introducing this part of the process at first, Boysen notes. “Initially, we weren’t able to pre-dry the textiles, and so the extra moisture content led to issues with hardening of the profiles. The next step was to add guide plates onto the oven so that we can pre-dry the textiles as well.” A future goal is to inverse the arrangement and create profiles where two woven fabric skins sandwich a UD pultruded core.

From there, the researchers were able to test pultrusion of more complex geometries, starting with L profiles and ultimately demonstrator omega-profile parts, with and without additional textile reinforcement.

According to the researchers, results so far have demonstrated 30% greater tensile strength and stiffness and porosity of less than 3% with a fiber volume content of up to 65%. 

What applications could this be used for? Circular Structures’ Greenlander brand aims to use pultrusion to manufacture camper profiles faster and with less material compared to hand layup and vacuum infusion of the same parts. The Greenboats brand could also use this technique to fabricate marine components like cable canals and stringers.

Learn more and get involved 

Cryogenic materials testing, thermoplastics research, process monitoring and natural fiber pultrusion represent only a few of the many projects FIBRE is working on with its industry and academic partners, at ECOMAT and its other sites. Visit to learn more about the organization’s ongoing projects and learn how to get involved.