Shape memory polymer facilitates controlled deployment

Shape memory polymers (SMPs) are smart materials that retain a programmed temporary shape and recover their original shape when heated. Fraunhofer IAP uses this one-way shape memory effect to enable controlled movement in 3D-printed components, reducing the need for conventional mechanical actuation systems. The researchers processed the developed polymers into filaments suitable for additive manufacturing and fabricated functional hinges and Hold-Down and Release Mechanisms (HDRMs). During launch, HDRMs securely restrain the satellite components and subsequently release them in a controlled manner once in orbit. Following release, the SMP-based hinges enable the solar panels to deploy through thermally activated shape recovery.
 

3D printing enables rapid prototyping

The 3D-printed hinge weighs approximately 1.4 grams. When thermally activated using a heating element, the SMP undergoes a programmed shape change, causing the hinge to unfold. Under controlled laboratory conditions, the hinge completes its deployment within 60 seconds when heated from 23 °C to 140 °C.
The additive manufacturing process also enables rapid production of these functional components. Printing either a hinge or an HDRM takes approximately 15 minutes, followed by an additional 30 minutes to program the desired temporary shape. Consequently, each of these components can be manufactured and programmed in less than one hour, highlighting the potential for rapid prototyping and flexible design adaptation.
 

4D printing simplifies the manufacturing of thermoresponsive components

In the 4D-printing approach used here, the shape-changing response is programmed directly into the component during fabrication, rather than in a separate post-processing step. This approach has enabled the development of 4D-printed HDRMs that can be manufactured in just five minutes. Like their 3D-printed counterparts, these mechanisms enable the controlled release of restrained satellite components upon thermal activation.
“With AM-SPACE, we have demonstrated how shape memory polymers can open up new approaches to the design of small satellites. These components combine lightweight construction with integrated functionality and the ability to undergo controlled shape changes when activated,” says Dr. Thorsten Pretsch, Head of the Functional Polymer Systems research division at Fraunhofer IAP. “In the future, this could enable satellite systems to be launched in a compact configuration and deployed as needed once in orbit. Beyond hinges and Hold-Down and Release Mechanisms, we see potential for further activatable components,” Pretsch adds.
 

Initial validation under laboratory conditions

Initial validation activities for the SMP-based hinges and HDRMs, including tests under cleanroom conditions, thermal cycling, and preliminary vacuum chamber experiments, have been successfully completed. Furthermore, one of the SMPs developed at Fraunhofer IAP has successfully passed outgassing tests conducted at the National Institute for Aerospace Technology (INTA) in Spain, supporting the assessment of its suitability for potential space applications. However, the performance and long-term reliability of the components under actual space conditions have yet to be demonstrated.
 

Next step: Toward in-orbit validation

Discussions are currently underway on a potential follow-up project to advance the technology toward an in-orbit demonstration. German Orbital Systems, an experienced CubeSat manufacturer with an established track record in satellite development and deployment, has expressed interest in evaluating the SMP-based components under actual space conditions.

 

Project Additive Manufacturing of Solar Panels for spACE applications (AM-SPACE)

Project duration:
October 2023 – September 2026

Funding:

PROFit Brandenburg and IBB Pro FIT

The project was funded by the Investitionsbank des Landes Brandenburg (ILB), co-financed by the European Union. The Berlin-based project partners received funding from Investitionsbank Berlin (IBB).
 

Project Partners:

Orion Additive Manufacturing GmbH

• Development of a 3D printer for processing polyether ether ketone (PEEK) reinforced with continuous carbon fibers
• 3D printing of commercially available PEEK material suitable for laser direct structuring (LDS)
• Additive manufacturing of solar panel substrates for a 1U CubeSat using continuous carbon fibers and LDS-compatible PEEK

Fraunhofer IZM

• Laser structuring and metallization of LDS-PEEK solar panel substrates to produce electrical conductor tracks
• Implementation of three-dimensional printed circuit board structures on the substrates and mounting of electronic components
• Reliability testing and characterization of the overall system, including vibration testing, thermal shock testing, Thermal online test for investigating electrical properties, and topography measurements

German Orbital Systems GmbH

• Development of the circuit board design for the three-dimensional LDS-PEEK substrates
• Development of the electronics for the LDS-PEEK solar panels and the heating elements used to activate the hinges and HDRMs
• Integration of the components developed by the project partners into the satellite system
• Testing and functional verification of the overall system