ROBUST SKIN: A MULTIDISCIPLINARY APPROACH TO ROBUST MEMBRANE WING DESIGN FOR SUSTAINABLE URBAN MOBILITY
Topic(s) : Material and Structural Behavior - Simulation & Testing
Co-authors :
Robin FACHTAN (GERMANY), Marcel FAILNER , Marco TOENJES (GERMANY), Wolfgang MACHUNZE (GERMANY), Uwe BEIER , Holger RUCKDÄSCHEL (GERMANY)Abstract :
This study presents an investigation into the design and feasibility of membranous wing structures for low velocity aircrafts for urban air mobility. Research was conducted in collaboration between Airbus Central Research and Technology, the Technical University of Munich (TUM), and Neue Materialien Bayreuth GmbH in the framework of the project "Robust Skin" (BFS AZ-1524-21). The interdisciplinary nature of the study includes materials, material design, process technology, component design, and testing method development, supported by analytical and simulation methods.
Compared to conventional aircrafts, urban aircrafts are operated with much lower cruise speeds and therefore lower acting aeroloads, which places different demands on the skin system. Due to the lower loads the wing skin thickness can be reduced (< 1.0 mm) compared to State of the Art (SoA) designs however they still need to be robust to withstand e.g. low velocity impacts such as hail. A hierarchical reinforced membrane skin material, based on the bionic concept of a dragonfly wing, was identified as a promising solution to combine the weight and robustness constraints.
To determine suitable ultra-light yet robust membrane materials, four material classes were investigated:
1.EPDM rubber with unidirectional carbonfiber reinforcement, resulting in a combination of robustness and stiffness
2.An elastomer-coated aramid fabric with high intrinsic robustness
3.A fabric composed of stretched ultra-high-molecular-weight polyethylene (UHMW-PE), which has a very high weight-specific tensile strength and robustness
4.A thin ply epoxy CFRP enabling ultra-lightweight membranes
After an initial phase with focus on the material processing and analytic thereof the investigation of the physical material behavior was the main subject of the project. Tensile tests with aged (UV, humidity) and unaged material coupons as well as a non-standardized impact tests of membranes in a pre-stressed, biaxial condition (see Figure 1) were performed with the scope to quantify the robustness of each chosen membrane materials and compare to SoA solutions. Beyond that also reinforced membranes were tested in how far the reinforcement influences the impact behavior.
Figure 1: Impact test for membrane materials under adjustable preloads
Gathered results from mechanical testing were used to supplement simulation models with real measured values for the anisotropic materials. Finally, a simulation of a generic but representative wing box was deduced to validate the investigated development approaches.
In conclusion, the study presents a synergistic approach of material design, processing, and simulation for an eco-efficient flight concept. The detailed exploration of material properties and their integration into innovative wing structures marks a significant contribution to the field of composite materials and aeronautical engineering.
Compared to conventional aircrafts, urban aircrafts are operated with much lower cruise speeds and therefore lower acting aeroloads, which places different demands on the skin system. Due to the lower loads the wing skin thickness can be reduced (< 1.0 mm) compared to State of the Art (SoA) designs however they still need to be robust to withstand e.g. low velocity impacts such as hail. A hierarchical reinforced membrane skin material, based on the bionic concept of a dragonfly wing, was identified as a promising solution to combine the weight and robustness constraints.
To determine suitable ultra-light yet robust membrane materials, four material classes were investigated:
1.EPDM rubber with unidirectional carbonfiber reinforcement, resulting in a combination of robustness and stiffness
2.An elastomer-coated aramid fabric with high intrinsic robustness
3.A fabric composed of stretched ultra-high-molecular-weight polyethylene (UHMW-PE), which has a very high weight-specific tensile strength and robustness
4.A thin ply epoxy CFRP enabling ultra-lightweight membranes
After an initial phase with focus on the material processing and analytic thereof the investigation of the physical material behavior was the main subject of the project. Tensile tests with aged (UV, humidity) and unaged material coupons as well as a non-standardized impact tests of membranes in a pre-stressed, biaxial condition (see Figure 1) were performed with the scope to quantify the robustness of each chosen membrane materials and compare to SoA solutions. Beyond that also reinforced membranes were tested in how far the reinforcement influences the impact behavior.
Figure 1: Impact test for membrane materials under adjustable preloads
Gathered results from mechanical testing were used to supplement simulation models with real measured values for the anisotropic materials. Finally, a simulation of a generic but representative wing box was deduced to validate the investigated development approaches.
In conclusion, the study presents a synergistic approach of material design, processing, and simulation for an eco-efficient flight concept. The detailed exploration of material properties and their integration into innovative wing structures marks a significant contribution to the field of composite materials and aeronautical engineering.