Development of a new generation of helicopter doors

The project focuses on the elaboration and partial validation of detailed overall concepts for a new generation of side and rear doors for helicopters, incorporating the specific functions. This is intended to achieve the goal of reducing the cost of a fully equipped door, while at the same time enhancing other features such as comfort perception, among others.

In the first step, the relevant requirements and evaluation criteria for both the structure and the specific door functions are elaborated and systematized. Subsequently, the technical solution spaces for the structural design of the door are defined based on the individual components, as well as the necessary joining and integration processes. A similar procedure is followed for the specific functions, such as noise and vibration insulation, tightness, kinematics, window and emergency exit functionality. At the same time, these solution spaces are translated into the industrial context and the corresponding material and process chain technical concepts are developed.

For the individual components, this concerns the materials used and the associated processes. The procedure for the joining and integration technologies and the special door functions is corresponding. The cross-functional process chain integrates all individual elements under industrial aspects including data handling in the context of digitized manufacturing. Individual processes or technologies are validated for validation during concept development with as little effort as possible.

From the knowledge gained, the best approaches are combined into a final integrated overall concept on the basis of a detailed evaluation, and individual but also complex critical elements are validated by implementation in hardware. The overall concept is to serve as a starting point for a follow-up project with the goal of complete implementation.

Criteria derivation for component development

• Development of an evaluable optimization strategy for the project procedure
• Determination of relevant key figures for the evaluation of the project status
• Differentiation of various target parameters for design, process and material selection

Lightweight concept development

• Conceptual development and evaluation of integrative and differential component designs
• Incorporation of different manufacturing options considering cost, complexity, technological maturity and structural performance
• Consideration and pre-estimation of different integrative add-on elements according to the possibilities of different manufacturing routes

Design

• Surface detailing for optimization of connection concepts, ergonomics and aerodynamics
• Intelligent integration of sensory and actuator components in the part
• Process-oriented surface design for thermoplastic and thermoset Vließ and SMC materials

Calculation

• Development of material- and process-specific modeling models
• Component optimization using finite element methods for weight optimization
• Calculation of different technological solution spaces and materials as input for manufacturing tests

Testing

• Development of a test strategy from material and process evaluation to the testing of complex components
• Evaluation of mechanical parameters using standardized and special test specimens

In the Light project, it can be shown that, compared to completely integrally manufactured continuous fiber carbon components, approximately weight-neutral and significantly more cost-effective components can be realized for aerospace applications. The high degree of functional integration possible with nonwoven and SMC materials is of particular benefit. Due to the process, more geometric possibilities are possible, such as ribs, which can be used as connecting points between two shells and as independent stiffeners. As a result of this and the high possible degrees of deformation, designs can be found which can realize shear fields in components even without the use of honeycombs.

Likewise, the isotropic material behavior of the materials makes a robust design possible, although very thin wall thicknesses of slightly more than one millimeter can be achieved, which is relevant for aerospace applications. Mechanical tests here suggest that even in such areas, little anisotropic flow path-related structures are produced.

Intelligent partitioning of the shells also makes it much easier to equip them with the necessary electronics, while maintenance behavior has also been improved. Above all, however, quality assurance can be carried out very easily with smooth pressed parts.

In general, it was possible to show under the given loads and boundary conditions to what extent a clever estimation of the possible as well as necessary degree of integration of a component to be designed as light as possible shows that the component which is lightest in theory does not always offer the lightest solution in the end when all components are combined. Within the framework of our multidimensional optimization in the LIGHT project, it was possible to develop a more favorable, better functioning overall component of the same weight. This can be seen as the basis for a variety of further developments, especially with regard to the use of nonwoven and SMC materials.

Our research project LIGHT is based on the funding initiative BayLu25. The funding program is mainly concerned with research, development and innovation projects basically in the field of action "Increasing productivity and material efficiency in the aviation industry".

Project duration: February 2021 to February 2024

Funding volume for the University of the German Armed Forces: 259,000€.

The project is funded by the Bavarian State Ministry of Economic Affairs, Regional Development and Energy.