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Thermal optimization of autoclave molds is essential to increase part quality, reduce manufacturing costs and increase autoclave capacity. Previous experience-based tooling designs allowed an optimization only after the mold was manufactured and tested. Manufacturing process simulation provides the capability for virtual tooling optimization within the design phase. Thereby, the range of possible optimizations increases and the tooling cost decreases. In order to use manufacturing process simulation efficiently, fast but accurate simulation methods must be available. The so-called shift factor approach was previously presented by the authors. This paper takes up the given approach and explains different influences on mold heat-up and how they can be covered in a thermal tooling simulation on an industrial scale. Proof of the simulation accuracy under realistic manufacturing conditions is provided together with an example of its application.

Out-of-plane ply wrinkling is a major quality issue for carbon fiber reinforced prepreg parts. Its triggers are numerous and not every influencing parameter is fully understood, yet. The research presented in this paper aims at providing a better insight into ply wrinkling generated during autoclave compaction using caul plates. A detailed description of the experimental set-up and the applied methodology is provided. Statistical analyses of varying influencing factors such as part thickness, geometry, tool–part interaction, and laminate lay-up are presented. This, in turn, generates a better understanding of their impact on fiber wrinkling risk and size. Part geometry and compaction deformation show the most significant influence on wrinkle size. However, for the given manufacturing concept, tool–part interaction also plays a significant role. It influences both the dimension and location of the wrinkles, as well as the existence and size of a critical flange length of the part. A noteworthy effect on wrinkle generation and size can also be observed when adding unidirectional plies to an otherwise fabric laminate.

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The H160-B is the latest helicopter design from AIRBUS HELICOPTERS with the extensive use of sandwich technology in the airframe. A sandwich with face sheets from CFRP and honeycomb cores is a robust outer skin of a helicopter. Furthermore it shows a very good tolerance to impact damages and a very good reparability. At Airbus Helicopters great experience is available which is required to understand and to control all manufacturing parameters, that are driving the quality of such parts. Powerful inspection technologies are in place to maintain the high level of manufacturing quality. In this paper an overview of the parts on this Helicopter made with sandwich technology will be given. These are cowlings and structural parts as well as principal structural elements (PSE) on main load paths. The respective certification requirements and related means of compliance demonstrations will be explained in detail. Special attention is paid to the applied methods for the damage tolerance demonstration of sandwich. The design and strength analysis was done with a combination of FEM analysis and analytical method, using basic allowable derived and validated by tests.

The H160-B is the latest recently certified helicopter from Airbus Helicopters with extensive use of composite materials in the airframe. In this paper an overview of the fuselage architecture and its design will be provided. During the design phase emphasis was laid on close cooperation between all the involved engineering disciplines like architecture, design, stress, tooling, manufacturing simulation and production. Target was to achieve smaller tolerances resulting in better fit of the parts during assembly, increase first time right and show compliance with the latest airworthiness requirements. For composite parts this process will be shown using the examples of a main frame in prepreg technology and the Upper Deck Framework in RTM technology. The substantiation of the airframe was based on the similar new structure approach with analytical tools for numerical simulation that have been supported by tests of novel design features.

During the autoclave manufacturing of sandwich components, several defects may arise. A typical defect in the use of honeycombs is core crush. The occurrence of this defect depends, among other things, on the angle of the honeycomb chamfer. To design this angle, the friction between honeycomb and prepreg must be known. Due to the low rigidity of Nomex® honeycomb in lateral direction, the determination of the frictional behavior between face sheets and honeycomb is a particular challenge. This paper shows the development of a test device for measuring the friction between honeycomb with film adhesive and carbon/epoxy prepreg for different temperatures and compressions corresponding to realistic manufacturing conditions. The device is also suitable for the evaluation of interlaminar friction between prepreg plies and tool-part-interaction. The requirements for the device are shown in detail. Advantages and disadvantages of various concepts for the individual modules are discussed in order to select the most promising design. As proof of concept, friction measurements between honeycomb and prepreg as well as prepreg to prepreg measurements are carried out. In the case of interlaminar measurements, the friction coefficient determined at 1 mm deformation deviates by 5.3% from already published values obtained with another device and is within the stated scatter range. The measurement results for honeycomb against prepreg are in direct correlation with manufacturing trials performed. Using the lowest coefficient of friction established, a critical angle of the honeycomb chamfer was determined. Subsequently, component samples were manufactured with an inclination angle of 7.5° above and 7.5° below the critical angle. The specimens with larger angle showed a strong core crush, whereas those with smaller angle exhibited no core crush. This demonstrates that with this device the honeycomb chamfer of sandwich components can be dimensioned based on the lowest friction coefficient determined between honeycomb and prepreg.