A review of radiative heating in automated layup and its modelling Automated layup processes are highly suitable for an efficient production of carbon fiber reinforced parts, especially for aerospace applications. Heat input by means of radiative heating offers advantages for these processes and is well established in different forms. The presented work reviews the modelling of radiative heating in automated layup, covering thermoset and thermoplastic materials. Laser and infrared heat sources are studied with their characteristics, similarities and differences, as well as optical interaction with the material. Numerical modelling of the heat transfer is presented with an emphasis on implementation of radiative heating. Literaturübersicht zur Strahlungserwärmung in automatisierten Faserablegeverfahren und deren Berechnung Automatisierte Faserablegeverfahren haben sich in der Luft-und Raumfahrt als geeignete Prozesse zur effektiven Produktion etabliert, wobei der Wärmeeintrag durch Strahlung weitrechende Vorteile bietet. Die vorliegende Arbeit fasst Untersuchungen zum Einsatz und insbesondere zur Berechnung von Strahlungsheizungen in spezifischen Anwendungen zusammen und berücksichtigt sowohl thermoplastische als auch duromere Verbundwerkstoffe. Dabei werden die Eigenschaften, Gemeinsamkeiten und Unterschiede von Laser und Infrarot Strahlungsquellen, sowie die optischen Interaktionen mit dem bestrahlten Material betrachtet. Die numerische Abbildung der Wärmeübertragung wird mit einem Fokus auf Strahlungserwärmung beleuchtet.

Full thermoplastic composite sandwich structures with a foam core offer the possibility to be manufactured by fusion bonding in significant shorter cycle times than thermoset-based sandwiches. However, the application of foam cores results in lower mechanical properties such as compression and shear strength compared to honeycomb cores, therefore foam-based sandwiches cannot compete with sandwich structures based on Aramid/phenolic honeycomb cores, the current state of the art. In order to improve the mechanical performance of foam core-based sandwiches while maintaining their advantages, concepts to reinforce the foams were developed in this study. By introducing rods either orthogonally or diagonally to the skin plane, which are fusion bonded to the skins during processing, the compression and shear properties can be improved by up to 1000% and 72%, respectively. Even when correcting for the weight increase, an improved specific compression strength could be achieved. And therefore, the pinning looks especially promising when only applied locally in highly loaded areas for example.

Control of material temperature distribution and governing phenomena during automated fiber placement is an important factor. Numerical modeling of the radiative heat transfer for a newly presented LED-based heating unit is developed and analyzed in theory. An optical model allows taking into account the radiative energy output of every individual LED. By adjusting the electrical input to the multiple LED arrays on the heating unit, the irradiance distribution on the substrate's surface can be controlled. To investigate the capability to adjust the surface temperature distribution resulting from this feature, thermal models for two and three dimensions are developed and employed for the calculated irradiance distributions. The resulting temperature distributions show that temperature gradients can be avoided or created, depending on the input to the heating unit. The results from the two models are compared and a method to select an appropriate model in general is proposed.