### Prior Work  
The active field of research in CFRPs and FDM has resulted in a plethora of publications regarding this topic which are presented in the following. Prior to the availability of a continuous prepreg filament short fiber filaments were widely used. The history of short fiber FDM is described in detail by [PERSON] et al. in [12]. This process has given way to the use of continuous fibers in recent years as the research in fiber pre-impregnation has progressed. This change is due to continuous fibers resulting in parts with far greater load capacity [3]. In the area of printing and impregnating fibers, several methods for both ex situ and in situ impregnation have been proposed. Ex situ prepreg filament exhibits greater material quality with the drawback of having to be manufactured prior to printing [2]. Furthermore, the equipment and morphological properties have been analyzed and elaboration can be found in [5]. Process and parameter optimization has been investigated with a special focus on the fiber volume fraction and porosity [3]. [PERSON] et al. point out that developed software needs to incorporate a stress analysis for CFRPs [9]. There have been multiple publications in which this is achieved in some form, although all were limited to the planar case. [PERSON] et al., as well as [PERSON] et al., chose a field-based method, showing great potential [13; 14]. [PERSON] et al. developed a method for multi-degree-of-freedom path planning incorporating a stress analysis. However, the possible geometries are limited for this algorithm as it requires flattening of the part resulting in the inability to print parts with non-zero gaussian curvature, meaning local curvature in more than one direction [15]. Multi-axis printing also enables the printing process to function without supporting structures completely. [PERSON] et al. showed this by using a geodesic distance field-based approach [16]. Path planning has been an active field of research for the automated fiber placement process for a long time. Thus, methods for complex geometries have been established over the years with approximate algorithms for path planning on curved surfaces being developed as early as 2004 by [PERSON] et al. [17]. For closed surfaces, [PERSON] et al. proposed a solution taking the minimum turning radius into consideration [18]. Newer methods for robotic fiber placement include the application to multi-axis revolution surfaces developed by [PERSON] et al. [19] and [PERSON] et al. using multi-guidelines on meshes to increase efficiency and applicability for complex geometries [20]. An extensive description and analysis of the state of the art of path planning methods used in automated fiber placement is performed in [21], where the methods using geodesic paths, fix angle paths, steering paths, seed curve projection, independent curves and parallel curves are presented. They have not been applied to the problem of 3D printing patches. Unwanted buckling and issues with highly curved surfaces remain a problem. Another approach to planning paths for CFRPs is to apply topology optimization in order to simplify the load transmission paths. This was performed by [PERSON] et al. in [22] using scaffolding paths and [PERSON] et al. in [23] using the medial axis transform as orientation. Both implemented path planning methods which aim to align the fibers with the principal directions of stress. This was applied to the use of short fibers by [PERSON] et al. in [24]. The concept of using FDM-based models for the manufacture of CFRPs was proposed in [25] eliminating the need for a separately built mold, reducing the cost and time needed for the production of CFRP parts. The first investigations into the multi-axis manufacture of CFRPs with FDM were made by [PERSON] et al. in [8] where the verification of the process proved its potential. [PERSON] et al. analyzed the multi-axis approach with a 12-axis machine in [11] identifying the necessities for enabling the flexible and dynamic robotic manufacturing process.