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Item type:Publication, Access status: with files , Instant geodesic draping for optimization and path-planning and its application to incremental composite sheet formingTechnical textiles and their use in composites are crucial for many high-performance applications. Utilizing them in applications dominated by iteration and individualization requires flexible manufacturing processes. One such process is Incremental Sheet Forming (ISF), the 3D-Printing of forming processes, which is currently being adapted to composites. Enabling ISF, and other dieless processes, and leveraging their flexibility requires optimization and path-planning tools. Such tools must consider material behavior, which in turn necessitates the use of simulation. While highly sophisticated methods for increasingly accurate modeling have been developed, the speed requirements of CAM workflows and optimizations have kept simple yet efficient approximations relevant, the most prominent being kinematic draping algorithms. This work presents a novel heat-method based alternative that globally computes fabric draping under an assumption of uniform tow distances. This assumption makes it especially well-suited for the subsequently implemented drape-aware ISF paths. Additionally, the developed algorithm is highly computationally efficient, which is harnessed for visualization and optimization. While these are only explored computationally, the path-planning is employed to produce and compare a demonstrator part in a double sided ISF process. The initial results for the draping algorithm show an up to 80x speed increase compared to kinematic draping. This allows for real-time draping visualization and sub-minute optimization. The demonstrator part proves that the derived paths can counteract wrinkling, an important failure mode observed with conventional strategies. These results demonstrate the great potential of geodesic draping for ISF in particular and flexible manufacturing, optimization and visualization tasks in general.Publicationtype: Journal Article23 6 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Double-sided incremental forming of continuous fiber reinforced thermoplasticsContinuous fiber reinforced thermoplastics (CFRTP) combine excellent mechanical properties with recyclability, weldability, and reshapeability. However, their conventional processing requires part-specific tooling, imposing high initial cost and lead times. This limits their applicability to small lot sizes. A flexible alternative could be Incremental Sheet Forming (ISF), which creates parts by moving a small, part-agnostic tool along numerically controlled paths. While ISF is established for metals, its adoption for CFRTP started only recently. In particular, the Double-Sided Incremental Forming (DSIF) process, which employs a second forming tool to improve quality and flexibility, has not been investigated in detail for CFRTP. Therefore, this work presents the first extensive study into DSIF of CFRTP, with a focus on establishing a baseline process. The conducted process characterization includes temperature and force assessments. Forming strategies were compared by forming cone frusta, yielding a multi-stage strategy combining spiral and fiber-following toolpaths, which produced wrinkle-free parts with good accuracy. Micrographs indicate good consolidation for the tested material and process conditions. Furthermore, a preliminary process parameter analysis, including temperature, support force, and step size, was conducted. The results indicate that DSIF can become a viable, flexible manufacturing route for CFRTP components and provide a sound foundation for future research.Publicationtype: Journal Article50 19 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Digital twins in aircraft production and MRO : challenges and opportunitiesThe digital twin (DT) concept, value-adding connecting the real and digital world, has been a rising trend in recent years, while the implementation and observation of challenges are still subject to research. Implementations of holistic Digital Twins of tangible and intangible assets of complex products or processes are often ideal-theoretic; instead, only subsystems and processes are replicated, which digital representations serve specific, meaningful applications. Specifically, with its distinct characteristics, the aviation industry and its production show various future application scenarios, which we use case-driven outline in this work. Therefore, we first summarize common, industry-neutral challenges of implementing Digital Twins and give an overview of aircraft production characteristics. Then, we will outline different fields of utilizing the Digital Twin concept and highlight integrational, organizational, and compliance-related challenges as well as opportunities in the context of aircraft production and Maintenance, Repair, and Overhaul (MRO). The use cases are located at different aircraft life cycle phases, from production system development, production supplying logistics, and Quality Assurance (QA) up to retrofit.Publicationtype: Journal Article81 161