BMWi funded project DigiPEP: Digital product development process for the design of TFP-preforms.Copyright: © Digel Sticktech
Stress-optimised and close-to-net-shape textile preforms for the production of fibre-reinforced plastics (FRP), so-called tailored textiles (TT), offer potential for reducing component weight and material usage while simultaneously increasing component performance. This makes them valuable for improving sustainability throughout the entire product life cycle of FRPs and for reducing costs in their production. One textile manufacturing process for the production of TT is Tailored Fibre Placement (TFP).
The TFP process is a variant of technical embroidery in which semi-finished products are produced by a CNC-controlled variable-axial placement of reinforcing fibres. This enables cutting rates of less than 5 % to be achieved with ease. This makes TFP a highly efficient process in terms of the use of fibre material compared to other preforming processes based on flat semi-finished products (waste 30-50 %). In addition, reinforcing fibres can be aligned along the principal stresses in the component in a way that is adapted to the in-service stress state, thus avoiding overdimensioning (weight, costs, CO2 emissions). Despite the high level of technology readiness level of TFP embroidery technology (TRL Level 9), TFP-optimised component design and embroidery pattern generation (machine code for production) represent a challenge for industrial application in small and medium series. Although (partial) solutions are already known for individual design steps (FEA, load path determination, failure models, path planning, draping, costs), the parameters of the development steps are mutually dependent, i.e. for each development step there are both retroactive interactions and interactions on the subsequent development steps. This results in highly iterative and costly development in practice, making the efficient development of TFP components currently unfeasible.
The aim of the research project is to establish TFP technology in the German economy - especially among SMEs - in order to implement material- and resource-efficient lightweight design. To achieve this goal, a holistic, digitally networked product development process (PEP) for TFP components is being developed and validated as part of the project. The solution approach is based on the methodology of model-based systems engineering (MBSE). Here, the linked value chain (design, structural mechanics, textile and manufacturing technology) is mapped in the form of a system model, aggregated and made up of individual digital sub-models. The sub-models (FEA, load path determination, strength model, web planning and draping) are interlinked at parameter level, creating complete digitisation and continuity of the data. Through the system model, the TFP component-optimised design can be carried out holistically for the first time, i.e. production-oriented and optimised with regard to costs, weight and performance. Already during the structural design, solutions are evaluated with regard to their drapability and costs by directly calculating a path planning in order to avoid costly iterations.
The Institute for Structural Mechanics and Lightweight Design provides sub-models for the system model within the project framework. The focus is on the modelling of the TFP material (in particular taking into account the selected manufacturing parameters) and the component optimisation with regard to the local component thickness and fibre orientation. Different optimisation algorithms are examined for their suitability in the project context.
The project consortium includes the companies Adesso SE, Digel Sticktech GmbH & Co. KG, EDAG Engineering GmbH, ModuleWorks GmbH and Ph-Mechanik GmbH, as well as RWTH Aachen University with the Institute for Textile Technology (ITA), the Institute for Machine Elements and Systems Engineering (MSE) and the Institute for Structural Mechanics and Lightweight Design (SLA). The Institute of Textile Technology is the project leader.