Modelling of the structure and the properties of 3D warp knitted spacer fabrics and experimental evaluation

• Applicants: Dr. Julia Orlik; Dr.-Ing. Kathrin Pietsch
• Subject Area: Lightweight Construction, Textile Technology ; Mechanical Properties of Metallic Materials and their Microstructural Origins ; Production Automation and Assembly Technology
• Term: since 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 272669503

Due to their 3D structure, spacer fabrics (AGW) possess outstanding properties such as compressive elasticity, permeability and permeability, resulting in enhanced functions of the products manufactured from them. AGW are already established as foam alternatives, upholstery pads and pressure-elastic components with rear-ventilation effect, filter materials and reinforcing materials for FKV.In the first two years (phase I) methods, algorithms and numerical tools for calculation as well as the experimental environment for the measurement of the effective compression stiffness of flat AGW structures, the flow properties and their effective permeability were developed. The result is a simulation model with which the macroscopic properties of AGWs in the unloaded and loaded state can be predicted. This provides AGW with an expandable tool for virtual, function-adapted product development that will replace the previously extremely time-consuming and costly experimental technology. Based on this, "inverse" problems" are calculated in the 3rd and 4th year (Phase II). The focus is on the possibilities of textile and confection technology for locally influencing the effective structural properties of the AGW in a function-adapted way. In particular, two functional examples are considered: - On the one hand, the flow processes in the distance space are to be adapted to the function. The 3D structure is to be optimized on the basis of an AGW coated on both sides with a good flow-through effect and sealed edges. Such scenarios are relevant for applications in which the clearance space is flooded with a circulating medium (tempered water), e.g. for photovoltaic modules and operating table supports. The aim is to find a suitable monofilament arrangement for different flow-through scenarios. Optionally, the effect of seams for local flow control in the distance space should be taken into account.- On the other hand, the effect of seams is investigated in order to achieve a local stiffening of the AGW surface according to the requirements. The aim here is to develop a method to variably design the distance between the knitted surfaces in the seam area and to achieve a defined curvature. A further goal is to find a suitable seam thickness and distance between two adjacent seams that provides a function-adapted combination of compression stiffness and AGW curvature between two seams. The final result is the provision of software prototypes for the virtual product development of function-adapted 3D surface structures, taking into account the confection processing. They allow a better understanding of the design, compression and mechanisms of moisture transport under different mechanical loading scenarios in flexible spacer structures.

• DFG Programme: Research Grants