Investigating the factors influencing the bridging of dry non-crimp fabric on a concave L-shaped mold in an automated draping process

Abstract

Dry technical textiles tend to bridge when draping in concave areas or complex geometries such as internal corners. The extent of bridging is based on the spring-back of the textile. In this study, the value for the spring-back for dry technical textiles is defined and a method to quantify the spring-back value is proposed. An automated continuous draping process is presented based on manual lay-up and draping process of dry non-crimp fabrics (NCF) which is used in the production of rotor blade shells for wind turbine blades. This process provides the basis for the study of spring-back behaviors. Within this process, a triaxial NCF sample is manually laid-up on an L-shaped mold and then automatically draped onto the edge using a draping tool. A laser scanner records the draping result and bridging of the NCF sample. Test series show the influence of the process parameters such as drape speed and drape force on the spring-back behavior. For the draping process under consideration, quadratic dependencies of these factors on the spring-back could be determined.