scope:

This DIN SPEC specifies a method for the automatic determination of the drapability of reinforcement textiles intended for use in continuous fiber reinforced materials.

The method is suitable for use with non-crimp and woven fabrics. When applying the method to multilayer non-crimp fabrics, it shall be noted that the evaluation of the fiber orientation and gaps only incorpora the uppermost layer. The method is applicable for dry textiles, e.g. made of glass rovings and untwisted carbon filament yarns. The textiles could have been treated with powder binder.

NOTE Other textiles can be tested based on this DIN SPEC.

This DIN SPEC specifies a method by which the textile fabric to be examined is deformed in a defined manner by a rotationally symmetrical deformation body. In the method, key figures and characteristic values that describe the textile to be examined with regard to its drapability are determined. For this, the mechanical resistance to a defined three dimensional deformation is measured and the resulting structural faults in the mesostructure and macrostructure are examined using a digital image analysis system and laser triangulation. Using the determined key figures, the processing behavior for the three dimensional deformation of the tested reinforcement textiles or the structural faults to be expected can be predicted.

The test is carried out on a circular test specimen, which the testing instrument - by means of a pneumatic test specimen holder - holds in position with a defined force, which is equal around the circumference of the retaining ring. During the test, the test specimen is incrementally deformed by a deformation body acting from below and measured after each stage.

Several images of the original undeformed test specimen and later of the deformed test specimen are recorded with a detail camera on a central circular path and evaluated. For non-crimp fabrics, the fiber orientation as well as the occurrence of gaps between the yarns of the non-crimp fabric are determined. For woven fabrics, the angle between the warp threads and weft threads as well as the area and proportion of the woven fabric gaps is determined. The out-of-roundness of the test specimen is additionally determined with an overall image camera.

Additionally, deformations out of the textile plane can be recorded on the rotating test specimen using a laser triangulation sensor and output as numerical values for the waviness and the loop formation.