Weft Yarn Interlacement Modelling for 3D Profiled Structures

Currently, generation of 3D woven T-joint models with complex weave geometries, using TexGen software, is a manual process. One of the main challenges to automatic generation of these textiles is the order in which the weft yarns interlace within the bifurcation region. This paper will demonstrate a method for predicting the order, based on the pattern draft and the information contained within it such as the direction of weft insertion and the beating action of the loom. The path of the entangling weft yarns and the yarn cross section orientation can then be modelled. Finally, a geometric transformation is applied to simulate the opening of the flanges so that the final model reflects the T-shaped profile.

Experimental Investigation on the Effect of Carbon Fiber Reinforcements in the Mechanical Resistance of 3D Printed Specimens

In the last years, fiber-reinforced polymer composites have been under study for additive manufacturing. For this purpose, it is important to assess the behavior of these materials in terms of mechanical properties. The present experimental study evaluates the mechanical resistance of both PLA and carbon fiber reinforced PLA. The work used a full factorial Design of Experiments (108 tests) selecting as factors the infill density, infill pattern, material, number of perimeters and printing orientation. The main results highlight that the most influential factors on the tensile strength are both type of material and number of perimeters. In this study, the use of reinforcements did not improve the mechanical resistance attained by the corresponding virgin material. Particularly, for some selected specimens, the porosity measured in the fracture section is larger for the reinforced PLA specimens, so they showed a smaller cross-section.

Optical Material Characterisation of Prepreg CFRP for Improved Composite Inspection

Automated fibre layup techniques are often applied for the production of complex structural components. In order to ensure a sufficient component quality, a subsequent visual inspection is necessary, especially in the aerospace industry. The use of automated optical inspection systems can reduce the inspection effort by up to 50 %. Laser line scan sensors, which capture the topology of the surface, are particularly advantageous for this purpose. These sensors project a laser beam at an angle onto the surface and detect its position via a camera. The optical properties of the observed surface potentially have a great influence on the quality of the recorded data. This is especially relevant for dark or highly scattering materials such as Carbon Fiber Reinforced Plastics (CFRP). For this reason, in this study we investigate the optical reflection and transmission properties of the commonly used Hexel HexPly 8552 IM7 prepreg CFRP in detail. Therefore, we utilise a Gonioreflectometer to investigate such optical characteristics of the material with respect to different fibre orientations, illumination directions and detection angles. In this way, specific scattering information of the material in the hemispherical space are recorded. The major novelty of this research are the findings about the scattering behaviour of the fibre composite material which can be used as a more precise input for the methods of image data quality assessment from our previous research and thus is particularly valuable for developers and users of camera based inspection systems for CFRP components.