Controlled atmospheric pressure resin infusion (CAPRI) is a variation of the vacuum-assisted resin transfer molding (VARTM) process. The CAPRI process increases the fiber volume fraction of the preform prior to infusion via debulking and applies a reduced pressure gradient during infusion to minimize thickness gradients during processing. This study experimentally investigates the effect of debulking and reduced pressure gradient on the incoming material parameters, process behavior and final dimensional tolerances. The effect of debulking on fabric permeability and compaction behavior has been investigated and shows a significant impact on the infusion time and final fiber volume fraction. Several E-glass plain weave preforms have been infused and flow, pressure and thickness data has been recorded and compared to traditional VARTM processing. A previously developed model uses the experimentally obtained permeability data and good agreement of the flow behavior is observed, the CAPRI process decreases thickness gradients to less than 1% while increasing fiber volume fraction by 5% in the composite part.

This paper presents the principles of industrial x-ray-computed tomography (XCT) and its enormous potentials for the non-destructive 3D measurement and quality assurance of technical parts. Due to many overall factors and many nonlinear factors having an influence on the tomographic imaging process, the reconstructed volume model and thus the measurement results, XCT is a complex technology. Until now for XCT the uncertainty in measurement in general cannot be quantified satisfyingly regarding the traceability to national standards and the comparability to other measurement devices, e.g. tactile coordinate measuring machines. In this work different procedures to determine the uncertainty in measurement are assessed considering their applicability for XCT. The procedure of using calibrated work pieces is regarded as the most promising. This procedure is evaluated for an aluminum test part. The effect of several system parameters, which can be influenced by the operator, on the uncertainty in measurement is analyzed. The possibility of partially minimizing the analysis effort by means of simulation is outlined. In detail, for bore holes the effect of random errors on the measurement result is simulated.

The present work describes a new method to measure the contour position of plane reinforcement fabrics for the manufacturing of structural composite parts. The pursued approach uses optical metrology based on laser light-section technology. In detail, a laser line is projected over the edge of a fabric layer and acquired with a digital camera, which is located under an offset angle to the laser sensor. This leads to a distinctive displacement of the laser line in the acquired image, which is proportional to the distance between the sensor and the fabric layer. The distorted line can be described as a step profile, to which an analytical function is fitted to calculate the horizontal edge position with sub-pixel accuracy. To measure the whole layer position, the edges are scanned with the laser sensor to provide multiple contour points. This allows the interpolation of the object contour. The interpolated contour can be compared with the specified position and dimension of the textile layer. This enables a closed-loop control of the cutting and build-up process of the preform. Thus, an efficient production process of fibre-reinforced plastics through an automated inline measurement is possible.

Fibre-reinforced plastics (FRP) are particularly suitable for components where light-weight structures with advanced mechanical properties are required, e.g. for aerospace parts. Nevertheless, many manufacturing processes for FRP include manual production steps without an integrated quality control. A vital step in the process chain is the lay-up of the textile preform, as it greatly affects the geometry and the mechanical performance of the final part. In order to automate the FRP production, an inline machine vision system is needed for a closed-loop control of the preform lay-up.This work describes the development of a novel laser light-section sensor for optical inspection of textile preforms and its integration and validation in a machine vision prototype. The proposed method aims at the determination of the contour position of each textile layer through edge scanning. The scanning route is automatically derived by using texture analysis algorithms in a preliminary step. As sensor output a distinct stage profile is computed from the acquired greyscale image. The contour position is determined with sub-pixel accuracy using a novel algorithm based on a nonlinear least-square fitting to a sigmoid function. The whole contour position is generated through data fusion of the measured edge points.The proposed method provides robust process automation for the FRP production improving the process quality and reducing the scrap quota. Hence, the range of economically feasible FRP products can be increased and new market segments with cost sensitive products can be addressed. MANUFACTURING OF COMPOSITE PARTS Manufacturing of composite partsFibre-reinforced plastics (FRP) have become an important material group for light-weight structures with advanced mechanical properties. FRP can be described as composite materials consisting of a textile reinforcement structure, e.g. fabrics, meshwork or unidirectional layers and the polymer matrix [1].Because of their excellent weight specific mechanical properties, FRP parts replace aluminium parts for aerospace applications. This trend is driven by a significant weight reduction, which leads to a lower fuel consumption thus cutting of operating costs. Different to metal parts, FRP usually do not have isotropic properties even for symmetric preform layups [1]. This means that only along the fibre orientation the maximum stiffness and strength in the composite part can be achieved. Hence it is important that the reinforcement fibres are aligned precisely in the directions of the major loads. The fibre alignment is greatly influenced during the preform production ( Fig. 1) as in this process step the single fabric layers are put in position. By the lay-up the dimension, the geometry and the mechanical properties of the composite part are determined. To ensure the maximum part performance, a quality control during this early process stage is vital. In particular, the cutting of the textile layers (1) and the preform lay-up (3) have to be controlled. Up to now, many FRP manufacturing ...

This paper presents an approach to assess the quality of the data extracted with computed tomography (CT) measuring systems to perform geometrical evaluations. The approach consists in analyzing the error features introduced by the CT measuring system during the extraction operation. The analysis of the features is performed qualitatively (using graphical analysis tools) and/or quantitatively (by means of the root-mean-square deviation parameter of the error features). The approach was used to analyze four sets of measurements performed with an industrial x-ray cone beam CT measuring system. Three test parts were used in the experiments: a high accuracy manufacturing multi-wave standard, a calibrated step cylinder and a calibrated production part. The results demonstrate the usefulness of the approach to gain knowledge on CT measuring processes and improve the quality of CT geometrical evaluations. Advantages and limitations of the approach are discussed.