Automatic Fiber Placement ( AFP ) Technology , Actual State and Future Improvement through Using NDT ( Ultrasonic ) Equipment in On-line Processing Prof . PhD
In this paper are presented all of the technologies used for research at the Institute for Advanced Composites and Robotics (IACR). Focus is put on the automated fiber placement (AFP) technology and the equipment used to perform this technology. Analysis presented, refer to possible mistakes in the final product, composite part intended to be a primary structure of an airplane, due to the inability to know the influence of the compacting roller, or the characteristics of the prepreg on the occurrence of micro voids in the laminate of the part produced. As a response to this acknowledgement, preliminary research is done at IACR where ultrasonic sensor is used for nondestructive testing (NDT) in composite materials. This preliminary research has shown that it should be further inspected whether ultrasonic sensor following the compacting roller, could improve the impacting process and diminish the number of voids in the final product.
Development of a theoretical model for a solvent-type prepreg manufacturing process
Abstract This paper presents a theoretical study of the impregnation of continuous fiber or cloth with thermosetting resin matrix materials. A model is developed to describe the resin, the volatile content and the coated resin thickness as functions of impregnation velocity for a solvent-type, vertical impregnating process. A power law is employed to account for the effect of shear rate on the resin velocity in the model. Results are obtained methodically through the separation of variables. A dimensionless number, called the impregnation number, is derived which expresses the relative importance among the viscous, inertial and gravity forces in the impregnation process. It is found that the dimensionless number is important in characterizing the maximum possible resin content for a given condition, and that an increase in the resin viscosity is much more effective than an increase in the impregnation velocity in achieving higher resin content. The volatile content is controlled by a combination of the impregnation velocity and the oven length. The predicted volatile contents agree well with the experimental results for a 177°C prepreg. The model is valid for predicting volatile content in the practical impregnation process.
Trajectory generation for open-contoured structures in robotic fibre placement
Composites have become common engineering materials in industries where the strength to weight performance of structures is a key design consideration. The major limiting factors are the high-manufacturing costs and low-production rates. Robotic fibre placement (RFP) is one alternative process to overcome the limiting factors and it is generally suitable for open-continuous components. A novel path planning algorithm for open-contoured structures, entitled the surface curve algorithm for robotic fibre placement (SCAR) is proposed. The algorithm aims to produce a uniform lay-up of composite lamina, without gap and overlap between subsequent tows. A numerical investigation into the characteristics of the algorithm is performed and presented. The algorithm is implemented on complex contoured surface and some of the results are presented in this paper.