Defect and damage detection in filament wound carbon composite cylinders: A new numerical-experimental methodology based on vibrational analyses

摘要

Due to its high efficiency, carbon fibre reinforced composite materials are used in many applications, including aeronautical, automotive, and civil structures. A wide range of manufacturing processes are used in composites production and each of these processes is marked by many processing parameters. However, because of the variations that are inherent to the manufacturing method, the final properties of the structure can be strongly affected, mainly the strength values. On the other hand, Vibration-Based Methods (VBM) has the advantage of simplicity and low cost, although it is very sensitive to variations in geometry and material properties. Therefore, it is strategic to deepen the research in this line to generalize the method, allowing its use in the industry as a solution to complicated real-life problems. Thus, this work presents a new numerical-experimental methodology to evaluate the effect of design parameter variations on the dynamic response of laminated composite cylinders. Numerical dynamic analyses are run via a Finite Element code, which is complemented with subroutines written in Python. A Design of Experiments (DoE) strategy is developed to reduce the number of experiments and to evaluate the effect of the design parameter variations. Three sets of nominally different composite cylinders are investigated [(90/60/-60)2/90]s, [(90/30/-30)2/90]s and [90/30/-60/60/-60/30/-30]s. System natural frequencies as taken as the primary response quantities. Frequency Response Functions (FRF) enrich the data set for more elaborate analysis. A DoE strategy is set up to deal with the range of design parameters and process parameters, a full factorial design is selected. Afterward, the results are discussed with proper attention for the potential and limitations of the proposed methodology from the perspective of usage to detect defects in real laminated composite cylinders. Finally, damage indices are calculated using the experimental FRFs magnitudes to quantify the influence of the undamaged and impact damage structure. The general conclusion is that the new methodology provides the foundations for the next generation of software systems for detecting defects from the manufacturing process and damage caused in-service of real composite structures.