SENSOR BASED ANALYSIS AND IDENTIFICATION OF LEAKAGES IN VACUUM BAGGING FOR HIGH PERFORMANCE COMPOSITE COMPONENTS

Abstract

Leakage detection is an essential process step in the manufacturing of high performance composite components. During production, a composite layup is hermetically sealed against the environment by auxiliary materials creating a so-called vacuum bag. Faulty vacuum bags lead to complex repair work and can drastically impair the quality of the composite. A two-stage process for automated leakage detection was developed at the German Aerospace Center in Stade. Possible leakage locations are limited by a sensor system for subsequent in-depth examination by infrared thermography. It was proven that the existence of leakages in vacuum bags can be explicitly identified by volumetric flow meters. During evacuation of the vacuum bag the volumetric flow rate converges towards a notably elevated threshold value. The magnitude of threshold flow was directly correlated to the leakage area. For multiple vacuum lines, the volumetric flow rate caused by a leakage was observed to distribute in a regular pattern. Localization via trilateration showed promising results to identify leak-prone areas in the vacuum bag. These areas can be examined by infrared thermography to get the exact position of the leak. The implementation of this two-stage process is expected to reduce both process times and effort.