NDE of heat and fatigue damages in CFRP composite laminates.

Large parts of the structure of the Gripen are made of CFRP composite materials. The composite can suffer from various forms of degradations, in particular heat damages and fatigue damages. A heat-damaged structure can be repaired in most cases. However it may be difficult to locate the heat damaged zone as it does not always show at the surface of the structure, and it is usually difficult to appreciate the real extent of the damaged zone. A visual control is not sufficient. Fatigued structures may present a significant reduction of stiffness and can therefore be unable to perform the task for which they have initially been designed. It is vital for safety reasons to locate the fatigued regions and repair the structure if possible.

Several NDE methods for the quantification and the qualification of damages in CFRP structures already exist. In this project we will be interested in acoustic, thermal and optical methods such as acoustic emission (AE), Thermography (TT) and Sherography (ST). The project will be based in a team of 5 engineers and typically requires a mix of experimental and theoretical work

· The first aspect of this project is to perform a thorough bibliographical work on the mode of failure of composite structures submitted to bending and heat and also on previous application of NDE methods to the detection of heat and fatigue damages in composites.
· The second aspect of this project is modelling. Using FEMLAB, composite laminates will be modelled. Later, the equations describing the initiation and the growth of delamination in composite will be computed. The purpose of the models is too enhanced our comprehension of various factors affecting the results of AE, ST and TT experiments.
· The third aspect of this project is experimental. Several NDE experiments will be performed on fatigued and heat affected composite samples in order to obtain quantitative information of the sensitivity of the NDE methods used.

Requirements:

You should be well educated in analytical methods, ideally in solid mechanics, or material science. Good knowledge of the Finite Element Method and MATLAB is required.
You should have a strong interest in performing practical experiments. No particular knowledge in NDE methods is required.
You are confident speaking and writing the English language, as well as the Swedish language.

Location: Linköping

Period: 20 weeks, starting during summer or august.

More information:
Lars Gustafson , Head of NDT department, phone 013-169158, E-mail [email protected]
Pierre Marty, Development engineer, phone 013-169152, E-mail [email protected]
Annika Arpfors, Human Resources Adviser, phone 013-169077, E-mail [email protected]

Application: Please send your application, in English and Swedish, to [email protected]