Non-destructive testing methods for composites

Fibre reinforced plastics (or composites) are gaining popularity in a wide range of industries due to their excellent properties, such as specific stiffness and strength and good resistance to environmental conditions. However, their complex structure brings also some challenges, detecting damage being one of them. This ninth white paper focusses non-destructive testing.

The manufacturing of composite materials often involves a great deal of manual work, often resulting in varying quality and performance of the part. Poor manufacturing cycles could lead to many different defects. Furthermore, during operation, the layered structure of a composite leads to a certain susceptibility to defects. Fatigue loading often leads to a dense network of micro-cracks, which manifests itself as a stiffness reduction at the macroscopic level. Small impact events could lead to the introduction of barely visible impact damage (BVID) that is almost impossible to detect by visual inspection. BVID is very critical for many applications, it consists of several damage features, in which the presence of delaminations is the most critical as these delaminations have a tendency to grow under further usage of the part.

It is clear that these damage features could jeopardize the structural health of the component. Hence, it is important to use appropriate testing methods in order to check whether the design criteria of the manufactured part are met, as well as to assure the structural integrity of the part during its operational lifetime.

While destructive testing and inspecting a finished product gives insight in the production quality and certainly plays an important role in quality assessment and control, in most cases, it renders the subject useless. Instead, non-destructive testing (NDT) approaches should be adopted. A broad overview of various NDT approaches is provided in this new white paper.

Detailed overview of NDT techniques

A broad range of NDT approaches which rely on different physical phenomena including mechanical waves, thermal waves and electromechanical waves, is available. The use of each specific NDT approach has certain advantages, disadvantages and limitations, making it important to select the correct technique for your application. A wide overview of existing NDT techniques is given in the whitepaper, starting from very simple, up to very advanced techniques.

The use of lightweight components stands or falls by the choice of materials. Product value, product costs, production costs, development costs and risks are however difficult to estimate when talking about less well-known materials such as composites. Moreover, the wide range of materials and processes makes selection even more difficult. This is why the SLC-Lab composite experts and the sustainability experts have come up with a series of white papers that go much deeper into the properties and possibilities offered by composites.

The white paper can be downloaded now.