Manufacturing and monitoring of composite structural components

Dispersion in complex anisotropic plate structures

An efficient numerical approach (WFE method) is used to determine the wave characteristics in laminated composite panels, and the results are compared to those from laboratory experiments. In addition to fiber-reinforced composites (CFRP/GFRP), also honeycomb sandwich panels are studied. Furthermore, interface disbonding between the face sheets and the core of such sandwich panels is modeled, and the dispersion characteristics of the two resultant waveguides are determined.

Wave scattering at damages in composite sandwich panels

Composite structures require careful monitoring to detect and characterize hidden defects at an early stage of their development so that preventive measures can be taken before the structure looses its load carrying capacity. Ultrasonic guided waves offer an attractive tool for inspecting relatively large plate-like structural components due to the waves’ long propagation range and sensitivity to defects in their propagation path. In this project, a detailed study of the interaction of Lamb waves and Rayleigh surface waves with defects for material compositions is carried out. 

Damage detection in the presence of geometrical discontinuities

Stiffeners are important structural components in modern composite structures. The safe operation of such structures requires careful monitoring as hidden defects may compromise the structural safety. In order to improve the reliability of guided ultrasonic damage detection for stiffened plate structures, theoretical, experimental and numerical studies are conducted, in an effort to understand the interaction of guided ultrasonic waves with stiffeners. Scattering of waves for various configurations of the stiffener are determined and compared to the scattering patterns at defects.

Manufacturing and testing of recyclable composite materials

Currently, many industries, such as aerospace and automotive, are shifting toward composite materials due to their excellent strength-to-weight and stiffness-to-weight ratios. Carbon and glass fiber-reinforced epoxy composites are the most commonly used materials, as they provide excellent mechanical properties. However, the fibers are synthetic and the epoxies are hard to recycle. Investigate sustainable alternatives to these materials by combining natural fibers such as jute, flax, and hemp, with recyclable polymers is thus imperative. Design and manufacturing of a variety of samples is accompanied by various destructive and nondestructive testing.

Christoph Schaal
Associate Professor of Mechanical Engineering