Prof Eckart Schnack from the Institute of Solid Mechanics, University of Karlsruhe, visited the Institute recently and gave a special seminar on "Quantitative Detection of Defects in Layered Composites - an Inverse Problem".

Eckart has participated in many WIT activities, including attending Conferences on BEM, Optimisation and Damage Mechanics. He is also a Member of the Editorial Board of the International Journal of Engineering Analysis with Boundary Elements (EABE).

Eckart has a long and distinguished career in Computational Mechanics, starting with his first degree and PhD from the Department of Mechanical Engineering at the University of Munich.

He started his academic career at the University of Kaiserslantern and thereafter was offered a Chair at two outstanding Institutes, ie the University of Hamburg and the University of Karlsruhe. He chose to take up his position at the Mechanical Engineering Department of the latter where he became the Head of the Institute of Solid Mechanics.

Eckart has a substantial number of publications in computational mechanics, dealing with a wide variety of topics, including Fracture Mechanics, Coupling of BEM and FEM, Shape Optimisation, Structural Optimisation, Damage Mechanics and others.

Composite materials are becoming more common in many engineering structures, particularly in aerospace, where fibre reinforced composites are vital parts of the structures of new planes. It is important to understand their behaviour in order to be able to reduce the weight of the new generation of planes with confidence.

Eckart referred to the different types of damage that can take place in these components and pointed out that 60% of all damage in Carbon Fibre Reinforced Plastic (CFRP) in airplanes is due to delamination.

The lecture started with a review of the advantages of shearography as an excellent technique to detect damage. The problem is how to detect the delamination that could be taking place inside the laminate. This is where the idea of using inverse analysis is applied in order to determine the internal effects from the complete measurable data on the surface.

Some of the problems with inverse solutions are related to the error in the data available. To solve this problem, one requires a regularisation procedure to smooth the noise of the data.

Eckart presented some examples showing the excellent convergence of the results for known internal position of the defects.

The presentation was followed with great interest by the WIT researchers and followed by numerous questions.