Professor Ioannis Doltsinis of the Faculty of Aerospace Engineering and Geodesics at the University of Stuttgart, gave a seminar on “Studies on the Strength of Porous Ceramics – Mechanical Testing and Numerical Modelling”.

Investigations on the reliability of filter supports were reported by Professor Doltsinis, based on experimentation and analysis. The research has been motivated by industrial interest in the strength of ceramic parts used in nanofiltration.

On the macroscopic level, analysis and computer simulation aim at exploring manufacturing conditions and explaining the mechanical state of the ceramic components. Examination of strength was based on the diametral compression (Brazilian) test as a substitute for the burst test. Characterization of the brittle rupture was discussed within the framework of Weibull statistics. The replacement of the bursting under interior pressure by the Brazilian test was justified by stress analysis. Professor Doltsinis explained the impact of the different loading modes on the strength statistics.

The effects of material and doping on strength were assessed to study damage prior to rupture. The study included microcracking prior to rupture and aging because of corrosive activity. Material strength statistics were incorporated in the finite element model and locations critical were estimated.

The strength of porous ceramics subjected to fluid pressure in the pores was determined by rupture resulting from progressive brittle fracturing on the microscale level. In this connection an appraisal of the constitutive relationships for the fracturing elastic continuum was given followed by the presentation of a numerical model considering cracking by separation at grain boundaries. The associated algorithm simulates damaging of artificial microstructures generated in the computer and determines rupture. Sampling statistics resembles the measurements on the component strength. The significance of various structural parameters of the porous material were also determined.

Professor Doltsinis’ research has important applications in practice, some of which were discussed in detail.

The lecture gave rise to a lively discussion.

Professor Doltsinis is author of two important books published by WIT Press, ‘Elements of Plasticity: Theory and Computation’, ISBN: 1-85312-702-7 and ‘Large Deformation Processes of Solids: From Fundamentals to Numerical Simulation and Engineering Applications’, ISBN: 1-85312-955-0.