Journal of Multiscale Modelling

Estimation of safety and reliability of engineering structures and components containing cracks or crack-like defects is one of the most important application field of fracture mechanics particularly in components, where limited defects can be accepted. Such design philosophy is usually called “damage tolerance”, formerly “safe life”. In such cases, safety and reliability of further operation, residual life assessment and specification of interval of damage development inspections are important issues. Existing exact knowledge on fatigue crack growth (FCG) parameters is an essential condition. Results of FCG measurement in an Al 7175-T7351 alloy of a particularly high homogeneity, carried out as a part of the Proficiency Test Program organized by Exova in France are presented in this work. Results were evaluated in terms of parameters C and m of the Paris dependence in the stable growth region. To pass the test program successfully, a particular attention was paid to improve and verify direct current potential drop (DCPD) method being used for the crack length measurement. In the paper, the results of the FCG measurements generated by different participating laboratories were analyzed. A distinct correlation between C and m values, so called “coupling”, was found and demonstrated. Some paradoxes of the assessment of laboratories were addressed, namely the fact that a laboratory assessed as unacceptable concerning one of the parameters generated much more accurate and useful data than another laboratory with a better assessment. Eventually, the results including their scatter were used to provide an example of probabilistic assessment of a simple beam residual life to show practical actual impacts of the scatter on the life assessment.

In the current study, a theoretical method is developed to predict the vibrational behavior of micro-circular disks filled with viscous fluids and numerical results are presented to validate the model. Vibrations with two outer boundary conditions, rigid and deformable vessel, are studied. The coupled governing equations of both rigid and deformable vessel vibration are solved by the analytical procedure, taking fluid–structure interaction into account. The fluid gap effect on the coupled eigenfrequencies is also considered. The frequency spectrum plots of the first several eigenfrequencies are presented in a wide range of fluid gap and elasticity ratio. The correctness of results is demonstrated using a commercial finite element software. It is shown that the obtained results through the proposed method reveal very good agreement with the numerical solution.

In this paper, we apply a new algorithm called method of directly defining the inverse mapping (MDDiM) that was introduced by Liao for finding a semi-analytical solution to nonlinear system of differential equations. We apply this new method to the autoignition of a monodisperse fuel spray model. We use this technique for finding the base functions in the considered algorithm. Our results include a comparison between a numerical simulation and an analytical solutions derived from the MDDiM.