Analyse et modélisation des fissurations dans les plaques trouées sous l’effet des conditions extérieures.

Abstract

The problem of cracks in continuous structures such as plates, beams, bars, trellis or hulls is often very apparent around riveting holes, notches or other connecting leaves. In fact, the holed plates assembled by riveting or bolted are of great importance in the fields of applications of mechanics, aeronautics, aerospace and civil engineering and they can be the object of considerable cracking around their holes. The presence of these cracks leads to a weakening of the structure as a result of concentrations of local stresses or deformations that can decrease their lifespan or even cause their total rupture or their disaster. These stress concentrators are often unavoidable due to the effect of external conditions such as: forces, stresses, temperature changes, humidity and others. It is therefore necessary to know these stress intensity factors associated with each geometrical plate, in order to analyse its state of stress and strain state as well as its cracking modes which can be according to modes I, II and III or mixed mode. The analysis of the propagation of cracks in industrial plate structures leads to evaluating their lifespan before their sudden rupture. In our work consists of the static and dynamic analysis of the propagation cracks around circular, elliptical holes and other shapes in thin 2D (two-dimensional) aluminum plates under the effect of external applied forces. The starting position of the hole is defined by a point on the edge of the hole and the angle of inclination with respect to the orthonormal axis (X, Y) whose center is the center of the hole. As well as the inclination of the load (mixed mode). Consequently, a calculation strategy is implemented based on the “special quarter point” finite element method involving the BEM and XFEM approach using ANSYS and ABAQUS software. The results obtained are allowed to define the modes of cracking in the holes of the plates. The values of the factor of stress intensities corresponding to each mode of cracking under the effect of external conditions such as the loading in mode I or in mixed mode were determined for the various calculation methods used and good agreement with the results. Analytical have been noticed. The numerical results are compared with the experimental results and good results have been observed. These stress concentrations are found in the vicinity of the holes which generate a plastic zone influencing the propagation path of the crack, which is advisable to distance the drilling of holes in the plates in order to avoid their easy ruptures and to increase their lifetime.