The knowledge of the mechanical behavior is essential to predict the lifetime of components in order to avoid any sudden break in service. In this context arises our study which aims firstly to study the behavior of an ABS plate reliability(acrylonitrile butadiene styrene) artificially damaged and subjected to uniaxial tensile loading and with the aim to predict the lifetime and know the limits that must not be exceeded as this can cause failure. To measure the criticality of the damage we based this work on the theory of the unified damage, secondly to consider the stress concentration phenomenon in the sample in the presence of a discontinuity. We will also treat in this manuscript the evaluation of the stress intensity factor by an analytical calculation using the method of superposition about a combined defect. The results obtained in the light of this study allowed us to determine the different stages of damage and critical defect size which leads to the ruin of the structure.