نمونه متن انگلیسی مقاله
The assessment of service life of composite thermo-structural parts is a primary issue for the aeronautic industry. To this end, a unified damage model for woven composites undergoing both static and fatigue loadings is presented here. Its specificity resides in its rate damage evolution law, which enables to predict the behaviour of the material under cyclic or random fatigue loadings.
Due to their excellent mechanical properties at high temperatures, ceramic matrix composites (CMC) are often selected for applications in hot part of engines. However, non-oxide composites are severely deteriorated under operating conditions in turbomachines. Consequently, for some engine components subjected to moderate thermomechanical loadings (between 800 and 1000°C), oxide/oxide CMCs are potential candidate materials in regard to their interesting trade-off between mechanical properties, thermal stability and cost. Hence, it seems necessary to develop efficient computational strategies for the design of composite parts submitted to both static and fatigue loadings. To fulfil these objectives, a specific damage model for this material has already been developed under static solicitations  at Onera but remained to be extended to fatigue loadings. To our knowledge, there is no model in the literature to predict the fatigue lifetime of oxide/oxide materials. A Damage Model for Polymer Matrix Composites, developed at Onera (named ODM-PMC), was recently extended to cyclic fatigue loadings  and validated through comparisons with the available experimental data. Nevertheless, some composite parts would be subjected to real fatigue solicitations, not necessarily cyclic, during all the lifetime of an aircraft. Fatigue models using the so-called “kinetic damage evolution law” – allow getting rid of the cycle notion and to handle random complex loadings.