Fatigue life prediction model of 2.5D woven composites at various temperatures

As one of the new structural layout in the family of woven composites, 2.5D Woven Composites（2.5D-WC） have recently attracted an increasing interest owing to its excellent properties, i.e. high specific strength and fatigue resistance, in the aerospace and automobile industry. Indepth understanding of the fatigue behavior of this material at un-ambient temperatures is critical for the engineering applications, especially in aero-engine field. Here, fatigue behavior of 2.5D-WC at different temperatures was numerically investigated based on the unit cell approach. Firstly, the unit cell model of 2.5D-WC was established using ANSYS software. Subsequently, the temperature-dependent fatigue life prediction model was built up. Finally, the fatigue lives alongside the damage evolution processes of 2.5D-WC at ambient temperature（20 ℃） and unambient temperature（180 ℃） were analyzed. The results show that numerical results are in good agreement with the relevant experimental results at 20 and 180 ℃. Fatigue behavior of 2.5D-WC is also sensitive to temperature, which is partially attributed to the mechanical properties of resin and the change of inclination angle of warp yarns. We hope that the proposed fatigue life prediction model and the findings could further promote the engineering application of 2.5D-WC, especially in aero-engine field.

Modified micro-mechanics based multiscale model for progressive failure prediction of 2D twill woven composites

To consider fiber random distribution at the microscale for the multiscale model based on the micro-mechanics failure(MMF)theory,clustering method is used for the extraction of amplification factors.As the clustering method is a kind of unsupervised machine learning method,the elements with similar mechanical behavior under external loading can be included in a cluster automatically at the microscale.With this modification,the fiber random distribution model can be used for multiscale damage analysis in the framework of MMF theory.To validate the modified multiscale analysis method,progressive damage analysis of a kind of 2D twill woven composites is conducted based on different microscale models.The stress values for microscale models with fiber hexagonal and random distribution patterns are compared first.Much higher stress concentration is generated in the fiber random distribution model due to the smaller inter-fiber distance especially under longitudinal shear loading.The obtained cluster distribution results exhibit the characters of the stress distribution in the two microscale models.Thereafter,tensile and compressive responses of the 2D twill woven composite are predicted with the modified multiscale analysis method and accuracy of the method is verified through comparison with published experimental results.From the simulation results,it can be found that the matrix damage initiation from the model based on the fiber random distribution model is premature compared with that from the model based on the fiber hexagonal distribution model.Besides,under tensile loading,the damage all initiates from the fill tows and propagates to the wrap tows.However,under compressive loading,the matrix damage initiates from the wrap tows in the model based on the fiber random distribution model.