Incorporating erosion and manufacturing defects in unified fatigue life models for additively manufactured TiB2/Al-Si composites

Erosion damage significantly reduces the fatigue life of engine blades. To satisfy modern aircraft lightweight requirements, particle-reinforced aluminum matrix composites are replacing traditional aluminum alloys. Assessing the erosion tolerance of these advanced materials is crucial for ensuring long-term performance. This study explores the effect of solid particle erosion on the fatigue behavior of selective laser melted TiB₂/Al-Si composites. Tension-tension fatigue tests were conducted under varying erosion conditions, followed by failure mechanism analysis based on fracture surface morphology. The results reveal a competitive relationship between additive manufacturing defects and erosion-induced defects in determining fatigue life. A unified method for evaluating effective defect size was developed to standardize the evaluation of erosion scars and inherent defects. Fatigue life exhibited a strong correlation with the estimated effective defect size. Extreme value statistics identified a critical defect size of 413 µm, governing this competition. Based on these findings, an erosion-fatigue life model was developed, incorporating a weighting function to dynamically switch the dominant defect type. This model effectively predicts fatigue life with a unified description of LOF and erosion defects, achieving a prediction error below 10 %. This study fills the gap in quantitative life prediction models for erosion-fatigue coupling, providing a foundation for the lifespan assessment of advanced aero-engine blades.