【摘要】 针对铝硅合金气缸盖高周疲劳（HCF）裂纹萌生寿命预测难的问题，建立孔隙代表性体积模型，探究孔隙特征对合金力学响应影响规律，得到孔隙非局部最大塑性剪应变幅△γ_max^p*与孔隙尺寸的关系，开展气缸盖高周疲劳强度评估研究．结果表明：大尺寸缩孔局部几何不规则凹陷和凸起处应力集中程度较高，孔隙尺寸是影响孔隙危害性的主要参数，△γ_max^p*随孔隙尺寸增加而加速升高，以△γ_max^p*驱动的裂纹萌生模型可实现试样在±2.5倍分散带内疲劳寿命预测．气缸盖底板和进/排气门壁面两侧机械应力较高，同时壁面位置孔隙尺寸较大，二者导致进气道壁面高周疲劳寿命较低．更多还原

【Abstract】 In order to deal with the challenges in predicting the high cycle fatigue（HCF） crack initiation life of cast Al-Si alloy cylinder head,the impact of pore characteristics on the mechanical response of cast Al-Si alloy was investigated through a representative volume element model containing the pore. The relationship between pore size and the non-local maximum plastic shear strain amplitude △γ_max^p* was established. The HCF strength of the cylinder head was evaluated based on the obtained model. The findings reveal a significant level of stress concentration at the local complex concave and convex positions of large pores. The harmfulness of pores is primarily determined by their size. With the increase in pore size, △γ_max^p* experiences an accelerated growth. The HCF life of samples extracted from the cylinder head can be predicted within ±2.5 times dispersion band using the crack initiation model driven by △γ_max^p*. The bottom plate,the inlet and the exhaust walls are the main parts of the cylinder head with high mechanical stress. The combination of high stress and large pores results in a low HCF life of the inlet wall.更多还原