MSD对老旧飞机搭接结构完整性的影响

利用FRANC2D/L对含MSD某型飞机机翼蒙皮搭接接头进行了有限元分析,得到了不同分布钉载下MSD裂纹应力强度因子(SIF)随裂纹扩展历程变化的计算曲线,和已有的文献比较表明,本文数值结果精确,方法可靠。计算结果表明,孔壁受载方式对SIF影响不大,但对MSD裂纹扩展方向有明显的影响;相对于均匀分布和集中力,二次分布的钉载更接近于实际的孔壁受载方式,且在计算时,应考虑其它排钉孔的受载。最后探讨了基于力学的评估含MSD搭接结构完整性的方法。

The effect of MSD on lap joints in aging aircraft

Wing lap joint of certain model military aircraft with multi-site damage(MSD) is analyzed using special code FRANC2D/L.The multiple site damage(MSD) stress intensity factors(SIFs) at each crack tip with different distribution loads at the rivet holes are computed and show that the analysis results have good coherence with the literature data.It is show that the SIF at each crack tip can be calculated by the crack growth simulation capability of FRANC2D/L.The SIF values are not sensitive to the rivet load distribution manner,which has seriously influence on MSD crack growth direction.Rivet loading can be best molded quadratic load distribution over one half of rivet hole relative to uniform load distribution and point load.As a result of this analysis,it is postulated that for MSD in aircraft lap joints,compliance measurements may provide a useful tool for assessing the structural integrity of the lap joints.