复合材料L型筋条-蒙皮胶接界面失效过程的数值模拟

Numerical Simulation Interfacial Fracture of Composite L-shaped Skin-to-stiffener Structures

用自定义的缝线模型和Cohesive单元方法,模拟了复合材料非缝合/缝合胶接L型筋条-蒙皮结构胶接界面在拉脱载荷作用下的失效过程;分析了第一排缝线位置和筋条突缘宽度对界面强度的影响。结果表明:对于非缝合结构,在载荷中心线附近区域,裂纹扩展受Ⅰ,Ⅱ型裂纹的共同作用;远离载荷中心线的区域,裂纹扩展时Ⅱ型裂纹起主导作用;对于缝合结构,裂纹扩展过程中载荷出现多次波动,载荷在第一排缝线断裂时达到峰值(拉脱强度);将第一排缝线缝合在筋条倒角与蒙皮接触的切点处,结构的强度较第一排缝线距离中心线8 mm时的提高了118.5%;筋条突缘宽度从25 mm降为20 mm后,强度下降了约18.2%,而从20 mm降至15 mm,强度几乎没有变化。

The interracial fracture process of stitched/non-stitched composite L-shaped skin-to-stiffener structures under pull-off load was simulated using self-defined suture model and Cohesive element method. The effects of the location of the first suture and the flange width of stiffener on interracial strength were analyzed. The results show that for non-stitched structure, the I-II mode cracks existed together near the load center line and the II mode crack was dominant far from the load center line. For stitched structure, the load waved during crack expansion process and reached the maximum value （pulling out strength） when the first suture fractured. The strength increased 118. 5% when the first suture transferred from the position of 8 mm from the load center line to the tangent of web-to-skin. The strength decreased about 18. 2% when the flange width of stiffener decreased from 25 mm to 20 mm, while it had almost no change when decreased from 20 mm to 15 mm.