层合板切口强度和切口敏感性的试验研究

STUDY OF TEST ON NOTCH STRENGTH AND NOTCH SENSITIVITY OF LAMINATES

提出了在复合材料板中人工预制尖锐切口的方法。进行了切口和无切口试样在载荷方向垂直于和平行于纤维面的三点弯曲破坏试验。测定了玻纤／环氧层合板的切口强度和切口敏感度。探讨了玻纤／环氧层合板的线弹性断裂力学的适用性。借助复合材料的ＷＥＫ断裂模型估计了层合板在尖切口前沿的损伤区尺寸。预测了切口强度。结果表明：对于玻纤／环氧层合板，若根据平面应变和小范围屈服的力学条件选择试样尺寸，则其三点弯曲的断裂应力、等效尖锐切口长度的均方根和形状因子的乘积基本上不随尖切口的长度而发生变化。

A method is presented for man prefabricating sharp notch in compsite plate.notched samples and unnotched samples were tested.These tests were broken by three point bending tests which loading directions were perpendicular to and palalled to fiber plane.Strength and sensitvity of a glass fiber/epoxy lamilate were measured.The application of linear elastic fracture mechanics to glass fiber/epoxy laminates was investigated.Damage zone sizes of forward position of sharp notch in laminates were estimated by means of WEK fracture model.Notch strength was predicted.Results show that fracture stresses by three point bending、average roots of equivalent shorp notch lengths and products of shape factor do not change along with the change of sharp notch length on the whole .The condition of above conclusion is that sample sizes of the glass fiber/exoxy laminates are taken according to mechanics conditions of plane strain and small scale yield.