CFRP加固含混合型边裂纹钢板的疲劳性能试验研究

Experimental study on fatigue properties of CFRP-repaired steel plates with a mixed-mode edge crack

为研究碳纤维增强复合材料(CFRP)对含初始边裂纹钢板疲劳性能的改善效果,使用MTS试验机对未加固及CFRP材料加固后的含边裂纹钢板进行疲劳试验,比较了裂纹形式、钢板初始损伤度、CFRP粘贴面以及CFRP材料种类(CFRP布与CFRP板)对钢板疲劳寿命的影响。共设计制作了3个未加固试件、3个CFRP布双面加固试件、3个CFRP布单面加固试件以及2个CFRP板双面加固试件。试验中利用改进的变角度加载装置,得到I型边裂纹试件与I/II混合型边裂纹试件,比较CFRP材料对含I型边裂纹及I/II混合型边裂纹试件疲劳寿命的改善效果。结果表明:双面粘贴CFRP材料能够极大提高含裂纹钢板的疲劳寿命,而单面粘贴CFRP的加固效果远不如双面粘贴的加固效果;CFRP布与CFRP板在相似补强率下对钢板疲劳寿命的改善效果相近;CFRP材料对含I型边裂纹钢板疲劳寿命的改善效果优于对含I/II混合型边裂纹钢板疲劳寿命的改善效果;双面粘贴CFRP布对钢板疲劳寿命的改善效果会随着初始损伤度的增大而增强。

To study the repair effects of carbon fiber reinforced polymer(CFRP)on the fatigue properties of edge-cracked steel plates,fatigue tests of the unrepaired and CFRP repaired steel plates with a mixed-mode edge crack were carried out using an MTS servo hydraulic testing machine.The effects of crack mode,initial damage degree,CFRP bonding sides and different CFRP materials on the fatigue properties of the steel plates were considered.Three unrepaired specimens,three specimens repaired with CFRP sheets on double sides,three specimens repaired with CFRP sheets on a single side,and two specimens repaired with CFRP plates on double sides were studied.Using the improved test fixture to apply loading at different angles in the tests,the repair effects of CFRP materials on the fatigue properties of steel plates with mode I edge cracks and steel plates with I/II mixed-mode edge cracks were compared.The results indicated that bonding CFRP on double sides greatly improves the fatigue lives of the specimens,but the repair effects of bonding CFRP sheets on a single side are far less than that on double sides.The repair effects of CFRP sheets and CFRP plates with a similar repairing ratio are similar.CFRP has better repairing effects on mode I cracked specimens than that on I/II mixed-mode cracked specimens.The improvements of fatigue life of steel plates repaired with CFRP sheets on double sides are enhanced with the increase of initial damage degree.