通过小孔模具成型并在升温固化前对纤维束加捻的方法制备了5种捻度(捻度t分别为1、2、2.5、3和4 n/cm)的z-pin。观察了各种捻度z-pin的外观形态,测试了各种z-pin的拉伸性能。通过单根z-pin从层合板中拔出的试验方法表征了z-pin与层合板之间的界面粘结性能。结果表明,加捻使z-pin主干发生扭曲,捻度越大,扭曲的程度越大;加捻使zpin的拉伸强度及伸长率降低了50%左右,使拉伸模量降低了30%左右;加捻可显著提高z-pin与层合板之间的界面粘结性能,捻度越大,界面剪切强度τd、最大摩擦力Ff、拔出功Wp越大;随着捻度的增大,z-pin与层合板间脱粘位置逐渐从zpin自身的纤维与树脂之间的F-R型细观界面向z-pin外层树脂与层合板树脂之间的R-R型细观界面转移。当捻度t=3n/cm时,与无捻z-pin相比,τd提高了61%,Ff和Wp均提高了2倍。
Five types of twisted z?pins( the twist degree are 1, 2, 2.5, 3 and 4 n/cm respectively) were prepared by means of draw forming from small?cavity mold and twisting before resin curing. Appearances of various twisted z?pins were observed, and the tensile properties of various twisted z?pins were tested. The interfacial adhesive properties between z?pins and laminates were charac?terized through single z?pin pull?out tests. The results show that twisting makes the stems of the z?pins distorted, the more twist de?gree is, the more distortion is. Twisting makes the tensile strength and the elongation reduce by about 50%, and the tensile modulus decreases by 30%. However, twisting improves the interfacial adhesive properties between z?pins and laminates significantly. The more the twist degree is, the higher the interfacial sheer strength τd, the maximum frictional force Ff, and the pull?out energy Wp are. With the increase of twist degree, the debonding location shifts from the
