复合材料翼面壁板剪切稳定性

Stability of composite stiffened panels in plane shear

基于长桁铺层数不同的两块复合材料翼面T型加筋壁板试件SS-1和SS-2开展剪切稳定性试验。试件SS-1和SS-2的L型层合板铺层分别为11层和14层,腹板铺层分别为22层和28层,缘条铺层分别为15层和18层。采用提出的工程方法进行壁板的剪切屈曲应变分析,方法中考虑了长桁尺寸和铺层数的影响,并应用有限元弧长法进行试件屈曲载荷、后屈曲承载能力及剪切屈曲模态分析。试验结果表明,屈曲发生之前试件蒙皮处于均匀纯剪切应变状态,后屈曲阶段试件发生了长桁-蒙皮脱粘破坏失效,长桁铺层数较多的试件SS-2具有更高的屈曲载荷和蒙皮局部屈曲应变。工程方法计算得到试件SS-1和SS-2的剪切屈曲应变相对于试验结果的误差分别为–14.9%和–9.2%。有限元弧长法分析得到试件SS-1的屈曲载荷和屈曲应变误差分别为1.9%和2.7%,且剪切屈曲模态与试验结果一致。弧长法对不同长桁铺层数的研究结果表明,长桁铺层较少时,壁板发生整体失稳的材料破坏,而长桁铺层数较多时,更容易发生长桁与蒙皮的脱粘失效。

Experiments for shear stability analysis were conducted on composite stiffened panels SS-1 and SS-2 with different T-stringer layups.The L laminate layers of SS-1 and SS-2 were 11 and 14 layers respectively,the web laminate layers were 22 and 28 layers respectively,and the edge strip laminate layers were 15 and 18 layers respectively.Considering the differences of dimension and ply number of stringers,a proposed engineering method was used to investigate the shear buckling strain of skins,and finite element analysis(FEA)with arc-length method was also carried out to predict the shear buckling load,post-buckling carrying capabilities,and buckling modes.Experimental results show that the skins between stringers are in pure shear with uniform shear strains before buckling,and debonding failure of skin and stringers occur during post-buckling stage,and SS-2 with more stringer plys poses higher buckling resistance with larger buckling load and strain.The errors of buckling shear strain for SS-1 and SS-2 by the proposed engineering method are–14.9%and–9.2%,respectively.The errors of buckling load and buckling strain by arc-length method for SS-1 are 1.9%and 2.7%,respectively,and the buckling modes are also consistent with the experiment results.The FEA results by arc-length method also reveal that material failure will occur with less stringer plys due to overall buckling of panels,and the debonding of skin and stringers are more readily realized with more stringer plys.