纤维金属层板金属层应变测量及应力预测方法

纤维金属层板作为一种新型复合材料，已开始应用于航空航天领域。脱离传统应变测量方法，应用一种新测量方法--数字化光学应变法，实现了层板中金属层应变的测量；同时以子层刚度理论获得层板的等效刚度矩阵，修正经典层板理论中整体刚度矩阵的求解方法，实现了金属层应力的更准确预测。以纤维增强铝锂合金2/1及3/2层板为例，使用光学应变法测量其金属层应变进而计算金属层应力，利用有限元仿真分析、经典层板理论及修正方法分别对其进行金属层应力预测。通过对比光学应变测量结果和有限元仿真结果，2/1及3/2层板光学应变测量结果与仿真结果最大误差分别为2.12%和3.68%，验证了新测量方法的准确性及实用性；通过对比光学应变测量结果和层板理论预测结果，2/1及3/2层板模型修正后结果比修正前准确率分别提升了2.91%和5.83%，验证了修正模型的有效性及先进性。

Strain measurement and stress prediction methods of metal layer in fiber metal laminates

Fiber metal laminates, as a new-type composite material, have been applied in aerospace field.Digital optical strain method is used to realize strain measurement of metal layer instead of traditional method of strain measurement.Meanwhile, in order to predict the stress distribution in metal layer accurately, the global stiffness matrix obtained from classic laminate theory is modified by the equivalent stiffness matrix from sub-laminate stiffness theory.Taking 2/1 and 3/2 laminates of glass fiber reinforced Al-Li alloy as an ex-ample, the stress distribution in metal layer of the laminates is determined based on the measured strain, finite element analysis, classical laminate theory and modified method.The comparison of stress distributions obtained from the measured strain and finite element analysis shows that the maximum errors are only 2 .12％and 3.68％for 2/1 and 3/2 laminates, respectively, which verifies the accuracy and practicability of the opti-cal strain method.By comparing the stress distributions from the optical strain method and laminate theory, the prediction accuracy of the modified model increases by 2.91％and 5.83％compared with that of original model for 2/1 and 3/2 laminates, respectively, which proves the effectiveness and advancement of the modi-fied model.