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以蒙皮材料Uretek3216L为对象开展了膜材的双轴循环拉伸力学性能试验研究.首先,通过一系列双轴循环试验获得了膜材的应力应变数据,并对其非线性、各向异性等性质进行了探讨分析.然后,运用应变残差最小二乘法,计算出不同应力比组合的弹性常数.最后,分析了应力比的组合方法及正交互补性质对膜材弹性常数的影响规律.结果表明,经纬向纱线卷曲形态的不均衡性是膜材正交异性特征的主要原因.膜材的弹性常数受应力比组合方法及正交互补性质的影响显著,且弹性模量随名义应力比的改变而有规律地变化.在结构设计中,需要根据具体受力状态及应力比范围来确定膜材的弹性常数,以提高设计分析的精确性;且考虑到弹性常数的多变性,采用2组界限弹性常数比仅采用1组更可取.
The biaxial cyclic tensile mechanical properties of the membrane were studied with the skin material Uretek 3216L.First, the stress-strain data of the membrane were obtained through a series of biaxial cycle tests, and the nonlinear and anisotropic properties Then the elastic constant of different stress ratio combination is calculated by using the least squares method of strain residual.Finally, the influence of the combination method of stress ratio and the orthogonal complementary nature on the elastic modulus of the membrane material is analyzed.Results The results show that the unbalanced yarn warp and weft yarns are the main reason for the orthotropic characteristics of the film.The elastic constants of the film are significantly affected by the stress ratio and the orthogonal complementarity, and the elastic modulus with the nominal stress ratio In the structural design, we need to determine the elastic constants of the membrane according to the specific state of stress and the ratio of stress to improve the accuracy of design analysis; and taking into account the variability of the elastic constant, using 2 The group boundary elastic constants are preferable to using only one group.