Poisson’s ratio design of polyimide composite membrane

The Poisson’s ratio of polyimide composite membrane material is one of the main reasons for membrane wrinkles introduced by the tensioning. Therefore it is critical to design the Poisson’s ratio of the membrane. With an optimized Poisson’s ratio, wrinkles on the tensioned membrane can be minimized or even eliminated. Considering a newly developed orthotropic fiber-reinforced polyimide composite membrane for space applications, the Poisson’s ratio of the composite membrane can be modified by using arrays of elliptical cuts. This study investigated the variations of the equivalent warp and weft Poisson’s ratios as the functions of the elliptical parameters. These parameters include:1) the distances between the edges of a vertical ellipse and its adjacent horizontal ellipse; 2) the ratio between the long axis and the summation of the short and long axes. How these factors to affect the effective Poisson’s ratios of the perforated membrane are also discussed. The effect of g on the effective Poisson’s ratio is mainly reflected in two aspects: one is that the value of g affects the rotation ability of the unit, and the other is that the value of g determines the effect of material parameters on the effective Poisson’s ratio after punching. The effect of the r value on the effective Poisson’s ratio mainly affects the rotation ability of the unit. The greater the g value, the greater the effective Poisson’s ratio. The greater the r value, the greater the rotation ability, and the smaller the effective Poisson’s ratio.