Membrane inflation of polymeric materials: Experiments and finite element simulations

Abstract

Abstract A high‐speed optical measurement system, which is capable of measuring transient surface shape, is used in the polymer membrane inflation experiments. The accurate measurement data, which is an array of points, with known Cartesian coordinates and with respect to a fixed coordinate system, provides a source for further bubble shape analysis. Inflation pressure is correlated with each bubble shape measurement. The measured results reveal the importance of the thermal warpage and temperature gradient in the bubble inflation tests. Potential errors in the material parameter calculation, which are caused by assuming uniform temperature and zero thermal warpage, are pointed out. Consequently, a finite element analysis has been carried out to simulate the membrane inflation with/without thermal warpage and the temperature gradient. The material parameters obtained considering the thermal warpage and temperature gradient yield improved agreement with the experimental data. Although in this paper the measurement data is mainly used for the determination of the material parameters in the bubble inflation tests, they are also a source of validating other computer‐aided simulations as well as in the study of the thermal shrinkage of polymer products.