Research on Yeoh-Revised hyperelastic constitutive model considering the volume almost incompressible premise for rubber materials

For the totally incompressible Yeoh (i.e., classic Yeoh) model predicts the equibiaxial tension (ET) stress lower, this paper proposes the totally incompressible Yeoh-Revised model to improve the prediction of ET stress. First, the fitting expression of the totally incompressible Yeoh-Revised constitutive model was derived under the presumption that fluororubber (FPM) and hydrogenated nitrile-butadiene rubber (HNBR) are isotropic and entirely incompressible. Meanwhile, the goodness-of-fit (R^2) statistic was used to assess the fitting outcomes of the three tension tests data (e.g., single tension (ST), ET and planar tension (PT)). Additionally, in order to fit the rubber materials tensile test data more accurately, we suggest a novel hyperelastic constitutive fitting method that takes into account the volume microscopic compressibility of rubber materials. The findings demonstrate that the totally incompressible Yeoh-Revised model's prediction of ET stress has marginally improved which neglecting the rubber materials’ volume microcompressibility, while the almost incompressible Yeoh-Revised model fits the ET stress significantly and accurately, and also enhances the forecast accuracy of overall R^2. Finally, the fitting formula of the almost incompressible constitutive model may be reduced to that of the totally incompressible model if the volume microcompressibility is disregarded, which is beneficial to more accurately forecast the experiment tests of rubber materials tension.