Finite Element Analysis Of Rubber Biaxial Tensile Specimen And Design Of Its True Biaxial Tensile Test Device

Rubber materials have large deformation range,strong bearing capacity and good performance,and are widely used in daily life,automobiles,medical treatment,national defense and other fields.In order to characterize the real mechanical properties of rubber materials,uniaxial tensile,plane tensile and compression test data alone are not sufficient to provide reliable parameters for the constitutive model when subjected to complex stress states.Isobiaxial tensile test data provide few sample points and are all in low stress and low strain states.Therefore,different proportions of biaxial stress tensile tests are required.In the field of rubber materials,there is no uniform standard for biaxial stretching method and sample shape.In this paper,a cross-shaped sample with open arm seam design is established.Through simulation analysis,it is proved that the open arm seam design can improve the uniformity of stress and strain distribution in the central test area,and the stress and strain value is much larger than that of the common cross-shaped sample.The finite element software ANSYS Workbench is used to simulate and analyze the influence of different arm joint parameters on the stress and strain distribution in the central test area.Through simulation analysis,it is concluded that:(1)The curve distribution of uniformity r in the central test area of the sample designed with open arm seams is more stable and the value is closer to 1.The stress value transferred to the central test area by the tensile arm of the sample is larger,it is necessary to open arm joint on cross specimen.(2)In equal biaxial stretching,the chamfer radius at the stretching arm is 1.5mm,and the equivalent stress distribution uniformity in the central testing area is high and the stress concentration degree is relatively small.(3)When the arm joint length is 10 mm,15 mm and 20 mm,the variation trend of stress and strain distribution uniformity in the central test area is approximately the same.Considering the influence of stress concentration,the arm joint length of 20 mm is more appropriate.(4)The stress-strain distribution of the samples with different arm seam widths in the central test area does not change obviously.With the increase of the arm seam width,the stress-strain value of the tensile arm increases,and the arm seam width of 1mm meets the design requirements.(5)When the number of arm joints is 3,5,7,the uniform range of stress and strain distribution in the central test area slightly increases with the increase of the number of arm joints.Considering the overall size of the tensile arm of the sample,it is advisable to take 3 pieces of arm seams.This paper studies and designs a small-scale true biaxial tensile testing device for rubber materials.It is expected that through the experimental research under different proportions of biaxial stress,the mechanical properties of the materials under actual service conditions can be obtained.