Experimental and numerical analysis of the buckling and postbuckling behavior of hyperelastic columns

•Experimental post-buckling analysis of elastomeric columns until failure.•Characterization of the hyperelastic material and stored energy function.•Estimate of critical load and imperfection by Southwell method including self-weight.•Analysis of evolution of stresses and strains in the pre- and post-buckling regimes.•Experimental results favorably compared with FE 3D simulations. There has been an increasing amount of research and applications of hyperelastic bars, many of which involving beneficial buckling. However, there is limited information available regarding the stability of hyperelastic structural elements. Therefore, the objective of this study is to investigate experimentally and numerically the pre- and post-buckling behavior of hyperelastic columns until failure. Several constitutive models for hyperelastic incompressible materials undergoing finite deformations are tested. Uniaxial compressive and tensile tests are used to obtain the material constants and identify the most accurate model for the considered material (polyvinyl siloxane). Three-dimensional finite elements simulations are used for comparison. The experimental program is conducted considering different lengths and boundary conditions, covering a wide range of slenderness ratios. The use of a digital image correlation measurement software during the tests allows for an in-depth analysis of the deformation field. The Southwell method is adopted to evaluate the critical load and initial imperfection magnitude. The results are then compared with analytical critical loads and the influence of axial shortening, shear and self-weight is assessed. Results show that the nonlinear equilibrium path is also influenced by axial and shear deformations, self-weight, and anticlastic deformations, even under small strains. Different buckling mechanisms are identified, with some columns exhibiting limit-point instability. Finally, the results demonstrate that the hyperelastic columns can sustain high levels of deformation without damage, crucial in practical applications such as vibration control, energy absorption and harvesting, metamaterial development, bioengineering and medicine and flexible robotics, among others.