Integrated Experimental and Numerical Comparison of Different Approaches for Planar Biaxial Testing of a Hyperelastic Material

Abstract

Planar biaxial testing has been applied to a variety of materials to obtain relevant information for mechanical characterization and constitutive modeling in presence of complex stress states. Despite its diffusion, there is currently no standardized testing procedure or a unique specimen design of common use. Consequently, comparison of results obtained with different configurations is not always straightforward and several types of optimized shapes have been proposed. The purpose of the present work is to develop a procedure for comprehensive comparison of results of biaxial tests carried out on the same soft hyperelastic material, using different types of gripping methods and specimen shapes (i.e., cruciform and square). Five configurations were investigated experimentally using a biaxial test rig designed and built by the authors, using digital imaging techniques to track the displacements of markers apposed in selected positions on the surfaces. Then, material parameters for a suitable hyperelastic law were determined for each configuration examined, employing an inverse method which combines numerical simulations with the finite element method (FEM) and optimization algorithms. Finally, efficiency of examined biaxial configurations was assessed comparing stress reductions factor, degree and uniformity of biaxial deformation, and operative strain ranges.

Evaluation on the fatigue behavior of sand-blasted AlSi10Mg obtained by DMLS

“…The entire section was reconstructed with the support of the Leica Application Suite v4.8 software. The whole sections were processed using a custom software for defects analysis coded within NI Labview environment that evolved from previous approaches used for marker tracking [49] and crack length tracking [50] during various experimental tests. This new optical measurement code allows the processing of single or multiple images and provides a text output file containing all the data of the most significant features of each defect identified in the image(s) such as: position, bounding box, orientation, elongation, area, maximum Feret diameter, and many others.…”

FE Model of Low Grade Rubber for Modeling Housing’s Low-Cost Rubber Base Isolators

“…Generally, this material undergoes very large strain and performs highly nonlinear in stress-strain relationship. The characteristic of hyperelastic material has confirmed its unique behavior through a series experimental testing and describes its actual behavior through a proper selection of constitutive model [11][12]. The highly demand of rubber material in various applications, has required a good understanding for the engineers regarding the unique behavior of rubber material.…”

Design and Optimization of a New Anti-reflux Biliary Stent With Retractable Bionic Valve Based on Fluid-Structure Interaction Analysis

“…The 3D model was modeled as hyperelastic materials using Mooney-Rivlin (MR) model, and the strain energy density W can be written as ( Kim et al, 2012 ) where C 10 and C 01 are empirical constants for the material, is the first deviatoric strain invariant, is the second deviatoric strain invariant, and μ 0 is the initial shear modulus of the material. Here, C 10 = 152.5 MPa and C 01 = 19.6 MPa, which was adopted from previous research ( Avanzini and Battini 2016 ). The mechanical properties of the 2D model material are: Mass density ρ = 7,800 kg/m 3 and Young’s modulus E = 210 GPa.…”