Design optimisation of biaxial tensile test specimen using finite element analysis

Tiernan, Peter; Hannon, Alan

doi:10.1007/s12289-012-1105-8

Cited by 28 publications

(11 citation statements)

References 12 publications

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“…In this case, the identification of an optimal shape remains a debated question, as demonstrated by the number of recent papers in which very different "optimized" specimens were proposed. Optimal cruciform specimens were investigated and analyzed by means of finite element method for stiff materials and soft materials, such as composites and various elastomers or polymeric membranes [2,[17][18][19]. Such "optimized" shapes may involve the introduction of different types of fillets between crossed arms, tapering of the arms, or the use of arms with slits (or even the combination of above variants).…”

Section: Introductionmentioning

confidence: 99%

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

Avanzini

Battini

2016

Advances in Materials Science and Engineering

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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.

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Section: Introductionmentioning

confidence: 99%

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

Avanzini

Battini

2016

Advances in Materials Science and Engineering

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“…Studies prove that the structural design of the cruciform specimen structure using finite elements is cost-effective: the stress uniformity can be improved [ 8 , 14 ], and the boundary stress concentration can be reduced [ 15 , 16 , 17 ]. Before the experimental verification, most scholars determined the optimal design of the cruciform specimen via the finite element method combined with parameter optimisation methods [ 18 , 19 , 20 ]. Structural optimisation problems can be solved using either a parametric or non-parametric approach [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

Designing a Cruciform Specimen via Topology and Shape Optimisations under Equal Biaxial Tension Using Elastic Simulations

2022

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Stress uniformity within the gauge zone of a cruciform specimen significantly affects materials’ in-plane biaxial mechanical properties in material testing. The stress uniformity depends on the load transmission of the cruciform specimen from the fixtures to the gauge zone. Previous studies failed to alter the nature of the load transmission of the geometric features using parametric optimisations. To improve stress uniformity in the gauge zone, we optimised the cross-arms to design a centre-reduced cruciform specimen with topology and shape optimisations. The simulations show that the optimised specimen obtains significantly less stress variation and range in the gauge zone than the optimised specimen under different observed areas, directions, and load ratios of von Mises, S11, S22, and S12. In the quantified gauge zone, a more uniform stress distribution could be generated by optimizing specimen geometry, whose value should be estimated indirectly each time through simulations. We found that topology and shape optimisations could markedly improve stress uniformity in the gauge zone, and stress concentration at the cross-arms intersection. We first optimised the cruciform specimen structure by combining topology and shape optimisations, which provided a cost-effective way to improve stress uniformity in the gauge zone and reduce stress concentration at the cross-arms intersection, helping obtain reliable data to perform large strains in the in-plane biaxial tensile test.

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“…At elevated temperatures, biaxial tensile tests are successfully used for yield locus determination, as shown, for example, by Merklein et al [ 20 ] for a magnesium alloy AZ31 up to 310 °C and Naka et al [ 21 ] for aluminum alloy AA5083 up to 300 °C. Numerous specimen shapes also exist for yield locus determination at room temperature in biaxial tensile tests [ 22 , 23 ]. Other approaches were developed to determine FLC points in the biaxial tension test, such as the sample shapes proposed by Zidane et al [ 18 ] or by Leotoing and Guines [ 24 ], which are primarily related to room temperature studies.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigations on Thermal Forming Limit Testing with Local Inductive Heating for Hot Forming of AA7075

et al. 2021

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Forming 7000-series aluminum alloys under elevated temperatures is particularly attractive due to their increased formability. To enable process design by finite element simulation for hot forming, strain-based criteria, such as temperature-dependent forming limit diagrams (TFLD), can be consulted to assess forming feasibility. This work numerically investigates the extent to which in-plane experimental concepts with partial inductive heating are suitable for detecting discrete failure points in TFLD. In particular, an alternative to the currently widely used thickness-reduced specimen geometries was created for cruciform specimens under biaxial tension. First, the temperature-dependent and strain-rate-dependent flow behavior was investigated for AA7075 under uniaxial tension. A heat source model for partial inductive heating was inversely parameterized based on heating experiments. Subsequently, the test procedures were simulated with different specimen geometries under discrete strain conditions. Different concepts were discussed for deriving a suitable specimen shape for the biaxial tension case, and the influence of different notch and slot forms were shown. The simulations showed that partial inductive heating was suitable to induce failure situations, thus creating TFLDs. For the biaxial tension case, a sufficiently large temperature gradient was required to use cruciform specimens without thickness reduction.

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Design optimisation of biaxial tensile test specimen using finite element analysis

Cited by 28 publications

References 12 publications

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

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

Designing a Cruciform Specimen via Topology and Shape Optimisations under Equal Biaxial Tension Using Elastic Simulations

Numerical Investigations on Thermal Forming Limit Testing with Local Inductive Heating for Hot Forming of AA7075

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