Unraveling the effect of boundary conditions and strain monitoring on estimation of the constitutive parameters of elastic membranes by biaxial tests

Simón-Allué, Raquel; Cordero, Alberto; Peña, Estefanía

doi:10.1016/j.mechrescom.2014.01.009

Cited by 13 publications

(22 citation statements)

References 12 publications

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“…We found that this is achieved using a system of tethers to apply forces with no restriction on the lateral displacement. As an extension to the previous simulation of biaxial experiments [13,16,17,28], we included the real tissue heterogeneities, anisotropy, and preconditioning, as well as the carriage and attachment geometries, to simulate as close to the real conditions of planar biaxial experimental configurations as possible.…”

Section: Discussionmentioning

confidence: 99%

“…Among some recent publications, they can be roughly separated into clamped [13][14][15][16][17], cruciform [13,16,17,[30][31][32][33], and tethered boundary condition [1,[9][10][11][12]. Clamping, as previously mentioned, produces a drastically different and highly heterogeneous stress field.…”

Section: Alternative Boundary Conditionsmentioning

confidence: 99%

“…second Piola-Kirchhof stress tensor S are computed using standard formulations t ¼ P Á F T and S ¼ F À1 P. It should be noted that the methods of attachment are generally separated into tethered [1,[9][10][11][12] and clamped boundaries [13][14][15][16][17]. In the present work, we focus on tethered boundary configurations.…”

Section: Planar Biaxial Testing Experimental Configurationmentioning

confidence: 99%

“…An alternative is to image the specimen in situ, which poses its own sets of challenges. Moreover, stress is only induced in the region bounded by the tethers [13,16,17], with the surrounding tissue deforming minimally. Therefore, the tether bounded area is best used for the specimen geometry.…”

Section: Mounting and Preconditioningmentioning

confidence: 99%

“…Perhaps the most important factors that were not explored in the previous literature are the position of the tethers, heterogeneity in tissue structure, and the effective specimen geometry [13,16,17,28]. In the present work, we explored four different arrangements of tethers (Figs.…”

Section: Effect Of Tethered Configurationmentioning

confidence: 99%

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A Generalized Method for the Analysis of Planar Biaxial Mechanical Data Using Tethered Testing Configurations

Zhang

Feng

Lee

et al. 2015

Journal of Biomechanical Engineering

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Simulation of the mechanical behavior of soft tissues is critical for many physiological and medical device applications. Accurate mechanical test data is crucial for both obtaining the form and robust parameter determination of the constitutive model. For incompressible soft tissues that are either membranes or thin sections, planar biaxial mechanical testing configurations can provide much information about the anisotropic stress-strain behavior. However, the analysis of soft biological tissue planar biaxial mechanical test data can be complicated by in-plane shear, tissue heterogeneities, and inelastic changes in specimen geometry that commonly occur during testing. These inelastic effects, without appropriate corrections, alter the stress-traction mapping and violates equilibrium so that the stress tensor is incorrectly determined. To overcome these problems, we presented an analytical method to determine the Cauchy stress tensor from the experimentally derived tractions for tethered testing configurations. We accounted for the measured testing geometry and compensate for run-time inelastic effects by enforcing equilibrium using small rigid body rotations. To evaluate the effectiveness of our method, we simulated complete planar biaxial test configurations that incorporated actual device mechanisms, specimen geometry, and heterogeneous tissue fibrous structure using a finite element (FE) model. We determined that our method corrected the errors in the equilibrium of momentum and correctly estimated the Cauchy stress tensor. We also noted that since stress is applied primarily over a subregion bounded by the tethers, an adjustment to the effective specimen dimensions is required to correct the magnitude of the stresses. Simulations of various tether placements demonstrated that typical tether placements used in the current experimental setups will produce accurate stress tensor estimates. Overall, our method provides an improved and relatively straightforward method of calculating the resulting stresses for planar biaxial experiments for tethered configurations, which is especially useful for specimens that undergo large shear and exhibit substantial inelastic effects.

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Section: Discussionmentioning

confidence: 99%

Section: Alternative Boundary Conditionsmentioning

confidence: 99%

Section: Planar Biaxial Testing Experimental Configurationmentioning

confidence: 99%

Section: Mounting and Preconditioningmentioning

confidence: 99%

Section: Effect Of Tethered Configurationmentioning

confidence: 99%

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A Generalized Method for the Analysis of Planar Biaxial Mechanical Data Using Tethered Testing Configurations

Zhang

Feng

Lee

et al. 2015

Journal of Biomechanical Engineering

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Biaxial Extension of Cruciform Specimens: Embedding Equilibrium Into Design and Constitutive Characterization

Vitucci

2024

Exp Mech

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Background Main desired features of biaxial tests are: uniformity of stresses and strains; high strain levels in gauge areas; reliable constitutive parameters identification. Despite cruciform specimen suitability to modern tensile devices, standard testing techniques are still debated because of difficulties in matching these demands. Objective This work aims at providing rational performance objectives and efficient cruciform specimens shapes in view of constitutive characterization. Methods Objective performance is evaluated along particular lines lying on principal directions in equibiaxial tensile tests. A rich specimen profile geometry is purposely optimized via finite elements analysis by varying cost function and material compressibility. Experimental tests, monitored via digital image correlation, are carried out for validation. Results New shapes are designed and tested in a biaxial tensile apparatus and show to perform better than existing ones. Elastic parameter identification is efficiently performed by only exploiting full field strain measurements along statically significant lines. Conclusions Small gauge areas and small fillet radii cruciform specimens approach the ideal deformation behaviour. For the constitutive parameters identification in planar tensile experiments, it suffices to monitor strains along the gauge lines.

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Effects of enzyme-based removal of collagen and elastin constituents on the biaxial mechanical responses of porcine atrioventricular heart valve anterior leaflets

et al. 2021

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Unraveling the effect of boundary conditions and strain monitoring on estimation of the constitutive parameters of elastic membranes by biaxial tests

Cited by 13 publications

References 12 publications

A Generalized Method for the Analysis of Planar Biaxial Mechanical Data Using Tethered Testing Configurations

A Generalized Method for the Analysis of Planar Biaxial Mechanical Data Using Tethered Testing Configurations

Biaxial Extension of Cruciform Specimens: Embedding Equilibrium Into Design and Constitutive Characterization

Effects of enzyme-based removal of collagen and elastin constituents on the biaxial mechanical responses of porcine atrioventricular heart valve anterior leaflets

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