Experimental investigation of the effects of infusing a foam into hydrogels on the hyperelastic coefficients

Raheem, Hassan Mansour; Al-Mukhtar, A. M.

doi:10.1002/mdp2.180

Cited by 5 publications

(3 citation statements)

References 13 publications

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“…Physically based constitutive models can better account for hyperelasticity, visco-hyperelasticity, and damage phenomena [28]. Recently, these models have also been employed to represent the mechanical behavior of hydrogels and their composites [29,30], while refined hyperelastic models such as the hyperfoam model can accurately describe polymeric foam fabricated through 3D printing [31]. It is worth noting that factors like temperature and aging time may influence the model parameters [32].…”

Section: Constitutive Model Of Hyperelastic Membrane Based On Equibia...mentioning

confidence: 99%

Simulation Analysis of Equibiaxial Tension Tests for Rubber-like Materials

Luo,

Zhu,

Zhao

et al. 2023

Polymers

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For rubber-like materials, there are three popular methods of equibiaxial tension available: inflation tension, equibiaxial planar tension, and radial tension. However, no studies have addressed the accuracy and comparability of these tests. In this work, we model the tension tests for a hyperelastic electroactive polymer (EAP) membrane material using finite element method (FEM) and investigate their experimental accuracy. This study also analyzes the impact of apparatus structure parameters and specimen dimensions on experimental performances. Additionally, a tensile efficiency is proposed to assess non-uniform deformation in equibiaxial planar tension and radial tension tests. The sample points for calculating deformation in inflation tensions should be taken near the top of the inflated balloon to obtain a more accurate characteristic curve; the deformation simulation range will be constrained by the material model and its parameters within a specific limit (λ ≈ 1.9); if the inflation hole size is halved, the required air pressure must be doubled to maintain equivalent stress and strain values, resulting in a reduction in half in inflation height and decreased accuracy. The equibiaxial planar tension test can enhance uniform deformation and reduce stress errors to as low as 2.1% (at λ = 4) with single-corner-point tension. For circular diaphragm specimens in radial tension tests, increasing the number of cuts and using larger punched holes results in more uniform deformation and less stress error, with a minimum value of 3.83% achieved for a specimen with 24 cuts and a 5 mm punched hole. In terms of tensile efficiency, increasing the number of tensile points in the equibiaxial planar tension test can improve it; under radial tension, increasing the number of cuts and decreasing the diameter of the punched hole on the specimen has a hedging effect. The findings of this study are valuable for accurately evaluating various equibiaxial tension methods and analyzing their precision, as well as providing sound guidance for the effective design of testing apparatus and test plans.

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Section: Constitutive Model Of Hyperelastic Membrane Based On Equibia...mentioning

confidence: 99%

Simulation Analysis of Equibiaxial Tension Tests for Rubber-like Materials

Luo,

Zhu,

Zhao

et al. 2023

Polymers

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“…It is assumed that the energy stored in hyperelastic materials depends solely on their initial and final states of deformation, which are independent of the path of deformation or load. Therefore, strain energy density functions (SEDFs) are commonly used to characterize hyperelastic materials such as rubber-like materials [9,10,19,20], various hydrogels, and their composite [27,28]. EAP is a kind of highmolecular polymer with viscoelasticity, and its nonlinear behavior can also be better described by SEDFs [17].…”

Section: Introductionmentioning

confidence: 99%

Equibiaxial Planar Tension Test Method and the Simulation Analysis for Hyperelastic EAP Membrane

Luo

Zhu

Zhao

et al. 2023

Advances in Polymer Technology

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The equibiaxial planar tension test is an important method for determining the mechanical properties of hyperplastic membranes, and it is also critical to designing an effective equibiaxial tension test rig to meet experimental accuracy requirements. However, any analysis addressing the accuracy of this test is not reported in the literature. In this paper, an equibiaxial planar tension apparatus is proposed for conducting single-corner-point tension tests on hyperelastic electroactive polymer (EAP) membranes. The experimental data were compared with those obtained from two-corner-point-fixed tension tests and fitted with nonlinear material models, and the model’s parameters were also evaluated. Finally, the widely-used finite element software ABAQUS was employed to simulate equibiaxial planar tension methods and investigate the impact of clamping mode and point number on test accuracy as well as the uniformity of overall deformation. The test results indicate that the stress-strain curves for the two tensions remain consistent across small stretch ratios. However, as the stretch ratio increases (about λ > 2.25 ) in two-corner-point-fixed tension, stress shielding may lead to a degradation of strain uniformity and result in greater stresses than single-corner-point tension. Additionally, both the three-parameter Yeoh model and the four-parameter Ogden model can provide an accurate description of the EAP membrane material. The simulation results indicate that the axial strain variation amplitudes remain below 5% within a region spanning approximately 80% of the specimen’s overall length from its center to edge and even below 1% within a region spanning 85% in the single-corner-point tension; stress inaccuracies increase with stretch ratio, while the calculated error is about 2.1% when λ = 4 in the single-corner-point tension test, which has the smallest stress error among the tests; when the number of tension points is increased, the overall deformation becomes more sufficient, and the test accuracy improves as well. The conclusions drawn from this paper will be beneficial in designing equibiaxial planar tension test rigs and analyzing their accuracy and uniformity of deformation.

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“…There are many patents [10][11][12], and several studies proposed prosthetic disc [13] that replaces the whole intervertebral disc, or they modeled the synthetic nucleus pulposus (NP), i.e., hydrogel [14,15]. However, the devices that available are not meant to be used in the lab for testing the materials for NP replacement.…”

Section: Introductionmentioning

confidence: 99%

Developing a novel functional disc emulator to investigate the nucleus pulposus replacement

Raheem

Rochefort

Bay

2021

J Mater Sci: Mater Med

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We have developed a simple, inexpensive and innovative device for reproducing the global mechanical behavior of spinal motion segments and the local mechanical environment experienced by lumbar intervertebral discs. The device has several broad functions: (1) exploration of the basic mechanics underlying this complex skeletal system, (2) connecting changes in tissue characteristics with overall motion segment function, and (3) evaluation of strategies for repair and replacement of disc components. This “disc emulator” consists of three main parts: (1) an artificial annulus fibrosus (AAF), made out of silicone, with lumbar disc geometry and adjustable material properties, (2) a hydrogel nucleus pulposus (NP) also with lumbar disc geometry and adjustable material properties, and (3) simulated vertebral bodies 3D printed with trabecular bone simulated by a rigid polymer (Acrylonitrile Butadiene Styrene, ABS) and end plates crafted from a compliant polymer (Thermoplastic Polyurethane, TPU). Mechanical compression experiments have been conducted using the disc emulator under similar protocols to published studies of human cadaver samples. Bulging of the artificial annulus fibrosus was examined under axial compression loads using digital image correlation (DIC), and results show close agreement. We see this approach of using anatomical geometry and multiple adjustable components as a useful means of creating accurate local stress/strain environments for preliminary material evaluation, without the variability and difficulty inherent indirect testing of cadaveric materials.

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Experimental investigation of the effects of infusing a foam into hydrogels on the hyperelastic coefficients

Cited by 5 publications

References 13 publications

Simulation Analysis of Equibiaxial Tension Tests for Rubber-like Materials

Simulation Analysis of Equibiaxial Tension Tests for Rubber-like Materials

Equibiaxial Planar Tension Test Method and the Simulation Analysis for Hyperelastic EAP Membrane

Developing a novel functional disc emulator to investigate the nucleus pulposus replacement

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