Macroindentation of a soft polymer: Identification of hyperelasticity and validation by uni/biaxial tensile tests

Chen, Zhaoyu; Scheffer, Tobias; Seibert, Henning; Diebels, Stefan

doi:10.1016/j.mechmat.2013.05.003

Cited by 41 publications

(15 citation statements)

References 44 publications

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“…However, increasing n to 4 finally yields a strain tensor field that shows the desired non-constant behaviour in space and has a similar structure as the reference solution. Furthermore, the symmetry of the result for e 22 corresponds to the observations made by Chen et al [6]. Thus, we conclude that this time our result can be regarded as correct.…”

Section: Experimental Evaluationsupporting

confidence: 90%

Lagrangian Strain Tensor Computation with Higher Order Variational Models

Hewer¹,

Weickert²,

Seibert³

et al. 2013

Procedings of the British Machine Vision Conference 2013

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The reliable estimation of the Lagrangian stress tensor from an image sequence is a challenging problem in mechanical engineering. Since this tensor involves first order motion derivatives, it appears tempting to estimate the optical flow field with a highly accurate variational model and compute its derivatives afterwards. In this paper we explain why this idea is inappropriate due to lower order smoothness assumptions and the ill-posedness of differentiation. As a remedy, we propose a variational framework that performs higher order regularisation of the optical flow field and directly computes the Lagrangian stress tensor from the image measurements. Due to its recursive structure, this framework is very generic. It can incorporate smoothness assumptions of arbitrary high order and allows to compute derivatives of any desired order in a stable way. With a biaxial tensile experiment with an elastomer we demonstrate that our novel approach gives substantially better results for the Lagrangian stress tensor than computing derivatives of the optical flow field. Moreover, it also outperforms a frequently used commercial software that marks the state-of-the-art for Lagrangian stress tensor computation.

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Section: Experimental Evaluationsupporting

confidence: 90%

Lagrangian Strain Tensor Computation with Higher Order Variational Models

Hewer¹,

Weickert²,

Seibert³

et al. 2013

Procedings of the British Machine Vision Conference 2013

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“…Hence, the relaxation tests of uniaxial tension and the simple shear tests with different loading velocities are taken as examples in this study. Due to the lack of appropriate data for these experiments, we followed the method applied in Chen et al [24][25][26] and got the corresponding virtual experiment data by using ANSYS, in which we assume the hyperelastic parameters are the same with the last group in Table 1, and the viscoelastic part is characterized by the following Prony series, …”

Section: Different Loading Histories and Virtual Experiments Datamentioning

confidence: 99%

“…Amin et al proposed an improved hyperelastic constitutive equation for rubbers in compression and shear regimes [1,22,23], the parameters in the equation were identified by experiment data and a nonlinear viscous coefficient was introduced to represent the rate-dependent properties. In recent years, a novel testing technique, named nanoidentation, to identify the material parameters for thin polymer layers was developed, a comprehensive review and the realization of the method for hyperelastic and viscoelastic models are presented by Chen et al [24][25][26] In this paper, the Ogden model is taken to characterize the hyperelastic properties of rubber-like materials. A professional method based on the pattern search algorithm (PSA) [27,28] and the Levenberg-Marquardt algorithm (LMA) [29] was developed to fit the unixial tension, biaxial tension, planar tension, and the simple shear experimental data of hyperelastic materials.…”

Section: Introductionmentioning

confidence: 99%

Parameter Identification Methods for Hyperelastic and Hyper-Viscoelastic Models

Wang

2016

Applied Sciences

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Abstract:In this paper, the Ogden model is employed to characterize the hyperelastic properties of rubber, and on the basis of a pattern search algorithm and the Levenberg-Marquardt algorithm, a professional method that can realize the comprehensive fitting of the uniaxial tension, biaxial tension, planar tension, and simple shear experimental data of hyperelastic materials was developed. The experiment data from Treloar (1944) was fitted very well, and the determined parameters by using this method were proven correct and practical in the numerical verification in ANSYS. Then, the constitutive model of the hyper-viscoelastic materials combining the Ogden model with the generalized Maxwell model was explained in detail, and the parameter identification method was also proposed by using the pattern search method. Then, three groups of relaxation tests of uniaxial tension and four groups of simple shear tests with different loading velocities were conducted to obtain the corresponding virtual experiment data. After discussing the constraints and initial setting values for the undetermined parameters, these virtual data of different loading histories were respectively employed to identify the parameters in the hyper-elastic model, and the accuracy and the reliability of the estimated parameters were also verified in ANSYS.

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“…Such experiments have to provide access to the model parameters and have to serve as an appropriate database for simulating a certain load case. The work of several authors has already shown, for example, that in order to perform multiaxial simulations, it is not sufficient to determine the model parameters in uniaxial experiments [11,12,13,14]. In the first part of this section, classical experiments for the characterization of beam-like structures will be described, which enable access to linear-elastic stiffnesses.…”

Section: Experimental Characterization Of Cables and Hosesmentioning

confidence: 99%

Towards Viscoplastic Constitutive Models for Cosserat Rods

Dörlich¹,

Linn²,

Scheffer³

et al. 2016

Archive of Mechanical Engineering

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Flexible, slender structures like cables, hoses or wires can be described by the geometrically exact Cosserat rod theory. Due to their complex multilayer structure, consisting of various materials, viscoplastic behavior has to be expected for cables under load. Classical experiments like uniaxial tension, torsion or three-point bending already show that the behavior of e.g. electric cables is viscoplastic. A suitable constitutive law for the observed load case is crucial for a realistic simulation of the deformation of a component. Consequently, this contribution aims at a viscoplastic constitutive law formulated in the terms of sectional quantities of Cosserat rods. Since the loading of cables in applications is in most cases not represented by these mostly uniaxial classical experiments, but rather multiaxial, new experiments for cables have to be designed. They have to illustrate viscoplastic effects, enable access to (viscoplastic) material parameters and account for coupling effects between different deformation modes. This work focuses on the design of such experiments.

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Macroindentation of a soft polymer: Identification of hyperelasticity and validation by uni/biaxial tensile tests

Cited by 41 publications

References 44 publications

Lagrangian Strain Tensor Computation with Higher Order Variational Models

Lagrangian Strain Tensor Computation with Higher Order Variational Models

Parameter Identification Methods for Hyperelastic and Hyper-Viscoelastic Models

Towards Viscoplastic Constitutive Models for Cosserat Rods

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