Control of tension–compression asymmetry in Ogden hyperelasticity with application to soft tissue modelling

Moerman, Kevin M.; Simms, Ciaran; Nagel, Thomas

doi:10.1016/j.jmbbm.2015.11.027

Cited by 51 publications

(30 citation statements)

References 49 publications

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“…each element may have different desired constitutive parameters. The non-linear elastic behavior of all materials is modeled using the following isotropic, and coupled hyperelastic strain energy density function [52]:…”

Section: F Constitutive Modelingmentioning

confidence: 99%

Automated and Data-driven Computational Design of Patient-Specific Biomechanical Interfaces

Moerman¹,

Sengeh²,

Herr³

2016

Preprint

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Abstract-Biomechanical interfaces are mechanical structures that form the connection between a device and a tissue region, and, through appropriate load transfer, aim to minimize tissue discomfort and injury. A patient-specific and data-driven computational framework for the automated design of biomechanical interfaces is presented here. Optimization of the design of biomechanical interfaces is complex since it is affected by the interplay of the geometry and mechanical properties of both the tissue and the interface. The proposed framework is presented for the application of transtibial amputee prostheses where the interface is formed by a prosthetic liner and socket. Conventional socket design and manufacturing is largely artisan, non-standard, and insufficiently data-driven, leading to discrepancies between the quality of sockets produced by different prosthetists. Furthermore, current prosthetic liners are often not patient-specific. The proposed framework involves: A) non-invasive imaging to record patient geometry, B) indentation to assess tissue mechanical properties, C) data-driven and automated creation of patientspecific designs, D) patient-specific finite element analysis (FEA) and design evaluation, and finally E) computer aided manufacturing. Uniquely, the FEA procedure controls both the design and mechanical properties of the devices, and simulates, not only the loading during use, but also the pre-load induced by the donning of both the liner and the socket independently. Through FEA evaluation, detailed information on internal and external tissue loading, which are directly responsible for discomfort and injury, are available. Further, these provide quantitative evidence on the implications of design choices, e.g. : 1) alterations in the design can be used to locally enhance or reduce tissue loading, 2) compliant features can aid in relieving local surface pressure. The proposed methods form a patient-specific, data-driven and repeatable design framework for biomechanical interfaces, and by enabling FEA-based optimization reduces the requirement for repeated patient involvement in the currently manual and iterative design process.

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Section: F Constitutive Modelingmentioning

confidence: 99%

Automated and Data-driven Computational Design of Patient-Specific Biomechanical Interfaces

Moerman¹,

Sengeh²,

Herr³

2016

Preprint

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“…Examples of such materials abound in the literature. Here we mention a few material cases to underline the significance of the taken approach, for example soft biological tissue [68], wood [69], metals [70], in addition to the widely known behavior of ceramics, geomaterials, and cementitious materials such as concrete.…”

Section: Homogeneous Deformationsmentioning

confidence: 99%

Hemivariational continuum approach for granular solids with damage-induced anisotropy evolution

Timofeev¹,

Barchiesi

Misra

et al. 2020

Mathematics and Mechanics of Solids

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Mechanical behavior of materials with granular microstructures is confounded by unique features of their grain-scale mechano-morphology, such as the tension–compression asymmetry of grain interactions and irregular grain structure. Continuum models, necessary for the macro-scale description of these materials, must link to the grain-scale behavior to describe the consequences of this mechano-morphology. Here, we consider the damage behavior of these materials based upon purely mechanical concepts utilizing energy and variational approach. Granular micromechanics is accounted for through Piola’s ansatz and objective kinematic descriptors obtained for grain-pair relative displacement in granular materials undergoing finite deformations. Karush–Kuhn–Tucker (KKT)-type conditions that provide the evolution equations for grain-pair damage and Euler–Lagrange equations for evolution of grain-pair relative displacement are derived based upon a non-standard (hemivariational) variational approach. The model applicability is illustrated for particular form of grain-pair elastic energy and dissipation functionals through numerical examples. Results show interesting damage-induced anisotropy evolution including the emergence of a type of chiral behavior and formation of finite localization zones.

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“…Computational modeling of passive skeletal muscle is thus essential to simulations of impact biomechanics [2]- [8], rehabilitation engineering [9], [10], surgical planning [11], [12], and bed sore development [9], [13]. These models rely on accurate material properties for skeletal muscle, which have been shown to be anisotropic [14], [15], time dependent [3]- [5], [16], [17], non-linear [3], [17], and asymmetric in regards to tension and compression [18], [19]. However, the compressive behavior of skeletal muscle is not fully understood, particularly regarding the differences in muscle response to in vivo loading conditions [3]- [5], [20].…”

Section: Introductionmentioning

confidence: 99%

An experimental and computational investigation of the effects of volumetric boundary conditions on the compressive mechanics of passive skeletal muscle

Vaidya

Wheatley

2020

Journal of the Mechanical Behavior of Biomedical Materials

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Computational modeling, such as finite element analysis, is employed in a range of biomechanics specialties, including impact biomechanics and surgical planning. These models rely on accurate material properties for skeletal muscle, which comprises roughly 40% of the human body. Due to surrounding tissues, compressed skeletal muscle in vivo likely experiences a semi-confined state. Nearly all previous studies investigating passively compressed muscle at the tissue level have focused on muscle in unconfined compression. The goals of this study were to (1) examine the stiffness and time-dependent material properties of skeletal muscle subjected to both confined and unconfined compression (2) develop a model that captures passive muscle mechanics under both conditions and (3) determine the extent to which different assumptions of volumetric behavior affect model results. Muscle in confined compression exhibited stiffer behavior, agreeing with previous assumptions of near-incompressibility. Stress relaxation was found to be faster under unconfined compression, suggesting there may be different mechanisms that support load these two conditions. Finite element calibration was achieved through nonlinear optimization (normalized root mean square error <6%) and model validation was strong (normalized root mean square error <17%). Comparisons to commonly employed assumptions of bulk behavior showed that a simple one parameter approach does not accurately simulate confined compression. We thus recommend the use of a properly calibrated, nonlinear bulk constitutive model for modeling of skeletal muscle in vivo. Future work to determine mechanisms of passive muscle stiffness would enhance the efforts presented here.

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Control of tension–compression asymmetry in Ogden hyperelasticity with application to soft tissue modelling

Cited by 51 publications

References 49 publications

Automated and Data-driven Computational Design of Patient-Specific Biomechanical Interfaces

Automated and Data-driven Computational Design of Patient-Specific Biomechanical Interfaces

Hemivariational continuum approach for granular solids with damage-induced anisotropy evolution

An experimental and computational investigation of the effects of volumetric boundary conditions on the compressive mechanics of passive skeletal muscle

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