Visco-hyperelasticity of Electro-active Soft Tissues

Gizzi, Alessio; Pandolfi, Anna

doi:10.1016/j.piutam.2014.12.018

Cited by 8 publications

(12 citation statements)

References 34 publications

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“…Using LaPlace's formula combined with the anisotropic geometrical properties of the abdominal tissues, mechanical stresses, deformations, and abdominal pressures defines the activity, limits, and consequences of an induced pneumoperitoneum. 12–15 Decreased compliance means that the same change in IAV results in a greater change in IAP. 4 With normal abdominal compliance being between 200 and 400 mL (mL/mm Hg), at 14 mm Hg that difference is 2,800 mL volume (200 mL × 14 = 2,800 mL and 400 mL × 14 = 5,600 mL or 5,600 – 2,800 = 2,800 mL).…”

Section: Discussionmentioning

confidence: 99%

Abdominal Compliance and Laparoscopy: A Review

Ott

2019

JSLS

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Background and Objectives: Creating and maintaining a pneumoperitoneum to perform laparoscopy is governed by gas laws and the limiting physical constraints of the abdomen. Methods: A review of how gas, biomechanical and physical properties affect the abdomen and a systematic structured Medline and PubMed search was conducted to identify relevant studies related to the topic. Results: Abdominal compliance is a measure of ease of abdominal expansion and is determined by the elasticity of the abdominal wall and diaphragm. It is the change in intra-abdominal volume per change in intra-abdominal pressure. Caution should be exercised with pressures exceeding 12 millimeters mercury since this is defined as intra-abdominal hypertension. Conclusions: Abdominal compliance has its limits, is unique for each patient and pressure-volume curves cannot be easily predicted. Using the lowest possible pressure to accomplish the surgical task without compromising surgical outcome is the desired goal. The clinical importance is caution and knowing there is a point where more pressure does not increase working space and only increases pressure.

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Section: Discussionmentioning

confidence: 99%

Abdominal Compliance and Laparoscopy: A Review

Ott

2019

JSLS

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“…Likewise, an anisotropic visco-hyperelastic formulation has been proposed by Gizzi and Pandolfi [70] to model the colon visco-electro-active response and the interaction of slow waves (electrical control activity) and fast waves (electrical response activity). The electrodynamics of the intestinal longitudinal muscular (LM) and the ICC (I) layers, i.e., dimensionless transmembrane potentials (u LM , u I ) and slow transmembrane currents (v LM , v I ) are defined using a pair of partial differential equations per layer:…”

Section: Constitutive Modeling Of Large Intestinal Smc Contractionmentioning

confidence: 99%

Virgin Passive Colon Biomechanics and a Literature Review of Active Contraction Constitutive Models

et al. 2022

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The objective of this paper is to present our findings on the biomechanical aspects of the virgin passive anisotropic hyperelasticity of the porcine colon based on equibiaxial tensile experiments. Firstly, the characterization of the intestine tissues is discussed for a nearly incompressible hyperelastic fiber-reinforced Holzapfel–Gasser–Ogden constitutive model in virgin passive loading conditions. The stability of the evaluated material parameters is checked for the polyconvexity of the adopted strain energy function using positive eigenvalue constraints of the Hessian matrix with MATLAB. The constitutive material description of the intestine with two collagen fibers in the submucosal and muscular layer each has been implemented in the FORTRAN platform of the commercial finite element software LS-DYNA, and two equibiaxial tensile simulations are presented to validate the results with the optical strain images obtained from the experiments. Furthermore, this paper also reviews the existing models of the active smooth muscle cells, but these models have not been computationally studied here. The review part shows that the constitutive models originally developed for the active contraction of skeletal muscle based on Hill’s three-element model, Murphy’s four-state cross-bridge chemical kinetic model and Huxley’s sliding-filament hypothesis, which are mainly used for arteries, are appropriate for numerical contraction numerical analysis of the large intestine.

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“…where ϵ 0 is the vacuum dielectric constant and Π accounts for electric distorsions due to materials deformations. Following previous works [120,[123][124][125], the local thermodynamics state is defined through an electrical Helmholtz free energy A characterized by the functional dependence on F, E and a collection of internal variables Q, such that:…”

Section: Active Electromechanicsmentioning

confidence: 99%

“…In Refs. [122,124,125], the active electromechanics setting was further extended to include viscous deformation and stochastic material properties [126,127] to model the colon wall. Assuming a generalized multiplicative decomposition of the deformation gradient (see Fig.…”

Section: Active Electromechanicsmentioning

confidence: 99%

Biomechanical Constitutive Modeling of the Gastrointestinal Tissues: Where Are We?

Patel¹,

Gizzi²,

Hashemi³

et al. 2021

Preprint

Self Cite

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The gastrointestinal (GI) tract is a continuous channel through the body that consists of the esophagus, the stomach, the small intestine, the large intestine, and the rectum. Its primary functions are to move the intake of food for digestion before storing and ultimately expulsion of feces from the rectum through the anal sphincter. The mechanical behavior of GI tissues thus plays a crucial role for GI function in health and disease. The mechanical properties are typically characterized by a constitutive biomechanical model, which is a mathematical representation of the relation between load and deformation in a tissue. Hence, validated biomechanical constitutive models are essential to characterize and simulate the mechanical behavior of the GI tract under physiological and pathological conditions. Numerous constitutive models have consequently been proposed over the past three decades, mainly inspired by work done in cardiovascular tissues. Here, a comprehensive review of these constitutive models is provided. This review is limited to studies where a model of the strain energy function is proposed to characterize the stress-strain relation of a GI tissue. Several needs are identified for more advanced modeling of GI biomechanics including: 1) Microstructural models that provide actual structure-function relations; 2) Validation of coupled electro-mechanical models accounting for active muscle contractions; 3) Human data under physiological and pathological conditions to develop and validate models. The findings from this review provide guidelines for using existing constitutive models as well as perspective and directions for future studies aimed at establishing new constitutive models for GI tissues.

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Visco-hyperelasticity of Electro-active Soft Tissues

Cited by 8 publications

References 34 publications

Abdominal Compliance and Laparoscopy: A Review

Abdominal Compliance and Laparoscopy: A Review

Virgin Passive Colon Biomechanics and a Literature Review of Active Contraction Constitutive Models

Biomechanical Constitutive Modeling of the Gastrointestinal Tissues: Where Are We?

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