Biomechanical Properties of Human Dilated Ascending Aorta

Abstract Aneurysms of ascending aorta are dilatation of the first part of the human aorta. They commonly show no clinical symptoms. This condition increases the risk of aorta dissection, which is a life-threatening condition. In this study we attempted to elucidate the changes in the biomechanical properties that occur in the dilated human ascending aorta. Fourteen specimens of ascending aorta wall were mechanically tested under a uniaxial tensile test. Two specimens from each ascending aorta anterior region were cut in longitudinal and circumferential directions. The samples were stretched until rupture of the sample occurred. The obtained experimental data were processed to determine maximal stress, maximal strain and the tangential modulus of elasticity in the linear part of the stress-strain curve. The obtained results showed a remarkable anisotropy of the ascending aorta tissue. We found higher strength of the tissue in the circumferential direction than in the longitudinal direction. There were no statistically significant differences between the strains of the samples. Tangential modulus of elasticity of the aortic samples in the longitudinal direction was significantly lower than the elastic modulus of the samples in the circumferential direction. The tissue in the circumferential direction is stronger and stiffer than in the longitudinal direction.

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Experimental investigations of the human oesophagus: anisotropic properties of the muscular layer in large deformation

10.1101/2021.07.18.452813 ◽

2021 ◽

Author(s):

Ciara Durcan ◽

Mokarram Hossain ◽

Gregory Chagnon ◽

Djordje Peric ◽

Lara Bsiesy ◽

...

Keyword(s):

Strain Rate ◽

Ex Vivo ◽

Longitudinal Direction ◽

Tensile Tests ◽

Endoscopic Biopsy ◽

Circumferential Direction ◽

Experimental Investigations ◽

Uniaxial Tensile ◽

Rate Dependency ◽

Muscular Layer

Technological advancements in the field of robotics have led to endoscopic biopsy devices able to extract diseased tissue from between the layers of the gastrointestinal tract. Despite this, the layer-dependent properties of these tissues have yet to be mechanically characterised using human tissue. In this study, the ex vivo mechanical properties of the passive muscularis propia layer of the human oesophagus were extensively investigated. For this, a series of uniaxial tensile tests were conducted. The results displayed hyperelastic behaviour, while the differences between loading the tissue in both the longitudinal and circumferential directions showcased its anisotropy. The anisotropy of the muscular layer was present at different strain rates, with the longitudinal direction being consistently stiffer than the circumferential one. The circumferential direction was found to have little strain-rate dependency, while the longitudinal direction results suggest pronounced strain-rate-dependent behaviour. The repeated trials showed larger variation in terms of stress for a given strain in the longitudinal direction compared to the circumferential direction. The possible causes of variation between trials are discussed, and the experimental findings are linked to the histological analysis which was carried out via various staining methods. Finally, the direction-dependent experimental data was simulated using an anisotropic, hyperelastic model.

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Tensile Properties of Polymer Repair Materials - Effect of Test Parameters

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1129.445 ◽

2015 ◽

Vol 1129 ◽

pp. 445-452

Author(s):

Z. Kamil ◽

G. Andrzej ◽

C. Sandra ◽

A.J. Barroso

Keyword(s):

Tensile Strength ◽

Tensile Test ◽

Modulus Of Elasticity ◽

Deformation Rate ◽

Effect Of Temperature ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Sample Shape ◽

Repair Materials ◽

Test Parameters

In this research, five types of polymer repair materials were selected for investigation of the influence of sample shape, deformation rate and test temperature on the mechanical properties determined with an uniaxial tensile test. The results showed the clear effect of measurement conditions on tensile strength, elongation and modulus of elasticity. The highest tensile strength and modulus of elasticity were exhibited by epoxy resin for the filling of concrete cracks, which achieved 1% elongation. The lowest coefficient of dispersion characterized the results of tensile test carried out using dumbbell samples at a deformation rate of 50 mm/min. The effect of temperature varied with the material type.

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Biomechanical and Elastographic Analysis of Mesenchymal Stromal Cell Treated Tissue Following Surgery

Journal of Biomechanical Engineering ◽

10.1115/1.4001382 ◽

2010 ◽

Vol 132 (7) ◽

Cited By ~ 1

Author(s):

Hazel Marie ◽

Yong Zhang ◽

Jeremy Heffner ◽

Heath A. Dorion ◽

Diana L. Fagan

Keyword(s):

Mechanical Property ◽

Tensile Test ◽

Tensile Testing ◽

Recovery Period ◽

Strain Analysis ◽

Biomechanical Properties ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Ongoing Research ◽

Uniaxial Tensile Testing

Hernia repair continues to be a problem facing surgeons today, particularly because of the high incidence of reoccurrence. This work presents preliminary data of a pioneering effort to investigate the effect of mesenchymal stromal cells (MSCs) on mechanical property enhancement in full thickness fascial defects. Heparinized MSCs harvested from a rabbit’s tibia/iliac crest were applied to two fascial defects on the rabbit’s abdominal wall, with two other defects acting as controls (no MSCs added). After an 8 week recovery period, the entire abdominal fascia was harvested for mechanical property testing and elastographic strain analysis. Preliminary results from uniaxial tensile testing indicate a significant increase in the modulus of toughness strain energy, with at least a 50% increase in the MSC treated defects as compared with the control defects. Results from the elastographic strain analysis show excellent correlation in the calibration of the elastography to the uniaxial tensile test, with nearly identical moduli of elasticity. In addition, the elastographs clearly show tissue property heterogeneity at all stages of tensile testing. The MSC treated tissue demonstrates promise of enhanced material properties over that of the nontreated tissue; testing and analysis is ongoing. The elastography provides pixel-level description of tissue property variations providing critical information on wound healing effectiveness that would be impossible with other methods. In the ongoing research, optical elastography, in combination with the traditional tensile test and tissue histology, will be used to characterize localized biomechanical properties directly within the defect area and to locate “crack” initiation and propagation sights as the material is strained to rupture.

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Abstract 368: Biomechanical Properties of Scar ECM: from the Acute to Chronic Stages of Myocardial Infarction

Circulation Research ◽

10.1161/res.117.suppl_1.368 ◽

2015 ◽

Vol 117 (suppl_1) ◽

Author(s):

Bryn Brazile ◽

J. R Butler ◽

Sourav Patnaik ◽

Yanyi Xu ◽

Andrew Claude ◽

...

Keyword(s):

Myocardial Infarction ◽

Heart Function ◽

Sodium Dodecyl ◽

Longitudinal Direction ◽

Biomechanical Properties ◽

Circumferential Direction ◽

Heart Cell ◽

Coronary Artery Ligation ◽

Artery Ligation ◽

Biaxial Behavior

Introduction: Myocardial infarction (MI) affects more than 8 million Americans, causing massive heart cell death and heart function decrease. To better understand the scar biomechanics, we characterized the mechanical properties of pure scar ECM, obtained by decellularizing the MI tissues. Materials and Methods: Infarcted rat hearts were generated by a permanent left coronary artery ligation (PLCAL) and harvested at 15 min, 1, 2, and 4 weeks (per acute to chronic stages of MI)(N = 6 each). Scar ECM were obtained by decellularizing the infarcted hearts in 0.1% sodium dodecyl sulfate (SDS) solution for 3 weeks. Scar ECM specimens were trimmed into square shape, and then subjected to biaxial testing with one edge aligned with the circumferential direction and the other edge aligned with the longitudinal direction of the rat heart. After 10 cycle preconditioning, an equibiaxial tension protocol of T circ : T rad = 30:30 N/m was performed to capture the tissue biaxial behavior. Results and Discussion: Scar ECM 15 minutes through 4 weeks post infarction showed a stiffening biaxial behavior along with the time (Fig.1). The decrease of extensibility along longitudinal direction was more noticeable than circumferential direction, which led to a decrease in degree of anisotropy. Conclusions: Scar ECM biomechanics showed a stiffening behavior with a marked reduction in extensibility (longitudinal) with time. This change in biomechanical properties can be correlated to the collagen structure changes with progression of MI. Knowledge of the structural-mechanical relationship of scar ECM will help us understand MI progression and help formulate regenerative therapies.

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Direct Evidence of Symmetry between Bilateral Human Corneas in Biomechanical Properties: A Comparison Study with Fresh Corneal Tissue

Journal of Ophthalmology ◽

10.1155/2021/8891412 ◽

2021 ◽

Vol 2021 ◽

pp. 1-7

Author(s):

Chao Xue ◽

Yaoqi Xiang ◽

Yi Song ◽

Min Shen ◽

Di Wu ◽

...

Keyword(s):

Biomechanical Properties ◽

Tangent Modulus ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Corneal Tissue ◽

Significant Difference ◽

Lenticule Extraction ◽

The Difference ◽

First Time ◽

Corneal Biomechanical Properties

Purpose. To investigate the difference between the eyes from the same human with respect to the biomechanical properties of fresh corneal tissues and investigate the assumption of similarity of the corneal biomechanical properties between the eyes. Methods. Strip specimens extracted through a small incision lenticule extraction (SMILE) surgery were tested using a uniaxial tensile test. The specimens were extracted vertically. Low-strain tangent modulus (LSTM), high-strain tangent modulus (HSTM), and tensile strength ( σ b ) were the biomechanical parameters used in the comparison of the eyes from the same human. Results. Ninety corneal specimens from 45 persons were included in this study. The LSTM of the left and right eyes were 1.34 ± 0.52 and 1.37 ± 0.46 MPa, while the HSTM were 50.53 ± 7.51 and 49.41 ± 7.01 MPa, respectively. There was no significant difference between the eyes in terms of LSTM, HSTM, and σ b P = 0.813 , 0.335 , and 0.605 , resp . . The LSTM and HSTM were significantly correlated with the spherical equivalent (SE) ( P ≤ 0.01 , P = 0.001 , resp.). Conclusions. The assumption that the corneal biomechanical properties of the eyes from the same human are similar has been confirmed for the first time using fresh human corneal tissue. This finding may be useful in further biomechanical studies.

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ANALYSIS OF SOUND SPEED IN LONGITUDINAL DIRECTION AT REFERENCE MOISTURE CONTENT (w = 12 %) IN SAWMILL ASSORTMENTS (FAGUS SYLVATICA, L.)

Akustika ◽

10.36336/akustika20203745 ◽

2020 ◽

pp. 45-50

Author(s):

Alena Rohanová

Keyword(s):

Moisture Content ◽

Modulus Of Elasticity ◽

Dynamic Modulus ◽

Sound Speed ◽

Longitudinal Direction ◽

Structural Timber ◽

Sound Speeds ◽

Dynamic Modulus Of Elasticity ◽

Round Timber

This paper explores the analysis of sound speeds in the longitudinal direction and their reduction to the reference moisture content w = 12 %. The sound speed cw was determined with Sylvatest Duo device. Moisture content of beech sawmill assortments (round timber: N = 16, logs: N = 2 × 16, structural boards: N = 54) in the range of 12 – 72 % was measured. For the analysis purposes, the sound speed was converted to reference conditions (c12, uref = 12%). A second-degree polynomial (parabola) with a regression equation of the form: c// = 5649 - 27,371 × w + 0.0735 × w2 was used to convert cw to c12, and correction of measured and calculated values was used as well. The sound speeds c12 in sawmill assortments (c12,round, c12,log, c12,board) were evaluated by linear dependences. Dependence was not confirmed for c12,round and c12,board1 (r = 0.168), in contrast for c12,round and c12,log2 the dependence is statistically very significant (r = 0.634). The results of testing showed that the most suitable procedure for predicting quality of structural timber is the first step round timber – log2, the second step: log2 - board2. More exact results of the construction boards were obtained from log2 than from log1. The sound speed is used in the calculation of dynamic modulus of elasticity (Edyn). EN 408 mentions the possibility of using dynamic modulus of elasticity as an alternative method in predicting the quality of structural timber.

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Biomechanical-Structural Correlation of Chordae tendineae in Animal Models: A Pilot Study

Animals ◽

10.3390/ani11061678 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1678

Author(s):

Justyn Gach ◽

Izabela Janus ◽

Agnieszka Mackiewicz ◽

Tomasz Klekiel ◽

Agnieszka Noszczyk-Nowak

Keyword(s):

Mitral Valve ◽

Complex Structure ◽

Future Research ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Histopathological Analysis ◽

Papillary Muscles ◽

Chordae Tendineae ◽

Structural Correlation ◽

Ring Valve

The mitral valve apparatus is a complex structure consisting of the mitral ring, valve leaflets, papillary muscles and chordae tendineae (CT). The latter are mainly responsible for the mechanical functions of the valve. Our study included investigations of the biomechanical and structural properties of CT collected from canine and porcine hearts, as there are no studies about these properties of canine CT. We performed a static uniaxial tensile test on CT samples and a histopathological analysis in order to examine their microstructure. The results were analyzed to clarify whether the changes in mechanical persistence of chordae tendineae are combined with the alterations in their structure. This study offers clinical insight for future research, allowing for an understanding of the process of chordae tendineae rupture that happens during degenerative mitral valve disease—the most common heart disease in dogs.

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Experimental and Numerical Evaluation of Mechanical Properties of 3D-Printed Stainless Steel 316L Lattice Structures

Journal of Materials Engineering and Performance ◽

10.1007/s11665-021-05737-w ◽

2021 ◽

Author(s):

M. Carraturo ◽

G. Alaimo ◽

S. Marconi ◽

E. Negrello ◽

E. Sgambitterra ◽

...

Keyword(s):

Mechanical Properties ◽

Stainless Steel ◽

Mechanical Behavior ◽

Numerical Simulations ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Lattice Structures ◽

Stainless Steel 316L ◽

Research Attention ◽

Octet Truss

AbstractAdditive manufacturing (AM), and in particular selective laser melting (SLM) technology, allows to produce structural components made of lattice structures. These kinds of structures have received a lot of research attention over recent years due to their capacity to generate easy-to-manufacture and lightweight components with enhanced mechanical properties. Despite a large amount of work available in the literature, the prediction of the mechanical behavior of lattice structures is still an open issue for researchers. Numerical simulations can help to better understand the mechanical behavior of such a kind of structure without undergoing long and expensive experimental campaigns. In this work, we compare numerical and experimental results of a uniaxial tensile test for stainless steel 316L octet-truss lattice specimen. Numerical simulations are based on both the nominal as-designed geometry and the as-build geometry obtained through the analysis of µ-CT images. We find that the use of the as-build geometry is fundamental for an accurate prediction of the mechanical behavior of lattice structures.

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Polar poly(n-butyl acrylate)-g-polyacrylonitrile elastomer with high temperature elasticity and healability as flexible electronic substrate

Fashion and Textiles ◽

10.1186/s40691-020-00235-4 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Yuzhu Zheng ◽

Deli Xu ◽

Shiyou Tian ◽

Manli Li ◽

Wenwen Wang ◽

...

Keyword(s):

High Temperature ◽

Graft Copolymer ◽

Butyl Acrylate ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Self Healing ◽

Chemical Structures ◽

Flexible Electronic ◽

Ag Nanowires ◽

Cyano Groups

AbstractIn this work, graft copolymer poly (n-butyl acrylate)-g-polyacrylonitrile with poly (n-butyl acrylate) as backbones and polyacrylonitrile as side chains (PnBA-g-PAN) was synthesized by macromonomer method and emulsion polymerization. The macromonomer was synthesized by atom transfer radical polymerization and end-group modification. The chemical structures and thermal properties of macromonomer and graft copolymer were investigated by FTIR, GPC, NMR and TGA, etc. The mechanical properties of graft copolymer elastomer was also measured by uniaxial tensile test. Rheological properties at different temperature and mechanical property demonstrated that graft copolymer elastomer possessed elasticity until 180 oC because of cyclization of cyano groups. Ag nanowires@PnBA-g-PAN composite elastomer was developed, and the resulted material exhibited autonomic healing property on account of segments’ flexibility and dynamic interaction between Ag nanowires (AgNWs) and cyano groups. This is a general method for generation of elastomer with high temperature elasticity and fast self-healing. The composite elastomer has potential application in flexible electronic conductor.

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Ability of Constitutive Models to Characterize the Temperature Dependence of Rubber Hyperelasticity and to Predict the Stress-Strain Behavior of Filled Rubber under Different Defor Mation States

Polymers ◽

10.3390/polym13030369 ◽

2021 ◽

Vol 13 (3) ◽

pp. 369

Author(s):

Xintao Fu ◽

Zepeng Wang ◽

Lianxiang Ma

Keyword(s):

Experimental Data ◽

Temperature Dependence ◽

Mechanical Response ◽

Constitutive Models ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Chain Model ◽

Stress Strain ◽

Filled Rubber ◽

Yeoh Model

In this paper, some representative hyperelastic constitutive models of rubber materials were reviewed from the perspectives of molecular chain network statistical mechanics and continuum mechanics. Based on the advantages of existing models, an improved constitutive model was developed, and the stress–strain relationship was derived. Uniaxial tensile tests were performed on two types of filled tire compounds at different temperatures. The physical phenomena related to rubber deformation were analyzed, and the temperature dependence of the mechanical behavior of filled rubber in a larger deformation range (150% strain) was revealed from multiple angles. Based on the experimental data, the ability of several models to describe the stress–strain mechanical response of carbon black filled compound was studied, and the application limitations of some constitutive models were revealed. Combined with the experimental data, the ability of Yeoh model, Ogden model (n = 3), and improved eight-chain model to characterize the temperature dependence was studied, and the laws of temperature dependence of their parameters were revealed. By fitting the uniaxial tensile test data and comparing it with the Yeoh model, the improved eight-chain model was proved to have a better ability to predict the hyperelastic behavior of rubber materials under different deformation states. Finally, the improved eight-chain model was successfully applied to finite element analysis (FEA) and compared with the experimental data. It was found that the improved eight-chain model can accurately describe the stress–strain characteristics of filled rubber.

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