A Standardised Approach to the Biomechanical Evaluation of Tracheal Grafts

The ideal tracheal substitute must have biomechanical properties comparable to the native trachea, but currently there is no standardised approach to evaluating these properties. Here we propose a novel method for evaluating and comparing the properties of tracheal substitutes, thus systematising both measurement and data curation. This system was tested by comparing native rabbit tracheas to frozen and decellularised specimens and determining the histological characteristics of those specimens. We performed radial compression tests on the anteroposterior tracheal axis and longitudinal axial tensile tests with the specimens anastomosed to the jaw connected to a measuring system. All calculations and results were adjusted according to tracheal size, always using variables relative to the tracheal dimensions, thus permitting comparison of different sized organs. The biomechanical properties of the decellularised specimens were only slightly reduced compared to controls and significant in regard to the maximum stress withstood in the longitudinal axis (−0.246 MPa CI [−0.248, −0.145] MPa) and the energy stored per volume unit (−0.124 mJ·mm−3 CI [−0.195, −0.055] mJ·mm−3). The proposed method is suitable for the systematic characterisation of the biomechanical properties of different tracheal substitutes, regardless of the size or nature of the substitute, thus allowing for direct comparisons.

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A Biphasic Approach for Characterizing Tensile, Compressive, and Hydraulic Properties of the Sclera

10.1101/2020.05.21.108936 ◽

2020 ◽

Author(s):

Dillon M. Brown ◽

Machelle T. Pardue ◽

C. Ross Ethier

Keyword(s):

Association Studies ◽

Compressive Strain ◽

Tensile Modulus ◽

Tensile Tests ◽

Biomechanical Properties ◽

Compression Testing ◽

Compression Tests ◽

Unconfined Compression ◽

Tensile Stiffness ◽

Poroelastic Theory

AbstractMeasuring the biomechanical properties of the mouse sclera is of great interest, since altered scleral properties are features of many common ocular pathologies, and the mouse is a powerful species for studying genetic factors in disease. Here, a poroelastic material model is used to analyze data from unconfined compression testing of both pig and mouse sclera, and the tensile modulus, compressive modulus, and permeability of the sclera are obtained at three levels of compressive strain. Values for all three properties measured simultaneously by unconfined compression of pig sclera were comparable to previously reported values measured by tests specific for each property, i.e., compression tests, biaxial tensile tests, and falling-head permeability assays. The repeatability of the approach was evaluated using test-retest experimental paradigm on pig sclera. Repeatability was low for measured compressive stiffness, indicating permanent changes to the samples occurring after the first test. However, reasonable repeatability for tensile stiffness and permeability was observed. The intrinsic material properties of the mouse sclera were measured for the first time. Tensile stiffness and permeability of the sclera in both species were seen to be dependent on the state of compressive strain. We conclude that unconfined compression testing of sclera, when analyzed with poroelastic theory, can be used as a powerful tool to phenotype mouse scleral changes in future genotype-phenotype association studies.Statement of SignificanceOcular biomechanics is strongly influenced by the sclera, the outermost white coat of the eye. Many ocular diseases are believed to be influenced by pathological changes to scleral microstructure and biomechanics, making intrinsic biomechanical properties an important outcome measure in many studies. However, the small mouse eye precludes the use of most traditional biomechanical characterization techniques. Here, we show that unconfined compression testing analyzed with poroelastic theory can produce measurements of biomechanical properties in the pig sclera comparable to those measured by other traditional techniques. Importantly, this technique can be successfully applied to the mouse sclera, enabling more widespread use of the species as a model for ocular disease.

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3D Printed Clamps for In Vitro Tensile Tests of Human Gracilis and the Superficial Third of Quadriceps Tendons

Applied Sciences ◽

10.3390/app11062563 ◽

2021 ◽

Vol 11 (6) ◽

pp. 2563

Author(s):

Ivan Grgić ◽

Vjekoslav Wertheimer ◽

Mirko Karakašić ◽

Željko Ivandić

Keyword(s):

3D Printing ◽

Fused Deposition Modeling ◽

Tensile Tests ◽

Biomechanical Properties ◽

Testing Procedure ◽

Laboratory Equipment ◽

Fused Deposition ◽

Custom Made ◽

3D Printed

Recent soft tissue studies have reported issues that occur during experimentation, such as the tissue slipping and rupturing during tensile loads, the lack of standard testing procedure and equipment, the necessity for existing laboratory equipment adaptation, etc. To overcome such issues and fulfil the need for the determination of the biomechanical properties of the human gracilis and the superficial third of the quadriceps tendons, 3D printed clamps with metric thread profile-based geometry were developed. The clamps’ geometry consists of a truncated pyramid pattern, which prevents the tendons from slipping and rupturing. The use of the thread application in the design of the clamp could be used in standard clamping development procedures, unlike in previously custom-made clamps. Fused deposition modeling (FDM) was used as a 3D printing technique, together with polylactic acid (PLA), which was used as a material for clamp printing. The design was confirmed and the experiments were conducted by using porcine and human tendons. The findings justify the usage of 3D printing technology for parts manufacturing in the case of tissue testing and establish independence from the existing machine clamp system, since it was possible to print clamps for each prepared specimen and thus reduce the time for experiment setup.

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Design and characterization of concrete masonry parts and structural concrete using repurposed plastics as aggregate

Journal of the Mechanical Behavior of Materials ◽

10.1515/jmbm-2019-0010 ◽

2019 ◽

Vol 28 (1) ◽

pp. 81-88

Author(s):

Miguel A. González-Montijo ◽

Hildélix Soto-Toro ◽

Cristian Rivera-Pérez ◽

Silvia Esteves-Klomsingh ◽

Oscar Marcelo Suárez

Keyword(s):

Structural Strength ◽

Construction Materials ◽

Tensile Tests ◽

Compression Tests ◽

Conventional Concrete ◽

Structural Capacity ◽

Plastic Type ◽

Concrete Mix ◽

Scientists And Engineers

AbstractHistorically known for being one of the major pollutants in the world, the construction industry, always in constant advancement and development, is currently evolving towards more environmentally friendly technologies and methods. Scientists and engineers seek to develop and implement green alternatives to conventional construction materials. One of these alternatives is to introduce an abundant, hard to recycle, material that could serve as a partial aggregate replacement in masonry bricks or even in a more conventional concrete mixture. The present work studied the use of 3 different types of repurposed plastics with different constitutions and particle size distribution. Accordingly, several brick and concrete mix designs were developed to determine the practicality of using these plastics as partial aggregate replacements. After establishing proper working material ratios for each brick and concrete mix, compression tests as well as tensile tests for the concrete mixes helped determine the structural capacity of both applications. Presented results proved that structural strength can indeed be reached in a masonry unit, using up to a 43% in volume of plastic. Furthermore, a workable structural strength for concrete can be achieved at fourteen days of curing, using up to a 50% aggregate replacement. A straightforward cost assessment for brick production was produced as well as various empirical observations and recommendations concerning the feasibility of each repurposed plastic type examined.

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Effect of Build Orientation on the Microstructure, Mechanical and Corrosion Properties of a Biodegradable High Manganese Steel Processed by Laser Powder Bed Fusion

Metals ◽

10.3390/met11060944 ◽

2021 ◽

Vol 11 (6) ◽

pp. 944

Author(s):

Martin Otto ◽

Stefan Pilz ◽

Annett Gebert ◽

Uta Kühn ◽

Julia Hufenbach

Keyword(s):

Electron Backscatter Diffraction ◽

Longitudinal Axis ◽

Manganese Steel ◽

Compressive Yield Strength ◽

Powder Bed Fusion ◽

Compression Tests ◽

Laser Powder Bed Fusion ◽

Corrosion Properties ◽

Powder Bed ◽

Manufacturing Technologies

In the last decade, additive manufacturing technologies like laser powder bed fusion (LPBF) have emerged strongly. However, the process characteristics involving layer-wise build-up of the part and the occurring high, directional thermal gradient result in significant changes of the microstructure and the related properties compared to traditionally fabricated materials. This study presents the influence of the build direction (BD) on the microstructure and resulting properties of a novel austenitic Fe‑30Mn‑1C‑0.02S alloy processed via LPBF. The fabricated samples display a {011} texture in BD which was detected by electron backscatter diffraction. Furthermore, isolated binding defects could be observed between the layers. Quasi-static tensile and compression tests displayed that the yield, ultimate tensile as well as the compressive yield strength are significantly higher for samples which were built with their longitudinal axis perpendicular to BD compared to their parallel counterparts. This was predominantly ascribed to the less severe effects of the sharp-edged binding defects loaded perpendicular to BD. Additionally, a change of the Young’s modulus in dependence of BD could be demonstrated, which is explained by the respective texture. Potentiodynamic polarization tests conducted in a simulated body fluid revealed only slight differences of the corrosion properties in dependence of the build design.

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Formability and Process Conditions of Magnesium Alloy Sheets

Materials Science Forum ◽

10.4028/www.scientific.net/msf.488-489.453 ◽

2005 ◽

Vol 488-489 ◽

pp. 453-456 ◽

Cited By ~ 11

Author(s):

Shi Hong Zhang ◽

Yong Chao Xu ◽

G. Palumbo ◽

S. Pinto ◽

Luigi Tricarico ◽

...

Keyword(s):

Deep Drawing ◽

Tensile Tests ◽

Process Conditions ◽

Drawing Ratio ◽

Temperature Range ◽

Fine Grained ◽

Axial Tensile ◽

Die Surface ◽

Lower Temperature Range ◽

Lower Temperature

Comparing the formability with each other, extrusion and various rolling experiments were carried out to make fine-grained AZ31 Mg sheets, and uni-axial tensile tests were carried out at different strain rates and temperatures to investigate the effect of different variables. A warm deep drawing tool setup with heating elements, which were distributed under the die surface and inside the blank holder, was designed and manufactured, and deep drawing was performed. Extruded Mg alloy AZ31 sheets exhibit the best deep drawing ability when working in the temperature range 250-350°C. Extruded and rolled sheets of 0.8 mm thick were also deep drawn in the lower temperature range 105-170°C，showing good formability and reaching a Limit Drawing Ratio up to 2.6 at 170°C for rolled sheets. At last, a sheet cup 0.4 mm thick was deep drawn successfully at 170 °C.

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Influence of strain rate, temperature and fatigue on the radial compression behaviour of Norway spruce

Holzforschung ◽

10.1515/hf-2016-0144 ◽

2017 ◽

Vol 71 (6) ◽

pp. 505-514 ◽

Cited By ~ 4

Author(s):

Carolina Moilanen ◽

Tomas Björkqvist ◽

Markus Ovaska ◽

Juha Koivisto ◽

Amandine Miksic ◽

...

Keyword(s):

Strain Rate ◽

Linear Model ◽

Norway Spruce ◽

Material Model ◽

Radial Compression ◽

Compression Tests ◽

Static Compression ◽

Rate Dependent ◽

Compression Model ◽

Wood Compression

Abstract A dynamic elastoplastic compression model of Norway spruce for virtual computer optimization of mechanical pulping processes was developed. The empirical wood behaviour was fitted to a Voigt-Kelvin material model, which is based on quasi static compression and high strain rate compression tests (QSCT and HSRT, respectively) of wood at room temperature and at high temperature (80–100°C). The effect of wood fatigue was also included in the model. Wood compression stress-strain curves have an initial linear elastic region, a plateau region and a densification region. The latter was not reached in the HSRT. Earlywood (EW) and latewood (LW) contributions were considered separately. In the radial direction, the wood structure is layered and can well be modelled by serially loaded layers. The EW model was a two part linear model and the LW was modelled by a linear model, both with a strain rate dependent term. The model corresponds well to the measured values and this is the first compression model for EW and LW that is based on experiments under conditions close to those used in mechanical pulping.

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Parametric study on the behaviour of bagasse ash-calcium carbide residue stabilized soil

MATEC Web of Conferences ◽

10.1051/matecconf/201819503015 ◽

2018 ◽

Vol 195 ◽

pp. 03015

Author(s):

John Tri Hatmoko ◽

Hendra Suryadharma

Keyword(s):

Calcium Carbide ◽

Friction Angle ◽

Tensile Tests ◽

Peak Strength ◽

Compression Tests ◽

Exchange Reactions ◽

Short Term ◽

Calcium Carbide Residue ◽

Stabilized Soil ◽

Strength And Stiffness

A series of experiments including unconfined compression tests, three-axial tests, compaction tests, and split tensile tests were undertaken to investigate the influence of compaction parameters on the behaviour of bagasse ash-calcium carbide residue stabilized soil. A preliminary study on soil with the addition of 4%, 6%, 8%, 10%, and 12% calcium carbide residue established that the lime fixation point (LFP) was 4%. Then 9% bagasse ash was added to soil with 4% calcium carbide residue, and the cation exchanges and pozzolanic reactions were investigated. The addition of calcium carbide residue to bagasse ash stabilized soil caused short-term changes due to cation exchange reactions, including an increase in the friction angle and cohesion in the stabilized soil. In addition, due to the short-term reaction, the maximum stiffness in three-axial tests occurred in the samples moulded with less than their optimum moisture content (OMC), whereas the peak strength occurred in the samples moulded at their OMC. After a 28-day curing period, pozzolanic reactions improved significantly the three-axial peak strength and stiffness of the stabilized soil, and the maximum three-axial shear strength and stiffness occurred in the samples prepared below their OMC.

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Effect of Loading Rate on Tensile Properties of Automotive Steel Sheet

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.690-693.211 ◽

2013 ◽

Vol 690-693 ◽

pp. 211-217

Author(s):

Jin Gui Qin ◽

Fang Yun Lu ◽

Yu Liang Lin ◽

Xue Jun Wen

Keyword(s):

Strain Rate ◽

Testing Machine ◽

Structural Response ◽

Tensile Tests ◽

Dynamic Tests ◽

Static Tests ◽

Split Hopkinson Tensile Bar ◽

Axial Tensile ◽

Static Tensile ◽

Cook Model

Results of uni-axial tensile loading of three automotive steels at different strain rates (0.0011–3200s-1) are reported here. Quasi-static tensile tests were performed under the strain rate of 1.1×10-3 s-1 using an electromechanical universal testing machine, whereas dynamic tests were carried out under the strain rate in the range of 1100 to 3200 s-1 using a Split Hopkinson Tensile Bar apparatus. Based on the experimental results, the material parameters of widely used Johnson–Cook model which described the strain rate and temperature-dependent of mechanical behaviour were determined. The experiments show that strain-rate hardening is superior to thermal softening: yield stresses, tensile strength, deformation, and energy dissipation increase with the strain rate from quasi-static tests to dynamic tests. The Johnson–Cook model can describe the behaviour of these steels and provides the opportunity to study the material and structural response.

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Influence of the surface modification by sanding of carbon textile reinforcements on the bond and load-bearing behavior of textile reinforced concrete

MATEC Web of Conferences ◽

10.1051/matecconf/201928904006 ◽

2019 ◽

Vol 289 ◽

pp. 04006

Author(s):

Cynthia Morales Cruz ◽

Michael Raupach

Keyword(s):

Surface Modification ◽

Reinforced Concrete ◽

Tensile Tests ◽

Measuring System ◽

Uniaxial Tensile ◽

Testing Time ◽

Textile Reinforced Concrete ◽

Load Bearing ◽

Surface Modified ◽

Bearing Behavior

In the context of the application of carbon Textile Reinforced Concrete (TRC) layers for the durable repair of building surfaces, uniaxial tensile tests on rectangular TRC samples were carried out to compare the bond and load-bearing behavior of an epoxy-impregnated carbon textile and its surface modified version. The aim of the surface modification, consisting of a subsequent coating with epoxy resin and sanding with quartz sand, is the improvement of the composite material regarding crack width reduction and an increase of the load-bearing capacity. A total of 15 series were examined and the parameters: reinforcement type, orientation and ratio were varied. In addition, long-term load tests were conducted. An optical 3D-video measuring system in combination with a DIC-software was used, which allowed the analysis of the process of crack formation during the entire testing time. With the surface modified reinforcement the formation of approx. 1.5 times the number of cracks with averagely 33 % smaller crack widths and up to 50 % smaller crack spacings were observed, regardless of the ratio of reinforcement. The residual behaviour of the series subjected to a permanent load of 1500 MPa over 1000 h showed no reduction of the tensile stress compared to short-term tests.

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Anisotropy Study of Inconel 718 alloy at Sub-Zero temperatures

E3S Web of Conferences ◽

10.1051/e3sconf/202018401004 ◽

2020 ◽

Vol 184 ◽

pp. 01004

Author(s):

L Jayahari ◽

K Nagachary ◽

Chandra Ch Sharath ◽

SM Hussaini

Keyword(s):

Mechanical Properties ◽

Strain Hardening ◽

Inconel 718 ◽

Anisotropy Parameter ◽

Tensile Tests ◽

Strain Hardening Exponent ◽

Inconel 718 Alloy ◽

Normal Anisotropy ◽

Axial Tensile ◽

Forming Characteristics

There is an increase in demand for new alloys in aerospace, power generation and nuclear industries. Nickel Based super alloys are known for having distinctive properties which are best suitable for these industries. In this study Nickel based super alloy Inconel 718, is used. Over the many years of intense research and development, these alloys have seen considerable evolution in their properties and efficiency. Behaviour of materials and its forming characteristics can be precisely analysed by determining anisotropic behaviour and mechanical properties. In the present study, tried to analyse the mechanical properties of Inconel 718 like yield strength (Ys), ultimate tensile strength (UTS), strain hardening exponent (n) and strain hardening coefficient (k). Uni-axial tensile tests were conducted on specimens with various parameters such as orientations, temperature and Strain rate. Anisotropy of Inconel 718 alloy was measured based on measurable parameters. The normal anisotropy parameter (f) and planer anisotropy (Δr) were measured and observed that the anisotropy parametres are incresed with the decrease in temperature.

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