A new load-controlled testing method for viscoelastic characterisation through stress-rate measurements

From a mechanical point of view, a native extracellular matrix (ECM) is viscoelastic. It also possesses time-evolving or dynamic behaviour, since pathophysiological processes such as ageing alter their mechanical properties over time. On the other hand, biomaterial research on mechanobiology has focused mainly on the development of substrates with varying stiffness, with a few recent contributions on time- or space-dependent substrate mechanics. This work reports on a new method for engineering dynamic viscoelastic substrates, i.e., substrates in which viscoelastic parameters can change or evolve with time, providing a tool for investigating cell response to the mechanical microenvironment. In particular, a two-step (chemical and enzymatic) crosslinking strategy was implemented to modulate the viscoelastic properties of gelatin hydrogels. First, gels with different glutaraldehyde concentrations were developed to mimic a wide range of soft tissue viscoelastic behaviours. Then their mechanical behaviour was modulated over time using microbial transglutaminase. Typically, enzymatically induced mechanical alterations occurred within the first 24 h of reaction and then the characteristic time constant decreased although the elastic properties were maintained almost constant for up to seven days. Preliminary cell culture tests showed that cells adhered to the gels, and their viability was similar to that of controls. Thus, the strategy proposed in this work is suitable for studying cell response and adaptation to temporal variations of substrate mechanics during culture.

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“…Moreover, the time constants were equivalent for both arms suggesting over parametrization. Previous studies corroborate this finding [43].…”

Section: Nanoindentation Data Analysissupporting

confidence: 79%

“…A high τ indicates that the material presents a tendency towards an elastic or 'solid-like' behaviour; conversely, a low τ indicates a tendency toward viscous or 'liquid-like behaviour'. In particular, when τ → ∞ the material is referred as pure elastic and when τ → 0 it is considered as pure viscous [25,43].…”

Section: Viscoelastic Parameter Estimationmentioning

confidence: 99%

Engineering Gels with Time-Evolving Viscoelasticity

2020

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“…Для исследования природных биологических костных и мягких тканей и искусственных материалов медицинского назначения, где обычно необходимы силы P ≫ 100 nN, используют наноиндентометры [13,17,245,246]. Для изучения биомеханики на клеточном уровне, где требуются силы 10 pN < P < 100 nN, используют AFM [247][248][249], в том числе, обеспечивающие микросекундное разрешение во времени и позволяющие осуществлять испытания в очень широком диапазоне скоростей нагружения (от 10 2 до 10 13 pN/s) [250][251][252].…”

Section: разрушение в микро- субмикрои наношкалеunclassified

Наноиндентирование И Механические Свойства Материалов В Субмикро- И Наношкале. Недавние Результаты И Достижения (О Б З О Р)

Головин¹

2021

Физика Твердого Тела

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The review discusses the details of various materials mechanical behavior in submicro- and nanoscale. Significant advances in this scope result from the development of wide family of load based precise nanotesting techniques called nanoindentation. But nowadays, nanomechanical properties are studied not only by nanoindentation techniques in narrow sense, i.e. local loading of macro, micro and nanoscale objects. Nanomechanical load testing is discussed here within a wider scope employing precise deformation measurement with nanometer scale resolution caused by various types of low load application to the object under study including uniaxial compression or extension, shearing, bending or twisting, optionally accompanied by in situ monitoring sample microstructure using scanning and transmission electron microscopy and Laue microdiffraction technique. The main courses of experimental techniques development in recent ten years along with the results obtained using them in single, poly and nano crystalline materials, composites, films and coatings, amorphous solids and such biomaterials as tissues, living cells and macromolecules are described. Special attention is paid to deformation size effects and atomic mechanisms in nanoscale. This review is a natural continuation and development of the review published at Fiz.Tverd.Tela vol.50, issue 12, 2008 of the same author that discusses details of nanomechanical properties of solids. Current review includes wider range of nanomechanical testing concepts and recent achievements in the scope. The work was supported by RFBR grant for project #19-12-50235.

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“…The results also show some significant discrepancies between the obtained transmissibility curves, specially in the amplitude of curve peaks. The discrepancies between the transfer functionsT sb and T sb have been again quantified using Equations (5)- (7). Figure 10 presents a comparison of the three errors as a function of the sweep rate for the spring coil case.…”

Section: Application Example Ii: a Coil Springmentioning

confidence: 99%

“…Several alternative models have been considered in literature. Two examples of this are the use of state-dependent viscoelastic models to represent the dynamic behaviour of rail pads [6], or the use of a fitted generalised Kelvin-Voigt model in a recently proposed load-controlled testing approach, suitable for testing a large variety of viscoelastic materials [7]. Regardless of the type of model assumed, its associated mechanical parameters (i.e., stiffness and/or damping values) usually have to be determined from experimental measurements.…”

Section: Introductionmentioning

confidence: 99%

An Efficient Experimental Methodology for the Assessment of the Dynamic Behaviour of Resilient Elements

et al. 2020

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The assessment of the dynamic behaviour of resilient elements can be performed using the indirect method as described in the standard ISO 10846-3. This paper presents a methodology for control the error on the estimation of the frequency response functions (FRF) required for the application of the indirect method when sweep sine excitation is used. Based on a simulation process, this methodology allows for the design of the sweep sine excitation parameters, i.e., the sweep rate and the force amplitude, to control three types of errors associated to the experimentally obtained FRF in the presence of background noise: a general error of the FRF in a selected frequency range, and the errors associated to the amplitude and the frequency of the FRF resonance peak. The signal processing method used can be also tested with this methodology. The methodology has been tested in the characterisation of two different resilient elements: an elastomer and a coil spring. The simulated error estimations has been found to be in good agreement with the errors found in the measured FRF. Furthermore, it is found that for large signal-to-noise ratios, both sweep rate and force amplitude significantly affect the FRF estimation error, while, for small signal-to-noise ratios, only the force amplitude can control the error efficiently. The current methodology is specially interesting for laboratory test rigs highly used for the dynamic characterisation of resilient elements which are required to operate efficiently, since it can be used for minimising test times and providing quality assurance. Moreover, the application of this methodology would be specially relevant when characterisation is done in noisy environments.

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A new load-controlled testing method for viscoelastic characterisation through stress-rate measurements

Cited by 20 publications

References 38 publications

Engineering Gels with Time-Evolving Viscoelasticity

Engineering Gels with Time-Evolving Viscoelasticity

Наноиндентирование И Механические Свойства Материалов В Субмикро- И Наношкале. Недавние Результаты И Достижения (О Б З О Р)

An Efficient Experimental Methodology for the Assessment of the Dynamic Behaviour of Resilient Elements

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