Linear and nonlinear mechanical responses of FG-GPLRC plates using a novel strain-based formulation of modified FSDT theory

Adventitial mechanics were studied on the basis of adventitial tube tests and associated stress analyses utilizing a thin-walled model. Inflation tests of 11 nonstenotic human femoral arteries (79.3 ± 8.2 yr, means ± SD) were performed during autopsy. Adventitial tubes were separated anatomically and underwent cyclic, quasistatic extension-inflation tests using physiological pressures and high pressures up to 100 kPa. Associated circumferential and axial stretches were typically <20%, indicating “adventitiosclerosis.” Adventitias behaved nearly elastically for both loading domains, demonstrating high tensile strengths (>1 MPa). The anisotropic and strongly nonlinear mechanical responses were represented appropriately by two-dimensional Fung-type stored-energy functions. At physiological pressure (13.3 kPa), adventitias carry ∼25% of the pressure load in situ, whereas their circumferential and axial stresses were similar to the total wall stresses (∼50 kPa in both directions), supporting a “uniform stress hypothesis.” At higher pressures, they became the mechanically predominant layer, carrying >50% of the pressure load. These significant load-carrying capabilities depended strongly on circumferential and axial in-vessel prestretches (mean values: 0.95 and 1.08). On the basis of these results, the mechanical role of the adventitia at physiological and hypertensive states and during balloon angioplasty was characterized.

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BIOMECHANICAL CHARACTERIZATION OF NORMAL AND PROLAPSED VAGINAL TISSUE SURROGATES

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519417501007 ◽

2018 ◽

Vol 18 (03) ◽

pp. 1750100 ◽

Cited By ~ 8

Author(s):

ARNAB CHANDA ◽

ZACHARY FLYNN ◽

VINU UNNIKRISHNAN

Keyword(s):

Mechanical Behavior ◽

Experimental Testing ◽

Low Cost ◽

Vaginal Tissue ◽

Novel Materials ◽

Tissue Interactions ◽

Surgical Suture ◽

Nonlinear Mechanical ◽

Implantation Techniques ◽

Linear And Nonlinear

In the recent years, poorly evaluated gynecological surgeries and urogynecological mesh implantations have been affecting millions of women in the US and across the globe. These failed surgeries could be mainly attributed to the nonavailability of vaginal tissues (due to ethical and biosafety issues), which does not allow any experimental testing of operation and mesh implantation techniques before an actual surgery. A surrogate which behaves biomechanically like the human vaginal tissue would be indispensable for simulating surgical suture of vaginal tissues in prolapse surgery, hysterectomy or surgery during traumatic child births (such as Cesarean). Also, vaginal tissue surrogates simulating the various prolapse conditions (such as vaginal tissue stiffening) would be very useful to evaluate tissue modifications due to prolapse, and also mesh and vaginal tissue interactions. In the current work, a low cost four-part silicone-based material was developed, which precisely simulates the linear and nonlinear mechanical behavior of the normal human vaginal tissue. Additionally, a range of four-part silicone-based novel materials were developed which precisely mimics the mechanical behavior of stiffened vaginal tissues at different degrees of prolapse. The linear and nonlinear mechanical behavior of all such novel materials were characterized using elastic and hyperelastic formulations. Such precisely characterized normal and prolapsed vaginal tissue surrogates have not been developed anywhere to date as per the best of our knowledge and would be clinically helpful for gynecological surgical planning in the future.

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Modelling of Linear and Nonlinear Mechanical Response

Mechanics of Microsystems ◽

10.1002/9781119053828.ch3 ◽

2018 ◽

pp. 73-90

Keyword(s):

Mechanical Response ◽

Nonlinear Mechanical ◽

Linear And Nonlinear

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Linear and nonlinear microrheology of lysozyme layers forming at the air–water interface

Soft Matter ◽

10.1039/c4sm00484a ◽

2014 ◽

Vol 10 (36) ◽

pp. 7051-7060 ◽

Cited By ~ 22

Author(s):

Daniel B. Allan ◽

Daniel M. Firester ◽

Victor P. Allard ◽

Daniel H. Reich ◽

Kathleen J. Stebe ◽

...

Keyword(s):

Mechanical Properties ◽

Water Interface ◽

Nonlinear Mechanical ◽

Air Water Interface ◽

Linear And Nonlinear

Microrheology tracks the evolution in the linear and nonlinear mechanical properties of layers of the protein lysozyme adsorbing at the air–water interface as the layers undergo a viscoelastic transition.

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Viscoelastic Rheological Behaviors of Polypropylene and LMPP Blends

Polymers ◽

10.3390/polym13203485 ◽

2021 ◽

Vol 13 (20) ◽

pp. 3485

Author(s):

Feichao Zhu ◽

Sohail Yasin ◽

Munir Hussain

Keyword(s):

Large Amplitude ◽

Viscoelastic Behavior ◽

Nonlinear Behavior ◽

Oscillatory Shear ◽

Large Amplitude Oscillatory Shear ◽

Mechanical Responses ◽

Nonlinear Viscoelastic ◽

Linear Viscoelastic ◽

Viscoelastic Behaviors ◽

Linear And Nonlinear

Dynamic oscillatory shear testing is used to investigate polymeric viscoelastic behaviors. Small and large amplitude oscillatory shear tests are the canonical method for characterizing the linear and nonlinear viscoelastic behaviors of any polymeric material. With prominent and abundant work on linear viscoelastic studies, the nonlinear behavior is evasive in terms of generating infinite higher harmonics in the nonlinear regime. For this reason, intrinsic nonlinearities from large amplitude oscillatory shear (LAOS) studies have recently been used for insights on microstructural behaviors. This study is carried out for linear and nonlinear viscoelastic behavior with a main focus on LAOS of isostatic polypropylene (iPP) and relatively new low molecular weight and low modulus polypropylene-based polyolefin (LMPP) blends. The morphological results showed reduced spherulitic crystal nucleus size and increased distribution in blends with increasing LMPP. The blends showed subtle linear viscoelastic responses with strong nonlinear mechanical responses to variant strain and stress compared to pure iPP. The intracycle strain thickening and intracycle strain stiffening of high-content LMPP blends were comparatively dominant at medium strain amplitudes.

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Toward Programmed Complex Stress-Induced Mechanical Deformations of Liquid Crystal Elastomers

Crystals ◽

10.3390/cryst10040315 ◽

2020 ◽

Vol 10 (4) ◽

pp. 315 ◽

Cited By ~ 1

Author(s):

Devesh Mistry ◽

Helen F. Gleeson

Keyword(s):

Liquid Crystal ◽

Complex Stress ◽

Stress Distributions ◽

Director Field ◽

Liquid Crystal Elastomer ◽

Mechanical Responses ◽

Mechanical Deformations ◽

Nonlinear Mechanical ◽

Liquid Crystal Elastomers ◽

Spatially Varying

We prepare a liquid crystal elastomer (LCE) with a spatially patterned liquid crystal director field from an all-acrylate LCE. Mechanical deformations of this material lead to a complex and spatially varying deformation with localised body rotations, shears and extensions. Together, these dictate the evolved shape of the deformed film. Using polarising microscopy, we map the local rotation of the liquid crystal director in Eulerian and Lagrangian frames and use these to determine rules for programming complex, stress-induced mechanical shape deformations of LCEs. Moreover, by applying a recently developed empirical model for the mechanical behaviour of our LCE, we predict the non-uniform stress distributions in our material. These results show the promise of empirical approaches to modelling the anisotropic and nonlinear mechanical responses of LCEs which will be important as the community moves toward realising real-world, LCE-based devices.

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