scholarly journals Moulding hydrodynamic 2D-crystals upon parametric Faraday waves in shear-functionalized water surfaces

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mikheil Kharbedia ◽  
Niccolò Caselli ◽  
Diego Herráez-Aguilar ◽  
Horacio López-Menéndez ◽  
Eduardo Enciso ◽  
...  
Keyword(s):  
Soft Matter ◽  
Shear Stiffness ◽  
External Control ◽  
Faraday Waves ◽  
Plane Shear ◽  
Unit Cell Size ◽  
Ordering Transitions ◽  
Water Surfaces ◽  
Ordering Transition ◽  
Surface Rigidity

AbstractFaraday waves, or surface waves oscillating at half of the natural frequency when a liquid is vertically vibrated, are archetypes of ordering transitions on liquid surfaces. Although unbounded Faraday waves patterns sustained upon bulk frictional stresses have been reported in highly viscous fluids, the role of surface rigidity has not been investigated so far. Here, we demonstrate that dynamically frozen Faraday waves—that we call 2D-hydrodynamic crystals—do appear as ordered patterns of nonlinear gravity-capillary modes in water surfaces functionalized with soluble (bio)surfactants endowing in-plane shear stiffness. The phase coherence in conjunction with the increased surface rigidity bears the Faraday waves ordering transition, upon which the hydrodynamic crystals were reversibly molded under parametric control of their degree of order, unit cell size and symmetry. The hydrodynamic crystals here discovered could be exploited in touchless strategies of soft matter and biological scaffolding ameliorated under external control of Faraday waves coherence.

scholarly journals Influence of laminate direction and glue area on in-plane shear modulus of cross-laminated timber

2020 ◽  
Vol 2 (12) ◽  
Author(s):  
Jonas Turesson ◽  
Zahra Sharifi ◽  
Sven Berg ◽  
Mats Ekevad
Keyword(s):  
Finite Element ◽  
Shear Modulus ◽  
Compression Test ◽  
Contact Area ◽  
Tall Buildings ◽  
Shear Stiffness ◽  
Finite Element Simulations ◽  
Plane Shear ◽  
Cross Laminated Timber ◽  
Diagonal Compression

AbstractThe use of cross-laminated timber (CLT) in constructing tall buildings has increased. So, it has become crucial to get a higher in-plane stiffness in CLT panels. One way of increasing the shear modulus, G, for CLT panels can be by alternating the layers to other angles than the traditional 0° and 90°. The diagonal compression test can be used to measure the shear stiffness from which G is calculated. A general equation for calculating the G value for the CLT panels tested in the diagonal compression test was established and verified by tests, finite element simulations and external data. The equation was created from finite element simulations of full-scale CLT walls. By this equation, the influence on the G value was a factor of 2.8 and 2.0 by alternating the main laminate direction of the mid layer from the traditional 90° to 45° and 30°, respectively. From practical tests, these increases were measured to 2.9 and 1.8, respectively. Another influence on the G value was studied by the reduction of the glue area between the layers. It was shown that the pattern of the contact area was more important than the size of the contact area.

A Simple Discrete Method for the Simulation of the Preforming of Woven Fabric Reinforcement

2012 ◽  
Vol 504-506 ◽  
pp. 213-218 ◽  
Author(s):  
Walid Najjar ◽  
Xavier Legrand ◽  
Cedric Pupin ◽  
Philippe Dal Santo ◽  
Serge Boude
Keyword(s):  
Inverse Method ◽  
Shear Stiffness ◽  
Tensile Tests ◽  
Woven Fabric ◽  
Uniaxial Tensile ◽  
Plane Shear ◽  
Discrete Method ◽  
Shell Elements ◽  
Woven Reinforcement ◽  
Good Agreement

In this paper, a discrete approach for the simulation of the preforming of dry woven reinforcement is proposed. A “unit cell” is built using elastic isotropic shells and axial connectors instead of bars and beams used in previous studies. Shell elements are used to take into account the in-plane shear stiffness and to manage contact phenomenon with the punch and die. Connectors reinforce the structure in the yarn directions and naturally capture the specific behavior of the fabric. To identify the material parameters, uniaxial tensile tests and bias tests have been employed. A numerical algorithm, coupling Matlab and Abaqus/Explicit, is used to determine the shear parameters by an inverse method. The model has been implemented in Abaqus to simulate hemispherical stamping. Experimental results are compared to numerical simulations, good agreement between both results is shown.

scholarly journals Comparison of Theoretical and Laboratory Out-of-Plane Shear Stiffness Values of Cross Laminated Timber Panels

Buildings ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 146 ◽  
Author(s):  
Jan Niederwestberg ◽  
Jianhui Zhou ◽  
Ying-Hei Chui
Keyword(s):  
Shear Modulus ◽  
Cross Section ◽  
Single Layer ◽  
Beam Theory ◽  
Shear Stiffness ◽  
Plane Shear ◽  
Shear Moduli ◽  
Cross Laminated Timber ◽  
Highly Sensitive ◽  
Out Of Plane

The lay-up of cross laminated timber (CLT) leads to significant differences in properties over its cross-section. Particularly the out-of-plane shear behavior of CLT is affected by the changes in shear moduli over the cross-section. Results from laboratory shear tests are used to evaluate the shear stiffness of 3- and 5-layer CLT panels in their major and minor strength direction. The results are compared to calculated shear stiffness values on evaluated single-layer properties as well as commonly used property ratios using the Timoshenko beam theory and the shear analogy method. Differences between the two calculation approaches are pointed out. The shear stiffness is highly sensitive to the ratio of the shear modulus parallel to the grain to the shear modulus perpendicular to the grain. The stiffness values determined from two test measurements are compared with the calculated results. The level of agreement is dependent on the number of layers in CLT and the property axis of the CLT panels.

scholarly journals Faraday waves in soft elastic solids

2020 ◽  
Vol 476 (2241) ◽  
pp. 20200129
Author(s):  
Giulia Bevilacqua ◽  
Xingchen Shao ◽  
John R. Saylor ◽  
Joshua B. Bostwick ◽  
Pasquale Ciarletta
Keyword(s):  
Soft Matter ◽  
Theoretical Explanation ◽  
Subharmonic Resonance ◽  
Viscous Fluids ◽  
Faraday Waves ◽  
Elastic Solids ◽  
Soft Solids ◽  
Elastic Bodies ◽  
Faraday Instability ◽  
Elastic Slab

Recent experiments have observed the emergence of standing waves at the free surface of elastic bodies attached to a rigid oscillating substrate and subjected to critical values of forcing frequency and amplitude. This phenomenon, known as Faraday instability, is now well understood for viscous fluids but surprisingly eluded any theoretical explanation for soft solids. Here, we characterize Faraday waves in soft incompressible slabs using the Floquet theory to study the onset of harmonic and subharmonic resonance eigenmodes. We consider a ground state corresponding to a finite homogeneous deformation of the elastic slab. We transform the incremental boundary value problem into an algebraic eigenvalue problem characterized by the three dimensionless parameters, that characterize the interplay of gravity, capillary and elastic waves. Remarkably, we found that Faraday instability in soft solids is characterized by a harmonic resonance in the physical range of the material parameters. This seminal result is in contrast to the subharmonic resonance that is known to characterize viscous fluids, and opens the path for using Faraday waves for a precise and robust experimental method that is able to distinguish solid-like from fluid-like responses of soft matter at different scales.

Depth Dependent In-Plane Shear Properties of the Corneal Stroma

2010 ◽  
Author(s):  
Steven Petsche ◽  
Peter Pinsky ◽  
Dimitri Chernyak ◽  
Jaime Martiz
Keyword(s):  
Shear Modulus ◽  
Patient Outcomes ◽  
Surgical Procedures ◽  
Refractive Surgery ◽  
Corneal Stroma ◽  
Shear Stiffness ◽  
Biomechanical Properties ◽  
Human Cornea ◽  
Plane Shear ◽  
Biomechanical Response

The popularity of refractive surgery to correct the vision of individuals with hyperopia or myopia is increasing. These procedures alter the tissue of the human cornea to cause a change in curvature (refractive power) of the cornea. Radial keratotomy, photorefractive keratectomy, LASIK, and LASEK are all types of refractive surgery. The outcomes of refractive surgical procedures must depend significantly on the biomechanical response of the tissue and therefore on the biomechanical properties of the cornea, or more specifically the corneal stroma which makes up 90% of the tissue. The missing link between computer models of these procedures and predicting patient outcomes is the biomechanical properties of the tissue, including shear modulus. This study aims to characterize the in-plane shear modulus of the corneal stroma through the depth by mechanical testing. Scant data, if any, exists about the shear stiffness and no data includes depth dependence. The stroma consists of sheets of collagenous lamellae in which fibrils are maintained at uniform spacing by glycoaminoglycan molecules. Studies have shown increased interweaving of the lamellae in the anterior third of the stroma compared to the central and posterior thirds [1]. Figure 1 shows the distinct interweaving in the anterior third [2]. It is hypothesized that more interweaving lamellae increases the in-plane shear stiffness. The shear modulus of the full cornea, as well as individual thirds, is examined in this study.

scholarly journals In-plane shear modulus of cross-laminated timber by diagonal compression test

BioResources ◽  
2019 ◽  
Vol 14 (3) ◽  
pp. 5559-5572 ◽  
Author(s):  
Sven Berg ◽  
Jonas Turesson ◽  
Mats Ekevad ◽  
Anders Björnfot
Keyword(s):  
Shear Modulus ◽  
Compression Test ◽  
Pure Shear ◽  
Shear Stiffness ◽  
Least Square ◽  
Compression Tests ◽  
Plane Shear ◽  
Cross Laminated Timber ◽  
Fe Simulations ◽  
Diagonal Compression

Cross-laminated timber (CLT) is an engineered wood material that is used in the construction industry, e.g., for floors, walls, and beams. In cases where CLT-elements are used as shear walls, the in-plane-stiffness is an important property. For non-edge glued CLT, in-plane shear stiffness is lower than for edge-glued CLT. To evaluate the non-edge glued CLT panel’s in-plane shear modulus, the diagonal compression test and finite element (FE) simulation was used. FE-models with both isotropic and orthotropic material models were used to calculate the shear stiffness. The FE models using pure shear loads were used as a reference to determine the correct value of the shear modulus. To verify the FE simulations, diagonal compression tests were conducted on 30 CLT samples. A calibration formula was derived using the least square method for calculation of shear modulus. The formula gave accurate results. The results showed that FE simulations can reproduce the same shear stiffness as tests of non-edge glued 3-layer and 5-layer CLT panels.

scholarly journals Comparison of Theoretical and Laboratory Out-of-Plane Shear Stiffness Values of Cross Laminated Timber Panels

2018 ◽  
Author(s):  
Jan Niederwestberg ◽  
Jianhui Zhou ◽  
Ying-Hei Chui
Keyword(s):  
Shear Modulus ◽  
Cross Section ◽  
Single Layer ◽  
Beam Theory ◽  
Shear Stiffness ◽  
Plane Shear ◽  
Shear Moduli ◽  
Cross Laminated Timber ◽  
Highly Sensitive ◽  
Out Of Plane

The lay-up of cross laminated timber (CLT) leads to significant differences in properties over its cross-section. Particularly the out-of-plane shear behavior of CLT is effected by the changes in shear moduli over the cross-section. Results from laboratory shear tests are used to evaluate the shear stiffness of 3- and 5-layer CLT panels in their major and minor strength direction. The results are compared to calculated shear stiffness values on evaluated single-layer properties as well as commonly used property ratios using the Timoshenko beam theory and the shear analogy method. Differences between the two calculation approaches are pointed out. The shear stiffness is highly sensitive to the ratio of the shear modulus parallel to the grain to the shear modulus perpendicular to the grain. The stiffness values determined from two test measurements are compared with the calculated results. The level of agreement is dependent on the number of layers in CLT and the property axis of the CLT panels.

scholarly journals Effects of Adhesive Connection on Composite Action between FRP Bridge Deck and Steel Girder

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Xu Jiang ◽  
Chengwei Luo ◽  
Xuhong Qiang ◽  
Henk Kolstein ◽  
Frans Bijlaard
Keyword(s):  
Adhesive Layer ◽  
Shear Stiffness ◽  
Experimental Investigations ◽  
Steel Girders ◽  
Plane Shear ◽  
Steel Girder ◽  
Composite Action ◽  
Four Point Bending ◽  
Frp Bridge Deck ◽  
Composite Bridge

The FRP-steel girder composite bridge system is increasingly used in new constructions of bridges as well as rehabilitation of old bridges. However, the understanding of composite action between FRP decks and steel girders is limited and needs to be systematically investigated. In this paper, depending on the experimental investigations of FRP to steel girder system, the Finite Element (FE) models on experiments were developed and analyzed. Comparison between experiments and FE results indicated that the FE models were much stiffer for in-plane shear stiffness of the FRP deck panel. To modify the FE models, rotational spring elements were added between webs and flanges of FRP decks, to simulate the semirigid connections. Numerical analyses were also conducted on four-point bending experiments of FRP-steel composite girders. Good agreement between experimental results and FE analysis was achieved by comparing the load-deflection curves at midspan and contribution of composite action from FRP decks. With the validated FE models, the parametric studies were conducted on adhesively bonded connection between FRP decks and steel girders, which indicated that the loading transfer capacity of adhesive connection was not simply dependent on the shear modulus or thickness of adhesive layer but dominated by the in-plane shear stiffness K.

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