Mechanical Modeling of Fabrics in Bending

2004 ◽  
Vol 71 (1) ◽  
pp. 32-40 ◽  
Author(s):  
T. J. Lahey ◽  
G. R. Heppler
Keyword(s):  
Nonlinear Elasticity ◽  
Evaluation System ◽  
Coulomb Friction ◽  
Experimental Results ◽  
Hysteretic Behavior ◽  
Elastic Behavior ◽  
Loading Conditions ◽  
Mechanical Modeling ◽  
Bending Tests ◽  
Nonlinear Elastic

A fabric bending model that includes contributions from nonlinear elasticity, and viscous and Coulomb friction with hysteretic effects is presented. The model allows the recovery of the loading, unloading and hysteresis behaviors observed in the Kawabata evaluation system (KES) bending tests and provides the ability to simulate a continuum of property curves and to extrapolate to loading conditions not covered in the KES regimen. Model results are compared to experimental results. It is found that hysteretic behavior is observed due to friction between the yarns, and that nonlinear elastic behavior arises from jamming of the yarns and their subsequent compression.

Mechanical Modeling of Fabrics in Bending

2002 ◽  
Author(s):  
T. J. Lahey ◽  
G. R. Heppler
Keyword(s):  
Evaluation System ◽  
Coulomb Friction ◽  
Viscous Friction ◽  
Static Friction ◽  
Experimental Results ◽  
Elastic Behavior ◽  
Inertial Effects ◽  
Mechanical Modeling ◽  
Bending Tests ◽  
Nonlinear Elastic

A model of fabric bending that includes a nonlinear elastic contribution, a viscous friction contribution, a Coulomb friction contribution, and a hysteretic contribution is presented. These are combined to recover the loading, unloading and hysteresis behaviors observed in the bending tests performed under the Kawabata Evaluation System. Results of the model and its components are compared and contrasted with experimental results. It is found that inertial effects dominate the behavior of the model in the early stages of the KES test and that, once the static friction threshold is overcome, friction arises from the slipping of the yarns with respect to each other. The results show that nonlinear elastic behavior arises from jamming of the yarns and their subsequent compression.

NESC VII European Project: Demonstration of Warm Pre-Stressing Effect in Biaxial Loading Conditions: Bending Tests on 18MND5 Cruciform Specimens and Their Interpretation

2012 ◽  
Author(s):  
C. Jacquemoud ◽  
T. Yuritzinn ◽  
S. Marie ◽  
D. Moinereau ◽  
M. Nédélec ◽  
...  
Keyword(s):  
Cleavage Fracture ◽  
Biaxial Loading ◽  
Experimental Results ◽  
Experimental Program ◽  
Loading Conditions ◽  
Bending Tests ◽  
Loading Cycle ◽  
European Project

In the framework of the NESC VII European project, a large experimental program has been dedicated to characterize the Warm Pre-Stressing (WPS) effect in different testing configurations. One of the CEA (France) contributions to this project is the realization of five point bending tests on large cruciform specimens considering different WPS loading cycles. The five cruciform specimens, sponsored by EDF (France) and IRSN (France), are made of 18MND5 steel. Two of them have been tested on a same LCF (Load-Cool-Fracture) loading cycle and two others on the same LCTF (Load-Cool-Transient-Fracture) loading cycle. The experimental results presented in this paper give a successful demonstration of the WPS effect in biaxial loading conditions either on a LCF or on a LCTF cycle. During the test interpretations, different models have then been tested and compared in order to evaluate their ability to predict the cleavage fracture in the case of different WPS loading cycles. They all provide very conservative predictions whatever loading cycle is concerned.

Circular Contact of Incompressible, Nonlinear-Elastic Bodies

2009 ◽  
Author(s):  
Emanuel Diaconescu ◽  
Marilena Glovnea ◽  
Filip Ciutac
Keyword(s):  
Nonlinear Elasticity ◽  
Simple Approach ◽  
Experimental Results ◽  
Contact Modeling ◽  
Elastic Bodies ◽  
Nonlinear Elastic ◽  
Theory And Experiments ◽  
Circular Contact ◽  
Good Agreement

Contact modeling of rubber bodies is based either on viscoelasticity, nonlinear elasticity or adhesion. This paper advances a simple approach to the analysis of the contacts involving incompressible, nonlinear elastic bodies and reports experimental results on rubber to justify this approach. A good agreement is found between theory and experiments.

Probing the damage zone on the San Andreas Fault at Parkfield

2021 ◽  
Author(s):  
Andrew Delorey ◽  
Paul Johnson
Keyword(s):  
Path Dependence ◽  
San Andreas Fault ◽  
Damage Zone ◽  
Relaxation Times ◽  
Hysteretic Behavior ◽  
Earth Tides ◽  
Elastic Behavior ◽  
Full Potential ◽  
San Andreas ◽  
Nonlinear Elastic

<p>Rocks are heterogeneous materials that exhibit nonlinear elastic (anelastic) behavior in both the laboratory and Earth. In the laboratory, investigators have observed complex relationships between stress and strain that include hysteresis, finite relaxation times, and rate and stress path dependence.  These behaviors are linked to stress, porosity, permeability, material integrity and material failure, many of the characteristics we care about in the upper crust.  A limited number of studies in the Earth have confirmed that nonlinear elasticity can be measured in situ, but due to logistical challenges these investigations have not achieved the full potential of what can ultimately be learned from this type of investigation.  We adapted a ‘pump-probe’ type experiment common in laboratory studies, using solid earth tides as the low frequency pump and empirical Green’s function as the high frequency probe.  By probing the velocity at different points in the pump cycle, we constrain some important information about the stress-strain relationship.  Near the San Andreas Fault, we observe strongly nonlinear elastic behavior that increases with decreasing distance to the fault that characterizes the damage zone.  We also constrain important aspects of hysteretic behavior that are related to damage properties and possibly pore pressure.</p>

Synthesis of the NESC VII European Project: Demonstration of Warm Pre-Stressing Effect in Biaxial Loading Conditions

2013 ◽  
Author(s):  
C. Jacquemoud ◽  
S. Marie ◽  
T. Yuritzinn ◽  
D. Moinereau ◽  
M. Nédélec ◽  
...  
Keyword(s):  
Cleavage Fracture ◽  
Biaxial Loading ◽  
Experimental Results ◽  
Experimental Program ◽  
Loading Conditions ◽  
Bending Tests ◽  
Loading Cycle ◽  
European Project

In the framework of the NESC VII European project, a large experimental program has been dedicated to characterizing the Warm Pre-Stressing (WPS) effect in different testing configurations. One of the CEA (France) contributions to this project is the realization of five point bending tests on large cruciform specimens considering different WPS loading cycles. The five cruciform specimens, sponsored by EDF (France) and IRSN (France), are made of 18MND5 steel. Two of them have been tested on a same LCF (Load-Cool-Fracture) loading cycle and three others on a LCTF (Load-Cool-Transient-Fracture) loading cycle. The experimental results presented in this paper give a successful demonstration of the WPS effect in biaxial loading conditions either on a LCF or on a LCTF cycle. During the test interpretations, different models have then been tested and compared in order to evaluate their ability to predict the cleavage fracture in the case of different WPS loading cycles. They all provide very conservative predictions whatever loading cycle is concerned.

Opto-mechanical modeling and experimental implementation of an FBG-based piezoelectric bimorph actuator for high voltage sensing applications

2021 ◽  
pp. 1045389X2110282
Author(s):  
Raúl E Jiménez ◽  
José P Montoya ◽  
Rodrigo Acuna Herrera
Keyword(s):  
High Voltage ◽  
Good Accuracy ◽  
Correction Term ◽  
Experimental Results ◽  
Mechanical Modeling ◽  
Piezoelectric Bimorph ◽  
Linear Strain ◽  
Voltage Sensing ◽  
Sensing Applications ◽  
Experimental Implementation

This paper proposes a highly simplified optical voltage sensor by using a piezoelectric bimorph and a Fiber Bragg Grating (FBG) that can be used for high voltage applications with a relatively good accuracy and stability. In this work the theoretical framework for the whole opto-mechanical operation of the optical sensor is detailed and compared to experimental results. In the analysis, a correction term to the electric field is derived to account for the linear strain distribution across the piezoelectric layer improving the designing equations and giving more criteria for future developments. Finally, some experimental results from a laboratory scale optical-based high voltage sensing setup are discussed, and shown to be in excellent agreement with theoretical expected behavior for different voltage magnitudes.

scholarly journals A set of measures for the systematic classification of the nonlinear elastic behavior of disparate rocks

2015 ◽  
Vol 120 (3) ◽  
pp. 1587-1604 ◽  
Author(s):  
Jacques Rivière ◽  
Parisa Shokouhi ◽  
Robert A. Guyer ◽  
Paul A. Johnson
Keyword(s):  
Elastic Behavior ◽  
Systematic Classification ◽  
Nonlinear Elastic

Failure of Polyurethane Foams under Different Loading Conditions

2008 ◽  
Vol 385-387 ◽  
pp. 205-208 ◽  
Author(s):  
Liviu Marsavina ◽  
Tomasz Sadowski ◽  
Dan Mihai Constantinescu ◽  
Radu Negru
Keyword(s):  
Mechanical Properties ◽  
Polyurethane Foam ◽  
Polyurethane Foams ◽  
Experimental Results ◽  
Loading Conditions ◽  
Sandwich Composites ◽  
Considerable Influence ◽  
Three Point Bending

Polyurethane foam materials are widely used as cores in sandwich composites, for packing and cushioning. This paper presents the experimental results obtained for the mechanical properties of polyurethane foams in different loading conditions and the influence of impregnation on the mechanical properties. A 200 kg/m3 density polyurethane foam was tested in tension, compression and three point bending. The experimental results show that the impregnation layer has no effect on the strength of the foam, but has considerable influence on the tensile and flexure modulus.

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