Evaluation of a Pseudo-Elastic Model for the Mullins Effect

2004 ◽  
Vol 32 (3) ◽  
pp. 120-145 ◽  
Author(s):  
W. V. Mars
Keyword(s):  
Pure Shear ◽  
Strain Curve ◽  
Elastic Behavior ◽  
Elastic Model ◽  
Mullins Effect ◽  
Stress Strain ◽  
Finite Element Program ◽  
Simple Tension ◽  
Element Program ◽  
Nonlinear Elastic

Abstract Typically, the stress-strain response in filled rubbers depends strongly on the maximum loading previously encountered. The phenomenon, known as the Mullins effect, can be idealized for many purposes as an instantaneous and irreversible softening of the stress-strain curve that occurs whenever the load increases beyond its prior all-time maximum value. At times when the load is less than a prior maximum, nonlinear elastic behavior prevails. Ogden and Roxburgh proposed an empirical model capable of describing this phenomenon, based on a pseudo-elastic concept. Their model, with minor adaptations, has recently been implemented in a commercial finite element program. This paper demonstrates the effectiveness of the implemented model for several benchmark cases including uniform hydrostatic loading, simple tension, pure shear, and equibiaxial tension. The paper also compares model predictions with experimental results for a series of experiments conducted with various combinations of axial tension/compression and torsion loading.

Duncan-Chang Nonlinear Elastic Model Considered Loess Structure

2011 ◽  
Vol 90-93 ◽  
pp. 176-181
Author(s):  
Chang Lu Chen ◽  
Sheng Jun Shao ◽  
Lin Ma
Keyword(s):  
Nonlinear Model ◽  
Stress Ratio ◽  
Structural Parameters ◽  
Strain Curve ◽  
Triaxial Tests ◽  
Model Parameters ◽  
Elastic Model ◽  
Stress Strain ◽  
Nonlinear Elastic ◽  
Intact Loess

Duncan-Chang nonlinear model has been modified and applied to the structural loess calculation. Based on structural studies and conventional triaxial tests, this paper has analyzed the mechanical properties of intact loess and the relationship between the stress ratio structural parameters and the strain, then the expression of generalized shear strain and stress ratio structural parameters are given to facilitate the engineering applications. On this basis, the stress-strain curve of intact loess was corrected by the use of the stress ratio structural parameters. The form of the intact loess stress-strain curves which have been revised has changed hardening from the softening or weak softening. The results show that the modified stress-strain curves of intact loess can apply Duncan- Chang nonlinear model to calculate and the model parameters are reasonable and effective. This method provides Duncan-Chang nonlinear model which is widely used in engineering with a new ways and means in intact structural loess application.

scholarly journals Black rubber and the non-linear elastic response of scale invariant solids

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Matteo Baggioli ◽  
Víctor Cáncer Castillo ◽  
Oriol Pujolàs
Keyword(s):  
Strain Curve ◽  
Effective Field ◽  
Elastic Response ◽  
Elastic Behaviour ◽  
Scale Invariant ◽  
Stress Strain ◽  
Nonlinear Stress ◽  
Hyper Elastic ◽  
Simple Class ◽  
Nonlinear Elastic

Abstract We discuss the nonlinear elastic response in scale invariant solids. Following previous work, we split the analysis into two basic options: according to whether scale invariance (SI) is a manifest or a spontaneously broken symmetry. In the latter case, one can employ effective field theory methods, whereas in the former we use holographic methods. We focus on a simple class of holographic models that exhibit elastic behaviour, and obtain their nonlinear stress-strain curves as well as an estimate of the elasticity bounds — the maximum possible deformation in the elastic (reversible) regime. The bounds differ substantially in the manifest or spontaneously broken SI cases, even when the same stress- strain curve is assumed in both cases. Additionally, the hyper-elastic subset of models (that allow for large deformations) is found to have stress-strain curves akin to natural rubber. The holographic instances in this category, which we dub black rubber, display richer stress- strain curves — with two different power-law regimes at different magnitudes of the strain.

scholarly journals Stress-strain curve of concretes with recycled concrete aggregates: analysis of the NBR 8522 methodology

2017 ◽  
Vol 10 (3) ◽  
pp. 547-567 ◽  
Author(s):  
D. A. GUJEL ◽  
C. S. KAZMIERCZAK ◽  
J. R. MASUERO
Keyword(s):  
Test Procedure ◽  
Strain Curve ◽  
Recycled Concrete ◽  
Load Test ◽  
Recycled Aggregates ◽  
Elastic Behavior ◽  
It Use ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Brazilian Standard

ABSTRACT This work analyses the methodology "A" (item A.4) employed by the Brazilian Standard ABNT 8522 (ABNT, 2008) for determining the stress-strain behavior of cylindrical specimens of concrete, presenting considerations about possible enhancements aiming it use for concretes with recycled aggregates with automatic test equipment. The methodology specified by the Brazilian Standard presents methodological issues that brings distortions in obtaining the stress-strain curve, as the use of a very limited number of sampling points and by inducing micro cracks and fluency in the elastic behavior of the material due to the use of steady stress levels in the test. The use of a base stress of 0.5 MPa is too low for modern high load test machines designed do high strength concrete test. The work presents a discussion over these subjects, and a proposal of a modified test procedure to avoid such situations.

scholarly journals On the behavior of slackline webbings under dynamic loads and the simulation of leash falls

2018 ◽  
Vol 233 (1) ◽  
pp. 75-85
Author(s):  
Panos J Athanasiadis
Keyword(s):  
Standardized Test ◽  
Strain Curve ◽  
Effective Modulus ◽  
Dynamic Loads ◽  
Elastic Response ◽  
Elastic Behavior ◽  
Stress Strain ◽  
Different Types ◽  
The Impact ◽  
Minimal Research

Slackline is a new and rapidly expanding sport, which has had minimal research published on it in terms of sport physics and engineering. Slackline dynamics strongly depend upon the elastic response of used webbing, typically made of polyester or nylon. Depending on the stress and strain rates applied, polymers are known to exhibit a visco-elastic behavior characterized by hysteresis effects. Through a series of carefully executed experiments, this study examined the behavior of slackline webbing under dynamic loads to determine the departures from the respective static response (stress–strain curves). Such knowledge is fundamental for the accurate simulation of slackline dynamics, so as to predict peak forces and aid safe rigging. The results demonstrate that the effective modulus during leash falls was significantly higher than the slope of the respective stress–strain curve, indicating a stiffer response. Also, the effective modulus increased with the applied pretension. Using the moduli determined experimentally for the rigged slacklines with different types of webbing, the respective leash falls were simulated numerically with high accuracy. A standardized test is proposed, to be adopted by the International Slackline Association and slackline webbing manufacturers, is proposed in order to provide key information on the response of each webbing available in the market under typical dynamic loads, similar to the “impact force” test designed for dynamic ropes by the International Climbing and Mountaineering Federation.

Computational Modeling of Interaction Between Actions and Action Effects of FPSO Topside Structures Subject to Jet Fire

2010 ◽  
Author(s):  
G. M. Katsaounis ◽  
D. Katsourinis ◽  
M. S. Samuelides ◽  
M. Founti ◽  
Jeom Kee Paik ◽  
...  
Keyword(s):  
Computational Modeling ◽  
Constitutive Relations ◽  
Finite Element Program ◽  
Effect Analysis ◽  
Ansys Cfx ◽  
Commercial Code ◽  
Time Histories ◽  
Element Program ◽  
Computational Fluid Dynamics Cfd ◽  
Nonlinear Elastic

This paper presents a computational modeling of accidental fire actions on the topside structures of a floating, production, storage and offloading (FPSO) unit. According to the assumed scenario, the accident results in a jet fire, which loads the structure by temperature increments and pressures generation on their exposed surfaces. Temperature distributions were obtained by computational fluid dynamics (CFD) simulations, using the ANSYS CFX commercial code. The temperature versus time histories computed were first approximated (idealized) by smoother curves, based on fewer time-points, while retaining the maximum and minimum values. A similar procedure was also followed for the pressure variations. For the consequence (action effect) analysis the LSDYNA nonlinear finite element program was employed and the structures were modeled using shell finite elements with nonlinear (elastic-thermal plastic) constitutive relations. On the structure surfaces non coinciding grids were used for the two kinds of analyses (i.e., the CFD and FEM), in order to accommodate the diverse requirements of the different problems. The procedure of assignment the pressure and temperature loadings directly from the CFD results to the FEM model is described and representative results are given through the application of the methodology to a sample problem.

The Effects of Strain Rate and Thickness on the Response of Thin Layers of Solder Loaded in Pure Shear

1997 ◽  
Vol 119 (2) ◽  
pp. 81-84 ◽  
Author(s):  
A. Gilat ◽  
K. Krishna
Keyword(s):  
Plastic Deformation ◽  
Shear Stress ◽  
Strain Rate ◽  
Mechanical Response ◽  
Pure Shear ◽  
Strain Curve ◽  
Thin Layers ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Stress And Deformation

A new configuration for testing thin layers of solder is introduced and employed to study the effects of strain rate and thickness on the mechanical response of eutectic Sn-Pb solder. The solder in the test is loaded under a well defined state of pure shear stress. The stress and deformation in the solder are measured very accurately to produce a reliable stress-strain curve. The results show that both the stress needed for plastic deformation and ductility increase with increasing strain rate.

Nonlinear Finite Element Analysis of Crack Tip of Rubber-Like Material

2007 ◽  
Vol 353-358 ◽  
pp. 1013-1016
Author(s):  
Jian Bing Sang ◽  
Su Fang Xing ◽  
Xiao Lei Li ◽  
Jie Zhang
Keyword(s):  
Finite Element ◽  
Energy Function ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Elastic Behavior ◽  
Element Analysis ◽  
Finite Element Program ◽  
User Subroutine ◽  
Element Program ◽  
Notch Tip

It has been well known that rubber-like material can undergo large deformation and exhibit large nonlinear elastic behavior. Because of the geometrically nonlinear of rubber like material, it is more difficult to analyze it with finite element near the notch tip. What is more, because there are varieties of the strain energy functions, implementation of these models in a general finite element program to meet the need of industry applications can be time consuming. In order to make use of the constitutive equation of Y.C. Gao in 1997 and analyze the notch tip of rubber-like material, a framework to implement the rubber-like material model is established within the general-purpose finite element program MSC.Marc. It will be very convenient to implement this isotropic hyperelastic model into the program with a user subroutine. This paper starts with the theoretical analysis based on the strain energy function given by Y.C. Gao in 1997. A user subroutine is programmed to implement this strain energy function into the program of MSC.Marc, which offer a convenient method to analyze the stress and strain of rubber-like material with the strain energy function that is needed. Though analysis with MSC.Marc, it is found that the result with finite element is consistent with the analytical result that given by Y.C. Gao in 1997, which testify that analyzing rubber like material with this method is reasonable and convenient.

scholarly journals Analysis of damage-plasticity model of concrete under uniaxial compression loading

2021 ◽  
Vol 10 (1) ◽  
pp. 29
Author(s):  
Mohammad Rafiqul Islam ◽  
Abbas Ali ◽  
Md. Jahir Bin Alam ◽  
Tanvir Ahmad ◽  
Salman Sakib
Keyword(s):  
Analytical Data ◽  
Strain Curve ◽  
Material Behavior ◽  
Elastic Behavior ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Compression Loading ◽  
Model Code ◽  
Concrete Damage ◽  
Two Phases

Concrete is a quasi-brittle material and shows different behavior in compression and tension. It shows elastic behavior at initial stage and damage-plasticity behavior beyond elastic limit. Therefore, development of material behavior model of concrete is a complex phenomenon. In this study, concrete damage plasticity theory has been described under experiment on concrete cylinder considering uni-axial compression loading and interpreted with analytical data calculated using CEB-FIP model code equation. The code has divided the stress-strain curve for concrete compression into three sections according to concrete’s elastic and non-elastic behaviors. Those three sections have been considered to calculate analytical data. In experiment, concrete behavior has been observed in two phases. The damage value for different stresses at the various points on the stress strain curve has been calculated. According to analytical data, the concrete shows elastic behavior up to 8.3MPa stress point and no damage occur in the concrete within the limit. However, in experimental data, concrete shows elastic behavior up to only 2.28MPa and damage occurred beyond the stress. Finally, the percentage of damage of concrete due to compression obtained from analysis and experiment has been assessed and compared. Above 32 percent of concrete damage is found for 22.5 MPa in both cases.  

Toward Material Parameters for Modeling Devices Made From an Epoxy-Based Shape Memory Polymer

2015 ◽  
Author(s):  
Veysel Erel ◽  
Jessica L. Berry ◽  
Arun Srinivasa ◽  
Terry S. Creasy
Keyword(s):  
Shape Memory ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Material Behavior ◽  
Elastic Behavior ◽  
Scanning Calorimetry ◽  
Element Analysis ◽  
Simple Tension ◽  
Nonlinear Elastic ◽  
Tension Experiments

Designing devices made from epoxy-based shape memory polymers is difficult because few material behavior parameters are available for these materials in the rubbery/shape changing region. This work examines the rubbery state, greater than 20° C above the glass transition temperature (Tg), as an elastomeric regime suited to characterization with simple tension and planar tension experiments. Differential scanning calorimetry (DSC) results show a 70° C Tg, which agrees with prior research. Simple tension experiments at 100° C exhibited nonlinear elastic behavior, and finite element analysis (FEA) agreed with the constitutive behavior exhibited in the experiments. Planar tension experiments exhibited novel results. The stress/strain response was sigmoidal with a significant plateau in stress followed by rising stress to failure. The typical 10:1 gage width/gage length ratio seemed to over constrain the material. The strain to failure is small, and suggests the material behavior is a hybrid of elastic and hyperelastic behavior.

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