Elastic Material Behavior

2015 ◽  
pp. 9-22
Author(s):  
Andreas Öchsner
Keyword(s):  
Elastic Material ◽  
Material Behavior

Simulation of Fatigue Crack Growth Using XFEM

2020 ◽  
Author(s):  
Durlabh Bartaula ◽  
Yong Li ◽  
Smitha Koduru ◽  
Samer Adeeb
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Elastic Material ◽  
Low Cycle Fatigue ◽  
Material Behavior ◽  
Plastic Behavior ◽  
Linear Elastic Material ◽  
Linear Elastic ◽  
Cyclic Approach

Abstract Pipelines carrying oil and gas are susceptible to fatigue failure (i.e., unstable fatigue crack propagation) due to fluctuating loading such as varying internal pressure and other external loadings. Fatigue crack growth (FCG) prediction through full-scale pipe tests can be expensive and time consuming, and experimental data is limited particularly in the face of large uncertainty involved. In contrast, numerical simulation techniques (e.g., XFEM) can be alternative to study the FCG, given that numerical models can be theoretically and/or experimentally validated with reasonable accuracy. In this study, capabilities and limitations of existing fatigue analysis code (e.g., direct cyclic approach with XFEM) in Abaqus for low cycle fatigue simulation are explored for compact-tension (CT) specimens and pipelines assuming linear elastic material behavior. The simulated FCG curve for a CT specimen is compared with that obtained from the analytical method using the stress intensity factor prescribed in ASTM E647. However, for real pipelines with elastic-plastic behavior, direct cyclic approach is not suitable, and an indirect cyclic approach is used based on the fracture energy parameters (e.g., J integral) calculated using XFEM in Abaqus. FCG law (e.g., power law relationship like Paris law) is used to generate the fatigue crack growth curve. For comparison, the FCG curve obtained through direct cyclic approach for pipelines assuming linear elastic material is also presented. The comparative studies here indicate that XFEM-based FCG simulation using appropriate techniques can be applied to pipelines for fatigue life prediction.

A note on the nonlinear mechanical behavior of planar random network structures subjected to in-plane compression

2011 ◽  
Vol 45 (25) ◽  
pp. 2697-2703 ◽  
Author(s):  
Pär E. Åslund ◽  
Per Isaksson
Keyword(s):  
Mechanical Behavior ◽  
Elastic Material ◽  
Random Network ◽  
Material Model ◽  
Element Model ◽  
Material Behavior ◽  
Fiber Networks ◽  
Damage Models ◽  
Plane Compression ◽  
Random Fiber Networks

The microstructural effect on the mechanical behavior of idealized two-dimensional random fiber networks subjected to in-plane compression is studied. A finite element model utilizing nonlinear beam elements assuming a linearly elastic material is developed. On a macroscopic level, random fiber networks often display an asymmetric material behavior when loaded in tension and compression. In mechanical models, this nonlinearity is traditionally described using continuum elastic-inelastic and/or damage models even though using a continuum approach risks overlooking microstructural effects. It is found that even though a linear elastic material model is used for the individual fibers, the network gives a nonlinear response in compression. The nonlinearity is found to be caused by buckling of individual fibers. This reversible nonlinear mechanism is limited in tensile loading and hence offers an alternative explanation to the global asymmetry of random fibernetworks.

scholarly journals Quasistatic Fracture using Nonliner-Nonlocal Elastostatics with Explicit Tangent Stiffness Matrix

2021 ◽  
Author(s):  
Patrick Diehl ◽  
Robert Lipton
Keyword(s):  
Continuum Mechanics ◽  
Elastic Material ◽  
Stiffness Matrix ◽  
Material Behavior ◽  
Test Problems ◽  
Tangent Stiffness ◽  
Tangent Stiffness Matrix ◽  
Fracture Simulation ◽  
Peridynamic Model ◽  
Quasistatic Fracture

We apply a nonlinear-nonlocal field theory for numerical calculation of quasistatic fracture. The model is given by a regularized nonlinear pairwise (RNP) potential in a peridynamic formulation. The potential function is given by an explicit formula with and explicit first and second derivatives. This fact allows us to write the entries of the tangent stiffness matrix explicitly thereby saving computational costs during the assembly of the tangent stiffness matrix. We validate our approach against classical continuum mechanics for the linear elastic material behavior. In addition, we compare our approach to a state-based peridynamic model that uses standard numerical derivations to assemble the tangent stiffness matrix. The numerical experiments show that for elastic material behavior our approach agrees with both classical continuum mechanics and the state-based model.The fracture model is applied to produce a fracture simulation for a ASTM E8 like tension test. We conclude with an example of crack growth in a pre-cracked square plate. For the pre-cracked plate, we investigated {\it soft loading} (load in force) and {\it hard loading} (load in displacement). Our approach is novel in that only bond softening is used as opposed to bond breaking. For the fracture simulation we have shown that our approach works with and without initial damage for two common test problems.

scholarly journals Adaptive, Small-Rotation-Based, Corotational Technique for Analysis of 2D Nonlinear Elastic Frames

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Jaroon Rungamornrat ◽  
Saethapoom Sihanartkatakul ◽  
Pattawee Kanchanakitcharoen
Keyword(s):  
Elastic Material ◽  
Numerical Technique ◽  
Body Movement ◽  
Material Model ◽  
Material Behavior ◽  
Algebraic Equations ◽  
Nonlinear Elastic Material ◽  
Computational Performance ◽  
Nonlinear Elastic ◽  
Small Rotation

This paper presents an efficient and accurate numerical technique for analysis of two-dimensional frames accounted for both geometric nonlinearity and nonlinear elastic material behavior. An adaptive remeshing scheme is utilized to optimally discretize a structure into a set of elements where the total displacement can be decomposed into the rigid body movement and one possessing small rotations. This, therefore, allows the force-deformation relationship for the latter part to be established based on small-rotation-based kinematics. Nonlinear elastic material model is integrated into such relation via the prescribed nonlinear moment-curvature relationship. The global force-displacement relation for each element can be derived subsequently using corotational formulations. A final system of nonlinear algebraic equations along with its associated gradient matrix for the whole structure is obtained by a standard assembly procedure and then solved numerically by Newton-Raphson algorithm. A selected set of results is then reported to demonstrate and discuss the computational performance including the accuracy and convergence of the proposed technique.

A Model for Hyper-Elastic Material Behavior Under Thermal Aging With an Application to Natural Rubber

2018 ◽  
Author(s):  
Ahmed G. Korba ◽  
Abhishek Kumar ◽  
Mark E. Barkey
Keyword(s):  
Natural Rubber ◽  
Aging Time ◽  
Elastic Material ◽  
Thermal Aging ◽  
Least Square ◽  
Material Behavior ◽  
Model Parameters ◽  
Stress Strain ◽  
Strain Behavior ◽  
Hyper Elastic

Numerous hyper-elastic theoretical material models have been proposed over the past 60 years to capture the stress-strain behavior of large deformation incompressible isotropic materials. Among them, however, only few models have considered the thermal aging effect on model parameters. Having a simple, closed-form equation that includes the effect of aging temperature and time in describing the stress-strain behavior could facilitate fatigue analysis and life time prediction of rubber-like materials. In this vein, this paper defines a new and simple Weight Function Based (WFB) model that describes hyper-elastic materials’ behavior as a function of aging time and temperature variations. More than 130 natural rubber specimens were thermally aged in an oven and tested under uni-axial loading to observe their stress-strain behavior at various temperatures and aging times. The temperature ranged from 76.7 °C to 115.5 °C, and the aging time from zero to 600 hours. The proposed WFB model is based on the Yeoh model and basic continuum mechanics assumptions, and it was applied to the tested natural rubber materials. Moreover, it was verified against Treloar’s historic tensile test data for uni-axial tension of vulcanized natural rubber material, and also compared to the Ogden and the Yeoh models. A non-linear least square optimization tool in Matlab was used to determine all hyper-elastic material model parameters and all other fitting purposes. The proposed model has better accuracy in fitting Treloar’s data compared to the Ogden and the Yeoh models using the same fitting tool under the same initial numerical conditions.

Modeling Pavement Response to Vehicular Traffic on Ohio Test Road

1998 ◽  
Vol 1629 (1) ◽  
pp. 24-31
Author(s):  
James C. Kennedy ◽  
R. Douglas Everhart
Keyword(s):  
Elastic Material ◽  
Cost Allocation ◽  
Laboratory Data ◽  
Primary Response ◽  
Pavement Management ◽  
Material Behavior ◽  
Pavement Rehabilitation ◽  
Pavement Response ◽  
Materials Used ◽  
Highway Pavement

Methods of cost allocation for highway pavement rehabilitation and maintenance activities and pavement management estimations are based on empirical and semiempirical founded predictions that come up short, particularly when a roadway is subjected to heavy multiaxle vehicles. Additionally, materials used in constructing the pavement structure do not always behave in an elastic manner, and the ability to predict the pavement response in the presence of other than elastic material behavior is essential. Finally, prediction of pavement states of distress, based on empirical methods, and elastic material behavior is inadequate, particularly when traffic of heavy vehicles is involved. Battelle has been working on a mechanistic approach to address the issues and concerns at the core of current pavement design methods. The overall approach consists of combining three major software modules—a structural module that includes a general primary response model, a material characterization module, and a damage and distress module—are interconnected so that the influence of one on the other is continually updated. Four miles of highway pavement have been heavily instrumented with structural and environmental sensors so that pavement response can be monitored on both short- and long-term bases. Field test results from these pavements have been acquired and, along with laboratory data, have been used to partially validate and provide insight into pavement behavior under various loading conditions. The unique requirements for the design and implementation of the structural and environmental sensing elements are discussed. The mechanistic aspects in the software for the structural and material models are described, and predicted and field-measured results are compared.

Validation of Orthotropic Parameters of Timber by Means of Elastic Layer Theory

2018 ◽  
Vol 776 ◽  
pp. 29-34
Author(s):  
Vera Hlavata ◽  
Pavel Kuklík ◽  
Jan Vanerek
Keyword(s):  
Elastic Material ◽  
Orthotropic Material ◽  
Elastic Layer ◽  
Back Analysis ◽  
Strip Footing ◽  
Material Behavior ◽  
Displacement Curve ◽  
Material Parameters ◽  
Present Solution ◽  
Timber Board

The known solution of isotropic elastic layer was modified for orthotropic elastic material behavior in this contribution. The solution was original derived for calculation of footing settlement. However it should be useful for estimation of orthotropic material parameters. Timber is classical orthotropic material. Timber board which is placed on the rigid basement it could be considered as the elastic layer. From the known load displacement curve we can, vice versa, estimate the material parameters. The present solution should be able to control loading by rigid strip footing acting perpendicular to the plane of orthotropy. The contribution summarize the first steps of the proposed back analysis.

scholarly journals Nonlinear-Elastic Orthotropic Material Modeling of an Epoxy-Based Polymer for Predicting the Material Behavior of Transversely Loaded Fiber-Reinforced Composites

2020 ◽  
Vol 4 (2) ◽  
pp. 46
Author(s):  
Caroline Lüders
Keyword(s):  
Elastic Material ◽  
Orthotropic Material ◽  
Material Model ◽  
Material Behavior ◽  
Fiber Reinforced Composites ◽  
Material Modeling ◽  
Reinforced Composites ◽  
The Matrix ◽  
Nonlinear Elastic ◽  
Loaded Fiber

Micromechanical analyses of transversely loaded fiber-reinforced composites are conducted to gain a better understanding of the damage behavior and to predict the composite behavior from known parameters of the fibers and the matrix. Currently, purely elastic material models for the epoxy-based polymeric matrix do not capture the nonlinearity and the tension/compression-asymmetry of the resin’s material behavior. In the present contribution, a purely elastic material model is presented that captures these effects. To this end, a nonlinear-elastic orthotropic material modeling is proposed. Using this matrix material model, finite element-based simulations are performed to predict the composite behavior under transverse tension, transverse compression and shear. Therefore, the composite’s cross-section is modeled by a representative volume element. To evaluate the matrix modeling approach, the simulation results are compared to experimental data and the prediction error is computed. Furthermore, the accuracy of the prediction is compared to that of selected literature models. Compared to both experimental and literature data, the proposed modeling approach gives a good prediction of the composite behavior under matrix-dominated load cases.

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