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Mohr Coulomb plasticity model

Hello everyone,

 

I am trying to implement a Mohr Coulomb plasticity model(no hardening at the moment) for the plane strain case. However, the results are not making so much sense.

I was wondering if any of you have tried to code this material model successfully before, or if you could provide me with some algorithm or reference which you know works properly.

 

Thank you.

Setareh

deformation gradient tensor

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I am working on a SPD (Sever Plastic Deformation) process using a dynamic Explicit simulation in ABAQUS software.

I have a question which every respected answer will be appreciated:

How can I get the deformation gradient tensor provided byABAQUS?

Thanks in advance.

Ramathasan Thevamaran's picture

Dynamic creation and evolution of gradient-nano-grained structures in single-crystal metallic microcubes

In an article published today in Science, we have demonstrated the creation of an extreme gradient-nano-grained (GNG) structure in single-crystal microcubes through high-velocity impact. We use the defect-free single-crystal silver microcubes, synthesized using a seed-growth process, as the model system, and fire them at supersonic velocities onto a rigid target to create the GNG structure.

Giorgio Carta's picture

Quasi-periodicity and multi-scale resonators for the reduction of seismic vibrations in fluid-solid systems

This paper presents a mathematical model for an industry-inspired problem of vibration isolation applied to elastic fluid-filled containers. A fundamental problem of suppression of vibrations within a finite-width frequency interval for a multi-scale fluid-solid system has been solved. We have developed a systematic approach employing full fluid-solid interaction and dispersion analysis, which can be applied to finite and periodic multi-scale systems.

Chao Chen's picture

Flaw sensitivity of highly stretchable materials

Elastomers and gels can often deform multiple times their original length. The stretchability is insensitive to small cuts in the samples, but reduces markedly when the cuts are large. This work shows that this transition occurs when the depth of cut exceeds a material-specific length, defined by the ratio of the fracture energy measured in the large-cut limit and the work to rupture measured in the small-cut limit.  This conclusion generalizes a result in the fracture mechanics of hard materials.

Real-time error controlled adaptive mesh refinement in surgical simulation: Application to needle insertion

Real-time error controlled adaptive mesh refinement in surgical simulation: Application to needle insertion
Link to paper: http://hdl.handle.net/10993/28624

New paper submitted to IJNMBE on the use of a posteriori error indicators for real time mesh adaptation during surgical simulation.

Stéphane Bordas

Quadratic stress criterion Ansys APDL.

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Hello people,

Does someone know if the quadratic stress criterion (QSC, Brewer and Lagace) for delamination onset is possible to be implemented in Ansys APDL for mixed mode cohesive zone modeling?

Cheers,

/R.

hd_ghasemi@yahoo.com's picture

A level-set based IGA formulation for topology optimization of flexoelectric materials

Abstract

This paper presents a design methodology based on a combination of isogeometric analysis (IGA),

level set and point wise density mapping techniques for topology optimization of piezoelectric /

flexoelectric materials. The fourth order partial differential equations (PDEs) of flexoelectricity,

which require at least C 1 continuous approximations, are discretized using Non-Uniform Rational

B-spline (NURBS). The point wise density mapping technique with consistent derivatives is

linst06's picture

Fringe Instability in Constrained Soft Elastic Layers

Soft elastic layers with top and bottom surfaces adhered to rigid bodies are abundant in biological organisms and engineering applications. As the rigid bodies are pulled apart, the stressed layer can exhibit various modes of mechanical instabilities. In cases where the layer’s thickness is much smaller than its length and width, the dominant modes that have been studied are the cavitation, interfacial and fingering instabilities.

Effects of surface tension and electrochemical reactions in Li-ion battery electrode nanoparticles

The size- and shape-dependency of the chemo-mechanical behavior of spherical and ellipsoidal nanoparticles in Li-ion battery electrodes are investigated by a stress-assisted diffusion model and 3D finite element simulations. The model features surface tension, a direct coupling between diffusion and elasticity, concentration-dependent diffusivity, and a Butler-Volmer relation for the description of electrochemical reactions that is modified to account for mechanical effects.

mohamedlamine's picture

Failure Envelope

A finite element software computes the stresses and/or strains sets values at each dynamic iteration step. These values can be plotted on a stress-space giving several failure envelopes. For an isotropic or an homogeneous mixture the Von Mises criterion represents an ideal envelope which may not coincide with the available envelopes but the stresses values can be checked with the material strength.

How to use rule-of-mixtures in order to obtain mechanical properties of bidirectional composites?

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Dear all,
We are easily able to obtain mechanical properties (such as elastic modulus, Poisson's ratio and ...) of a unidirectional lamina composite by means of rule-of-mixture. 
For instance, in case of "longitudinal loading", strength of the fiber-reinforced composite for long continuous fibers will be like:
Ec=Ef*Vf+Em*Vm.

I have two main questions: 
First, are these relations (longitudinal and transverse loading) hold for bidirectional composite? if not, how can we obtain relative elastic modulus? 

The Mechanical Laboratory of Sousse Scientific Workshop

The Mechanical Laboratory of Sousse (LMS) of the National School of Engineers of Sousse intends to organize annual scientific workshop on one of the four research themes identified by the laboratory teams. This first Workshop is proposed by the LMS team: “Fatigue of Materials and Structures”. The proposed theme is ” Mechanical performance of materials: From experiments to predictive approaches”.

The Mechanical Laboratory of Sousse Scientific Workshop

The Mechanical Laboratory of Sousse (LMS) of the National School of Engineers of Sousse intends to organize annual scientific workshop on one of the four research themes identified by the laboratory teams. This first Workshop is proposed by the LMS team: “Fatigue of Materials and Structures”. The proposed theme is ” Mechanical performance of materials: From experiments to predictive approaches”.

How to develop a new constitutive model from scratch?

Dear all  iMechanica, I wonder if there is any good  material on constitutive modeling that explains how to develop a new constitutive model from scratch, e.g. from the experimental data say uniaxial tension and compression. Where should one start to develop a new constitutive model? What laws should the model obey?  These questions perhaps are addressed in many continuum mechanics text books. but I am looking for materials that explain in a concise (short) and easy to understand way.

How to use non-dimensional form in open source codes instead of Units

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I am using an open source FEM platform, which requires you to convert your equation system to non-dimensional form. So, there are no units specified for the parameters in the problem. If you use compatible input units, you should expect the output in matching unit - just like one would do in a normal python or C++ code for solving physical problems. I have an elasto-plastic dynamic problem to solve, and these are the parameters for the Drucker-Prager Soil Model for soft clay.

E = 5000000;                 // Young's Modulus in N/m^2 or Pa

Problem between diaphragm and embeded region in ABAQUS

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Hello every one,

I am modeling a core (C shape) subjected to lateral load. I used embeded region constraint to contact steel bars and stirrups to the solid core. Then i want to apply the load at one end of core, but i need to contact all points in this end with a diaphragm to take the effect of the slab which aren't modeled. But i thing that ABAQUS doesn't permit to use two constraints at the same point. So what can i do to constrain the steel bars to core and also to constrain all points at one end with a diaphragm.

Thanks in advance

Rectangular frame calculation by beam finite elements

Beam elements are very widely used in structural engineering. Here we consider the methodology for calculating the rectangular frames with articulated or rigid nodes. The load is evenly distributed and concentrated.  The result is exactly the same with the results of the method of force and displacement method. A practical example of the calculation of the frame.

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