Dear all,

         I am new to X-FEM, started reading papers a couple of weeks before. I understood, functions[heaviside,sign..] are used to enrich the nodes to simulate virtually the discontinuity and asymptotic functions are used to charecterize the crack tip,other than this regular FEM nodes are there. I have few questions. 

1.what is the role of the asymptotic functions and its unknown co-efficient 'b' in charecterizing the crack tip. What are the parameters do these functions exactly charecterize means wat are the details can we extract from these fns n co-effs?

Prof Jean -Baptiste Leblond (http://www.lmm.jussieu.fr/~leblond/)

kindly invited me to give a seminar at Inst. d'alembert - Paris VI

Hi

I am trying to predict load-displacement curve for concrete cube numerically through ABAQUS. I am just beginer with ABAQUS, I have gone through the concrete material models available in ABAQUS. I found that smeared crack model well suite for analysis. Initially I am simulating a 2D model, I am using plane stress elements with static, Riks options, even I could able to complete the analysis, I am confused how to view the cracked elements and how to plot load-displacement curve.

I want to know whether I am going in a right path by using smear cracking model for crack propagation.

Thank you for your reply

Regards

Gouse 

I am working on crack propagation . I am trying to figure what factors should be taken into account when the crack is being propagated using XFEM.

I am especially interested to know what happens to the additional dof's corresponding to enriched nodes. Once the crack is propagated and crack tip is at new location , we add new dof's corresponding to enrichment functions , but what happens to the information stored by the dof's of previous enriched nodes,do we forget them altotgether , or do we map it to the new enriched nodes?

Hi everyone,

Anyone can tell me how to determine the fracture energy for crack propagation in a 4 points bending notched beam (mode I)?

In fact, in a 4 points bending, there are different displacements: displacement mesured at the upper supports (u), displacement mesured at the midle of the beam (deflection of the beam, f), crack opening displacement (COD), and others ... Among these first two displacements, it's u which corresponds to the mesured force. However, this one includes also bias effect (punching effect = "effet de poiçonnement" in french). So my question is which one of these two displacements must be used to calculate fracture energy?

doi: 10.1016/j.engfracmech.2007.08.012 

<>To describe the crack propagation in a fluid saturated solid I have idea to combine the Strong Discontinuity (XFEM) with the fluid, but at the micro-scale, which probably means to use (Navier-)Stokes equations or some modification of them. <>

Considering the MD (molecualr dynamics) simulation programs, they enable us to define the initial crack and then using different theories they propagate the crack. This process is actually a dynamic feature at least when the sample is going to fail. Here is the question that present in the most modellers assumptions, which will limit the simulation or maybe it is not possible to simulate the process with out these assumptions. One of them which I would like to know your ideas about is the linear velocity which come into conclusions before the simulations start. Actually is this linear velocity remains constant or increase with definite constant acceleration (rate) as crack propagates? I think the answer is No, so why we assume that this theory is accurate?