Materials Forum

In classical plasticity models, the physical length scale is not considered to control the size effects. Strain gradient plasticity models include one or more length scales that control size effects. Stress gradient plasticity model is introduced with a specific physical length scale and does not include any additional parameters.

I need to edit user subroutine for existing Johnson Cook model (MAT_015) in LS DYNA. I have downloaded object files. However, I could not find any subroutine file for MAT_015. I need to edit the model and add 2 more parameters to increase its accuracy. Creating it from scratch is really a lengthy task. Can anyone help me in this regard? Thank you. 

Hello,

I am trying to find out how to identify specified parameters of ductile damage material in its stress-strain curve in Abaqus. I created a one-element model with a dimension of 1x0.2x1 (0.2 in y-direction) and simulated a tensile test in y-direction with a displacement condition of 0.02mm.

I have the following parameters for the material:
Elastic modulus = 250
Yield stress σ: 50
Fracture energy rate for the damage evolution: 2.5

Dear friends,

Hi

I want to model a composite material by means of phase field microelasticity (PFM) theory. This method is mainly used by Khachaturyan in recent years. I am very new in this field and I cannot undrestand how to consider the volume fraction of the inclusions in the formulations. Is there anyone who could help me in the field of phase field approaches??? It would be great if anyone can provide me with some information about the algorithm which was used to compute the mechanical properties of composite materials by means of phase field approaches.

As a result of loading, there is grain distortion, which results in lattice distortion. when lattice distortion happens, then lattice parameter changes. The change in lattice parameter, (a), results in a dislocation's burger's vector size change, since it has the lattice parameter size in its formula. Consequently, one can conclude that the size of burger's vector of a dislocation changes as a result of loading! . Still, is it practically safe to assume that the the change in its size is negligible compared to its initial size before loading?

I need to calculate the size or magnitude of the burger's vector of a dislocation in crystalline materials, metals. Obviously and typically, it can be measured via XRD or the electron microscopy methods, TEM and SEM. The question is:

could it also be measured via high precision optical microscopes, as precise as 1nm ?

Hello everyone,

I have a simple ABAQUS model with cohesive surface and I want to create a comparable model with cohesive elements instead of the surface. Applying the same properties onto the cohesive elements does not give me the desired results. Then I read somewhere that the properties cannot be applied on the elements directly the same way.

So how do I apply my interface properties onto the material of the cohesive elements? I thought that I should consider the thickness of the elements, but still until now I have not succeeded yet...

Thank you in advance.

Hello,

I want to analyze the interface between the fiber and the matrix in a fiber reinforced composite and I am now looking for the right material model.

In Abaqus there are the options of using cohesive elements or cohesive surface. As an alternative I want to model the interface as a third layer with solid elements.

My idea is to use the existing model Concrete Damaged Plasticity. Does this make sense?

Thank you in advance.