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3D Printing of cylindrical shells with varied stiffness

Submitted by Nan Hu on

Hi, all,

I'm planning to print a series of cylindrical shells with different material patches on shell surface. The size is about 100 mm in length, 80 mm in diameter and 0.5 mm in shell thickness. The shell was designed with varied stiffness by using two different material properties. The 3D assembly has been created with two groups such that it is easy to select one group for a specific material. I wonder did any of you try some commercial 3D printing companies or providers who can fabricate similar structure with varied stiffness and afforable cost. Let me know. Thanks!

SIF semi-elliptical crack in pipelines

Submitted by Nelver Sánchez on

Dear all,

I am working in my under-graduate thesis. Basically, i'm trying to calculate the SIF and J-Integral for semi-elliptical surface crack using CINT command in ANSYS APDL (all of this in a pipeline model). I have seen one paper shows SIF's distribution along the crack front like the following picture (fig. 8):

In my analysis I have obtained the following distribution (I have used a/c=0.5 with a/tc and tc/Rc equal to the fig. 8):

Microstructurally based cross-slip mechanisms and their effects on dislocation microstructure evolution in fcc crystals

Submitted by ahmed.hussein on

Three newly identified cross-slip mechanisms from atomistic simulations of fcc crystals, namely surface, bulk and intersection cross-slip types, were hierarchically informed into discrete dislocation dynamics simulations. The influence of each cross-slip type on the evolution of the dislocation microstructure in face-centered cubic microcrystals having different crystal sizes and initial dislocation densities was investigated.

Postdoc Positions at Brown University (Solid Mechanics), Providence RI

Submitted by Allan F Bower on

The solid mechanics program at Brown has two openings for postdoctoral research associates in the areas of computational modeling of battery electrode materials, and computational design of advanced high-strength steels.   One position is available immediately; the other towards the end of August.   Both projects will have opportunities to work closely with experimental and industrial collaborators.

Problem with user routine (USERELEM) of Ansys

Submitted by r_n_s_s on

Dear imechanica friends,

 

I am using userelem in Ansys. When I model a curved shaped structure like a shell, and mesh it in the context of the element ET300, I get error below:

‘unable to mesh area 3 because of shape problems. It may help to change element size on edges of area’

When I use a trick to call ET181 and then mesh, and then change the element type to ET300, the following error is appeared!

‘Negative element Jacobian value 0 at element 10. This is due to wrong element order or bad mesh’