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Difficulties in indexing monoclinic crystalline materials by wide angle X-ray diffraction

Submitted by Xian Chen on
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X-ray diffraction
monoclinic

For monoclinic polycrystalline materials, how can we uniquely index the X-ray diffraction spectrum so that we can calculate the accurate lattice parameters a, b, c and beta? Due to the fact that there are four unknown variables coupled to determine d-spacings, we can not easily read out the lattice parameters until enough diffraction peaks positions are obtained correctly. This leads to two questions

1. How do we get the full diffraction peaks from a monoclinic polycrystalline sample if it is partially textured?

Weyl Geometry and the Nonlinear Mechanics of Distributed Point Defects

Submitted by arash_yavari on
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In this paper we obtain the residual stress field of a nonlinear elastic solid with a spherically-symmetric distribution of point defects. To our best knowledge, this is the first nonlinear solution for point defects since the linear solution of Love in the 1920s.

residual stress distribution in pipe

Submitted by amir r on
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Hi every body

I study the residual stress derived from a circumferential weld on the end of a pipe and degree of freedom in the other end have been taken

but i have a problem in residual stress distribution along axis of pipe.

 its known that the axial stress at the end of constrainted end should be zero or little but mine is in order of 100 MPa while residual stress is 300 MPa.

can anybody give me a hint about whats the source of error



thanks

PBC implementation in equilibrium equation

Submitted by xiashengxu on
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Finite Element Method
FEM
equilibrium e.q.
periodical boundary condition

Hi, guys,

 Do some of you know how Periodical Boundary Condition is implemented in equilibrium equation while using FEM:

div{ C:sym[grad(u)] } = 0 ,where the displacement u is periodical.

Is there any (detailed) documentation about this stuff?

 

Thank you very much!

 

How to find the average temperature a surface? ABAQUS -Heat transfer -user subroutine

Submitted by hoomaniii on
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ABAQUS
heat transfer
subroutine
film
surface average temperature

I want to model a concrete slab with a void inside the concrete. It is a thermal analyse where I apply a heat flux to the bottom surface. Within the void heat is transferred by radiation and convection. For simulating heat convection within the void, I use the surface film condition function in interaction module. I have to define the film coefficient and sink temperature. I decided to use the average temperature of the void surface for sink temperature. I don’t know how to define the average surface temperature. I think I have to use Abaqus Subroutine.



a question about vibration of plates having variable thickness

Submitted by sayad.boreyri on
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plate
free vibration
semi-analytical solution

Hi everybody!

for plates with constant thickness and two opposite sides simply-supported B.Cs, we can write w(x,y)=f(y)*sin(m.Pi.x) and solving the problem from this viewpoin.

I wonder whether this approach is true for plates with (linearly) variable thickness?

many thanks

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