## General Mechanical

Topics relate to Mechanical Enterprise, Motion, Additive Print and more

#### Heat treatment – 2D/3D transient thermal analysis

• Khawla Akrout
Subscriber
Hello everyone, I'm working on a homogenous heat treatment process for 6xxx series al alloy as part of my engineering thesis. The aim is to optimize the temperature and time of the heat treatment in the furnace, and determine the optimal length of the wire in the spool, to achieve high tensile strength and conductivity. I'm new to ANSYS and I have only used ABAQUS for my uni projects, so I'm learning from YouTube tutorials.

My model is very small, an electrical automotive wire (0.81mm rod composed of 7 x 0.3mm compressed strands). The body is designed and imported from Solidworks, while the air volume is created with the DesignModeler.

My goal was to simulate the thermal behavior of a wire bundle using a 2D reduced model starting with 7 rods and going up from there (to reduce calculation time). However, I faced some challenges with the heat transfer between the air and the rods. I created a rectangular domain for the air, but I could not make the temperature of the air affect the temperature of the rods.

I then attempted to create a 3D model with a length of 0.5mm, but I faced some challenges. I could not separate the air from the 7 rods using the Boolean Subtract feature, I thinnk the problem is that the distance between the rods was too small. I tried to use only one rod instead, but then I could not mesh the air cube with any mesh sizing, body sizing, or mesh contacts options. I wonder if there is a better way to do this.

As a last resort, I attempted to use fluent for a single 3D rod. However, I encountered meshing issues due to overlapping contacts that I could not resolve.

Could the problems be attributed to the rod design?

• Aniket
Ansys Employee

For 2D model have you tried using recommended initial time step value? From results it seems like it is reaching steady state, probably running for very small time with smaller timesteps may help?

-Aniket

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• Khawla Akrout
Subscriber

I started with minutes 30 to 15 to only 10 then tried seconds 30 to 10, yet I also couldn't figure out why it shows the initial time step error each time.

• Aniket
Ansys Employee

Please check section 3.4.32 General option. This guide explains it for APDL, but core concepts should be the same for Mechanical too.

https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v231/en/ans_the/Hlp_G_THE3_5.html%23aPpQxq1d0mcm

-Aniket

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• Rahul Kumbhar
Ansys Employee

Are you modeling the air as solid volume with some thermal conductivity value? You can set different initial/body temperatures for wires and air volume.

For 3D geometry issue, I think Boolean fails because of zero/almost zero thickness between the wires. At such cases, you should create a closed contact between wires and do not model the air in such tiny gap.

• Khawla Akrout
Subscriber

I assigned air as fluid and assigned as Air from the materials library. I'll try a closed contact, thanks.