Ablation-Charring

Use the Ablation-Charring type modeling object to simulate the material transformation that an object undergoes when it is exposed to an intense transient heat source.

The ablation or charring of a material occurs at the phase change temperature.

In transient analyses:

• The thermal solver models ablation or charring of 3D solids, 2D shells, or axisymmetric elements that are assigned a material that is controlled by an Ablation-Charring modeling object.

• 2D multi-layer shell elements ablate or char one layer at a time. After a 2D multi-layer shell element has been ablated, the conductivity in the plane is not affected.

• An element that is ablated or charred does not change back to its original state even if its temperature falls below the defined phase change temperature. Unlike phase change modeling, the transformation is not bidirectional.

Note:

You must select only implicit time integration methods when you model the material ablation.

Ablation

Ablation is the loss of material from the surface of an object by an erosive process such as vaporization, melting, or chipping.

• When an element that is ablating reaches the defined phase change temperature, the solver increases its thermal conductivity by a factor of 1.0 x 105 and reduces its capacitance by a factor of 1.0 x 10-6.For example, material removal due to ablation can occur on the following surfaces: The protective coating of orbital vehicles.The surface of tissue that is subject to treatment by medical lasers.The surface of passive retardant materials or thermal or thermal protection systems that are exposed to fire.

Charring

Charring is a chemical process that occurs when a solid that is subjected to intense heat is incompletely combusted.

• When an element that is charring reaches its defined phase change temperature, the element or layer is transformed into the specified Ablation-Charring material. For example, material transformation due to charring can occur in the following conditions:Plastic degradation due to high temperatures.Polymer curing due to chemical or heat induced reactions.PCB failure due to voltage peaks.

In addition to the thermal properties, the ablating or charring material must have the following material properties defined in the Thermal group of the Materials dialog box:

• Phase Change Temperature

• Latent Heat

Where do I find it?

Application	Pre/Post
Command Finder	Modeling Objects
Menu	Insert → Modeling Objects
Location in dialog box	Type list → Ablation-Charring → Create

How do I

Model phase change in a thermal or coupled model

Model ablation or charring in a thermal analysis

Learn more

Modeling phase change

Quick links

Command reference

Pre/Post video examples

Bulk Entry Descriptions

Simcenter 3D tutorials

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Simcenter 3D Thermal/Flow, Electronic Systems Cooling, and Space Systems Thermal boundary conditions

Ablation-Charring, Simcenter 3D 2021.1 Series

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