Microwave and induction heating

Start from a defined power input.

Internal heating adds absorbed power to the existing transient thermal calculation. Conduction carries that heat between plies while convection, radiation, tool contact and any linked cure reaction remain active. The source belongs to the thermal case and references an equipment record; changing an equipment label or rating alone does not turn heating on.

The available thermal models are Microwave calibrated heating, Microwave layered absorption, Induction calibrated heating, Induction analytical coil heating. These are separate from standalone RF shielding and effective-medium studies. The thermal case must explicitly select a supported source and its inputs.

Account for watts before comparing temperatures.

For watt-based modes, enter full-on power in W, exposed area in m² and a duty fraction. Analytical coil mode instead starts from prescribed RMS current, coil geometry and the rectangular target. The window determines when the source is active. Duty is applied once; surface area converts deposited watts to the local per-area heat input.

For layered microwave mode, the power after duty and coupling is incident at the planar stack. The field calculation then divides it into reflection, transmission and absorption. It cannot start from already absorbed watts. Keep the source of the calibration and the measurement reference plane with the case.

Choose how to define heat deposition.

Calibrated microwave or induction deposition

Select the physical plies that receive heat. A uniform profile gives constant power density in that selected material volume. An exponential profile weights the deposition from the incident side using a supplied penetration depth. Its integrated weights are normalized so that mesh subdivision preserves deposited power.

For calibrated induction, power and penetration depth are calibration inputs for the actual coil, gap, frequency, susceptor and material. The model does not infer eddy currents, skin depth or magnetic hysteresis. A hot selected layer follows the supplied profile; it is not an independent prediction of selective coupling.

Layered dielectric microwave absorption

Every physical ply needs explicit relative permittivity, dielectric loss tangent and conductivity at the operating frequency. The model uses a planar, normal-incidence, scalar, nonmagnetic stack between air half-spaces. It resolves absorption through the thickness and preserves reflection and transmission in the power balance.

The selected plies are a reporting region in this mode. Losses in other plies remain physical and remain in the thermal calculation. Dielectric properties stay fixed during the run. A thermal conductivity table or a carbon-fiber name does not supply dielectric data.

If measured dielectric loss already includes conduction, do not add the same conductivity loss again. The COMSOL frequency-domain reference explains the distinction between total complex-permittivity loss and separately represented conductivity, and why harmonic sign conventions matter.

Analytical coil heating: current, field and Joule heat.

Induction analytical coil heating starts from prescribed RMS coil current. A circular loop, rectangular wire segments or a finite solenoid represented by circular loops supplies the free-space magnetic field. The actual rectangular target size and position determine where that field is sampled and integrated.

Each modeled conducting ply is an isolated, isotropic thin sheet with an explicit effective conductivity for closed in-plane current paths. Do not substitute individual fiber conductivity or calculate heat from magnetic-field magnitude alone. Carbon-fiber contacts and architecture can control those paths; this model does not solve an interply electrical network.

Connect the source to the thermal stack.

The layer-fitted thermal cells receive integrated source power. Each ply retains its own thermal properties, and configured interface resistance acts between neighboring plies. Source heat and cure heat are distinct contributions. The calculation saves the actual cell mapping, per-ply power and temperature history together.

Generic laminate heating does not add melting or crystallization latent heat automatically. Contact/healing indices and optional scaled strength do not turn the thermal calculation into a weld qualification.

Moving exposure follows the case speed.

A stationary case uses a source window in seconds. For a moving case, a configured travel zone is converted using the linked positive case speed: entry time = entry distance / speed, and exposure duration = zone length / speed. Review the resulting time window after changing speed.

This is the thermal history of a travelling material point. It resolves heat spreading through thickness, without axial conduction or a complete production-line startup. Analytical coil mode samples the free-space field over the moving finite patch and supplies its area-averaged heat to that thermal history. Pressure remains the independently configured process/contact history.

Heating and welding quality are connected, but distinct.

Intimate contact describes the nominal area that touches under compression. Thermoplastic healing describes interdiffusion while the interface is hot, and coupled bonding tracks the age of newly contacting areas. These models need their own material and surface calibration. They do not establish compatibility between dissimilar polymers.

Use the correct physical interface and compare its temperature, pressure, contact and healing histories. An optional fully healed strength scales the bonding index only when supplied; it is not a certified weld allowable. Thermoset cure exotherm is available on compatible thermal cases, but thermoplastic healing is not a thermoset chemical-bonding model.

Set up, run and inspect.

1. Create or review the source under Equipment → Heating → Electromagnetic.
2. Open Cases → Thermal → Incoming material conditions → Internal heating → Configure sources.
3. Select equipment and the heating mode. Enter the power basis or analytical coil current/geometry, duty and time window or moving travel zone. Identify the physical plies or reporting region.
4. For layered microwave mode, supply dielectric inputs for every ply. For calibrated mode, document the deposited power and profile basis. For analytical induction, supply closed-loop sheet conductivity and review every approximation guard.
5. Run the thermal case. Open Internal heating → Microwave / induction heating to compare power, depth profiles and temperatures; inspect separately linked contact/healing outputs.
6. Check mesh and time resolution, power balance and the applicable calibration range against measurements.

The source plot uses steps at source events. Long depth–time maps preserve the peak saved heat per cell in each displayed time bin. CSV keeps the saved cell values; display binning does not rerun the solution.