Add thermal effects to the multiplicative split material by rjoussen · Pull Request #2083 · 4C-multiphysics/4C

rjoussen · 2026-06-15T10:15:43Z

Description and Context

For now, the last PR to make the viscoplastic factor thermo-coupled:

Heat source due to plastic dissipation is wired from the viscoplastic factor to the thermo element implementation.
Stress contribution due to thermal expansion is added
Two new regression tests are added, for partitioned and monolithic TSI, respectively. Including both is because the call order and, hence, the caching behavior are quite different for the two algorithms. They use identical result tests to demonstrate consistency. Though it should be noted that using a partitioned algorithm for the viscoplastic material in its current form is not recommended, since this leads to many re-evaluations of the material without a valid cache being present and consequently repeated return-mappings (or "constitutive updates" in the future), which probably mitigates all advantages a partitioned algorithm might have.

Current Limitations:

Supported only for a single viscoplastic factor.
The thermo-elastic contribution to the thermo equation via stress_temperature_modulus_and_deriv is neglected so far.

Related Issues and Pull Requests

following #2041
Doesn't touch any factor code, so independent of #2082 (@dragos-ana) Edit: I ended up re-designing some of the ThermalQuantities struct, mainly due to performance concerns, which now lead to some changes in the factor, but quite limited. The thermal expansion evaluations now also use tensors instead of matrices.

Copilot

Pull request overview

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Copilot was unable to run its full agentic suite in this review.

This PR thermo-couples the multiplicative split defgrad elast-hyper material by adding thermal expansion stress contributions and wiring plastic-dissipation heat sources into the thermo element, plus adding regression coverage for monolithic vs partitioned TSI.

Changes:

Add thermal expansion parameters and thermal-stress contributions to MAT_MultiplicativeSplitDefgradElastHyper
Extend thermo element dissipation handling to support multiplicative-split viscoplastic heat sources
Add two TSI regression tests (monolithic + partitioned) to validate consistency

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
unittests/mat/4C_multiplicative_split_defgrad_elasthyper_test.cpp	Updates unit test setup and adapts to new `evaluated_sdi_fin` signature requiring thermal quantities
tests/list_of_tests.cmake	Registers new thermo-viscoplastic TSI regression tests (monolithic/partitioned)
tests/input_files/mat_iso_thermoviscoplast_refJC_log_timint_tsi_partitioned.4C.yaml	Adds partitioned TSI input exercising thermo-viscoplastic dissipation + thermal expansion
tests/input_files/mat_iso_thermoviscoplast_refJC_log_timint_tsi_monolithic.4C.yaml	Adds monolithic TSI input exercising the same scenario for consistency
src/tsi/4C_tsi_monolithic.cpp	Sets differentiation type to temperature for structure coupling matrix assembly
src/thermo/src/element/4C_thermo_ele_impl.cpp	Extends dissipation evaluation/tangents to handle multiplicative-split material heat source and derivatives
src/mat/4C_mat_trait_thermo_solid.hpp	Adjusts `ThermoSolid` trait inheritance (removes `Solid`)
src/mat/4C_mat_multiplicative_split_defgrad_elasthyper.hpp	Adds thermo-solid trait, thermal expansion API, and heat-source evaluation entry point
src/mat/4C_mat_multiplicative_split_defgrad_elasthyper.cpp	Implements thermal expansion stress contribution and heat source forwarding to viscoplastic factor

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Copilot

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

- Heat source due to plastic dissipation is wired from the viscoplastic factor to the thermo element implementation. - Stress contribution from thermal expansion is added - Two new regression tests are added, for partitioned and monolithic TSI Limitations: - Supported only for a single viscoplastic factor. - The thermo-elastic contribution in the via `stress_temperature_modulus_and_deriv` is neglected so far.

rjoussen · 2026-06-17T09:13:01Z

Thanks for running copilot @c-p-schmidt, mine ran out of tokens apparently :)

dragos-ana

Looks great!
Particularly, your use of tensors and the newly added TensorAndTemperatureDerivative have simplified the code a lot!
I added some minor comments / suggestions

dragos-ana · 2026-06-19T22:49:36Z

+    void reinit(const Core::LinAlg::Tensor<double, 3, 3>* defgrd,
+        const Core::LinAlg::SymmetricTensor<double, 3, 3>& glstrain, double temperature,
+        unsigned gp) override { /* do nothing */ };
+


This has nothing to do with your PR, but reinit is a very strange / non-descriptive name for what the function does.

Maybe a matter for private discussion, but shouldn't we at least include the stress-temperature modulus into the residual and neglect the linearization first?

dragos-ana · 2026-06-19T22:59:39Z

+     * @brief Evaluate the mechanical dissipation produced by this material. Currently, this is only
+     * enabled for the viscoplastic factor.


Suggested change

* @brief Evaluate the mechanical dissipation produced by this material. Currently, this is only

* enabled for the viscoplastic factor.

* @brief Evaluate the heat source produced by this material. Currently, this is only

* enabled for the viscoplastic factor.

To prevent confusion as also noted in a previous PR ;) It's still my opinion that this is better named as the Taylor-Quinney heating, but I am also fine with heat source.

dragos-ana · 2026-06-19T23:27:37Z

+  }
+  else if (num_contributions > 1)
+  {
+    FOUR_C_THROW("Mechanical Dissipation is only implemented for a single factor so far.");


Suggested change

FOUR_C_THROW("Mechanical Dissipation is only implemented for a single factor so far.");

FOUR_C_THROW("Evaluation of additional heat source is only implemented for a single factor so far.");

dragos-ana · 2026-06-19T23:28:43Z

      Core::LinAlg::Matrix<8, 1> curr_delta{Core::LinAlg::Initialization::zero};

+      //! thermal contribution due to thermal expansion to the thermo-elastic 2PK stress
+      TensorAndTemperatureDerivative curr_ST{};


Suggested change

TensorAndTemperatureDerivative curr_ST{};

TensorAndTemperatureDerivative curr_ST_and_temp_deriv{};

Maybe?

dragos-ana · 2026-06-19T23:34:47Z

+  TIMESTEP: 0.05
+  NUMSTEP: 200


TSI Dynamic governs the time settings, but it would be nice if they match the set values in both the dedicated structure and thermal sections.

dragos-ana · 2026-06-19T23:36:09Z

+SOLVER 2:
+  SOLVER: Belos
+  SOLVER_XML_FILE: "xml/linear_solver/iterative_gmres_template.xml"
+  PRECONDITIONER_XML_FILE: "xml/block_preconditioner/thermo_solid.xml"


If I see this right, Belos is not used here at all? Maybe it should be removed if that is not the case.

dragos-ana · 2026-06-19T23:47:09Z

+    thermoplhyperelast = std::dynamic_pointer_cast<Mat::ThermoPlasticHyperElast>(structmat);
+    // true: error if cast fails


Since the dynamic pointer cast does not throw by default, it could be helpful to explicitly assert that it is not a nullptr after the cast.

rjoussen self-assigned this Jun 15, 2026

Copilot AI review requested due to automatic review settings June 15, 2026 10:15

rjoussen added the type: enhancement A new feature or enhancement to be implemented label Jun 15, 2026

Copilot AI reviewed Jun 15, 2026

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Copilot started reviewing on behalf of rjoussen June 15, 2026 10:30 View session

rjoussen force-pushed the add-thermal-effects-to-multsplit-material branch from 2580977 to b1124a5 Compare June 16, 2026 18:59

rjoussen requested a review from Copilot June 16, 2026 19:03

Copilot AI reviewed Jun 16, 2026

rjoussen marked this pull request as draft June 16, 2026 19:29

rjoussen force-pushed the add-thermal-effects-to-multsplit-material branch from b1124a5 to 0139ca2 Compare June 17, 2026 07:32

rjoussen requested a review from Copilot June 17, 2026 07:46

Copilot AI reviewed Jun 17, 2026

rjoussen marked this pull request as ready for review June 17, 2026 08:40

rjoussen requested review from c-p-schmidt and dragos-ana June 17, 2026 08:40

c-p-schmidt requested a review from Copilot June 17, 2026 08:43

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Comment thread src/mat/4C_mat_multiplicative_split_defgrad_elasthyper_service.hpp

Comment thread src/thermo/src/element/4C_thermo_ele_impl.cpp Outdated

rjoussen force-pushed the add-thermal-effects-to-multsplit-material branch from 0139ca2 to d59f530 Compare June 17, 2026 09:11

rjoussen mentioned this pull request Jun 17, 2026

Remove thermo trait from thermo solid trait #2075

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dragos-ana reviewed Jun 19, 2026

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		* @brief Evaluate the mechanical dissipation produced by this material. Currently, this is only
		* enabled for the viscoplastic factor.

	FOUR_C_THROW("Mechanical Dissipation is only implemented for a single factor so far.");
	FOUR_C_THROW("Evaluation of additional heat source is only implemented for a single factor so far.");

	TensorAndTemperatureDerivative curr_ST{};
	TensorAndTemperatureDerivative curr_ST_and_temp_deriv{};

		thermoplhyperelast = std::dynamic_pointer_cast<Mat::ThermoPlasticHyperElast>(structmat);
		// true: error if cast fails

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rjoussen commented Jun 15, 2026 •

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