The compression cap yield surface currently lacks a hardening law. As a first step, we need to implement linear hardening for the cap (i.e., evolving the cap/preconsolidation stress with plastic volumetric strain), add unit tests, and update documentation accordingly
Compression cap behavior is meant to represent compaction/crushing and plastic volumetric hardening at high confining pressures. The current implementation provides cap geometry and parameters (e.g., preconsolidation stress, cap size), but does not evolve them through hardening. This means the cap does not expand/translate as plastic volumetric strain accumulates, which is inconsistent with the intended cap model description.
- Add a hardening rule that updates the cap position (e.g., preconsolidation stress) based on accumulated plastic volumetric strain.
- Ensure hardening is applied only for cap-related plasticity (cap return region(s)).
- Include configuration via material properties where applicable (existing variables include GEO_CAP_HARDENING_TYPE, GEO_PRECONSOLIDATION_STRESS, etc.)
Acceptance Criteria
Functional
A linear cap hardening option is implemented and enabled via material properties (e.g., GEO_CAP_HARDENING_TYPE = "linear" or similar string choice). [Mohamed Nabi in chat | Teams], [deltares-m...epoint.com]
Under cap-dominated loading, the cap evolves according to the linear hardening rule.
No change in behavior for existing cases unless cap hardening is explicitly enabled (or default behavior is documented).
Testing
Unit tests exist and validate:
- No hardening case: cap parameter remains constant when hardening is disabled.
- Hardening enabled: cap parameter increases monotonically with accumulated plastic volumetric strain during isotropic compression.
Documentation
README_cap.md includes a section describing:
The linear hardening equation
Required/optional material properties
A minimal example configuration
Notes on sign conventions (compression positive) consistent with the implementation.
The compression cap yield surface currently lacks a hardening law. As a first step, we need to implement linear hardening for the cap (i.e., evolving the cap/preconsolidation stress with plastic volumetric strain), add unit tests, and update documentation accordingly
Compression cap behavior is meant to represent compaction/crushing and plastic volumetric hardening at high confining pressures. The current implementation provides cap geometry and parameters (e.g., preconsolidation stress, cap size), but does not evolve them through hardening. This means the cap does not expand/translate as plastic volumetric strain accumulates, which is inconsistent with the intended cap model description.
Acceptance Criteria
Functional
A linear cap hardening option is implemented and enabled via material properties (e.g., GEO_CAP_HARDENING_TYPE = "linear" or similar string choice). [Mohamed Nabi in chat | Teams], [deltares-m...epoint.com]
Under cap-dominated loading, the cap evolves according to the linear hardening rule.
No change in behavior for existing cases unless cap hardening is explicitly enabled (or default behavior is documented).
Testing
Unit tests exist and validate:
Documentation
README_cap.md includes a section describing:
The linear hardening equation
Required/optional material properties
A minimal example configuration
Notes on sign conventions (compression positive) consistent with the implementation.