From 2b10fc153b291a1e7d8c388f559b86877b143b51 Mon Sep 17 00:00:00 2001 From: William Zunker Date: Fri, 3 Jan 2025 17:43:38 -0500 Subject: [PATCH] Started adding mdr model to pair_granular.rst --- doc/src/pair_granular.rst | 62 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) diff --git a/doc/src/pair_granular.rst b/doc/src/pair_granular.rst index e0f15ccd62..2aec9828ea 100644 --- a/doc/src/pair_granular.rst +++ b/doc/src/pair_granular.rst @@ -82,6 +82,7 @@ and their required arguments are: 3. *hertz/material* : E, :math:`\eta_{n0}` (or :math:`e`), :math:`\nu` 4. *dmt* : E, :math:`\eta_{n0}` (or :math:`e`), :math:`\nu`, :math:`\gamma` 5. *jkr* : E, :math:`\eta_{n0}` (or :math:`e`), :math:`\nu`, :math:`\gamma` +6. *mdr* : :math:`E`, :math:`\nu`, :math:`Y`, :math:`\Delta\gamma`, :math:`\psi_b`, :math:`e` Here, :math:`k_n` is spring stiffness (with units that depend on model choice, see below); :math:`\eta_{n0}` is a damping prefactor (or, in its @@ -162,6 +163,45 @@ initially will not experience force until they come into contact experience a tensile force up to :math:`3\pi\gamma R`, at which point they lose contact. +The *mdr* model is a mechanically-derived contact model able to capture the +contact response between adhesive elastic-plastic particles into large deformation. +The inputs to the model are primarily physical material +properties: Young's Modulus :math:`E`, Poisson's ratio :math:`\nu`, +yield stress :math:`Y`, effective surface energy :math:`\Delta\gamma`, and +coefficent of restitution :math:`e`. The execption is the critical confinement +ratio :math:`\psi_b` which is a geometrically motivated criterion for determining +when the bulk elastic response will trigger. The adhesive response is based on +a JKR-type fracture mechanics based formulation that is valid into large deformation. + +The majority of the theoritical foundations of the *mdr* model are developed in the +two part series :ref:`Zunker and Kamrin Part I ` and +:ref:`Zunker and Kamrin Part II `. Additional development +of the model and demonstration of its ability to simulate industrially relavant +powder compaction processes are presented in :ref:`Zunker et al. ` + +.. note:: + + The *mdr* model requires some specific settings to function properly, + please read the following text carefully to ensure all requirments are + followed. + +Newton's third law must be set *off*. This ensures that the neighbor lists +are constructed properly for the topological penalty algorithm used to screen +for non-physical contacts occurring through obstructing particles, an issue +prevelant under large deformation conditions. For more information on this +algorithm see :ref:`Zunker et al. ` + +.. code-block:: LAMMPS + + newton off + +The damping model must be set to *none*. The *mdr* model already has a built +in damping model. + +.. code-block:: LAMMPS + + pair_coeff * * mdr 5e6 0.4 1.9e5 2 0.5 0.5 damping none + ---------- In addition, the normal force is augmented by a damping term of the @@ -870,6 +910,28 @@ solids. Proc. R. Soc. Lond. A, 324(1558), 301-313. Y. P. (1975). Effect of contact deformations on the adhesion of particles. Journal of Colloid and interface science, 53(2), 314-326. +.. _Zunker2024I: + +**(Zunker et al, 2024)** Zunker, W., & Kamrin, K. (2024). +A mechanically-derived contact model for adhesive elastic-perfectly +plastic particles, Part I: Utilizing the method of dimensionality +reduction. Journal of the Mechanics and Physics of Solids, 183, 105492. + +.. _Zunker2024II: + +**(Zunker et al, 2024)** Zunker, W., & Kamrin, K. (2024). +A mechanically-derived contact model for adhesive elastic-perfectly +plastic particles, Part II: Contact under high compaction—modeling +a bulk elastic response. Journal of the Mechanics and Physics of Solids, +183, 105493. + +.. _Zunker2025: + +**(Zunker et al, 2025)** Zunker, W., Dunatunga, S., Thakur, S., +Tang, P., & Kamrin, K. (2025). Experimentally validated DEM for large +deformation powder compaction: mechanically-derived contact model and +screening of non-physical contacts. engrXiv. + .. _Luding2008: **(Luding, 2008)** Luding, S. (2008). Cohesive, frictional powders: