Modeling particulate self-healing materials and application to uni-axial compression
The paper presents a model for self-healing in particulate materials based on a recently proposed piecewise linear contact model for elasto-plastic, adhesive, viscous, frictional particle-particle interactions. The used discrete element model (DEM) complements experiments on the scale of small representative volume elements (RVEs) and provides all information about all particles at any time. DEM requires only the contact forces and torques as the basic input to solve the equations of motion for all particles. The macroscopic material properties (e. g. elastic moduli, cohesion, friction, yield strength, dilatancy, anisotropy, etc.) are measured from the RVE tests. The proposed self-healing model admits to examine the damage detection sensitivity and rate and also the strength of the healed contacts. First, the authors briefly introduce a method that allows to simulate self-healing solid materials as granular packing. They discuss the normal and tangential contact forces and also viscous damping. Then, the tablet preparation of test samples is presented by including the stages of (i) creation of a loose configuration, (ii) pressure sintering, (iii) remove the pressure from the sample walls, and (iv) final relaxation of the system. As a result, a RVE sample is stated. Then, uni-axial unconfined compression is applied to the samples and the stress response is studied in the elastic regime, at the onset of, and during failure and also in the softening regime. In order to model a self-healing material, the local detection of damage is fulfilled and local healing initiates when damage is detected. With this aim, the authors introduce a self-healing scheme that is compatible with the developed contact model. Then compression tests for a self-healing material are presented. For fixed damage sensitivity and a fixed damage detection rate, damage is detected and healed by increasing the adhesive force instantaneously in the case of the healing criteria fulfillment. The results of the tests are compared to two extreme cases: one without healing and other with ``full'' or ``pre-emptive'' global healing, where healing has been applied to all contacts prior to the compression test.
scientific article; zbMATH DE number 5605030