Implementation and Verification of Linear Cohesive Viscoelastic Contact Model for Discrete Element Method

PurposeThis paper aims to simulate a punch shear test of partly consolidated ice ridge keel by using a three-dimensional discrete element method. The authors model the contact forces between discrete ice blocks with Hertz–Mindlin contact model. For freeze bonds between the ice blocks, the authors apply classical linear cohesion model with few modifications. Based on punch shear test simulations, the authors are able to determine the main characteristics of an ice ridge from the material parameters of the ice and freeze bonds.Design/methodology/approachThe authors introduced a discrete model for ice that can be used for modelling of ice ridges. The authors started with short introduction to current status with ice ridge modelling. Then they introduced the model, which comprises Hertz–Mindlin contact model and freeze bond model with linear cohesion and softening. Finally, the authors presented the numerical results obtained using EDEM is commercial Discrete Element Modeling software (EDEM) and analysed the results.FindingsThe Hertz–Mindlin model with cohesive freeze bonds and linear softening is a reasonable model for ice rubble. It is trivial that the ice blocks within the ice ridge are not spherical particles, but according to results, the representation of ice blocks as spheres gave promising results. The simulation results provide information on how the properties of freeze bond affect the results of punch shear test. Thus, the simulation results can be used to approximate the freeze bonds properties within an ice ridge when experimental data are available.Research limitations/implicationsAs the exact properties of ice rubble are unknown, more research is required both in experimental and theoretical fields of ice rubble mechanics.Originality/valueBased on this numerical study, the authors are able to determine the main characteristics of an ice ridge from material parameters of ice and freeze bonds. Furthermore, the authors conclude that the model creates a promising basis for further development in other applications within ice mechanics.

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Discrete Element Method Modelling of the Diametral Compression of Starch Agglomerates

Materials ◽

10.3390/ma13040932 ◽

2020 ◽

Vol 13 (4) ◽

pp. 932

Author(s):

Józef Horabik ◽

Joanna Wiącek ◽

Piotr Parafiniuk ◽

Mateusz Stasiak ◽

Maciej Bańda ◽

...

Keyword(s):

Discrete Element Method ◽

Potato Starch ◽

Discrete Element ◽

Contact Model ◽

Ductile Material ◽

Diametral Compression ◽

Elastic Plastic ◽

Linear Elastic ◽

Dem Simulations ◽

Element Method

Starch agglomerates are widely applied in the pharmaceutical, agricultural, and food industries. The formation of potato starch tablets and their diametral compression were simulated numerically and verified in a laboratory experiment to analyse the microscopic mechanisms of the compaction and the origins of their breakage strength. Discrete element method (DEM) simulations were performed using EDEM software. Samples comprised of 120,000 spherical particles with radii normally distributed in the range of 5–36 μm were compacted in a cylindrical die with a diameter of 2.5 cm. The linear elastic–plastic constitutive contact model with a parallel bonded-particle model (BPM) was used to model the diametral compression. DEM simulations indicated that the BPM, together with the linear elastic–plastic contact model, could describe the brittle, semi-brittle, or ductile breakage mode, depending on the ratio of the strength to Young’s modulus of the bond and the bond-to-contact elasticity ratio. Experiments confirmed the findings of the DEM simulations and indicated that potato starch (PS) agglomerates can behave as a brittle, semi-brittle, or ductile material, depending on the applied binder. The PS agglomerates without any additives behaved as a semi-brittle material. The addition of 5% of ground sugar resulted in the brittle breakage mode. The addition of 5% gluten resulted in the ductile breakage mode.

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