Discrete element modeling of the compression molding of polymer–crystal composite particles

Parameter calibration of discrete element model for gluten densification molding

The densified powder material is convenient for storage and transportation, with broad market application prospects. In this study, the discrete element model parameters required for simulating gluten densification were calibrated using the Hertz-Mindlin with JKR contact model. Initially, physical testing techniques were utilized to assess the size distribution, density, and angle of repose (AoR) of gluten particles. Following this, the Plackett-Burman test, the steepest ascent test, and the Box-Behnken test were conducted, and the significant factors were obtained: The coefficient of rolling friction (P-P) was 1.038, the coefficient of static friction (P-P) was 0.071, and the surface energy (P-P) was 0.047. Finally, the AoR and densification simulations were performed under the optimal parameter combination, along with validation tests. The results showed that the relative error between the simulated and tested AoR was 0.52%. The compression ratio and compression force curves of simulated and actual were similar.

Polymer-based graphene composite molding: a review

Polymer-based graphene composite products with high mechanical properties, heat resistance, corrosion resistance and electrical conductivity are obtained by different molding technologies. Although these processes conveniently realize the molding of polymer composites, it is often difficult to control the product quality because of the fluctuation of the temperature and pressure threshold. At the same time, a high temperature or external load will carbonize polymer composites or cause excessive porosity to influence the compacted density and electrical conductivity. In this review, additive manufacturing, injection molding, extrusion molding, hot pressing, spark plasma sintering, electromagnetic-assisted molding and other processing methods were introduced. Meanwhile, the powder molding mechanism and material constitutive model were introduced, providing appropriate molding methods and theoretical guidance based on the performance of raw materials and the performance requirements of products.

A Density-Dependent Modified Doraivelu Model for the Cold Compaction of Poly (Ether Ketone Ketone) Powders

The cold compaction of poly (ether ketone ketone) (PEKK) powder was studied by experiments and simulations based on the modified Doraivelu model. Although this model can successfully predict the compaction behavior of metal powders, discussion of the prediction of polymer powders is lacking. Based on the mechanical theory of metal plasticity, the modified Doraivelu model was established by introducing the material parameters m and n. The modified model can predict the compaction density of PEKK powder during cold compaction. A sub-increment method for this constitutive model was then established and implemented into a finite-element model by using the user-defined material subroutine UMAT in ABAQUS/Standard. Consequently, the material parameters of the modified Doraivelu model were identified by an inverse method using the experimental data and simulation results. It was found that when m = 0, n = 4, and the initial relative density was 0.4485, the simulation results were the closest to the experimental ones.