Creation, optimization and verification of a three dimensional numerical model to simulate a dragline bucket during the digging cycle using modern DEM software

[摘要] Dragline bucket designers are required to evaluate new bucket designs by building and testing scale buckets. Concerns about the reliability and accuracyof scale testing have been raised in recent years, but there was no alternative.However, recent advances in computing power and granular flow modeling arechanging this and, we are entering an era where it is possible to numericallysimulate dragline bucket filling. However, verification of the numerical simulationis necessary before useable data can be obtained.This thesis explains the algorithm used by modern discrete element codesto simulate granular materials. The process used to create the numerical modeland calibrate the material will be discussed. An experimental test bench wasalso built to record experimental data for the verification the numerical model.As the project progressed it became clear that the time needed to run asingle simulation dramatically limits the number of simulations that could berun. Consequently, different approaches that could reduce simulation timewere also investigated.Unlike the other material parameters, there is no test that can be used todirectly calibrate the damping. An array of numerical simulations were thereforeconducted testing different damping schemes. The comparison performedbetween the numerical and experimental data showed that the numerical modelscould not accurately simulate the experimental measurements of the scalemodel dragline bucket. The numerical model did, however, predict many of the trends identified in the experimental simulation. With more realistic contactmodels and better computer facilities, nonetheless, it is highly probablethat numerical models will be capable of simulating dragline bucket fillingaccurately. Further study is, therefore, justified.

[发布机构] Stellenbosch University