Peter A. Cundall

Bio: Peter A. Cundall is an academic researcher. The author has contributed to research in topics: Discrete element method & Screw conveyor. The author has an hindex of 2, co-authored 2 publications receiving 90 citations.

Three-Dimensional DEM Simulations of Bulk Handling by Screw Conveyors

Abstract: A numerical analysis using the 3D distinct element method (DEM) is conducted in order to examine the performance of screw conveyors. In particular, the simulation of horizontal and vertical types is studied. The results are compared with previous work and empirical equations. As a result, it is determined that this method is sufficiently well developed and useful to analyze the performance of screw conveyors.

Revista Brasileira de Engenharia Agrícola e Ambiental

Abstract: A B S T R A C T Soil compaction influences all stages of crop growth, but in many low yield sugarcane fields critical levels and effects of soil compaction are ignored. Therefore, identifying localization and intensity of compaction are very relevant for descompactation of soil. In this context, this study aimed to apply three criteria for delineating zones for soil compaction management: soil layer where first appear values of soil penetration resistance considered critical for sugarcane growth; cone index for 0-40 cm layer, and depth of occurrence of maximum soil penetration resistance. Sampling was carried out in a grid with 113 points spaced at 100 m, georeferenced by means of a Global Positioning System receiver. Soil penetration resistance in eight layers of 5 cm depth, cone index and depth of occurrence of maximum penetration resistance were determined from data gathered by an automatic measuring penetrometer. Estimative of non-sampled values were obtained by means of kriging interpolation, which allowed drawing of contour maps and the definition of four regions in the field for site specific subsoiling . Palavras-chave: Saccharum ssp. resistencia do solo a penetracao geoestatistica penetrometro

Dynamic modulus simulation of the asphalt concrete using the X-ray computed tomography images

Abstract: The objective of this study is to predict the dynamic modulus of asphalt mixture using both two-dimensional (2D) and three-dimensional (3D) Distinct Element Method (DEM) generated from the X-ray computed tomography (X-ray CT) images. The 3D internal microstructure of the asphalt mixtures (i.e., spatial distribution of aggregate, sand mastic and air voids) was obtained using the X-ray CT. The X-ray CT images provided exact locations of aggregate, sand mastic and air voids to develop 2D and 3D models. An experimental program was developed with a uniaxial compression test to measure the dynamic modulus of sand mastic and asphalt mixtures at different temperatures and loading frequencies. In the DEM simulation, the mastic dynamic modulus and aggregate elastic modulus were used as input parameters to predict the asphalt mixture dynamic modulus. Three replicates of a 3D DEM and six replicates of a 2D DEM were used in the simulation. The strain response of the asphalt concrete under a compressive load was monitored, and the dynamic modulus was computed. The moduli of the 3D DEM and 2D DEM were then compared with both the experimental measurements results. It was revealed that the 3D discrete element models successfully predicted the asphalt mixture dynamic modulus over a range of temperatures and loading frequencies. It was found that 2D discrete element models under predicted the asphalt mixture dynamic modulus.

Three-Dimensional Discrete Element Models for Asphalt Mixtures

Abstract: The main aim of this paper is to develop three-dimensional (3-D) microstructure-based discrete element models of asphalt mixtures to study the dynamic modulus from the stress-strain response under compressive loads. The 3-D microstructure of the asphalt mixture was obtained from a number of two-dimensional (2-D) images. In the 2-D discrete element model, the aggregate and mastic were simulated with the captured aggregate and mastic images. The 3-D models were reconstructed with a number of 2-D models. This stress-strain response of the 3-D model was computed under the loading cycles. The stress-strain response was used to predict the asphalt mixture's stiffness (modulus) by using the aggregate and mastic stiffness. The moduli of the 3-D models were compared with the experimental measurements. It was found that the 3-D discrete element models were able to predict the mixture moduli across a range of temperatures and loading frequencies. The 3-D model prediction was found to be better than that of the 2-D model. In addition, the effects of different air void percentages and aggregate moduli to the mixture moduli were investigated and discussed.