Effect of contact location on the crushing strength of aggregates

Abstract

This work deals with the effect of the contact location distribution on the crushing of granular materials. At first, a simple drop weight experiment was designed in order to study the effect of the location of three contact edges on the fracture pattern and the strength of a model cylindrical particle. The sample was placed on two bottom contact edges symmetrically distributed with reference to the vertical symmetry plane of the particle and subjected to an impact at the top. Angle α between the plane connecting a bottom contact edge to the centerline of the cylinder and a vertical plane was varied. The energy required to fracture the particle was shown to be an increasing function of angle α. Peculiar crack patterns were also observed. Then, we present a discrete model of grain fracture based on the work of Neveu et al. (2016) and employ it for a numerical analysis of the problem. The cylindrical particle is discretized by means of a space filling Voronoï tessellation, and submitted to a compression test for different values of angle α. In agreement with experiments, simulations predict a strong effect of the contact orientation on the strength of the particle as well as similar fracture patterns. The effect of the number of contacts is also explored and the importance of a potential pre-load is emphasized. We show that the fracture pattern: (i) is diametrical in case of diametrically opposed edges, (ii) has an inverted Y-shape in the case of three or four edges. Interestingly, in the latter case, if one of the lateral edges is slightly shifted, the fracture initiates and even propagates diametrically. Furthermore, the particle strength increases with the number of contacts.

DEM Modeling of Crushable Grain Material under Different Loading Conditions

“…Using drop weight crushing tests, Artoni et al [21] showed a strong effect of contact orientation on particle strength as well as similar fracture patterns.…”

“…From the review of experimental works, it should be noted that the coordination number was restricted to grains with a few coordination number less than or equal to 6 for Salami et al [10] and 4 for Artoni et al [21]. This restriction is not representative of particles that are part of a well graded granular assembly.…”

“…Further, it is difficult to define the stress and to capture critical contact force and crushing evolution in testing specimens. Compared with experimental investigations numerical simulations offer the chance to observe process dynamics in given time and spatial coordinates [21,22]. Detailed micro and macro scale information can also be recorded.…”

Numerical Analysis of Shear and Particle Crushing Characteristics in Ring Shear System Using the PFC2D

“…In the past decades, the particles generated for any granular assembly were simply circular or spherical; however, with the modern DEM, one can create a general particle shape using two or more circular or spherical particles [ 28 , 29 , 30 ]. The process of creating a particle of any shape is termed the clump or clustering method [ 27 ].…”

Establishment of a Laminated Crushed Products Function and Numerical Analysis

“…In addition, the drop weight test (DWT) is widely used. DWT has been used to research the functional relationships between impact energy and crushed products and between contact location and fragmentation morphology [16,17].…”