Numerical Simulation of Fragment Separation during Rock Cutting Using a 3D Dynamic Finite Element Analysis Code

Abstract

To predict fragment separation during rock cutting, previous studies on rock cutting interactions using simulation approaches, experimental tests, and theoretical methods were considered in detail. This study used the numerical code LS-DYNA (3D) to numerically simulate fragment separation. In the simulations, a damage material model and erosion criteria were used for the base rock, and the conical pick was designated a rigid material. The conical pick moved at varying linear speeds to cut the fixed base rock. For a given linear speed of the conical pick, numerical studies were performed for various cutting depths and mechanical properties of rock. The numerical simulation results demonstrated that the cutting forces and sizes of the separated fragments increased significantly with increasing cutting depth, compressive strength, and elastic modulus of the base rock. A strong linear relationship was observed between the mean peak cutting forces obtained from the numerical, theoretical, and experimental studies with correlation coefficients of 0.698, 0.8111, 0.868, and 0.768. The simulation results also showed an exponential relationship between the specific energy and cutting depth and a linear relationship between the specific energy and compressive strength. Overall, LS-DYNA (3D) is effective and reliable for predicting the cutting performance of a conical pick.

Numerical Simulation of Rock Plate Cutting with Three Sides Fixed and One Side Free

“…is result is same to the traditional rock cutting that, in the lower cutting speed, the cutting force varies nonsigni cantly [23]. erefore, it was meaningless to research the cutting speed in uence on cutting performance and cutting peak force.…”

“…e con dence level is very important to evaluate the accuracy of regression analysis results. 0.95 is most frequently used con dence level [23]. At the con dence of 0.95, the regression results to predict the peak cutting force are shown in Table 6.…”

Experimental and Numerical Studies on Rock Cutting with Saw Blade and Conical Pick Combined Cutting Method

“…e correlation coefficients of 0.9998, 0.8643, 0.9905, 0.9915, 0.9953, and 0.9981 demonstrates close relationships between peak cutting forces and cutting parameters. e confidence factor is a significant criterion for evaluating reliability of regression analysis results [33]. e confidence level of all numerical fittings in this paper is 0.95, which requires the prob(P) value greater than F value in statistics be less than 0.05; only in this way, the result is credible and has a significant difference.…”

Waterjet Erosion Model for Rock-Like Material Considering Properties of Abrasive and Target Materials

“…This model is suitable for high-stress, large-strain conditions such as those present in crater formations, concrete spalling, and impact-induced fracture inside concrete [47]. Therefore, microcrack generation using a conical pick in rock [48], the unloading characteristics of rock [49], and the smeared crack approach for concrete damage progression under repeated impact [50,51] have been simulated using the CSCM. The properties of the target were measured and computationally modeled via numerical analysis (unconfined compressive strength: 236 MPa; tensile strength: 11 MPa; Young's modulus: 56.5 GPa; Vickers hardness: 980 kg/mm 3 ) ( Figure 5 and Table 3).…”

“…To reduce the boundary effect, the target geometry was established at eight times the radius of the largest abrasive particle (i.e., 2 ⁄ = 0.172 mm), and the nonreflecting boundary condition was set on an outside surface in the model. The damage constitutive law and erosion criteria were used for evaluating nonlinear rock erosion, crack extension, and fragment formation upon contact [43,48]. The During collision between a spherical abrasive particle and a box-shaped target rock at normal incidence, the entire model is symmetrical about the x and y axes; hence, a 1/4 symmetry physical model could be used.…”