No abstract

No abstract

In this work, the particle jetting behavior in a blast-driven dense particle bed is studied at early times. Four-way coupled Euler–Lagrange simulations are performed using a high-order discontinuous Galerkin spectral element solver coupled with a high-order Lagrangian particle solver, wherein the inter-particle collisions are resolved using a discrete element method collision model. Following the experiments of Rodriguez et al. [“Formation of particle jetting in a cylindrical shock tube,” Shock Waves 23(6), 619–634 (2013)] and the simulations of Osnes et al. [“Numerical simulation of particle jet formation induced by shock wave acceleration in a Hele-Shaw cell,” Shock Waves 28(3), 451–461 (2018)], the simulations are performed in a quasi-two-dimensional cylindrical geometry (Hele-Shaw cell). Parametric studies are carried out to assess the impact of the coefficient of restitution and the strength of the incident shock on the particle jetting behavior. The deposition of vorticity through a multiphase (gas–particle) analog of Richtmyer–Meshkov instability is observed to play a crucial role in channeling the particles into well-defined jets at the outer edge of the particle bed. This is confirmed by the presence of vortex pairs around the outer jets. Furthermore, the effect of the relaxation of the relative velocity between the two phases on the vorticity generation is explored by analyzing the correlation between the radial velocity of particles and the radial velocity of the gas at the particle location.

No abstract

This paper investigates the orthotropic properties of Fused Deposition Modeling (FDM)-printed Acrylonitrile Styrene Acrylate (ASA) material with different raster configurations. The elastic properties were determined using a non-destructive ultrasonic technique. This technique allows us to deduce the orthotropic elastic constants from the material density and the velocities of the longitudinal and shear waves propagating through the material along different directions. Tensile tests were performed in addition to ultrasonic tests to obtain the yield properties of the ASA material and to validate the elastic constants determined by the ultrasonic tests, which have shown very close correspondence. Finally, numerical verification was performed by comparing the experimental results of the three-point and four-point bending tests with the finite element simulation results which have as input the material properties from the ultrasonic testing. The simulation results have shown excellent agreement with the experimental results, implying that the material properties obtained from the ultrasonic testing were highly accurate comparing to the actual orthotropic elastic properties of the 3D-printed ASA material.

No abstract

This paper investigates the differences in structural response of lightweight internal structures using finite element (FE) simulation to provide quantitative comparison of the advantages of each type of structure. Various configurations, corresponding to different amounts of weight savings, were studied under distributed pressure loading and bending moment loading conditions. It was found that for configurations with less weight savings, the kagome possesses better performance than the honeycomb structure. However, as the amount of weight savings increases, the trend was observed to be reversed, with the honeycomb structure providing much better performance than the kagome structure. In general, it was shown that the honeycomb structure possesses better performance than the kagome structure under cantilever loading conditions.

In this work, three-dimensional Euler-Lagrange point-particle simulations of a shock wave interacting with a fixed bed of particles are carried out. The results from the particle-resolved simulations are used to assess the performance of the point-particle drag models during short time scales. We demonstrate that in a one-way coupled regime, the point-particle simulations recover the dominant gas dynamic features of the flow and are in a good agreement with the exact Riemann solution of a shock traveling through a sudden area contraction. Although the particle-resolved simulations are inviscid, we show that a dissipative drag is necessary to predict the mean behavior of the gas. As a model for the inviscid shock-induced drag two different models are presented in lieu of the quasi-steady drag. Finally, two-way coupled simulations are performed at four different particle volume fractions f0.10, 0.15, 0.20, 0.25g and three different incident shock Mach numbers f1.22, 1.66, 3.0g and compared against the data from particle-resolved inviscid simulations. At a lower Mach number (1.22), averaged flow quantities from the two-way coupled simulations agree well with the particle-resolved simulations. As the Mach number increases, we observe that the discrepancies between the point-particle and the particle-resolved simulations grow. A sensitivity analysis of the drag models involved reveals a strong influence of the inviscid-unsteady force on the gas quantities especially in the case of a strong shock interacting with a dense bed of particles. The use of Mach correlation beyond the subcritical regime coupled with the model for volume fraction correction is identified as a probable cause for the additional drag.