Shock loading of layered materials with SPH

Hypervelocity impacts into structures produce shock waves propagating through the colliding bodies. SPH has given insight into shock loading of homogeneous materials; nevertheless, shock wave propagation through solids with discontinuous density distribution, has not been considered in depth, yet. In previous studies using SPH, impact loading of laminated or composite materials was modeled by homogenization of the structure or under the assumption of being functionally graded materials. Both models neglect the reflection-transmission effects on the interface of different density materials. To capture these reflection-transmission effects, a holistic treatment for the multi-phase material is proposed, with kernel interaction over all parts of the structure. The algorithm employs a variable smoothing length formulation. A dissipative mass flux term is also introduced in order to remove spurious post-shock oscillations on the interface of different materials. In this paper, the SPH solution is presented, along with a relevant benchmark case. The algorithm’s performance is studied and the necessity of a variable smoothing length formulation is investigated

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Shock loading of layered materials with SPH

Hypervelocity impacts into structures produce shock waves propagating through the colliding bodies. SPH has given insight into shock loading of homogeneous materials; nevertheless, shock wave propagation through solids with discontinuous density distribution, has not been considered in depth, yet. In previous studies using SPH, impact loading of laminated or composite materials was modeled by homogenization of the structure or under the assumption of being functionally graded materials. Both models neglect the reflection-transmission effects on the interface of different density materials. To capture these reflection-transmission effects, a holistic treatment for the multi-phase material is proposed, with kernel interaction over all parts of the structure. The algorithm employs a variable smoothing length formulation. A dissipative mass flux term is also introduced in order to remove spurious post-shock oscillations on the interface of different materials. In this paper, the SPH solution is presented, along with a relevant benchmark case. The algorithm’s performance is studied and the necessity of a variable smoothing length formulation is investigated

Development of a blood flow model including hypergravity and validation against an analytical model

Fluid structure interaction (FSI) appears in many areas of engineering, e.g. biomechanics, aerospace, medicine and other areas and is often motivated by the need to understand arterial blood flow. FSI plays a crucial role and cannot be neglected when the deformation of a solid boundary affects the fluid behavior and vice versa. This interaction plays an important role in the wave propagation in liquid filled flexible vessels. Additionally, the effect of hyper gravity under certain circumstances should be taken into account, since such exposure can cause alterations in the wave propagation underexposed. Typical examples in which hyper gravity occurs are rollercoaster rides and aircraft or spacecraft flights. This paper presents the development of an arterial blood flow model including hyper gravity. This model has been developed using the finite element method along with the ALE method. This method is used to couple the fluid and structure. In this paper straight and tapered aortic analogues are included. The obtained computational data for the pressure is compared with analytical data available

From continuum mechanics to SPH particle systems and back : systematic derivation and convergence

In this paper, we employ measure theory to derive from the principle of least action the equation of motion for a continuum with regularized density field. The eventual equation of motion depends on the order in which regularization and the principle of least action are applied. We obtain two different equations, whose discrete counterparts coincide with the scheme used traditionally in the Smoothed Particle Hydrodynamics (SPH) numerical method, and with the equation treated by Di Lisio et al. in 1998, respectively. Additionally, we prove the convergence in the Wasserstein distance of the corresponding measure-valued evolutions, moreover providing the order of convergence of the SPH method. The convergence holds for a general class of force fields, including external and internal conservative forces, friction and non-local interactions. The proof of convergence is illustrated numerically by means of one and two-dimensional examples. Keywords: Smoothed Particle Hydrodynamics, principle of least action, Wasserstein distance, measure-valued equations, convergence rat

On the derivation of SPH schemes for shocks through inhomogeneous media

Smoothed Particle Hydrodynamics (SPH) is typically used for the simulation of shock propagation through solid media, commonly observed during hypervelocity impacts. Although schemes for impacts into monolithic structures have been studied using SPH, problems occur when multimaterial structures are considered. This study begins from a variational framework and builds schemes for multiphase compressible problems, coming from different density estimates. Algorithmic details are discussed and results are compared upon three one-dimensional Riemann problems of known behavior.</p