Wave formation in a high-velocity symmetric impact of metal plates

Abstract

The impact of metal plates is considered within the framework of the model of a viscous incompressible fluid. The beginning of the wave-formation process in the model is equivalent to the initial stage of origination of instability of a steady flow in Landau's scenario. To establish the correspondence between the model and the real process, a series of experiments is performed on a symmetric impact of plates made of an aluminum alloy with identical impact angles and different velocities of the contact point. At high values of the Reynolds number and, hence, at high velocities of the contact point, wave excitation is shown to have a soft character; at lower values of Reynolds number, there exists a metastability region where the wave-excitation regime is rather hard; at even lower Reynolds numbers, no action can lead to wave formation, as it follows from the theory. Thus, Landau's model of origination of instability of a steady fluid flow is found to agree with the process of wave formation in an oblique impact of metal plates.The wave-formation process in explosive welding of metals is considered in many papers; a brief list of these papers can be found in [1]. At least 15 various models of the process have been proposed. The difference in mechanisms believed to be responsible for this phenomenon is rather large. Thus, for instance, the fluid medium in some models is considered either as an ideal fluid or as a fluid possessing some real physical properties, such as viscosity, surface tension, and compressibility. Other models take into account elastic and strength properties of the medium. The main criterion of reliability of this or that model was assumed to be good agreement between the theoretically predicted dependence of the wave size on the impact angle and the experimental curve. Comparisons of theoretical predictions were performed with the empirical relations λ = Aδ sin 2 (ϕ/2), a/λ ≈ 0.25(1)

Review of recent developments in manufacturing lightweight multi-metal gears

“…According to Groche et al [60], there is limited knowledge on the optimal parameters to form solid state bonds with this method and therefore preforms can only be produced through trial and error methods. However, the literature generally agrees that the variables of collision angle and speed of impact are of significant influence to the success of a multi-metal bond [115]. It should be noted that bonds produced between two metals with this process result in a wavy edge due to the shock waves travelling through the workpieces, as shown in Fig.…”

Proofs and Contradictions for Wave Formation Theories in Collision Welding

“…Another fluid theory was studied by Pai et al [17]. They suggest a similarity between the wave formation in collision welding and the Darrieus Landau instability.…”

“…He studied an analogy with a silicone putty tray moved with constant velocity under a water jet. His theory was later confuted, due to some anomalies by Bahrani et al [17]. The same authors corrected the model, introducing a different behavior of the workpieces.…”

“…This formation of waves is strictly connected with the material and process parameters. The factors that have been investigated are collision angle [13,14,15,16,21], collision point velocity [13,17,18,19,22], thickness [19,21,23,24,26], material density [20], material hardness [13,25] and surface roughness [25,27,3].…”

Formation and structure of vortex zones arising upon explosion welding of carbon steels

“…The problem of the explanation of the origin of waves and vortices upon explosion welding of metals was analyzed in many works [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. In the special lit erature, the model of the formation of waves and vor tices presented by Bahrani et al [5] is frequently cited.…”