scholarly journals Effects of Metal Particles on Cold Spray Deposition onto Ti-6Al-4V Alloy via Abaqus/Explicit

2020 ◽  
Vol 7 (2) ◽  
pp. E19-E25
Author(s):  
W. J. W. J.
Keyword(s):  
Kinetic Energy ◽  
Internal Energy ◽  
Spray Deposition ◽  
Pure Aluminum ◽  
System Component ◽  
Tungsten Alloy ◽  
Initial Kinetic Energy ◽  
Aluminum Particles ◽  
Foundation Pit ◽  
Deposition Effect

Titanium alloy is the main structural material of the aerospace system component. About 75 % of titanium and titanium alloys in the world are used in the aerospace industry. Hence, it is of great significance to study the surface deposition characteristics by cold spraying technology, taking Ti-6Al-4V alloy as an example, smoothed particle hydrodynamics (SPH) method in Abaqus/Explicit was used to spray aluminum, Ti-6Al-4V, copper, tungsten alloy (W alloy) and titanium particles onto Ti-6Al-4V substrate. The simulation results show that the deposition effect is good over 600 m/s, and higher energy is obtained for Ti-6Al-4V particles with the same properties as the matrix. For aluminum, Ti-6Al-4V, copper, W alloy, and titanium particles with different properties, under the same initial speed condition, the greater the density of the material, the deeper the foundation pit. W Alloy has the largest initial kinetic energy, the deepest foundation pit, and better surface bonding performance. The aluminum particle has the smallest initial kinetic energy, the shallowest foundation pit. However, the deposition effect of multiple aluminum particles has not improved. The collision process’s kinetic energy is transformed into internal energy, frictional dissipation, and viscous dissipation. Besides, the internal energy is mainly plastic dissipation and strain energy. Therefore, it is recommended to use Ti-6Al-4V, copper, nickel, W alloy, and titanium particles for different occasions, such as Ti-6Al-4V substrate surface restorative and protective coatings. Pure aluminum particles are not recommended.

scholarly journals Consistent segregated staggered schemes with explicit steps for the isentropic and full Euler equations

2018 ◽  
Vol 52 (3) ◽  
pp. 893-944 ◽  
Author(s):  
Raphaèle Herbin ◽  
Jean-Claude Latché ◽  
Trung Tan Nguyen
Keyword(s):  
Energy Balance ◽  
Kinetic Energy ◽  
Internal Energy ◽  
Euler Equations ◽  
Left Hand ◽  
Isentropic Euler Equations ◽  
Space Discretization ◽  
Face Centered ◽  
The Stability ◽  
Stability And Consistency

In this paper, we build and analyze the stability and consistency of decoupled schemes, involving only explicit steps, for the isentropic Euler equations and for the full Euler equations. These schemes are based on staggered space discretizations, with an upwinding performed with respect to the material velocity only. The pressure gradient is defined as the transpose of the natural velocity divergence, and is thus centered. The velocity convection term is built in such a way that the solutions satisfy a discrete kinetic energy balance, with a remainder term at the left-hand side which is shown to be non-negative under a CFL condition. In the case of the full Euler equations, we solve the internal energy balance, to avoid the space discretization of the total energy, whose expression involves cell-centered and face-centered variables. However, since the residual terms in the kinetic energy balance (probably) do not tend to zero with the time and space steps when computing shock solutions, we compensate them by corrective terms in the internal energy equation, to make the scheme consistent with the conservative form of the continuous problem. We then show, in one space dimension, that, if the scheme converges, the limit is indeed an entropy weak solution of the system. In any case, the discretization preserves by construction the convex of admissible states (positivity of the density and, for Euler equations, of the internal energy), under a CFL condition. Finally, we present numerical results which confort this theory.

Photochemistry of van der Waals Complexes and Small Clusters

1996 ◽  
Author(s):  
C. Jouvet ◽  
D. Solgadi
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Internal Energy ◽  
Energy Surface ◽  
Van Der Waals ◽  
Van Der Waals Complexes ◽  
Small Subset ◽  
Energy Effect ◽  
Precise Control

In a chemical reaction, the shape of the potential energy surface (PES) dictates the reaction rate and energy disposal in the products. Not only does the dynamics depend crucially upon the features of the surface, but, ultimately one seeks to influence the course of the reaction by preparing selectively certain regions of the surface. For harpooning reactions, the propensity rules for energy disposal in the products (influence of the entrance kinetic energy, effect of the early or late barrier) have been established by Polanyi (1972) and have been used later as guidelines. Here, the surface may easily be modeled in simple terms using long-range electrostatic interaction in the entrance valley. There was, then, need of an experimental method which allows the possibility of observing directly the characteristic regions of this potential energy surface, but also to investigate precisely the surface in other types of reaction. The study of the reactivity of van der Waals complexes is intended to fulfil this purpose. In classical experiments, the surface is obtained by inversion of the experimental data which are differential cross sections and internal energy distribution of the products. This procedure is difficult and not unambiguous. The first step is to determine the correlation between the entrance channel's parameters (kinetic energy, internal energy, angular momentum) and the final states of the products (kinetic energy, internal energy, angular distribution). This requires a precise control of the entrance channel. Therefore, the goal of many experiments is to reduce the initial states to a small subset, and to measure the energy disposal in the products with the greatest accuracy. This was first achieved by controlling the kinetic energy of the reactants in crossed beam experiments. Later, a certain control of the collision geometry was obtained by orienting the molecules or the atomic orbitals in crossed beam experiments or by using prealigned systems in a van der Waals complex: this subject is discussed in Buelow et al. (1986).

scholarly journals Long-Term Analysis of Atmospheric Energetics Components over the Mediterranean, Middle East and North Africa

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 976
Author(s):  
Silas Michaelides
Keyword(s):  
Middle East ◽  
Kinetic Energy ◽  
Energy Conversion ◽  
Internal Energy ◽  
North Africa ◽  
Climatic Data ◽  
Monthly Means ◽  
Seasonal Behavior ◽  
Long Term Changes

In this research, one aspect of the climate that is not commonly referred to, namely, the long-term changes in the components of the atmospheric energy, is investigated. In this respect, the changes in four energy forms are considered, namely, Kinetic Energy (KE), Thermal Energy (TE), Internal Energy (IE), Potential Energy (PE) and Latent Energy (LE); the Energy Conversion (EC) between Kinetic Energy and Potential plus Internal Energy (PIE) is also considered. The area considered in this long-term energetics analysis covers the entire Mediterranean basin, the Middle East and a large part of North Africa. This broad geographical area has been identified by many researchers as a hot spot of climate change. Analyses of climatic data have indeed shown that this region has been experiencing marked changes regarding several climatic variables. The present energetics analysis makes use of the ERA-Interim database for the period from 1979 to 2018. In this 40-year period, the long-term changes in the above energetics components are studied. The monthly means of daily means for all the above energy forms and Energy Conversion comprise the basis for the present research. The results are presented in the form of monthly means, annual means and spatial distributions of the energetics components. They show the dominant role of the subtropical jet-stream in the KE regime. During the study period, the tendency is for KE to decrease with time, with this decrease found to be more coherent in the last decade. The tendency for TE is to increase with time, with this increase being more pronounced in the most recent years, with the maximum in the annual mean in KE noted in 2015. The sum of Potential and Internal energies (PIE) and the sum of Potential, Internal and Latent energies (PILE) follow closely the patterns established for TE. In particular, the strong seasonal influence on the monthly means is evident with minima of PIE and PILE noted in winters, whereas, maxima are registered during summers. In addition, both PIE and PILE exhibit a tendency to increase with time in the 40-year period, with this increase being more firmly noted in the more recent years. Although local conversion from KE into PIE is notable, the area averaging of EC shows that the overall conversion is in the direction of increasing the PIE content of the area at the expense of the KE content. EC behaves rather erratically during the study period, with values ranging from 0.5 to 3.7 × 102 W m−2. Averaged over the study area, the Energy Conversion term operates in the direction of converting KE into PIE; it also lacks a seasonal behavior.

scholarly journals Theoretical and Numerical Investigation on Perforation Resistance of Monolithic and Segmented Concrete Targets with Steel Liners under Normal Penetration

2019 ◽  
Vol 2019 ◽  
pp. 1-20
Author(s):  
Yi Cheng ◽  
Zhimin Xiao ◽  
Yuan Zhang
Keyword(s):  
Kinetic Energy ◽  
Contact Stiffness ◽  
Projectile Energy ◽  
Initial Kinetic Energy ◽  
Residual Velocity ◽  
Velocity Prediction ◽  
Steel Liner ◽  
The Impact ◽  
First Time ◽  
Better Than

Steel-concrete composites are important armor protective materials with the increasing power of precision-guided weapons. In this study, the formula of residual velocity as well as the ratio between residual and initial kinetic energy (Er/E0) for concrete targets with a rear steel liner was derived. By establishing finite element models of steel liner concrete targets through ANSYS/LS-DYNA, the effect of the steel liner layout on the perforation resistance was analyzed for both monolithic and segmented concrete targets, which were compared in terms of projectile kinematics characteristics, projectile energy consumption, and target damages. Four main conclusions were drawn: (1) a residual velocity prediction model of concrete targets with a rear steel liner was accurately proposed for the first time when velocity reduction coefficient η was 0.15 and the derived Er/E0 could be used to evaluate their corresponding perforation resistance; (2) moving back the steel liners enhanced the perforation resistance of both monolithic and segmented targets, but the performance of the latter was inferior to that of the former, which was reduced by 10%–16% under the same conditions; (3) during middle- and low-speed perforations, the projectile impact force was more influenced by the contact stiffness than the impact velocity; and (4) regarding the segmented targets, the perforation resistance of the 2nd target was better than the 1st target, which consumed about 10%–20% more projectile kinetic energy.

Optische Anregung beim Ladungsaustausch von Edelgasionen für Stoßenergien von 5 bis 300 eVolt

1968 ◽  
Vol 23 (7) ◽  
pp. 970-978
Author(s):  
H. Schlumbohm
Keyword(s):  
Charge Transfer ◽  
Kinetic Energy ◽  
Internal Energy ◽  
Excited States ◽  
Cross Sections ◽  
Ground Level ◽  
High Rate ◽  
Transfer Processes ◽  
The Cross ◽  
Threshold Energies

Measurements of the photoemission caused by collisions of ground level He+- and Ne+-ions with Ar- and Kr-atoms have shown several multipletts of Ar II and Kr II within the investigated wavelength range of 3500 to 5500 A. At a high rate the charge transfer processes occur into excited states of Ar* and Kr*. The reactions are endothermic with a deficit of internal energy between 6 and 19 eV.The cross sections measured for several chosen transitions start at characteristic threshold energies between 10 and 25 eV. Above the threshold the cross sections rise slowly with increasing energy when Ne* is the colliding ion and very fast for He+. Above 50 to 100 eV the cross sections show nearly constant values. — The minimum kinetic energy values are calculated, which can just fill up the deficits of internal energy, and are shown to be equal to the measured threshold energies. Thus it follows that the pseudo-crossing of the potential energy curves of the quasimolecules occurs at an energy value equal to the asymptotic level of the above curve.

scholarly journals The total ionisation due to the absorption in air of slow cathode rays

1927 ◽  
Vol 115 (772) ◽  
pp. 609-624 ◽  
Keyword(s):  
Kinetic Energy ◽  
Minimum Energy ◽  
Average Energy ◽  
Initial Energy ◽  
Electronic Energy ◽  
Initial Kinetic Energy ◽  
Ionisation Potential ◽  
Normal Atom ◽  
The Impact ◽  
Average Expenditure

The object of the experiments here described is to measure the average ionisation produced by the absorption in air of an electron with definite initial energy. From this the average expenditure of energy associated with the formation of a pair of ions can be estimated. The initial energies considered ranged between 200 and 1000 electron-volts. Experiments on ionisation by electronic impact have generally been concerned, either with a determination of the ionisation potential of the gas, or with the ionisation per unit path due to an electron having a definite energy. The ionisation potential has been measured by determining the minimum energy a stream of electrons must have in order to ionise, even occasionally, a normal atom. It represents the energy expended by the ionising electron if no kinetic energy be transferred to either of the ions formed. If at the impact an atomic electron were ejected with appreciable kinetic energy, the energy expended by the ionising electron would be correspondingly increased above the ionisation potential. Also electrons may dissipate their energy by processes other than ionisation, notably by excitation and by dissociation of diatomic molecules. For these reasons the average expenditure of electronic energy per pair of ions should exceed the ionisation potential. The excess of this average energy would indicate the extent to which processes other than ionisation contribute to the dissipation of the initial kinetic energy of the electrons. The purpose of the present experiments is to obtain further information on this phase of the ionisation problem.

L'explosion isotherme

1982 ◽  
Vol 60 (2) ◽  
pp. 168-178
Author(s):  
L. Brun ◽  
R. Roguet
Keyword(s):  
Kinetic Energy ◽  
Specific Heat ◽  
Internal Energy ◽  
Expansion Velocity ◽  
Von Neumann ◽  
Self Similar ◽  
Similar Solutions

The isothermal explosion model of Korobeinikov has been generalized to include the specific heat varying as temperature to the power k. Unlike Korobeinikov the different phases of the motion arc considered. The eventual self-similar solutions only exist for k > −1/2 and resemble that for k = 0 (the Korobeinikov value). For all k ≥ 0 the limiting expansion velocity is given by the von Neumann–Taylor–Sedov result (independent of k) and for k > 0 the internal energy decreases steadily. For k > 1/2 there is first an intermediate detonation phase. For −1/2 < k < 0 the kinetic energy first increases, then decreases, and the expansion law depends on k.

High-Resolution Measurements of Initial Kinetic Energy of Fragment Ions Produced in Fast Heavy Ions ? C60

2001 ◽  
Vol T92 (1) ◽  
pp. 179-181 ◽  
Author(s):  
T. Majima ◽  
A. Itoh ◽  
H. Tsuchida ◽  
A. Yogo ◽  
Y. Hamamoto
Keyword(s):  
High Resolution ◽  
Kinetic Energy ◽  
Heavy Ions ◽  
Initial Kinetic Energy ◽  
Fragment Ions
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