High-speed Aluminum Research Articles

Transportation and deformation of high-speed aluminum nanoparticles in inert gas with molecular dynamics study

In addition to complex deformation, high-speed nanoparticles in gas are also accompanied by significant size and interfacial effects. In this work, we simulate the transportation behavior of high-speed aluminum nanoparticles in helium gas with the classical molecular dynamics method. The evolution of aerothermodynamic quantities of solid particles and liquid particles is revealed, and different temperature rise effects are found. Furthermore, the melting of aluminum particles induced by high aerodynamic drag force is discovered, and the melting threshold conditions are proposed. In low-density (0.002 g/cm3) and high-density (0.02 g/cm3) gas, the initial velocity at which particles start to melt is 6 and 4 km/s, respectively. During the deformation of solid particles, the evolution of dislocation motion is discussed, and the evolution of the development characteristics of the molten layer is given. During the deformation of the liquid particles, vibration deformation and bag deformation modes are observed. The threshold conditions for deformation mode transitions are also given. Only in high-density gas, bag deformation occurs when the initial velocity of particles (D > 5 nm) exceeds 6 km/s. The local mechanical quantity of gas is used to explain the variation of the drag force of the particles. Moreover, the drag force model is corrected according to temperature and deformation effects. Within a certain period, the model results overestimate the drag force, and the error with the simulation results is about 25%. This provides a model reference for high-speed nanoparticle dynamics and two-phase flow problems.

Fatigue Estimation on a High-Speed Wave Piercing Catamaran During Normal Operations

The estimation of fatigue life in the design process is particularly important for weight-optimised ships such as high-speed aluminium craft, but to date no research has been published on the fatigue accumulation on large wave-piercing catamarans, focusing on long-term operations. This paper assesses the applicability of classification society rules for high-speed catamarans with respect to fatigue design. This was achieved by comparing the long-term distributions of stress, measured on a 111m long wave-piercing catamaran ferry whilst operating in the Canary Islands and during the delivery voyage, with load spectra estimated using a method accepted by the classification society, DNV. The paper also proposes an improved distribution fitment method for fatigue analysis. A detailed method to convert measured stress histories in the time domain into an appropriate stress-spectrum and fitment of Weibull parameters is presented. Results show that the simplified method accepted by the classification society is highly conservative regarding fatigue estimation compared to fatigue results based on measured data. The proposed combined Weibull fitment method substantially improves the accuracy of simplified fatigue analysis methods.

Повышение эффективности подготовки производства при высокоскоростном фрезеровании деталей из высокопрочных алюминиевых сплавов

The investigation results of tool setup balancing are presented. There is described impact of tool setup imbalance at high-speed aluminum alloy milling upon surface roughness. It is shown that tool balancing in class range investigated ensures specified surface roughness at finishing.

High-speed aluminum metallurgy

High-speed aluminum metallurgy

Centrifugal stress analysis and structure optimization of large and high-speed end milling cutter

In the high-speed milling process of large end milling cutter, the stress of cutter caused by centrifugal force accounts for a large proportion of the total stress of the cutter and has a great influence on the milling process. In this paper, an end milling cutter with a diameter of 2,800 mm used on large and high-speed aluminum blank milling machine tools is taken as a research object, and the equations of internal stress caused by centrifugal force have been derived by using analytic method. On this basis, the factors affecting the internal stress were analyzed. Furthermore, the analytic results and the finite element analysis results were compared in order to confirm their correctness. Finally, according to the results of stress analysis, structure topology optimization design for large end milling cutter was carried out in order to reduce the weight and centrifugal force of the cutter.

Ultimate strength characteristics of aluminium plates for high-speed vessels

Marine-grade aluminium alloy is an established structural material for medium- to high-speed commercial craft and has also been used as the primary hull material for several naval vessels. The analysis of large high-speed craft operating in deep ocean environments requires rigorous methodologies to evaluate the ultimate strength of the hull girders. Representative plate load-shortening curves form part of simplified hull girder ultimate strength methodologies; for the case of a high-speed aluminium vessel, the curves need to account for the effects of parameters including alloy type, geometric imperfection, softening in the heat-affected zone, residual stresses, lateral pressure and biaxial load. This paper examines the strength of a series of unstiffened aluminium plates with material and geometric parameters typical of the midship scantlings of a high-speed vessel, using a non-linear finite element approach. The parametric studies show that these factors can have a significant influence on the strength behaviour of the plates both prior to and after the collapse point has been attained.

The Prediction, Measurement, and Analysis of Wake Wash from Marine Vessels

In the marine environment, wake wash from passing vessels can be detrimental to a shoreline environment, damage shoreline property and disturb or damage other marine operations. Slowdowns to prevent such impact can hamper or curtail high-speed vessel operations that depend on speed for successful service. To prevent this failure, low-wash vessel designs are needed and success must be assured before significant dollar investments are made. This paper describes establishment of "no harm" wash criteria, prediction of wash using computational fluid dynamics for various speeds of high-speed aluminum catamarans, techniques of measurement and analysis of the wash from actual vessels, and agreement between wash predictions and wash measurements. This paper documents a successful program which Washington State Ferries used to procure new, high-speed environmentally friendly passenger ferries for operation on Puget Sound.

Engineering and Operation of a High-Speed Aluminum Cold Rolling Mill

This paper covers the selection and layout of the electrical equipment and factors governing the choices made for the Alcan Aluminum Corporation 8000 ft/min 4-high cold reducing mill located at Oswego, N.Y. Many of the new features of the mill are outlined, and an evaluation is made of their effectiveness in operation. Operating experiences and operator training are also described.

Electrical Equipment for a High-Speed Aluminum Rolling Mill

The electrical equipment and systems for a specific aluminum cold rolling mill for attaining rolling speeds in access of 8000 ft/min are described. New systems applications in automatic guage control, main drive systems control, automatic mill preset functions, automatic sequencing, and positioning systems are also presented.