Material Flow Velocity Research Articles

3D numerical analysis of material flow behavior and flash formation of 45# steel in continuous drive friction welding

The flow behaviour and flash formation of ring component for 45# steel in continuous drive friction welding (CDFW) process were investigated. A 3D thermo-mechanical coupled finite element method was used to conduct this research. Seven welding schemes with different friction pressures, friction times and rotational velocities were carried out. The influences of friction pressure, friction time and rotational velocity on the material flow behaviour at the friction surface and flash formation were analyzed. Research results show that higher peak temperature, larger region with high temperature and larger axial pressure are all good for the increase of material flow velocity. During the CDFW process, the material near the edge of friction surface flows towards the outside of joint, which makes the appearance of flashes. With the increase of rotational velocity, friction time and friction pressure, the dimensions and the bending degree of flashes increase. The reasonable welding parameters of ring structure for 45# steel, whose inner diameter and outer diameter are 50 mm and 80 mm, respectively, are the friction pressure of 100 MPa, the friction time of 4 s and the rotational velocity of 1600 r/min.

Numerical simulation of material flow behavior of friction stir welding influenced by rotational tool geometry

Considering the practical geometry of rotational tool and the relation between the material parameters and temperature, the finite volume model of friction stir welding is established on basis of the ANSYS FLUENT software. The effect of shoulder geometry and pin geometry on material plastic flow behavior is studied. The results of numerical simulation show that the flow velocity of material decreases with the increase of the distance away from the weldment surface or the rotational axis of pin. The flow velocity of material inside weldment is increased by decreasing the cone angle of pine or decreasing the width of screw groove. When the rotational tool with the left screw pin rotates clockwise, the flow direction of material near pin is downward while the flow direction near the thermal–mechanical affected zone is upward, which is opposite to that of the right screw pin. From the view of improvement of material flow, the concentric-circles-flute shoulder is better than the inner-concave-flute shoulder or the plane shoulder. Therefore, choosing the reasonable shoulder geometry and the reasonable pin geometry can be good for improving the material flow during the friction stir welding process and avoiding the root defects.

Experimental Evaluation of Refined, Bleached, and Deodorized Palm Olein and Palm Stearin in Cold Extrusion of Aluminum A1050

The performance of palm oil as a lubricant in a cold metal forming process was tested and evaluated by carrying out plane strain extrusion experiments and experimental analyses using a visioplasticity method. In the present research, two types of refined palm oil, refined, bleached, and deodorized (RBD) palm olein and RBD palm stearin, were tested as lubricants. The workpiece material was aluminum JIS-A1050. The experiments were carried out at room temperature (22°C). Paraffinic mineral oils with varying degrees of viscosity were tested for comparison. The experiment used an extrusion apparatus in which the taper dies were facing together, with zero frictional constraint at the contact plane (corresponding to the plane plate tool) conducted, and results were compared with those extruded with lubricants. Extrusion load and surface roughness of the billets were measured and compared. The distribution of the material flow velocity and effective strain in the exit zone of the billets were calculated using the visioplasticity method, and these data were also compared. The results confirmed that RBD palm olein and palm stearin provide sufficient lubrication performance in the cold work metal forming process.

Effect of Baffle-block on Material Flow Velocity during Thin-walled Hollow Aluminum Profile Extrusion

The extrusion process of a thin-walled hollow aluminum alloy profile with small features is simulated by using arbitrary Largrang-Euler(ALE) algorithm based HyperXtrude software.The material flow velocity standard deviation in the exit of the die hole is used as a criterion to evaluate velocity uniformity.By designing a series of baffle-blocks,the material flow velocity and the deformation of extrudate are controlled effectively.Effect of baffle-blocks on velocity uniformity is analyzed and a design method of baffle-blocks is proposed.The simulation results demonstrate that the section shapes of baffle-blocks play a key role in controlling material flow velocity in exit.When baffle-blocks have a reasonable section shape,material flow velocity and the deformation of extrudate can be controlled effectively and qualified profiles can be gained by adjusting height and distance between baffle-blocks and mold hole.In a certain range of the baffle-block’s height,the increase of the height of baffle-block can increase the uniformity of the materials flow velocity effectively.However,the increase of the width of baffle-blocks may not work on the balance of material flow material.

Cerebral vasoreactivity in hypocapnia and hypercapnia in patients with diabetes mellitus type 2 with or without arterial hypertension

Background and purposeDiabetes mellitus (DM) is an independent risk factor for cardiovascular diseases. The origin of diabetic microangiopathy is multifactorial; it affects all layers of the artery wall, causing endothelial and vasoreactivity impairment. The incidence of cerebral vasoreactivity failure in diabetic patients without stroke history is not precisely determined yet. The aim of the study was to assess the cerebrovascular reactivity in hypocapnia and hypercapnia in patients with type 2 DM with or without arterial hypertension without artery stenosis and stroke history, with the use of transcranial Doppler examination. Material and methodsThe mean blood flow velocity, pulsatility index and parameters of cerebrovascular reactivity were measured in 53 patients with type 2 DM (aged 42–72 years, mean 59.5 ± 7.9) and in 27 healthy volunteers (aged 36–74 years, mean 57.0 ± 10.4). Diabetics were further divided into two subgroups according to the presence or absence of arterial hypertension. ResultsThe index of cerebrovascular reactivity in hypocapnia and hypercapnia was significantly worse and time needed to normalization of blood flow velocity was significantly longer in patients with DM in comparison with healthy volunteers. ConclusionsMost DM type 2 patients without stroke history had decreased values of cerebral vasoreactivity parameters, which suggests the presence of microangiopathy.

Numerical Simulation of Extrusion Process and Die Structure Optimization for a Complex Aluminum Multicavity Wallboard of High-Speed Train

The extrusion die plays a crucial role in the quality control of aluminum alloy profile production. In practice, the extrusion die design mainly depends on the experience and intuition of the die designers. The designed and manufactured dies are usually tested and modified many times before putting into practical extrusion production, and difficult to be guaranteed as optimal ones. In this paper a method of die design based on numerical simulation was proposed in order to optimize the die structure and enhance the level of die design. Firstly, the extrusion process of a large wallboard of high-speed train was simulated by means of HyperXtrude software. It was found that a severe non-uniform velocity distribution emerged in the cross-section of the extrudate and twist deformation occurred, therefore the initial die was not an acceptable one. Then, three times of modifications to the die structure were made to optimize the die structure and improve the product quality. Finally, an optimal die structure with uniform material flow velocity in the cross-section of the die exit was obtained. A sound wallboard extrudate of high-speed train was produced. The die design methods for complex extrusion profiles were summarized and proposed, including the design methods of porthole area of multi-cavity dies, the baffle plate, and the sunken port bridge structure.

RETRACTED: A Novel Method for the Treatment of Wastewater Containing High Concentration of Copper and Arsenic

Arsenic contamination of water and associated health risks have been reported in many regions of China. Leaching of arsenic from industrial wastewater into groundwater may cause severe contamination, which requires proper treatment before its emission. Therefore, sulfur dioxide reduction combined diffusion dialysis method is adopted to dispose the wastewater containing high concentration of copper and arsenic. Effects of the sulfur dioxide reduction process of the flow of sulfur dioxide, reaction time, reaction temperature and stirring speed and the diffusion dialysis process of the influent acidity, water flow velocity and material flow velocity on the ratio of separation of arsenic and copper were studied in this paper. The results show that on the conditions of the flow of sulfur dioxide of 3 kg/h, reaction time of 1h, at room temperature, stirring speed of 800 r/min and influent acidity of 5 g/L, water flow velocity of 400 ml/h, material flow velocity of 400 ml/h, the integrated effect of separation is best. The separation ratio of copper reaches 94.71 % and that of arsenic is up to 95.63 %.

Die structure optimization for a large, multi-cavity aluminum profile using numerical simulation and experiments

The steady state extrusion process of a large, multi-cavity aluminum profile for high-speed train was simulated using the Arbitrary Lagrangian Eulerian (ALE) algorithm. The simulation result of the initial design shows that the material flow velocity in the bearing exit is non-uniform. Comparing the obtained extrudate front end of the simulation with the experimental results of the initial design, it is clear that the metal in thick-walled regions of the profiles in both results flows faster than that in the other regions of the profiles. Moreover, the distorted metal in the six inclined ribs shown in both results are very similar to each other. Aiming at a uniform flow velocity, four kinds of structure optimizations were proposed and simulated. The methods of resizing portholes, adding bosses, chamfering mandrels, and adjusting the length of the bearings can balance the local metal flow velocity effectively. Finally, a perfect simulation result with exit velocity difference of 18.7mm/s and little distortion was obtained. Through the effective prediction of flow velocity in the simulation extrusion, the qualified profiles with few trial and error extrusions were manufactured successfully. The case study demonstrates that the ALE method is a viable predictive tool for die design, and the approach is applicable to the extrusion of other alloys for any other extrudate shapes.

Material and velocity effects on cavitation erosion pitting

Cavitation erosion during the incubation period was investigated via pitting tests conducted on three different materials: an Aluminum alloy, a Nickel Aluminum Bronze alloy and a Duplex Stainless Steel. Pitting tests were conducted in a cavitation tunnel in the velocity range 45-90 m/s at a constant cavitation number. The test section was made of a straight nozzle 16 mm in diameter discharged into the radial 2.5 mm space between two flat walls. Cavitation appears in the form of a toroidal cavity attached to the nozzle exit and damage on the samples facing the nozzle is concentrated in a circular ring centered in the cavity closure region. The exposure time was adjusted to avoid pit overlapping. The material surface was examined using a conventional contact profilometer which allowed us to identify the pits, count them, and measure their main characteristics such as depth, surface area, and volume. From these the pitting rate, the coverage rate, and the depth of deformation rate were defined. Pits were classified according to their diameter. For all materials and operating conditions, pitting rate appears to follow an exponential law in relation to the pit diameter. This law depends upon two parameters only, which were identified as the coverage time (i.e. the time required for the surface to be covered by erosion pits) and a characteristic pit diameter i, which corresponds to the pits whose contribution to the coverage process is the highest. Scaling laws for pitting were derived accounting for both material properties and flow velocity, and a procedure to make pitting test results non-dimensional is proposed. The influence of the material on pitting test results was analyzed. It is shown that the damage is not correlated in simple terms with the elastic limit determined from conventional tensile tests and it is conjectured that other parameters such as the strain rate might play a significant role and should be included in the analysis. The effect of flow velocity on both parameters and i was analyzed and a classical power law was found for the influence of the flow velocity on pitting rate for all three materials. Finally, some analysis and discussion is given concerning distributions of pit volume and pit depth.

Optimization design of baffle plates in porthole die for aluminium profile extrusion

During the hot extrusion, material flow uniformity plays an important role in the extrusion process and product quality. In practice, material flow could be balanced by many means, e.g. by adjusting the layout and shapes of portholes, by designing various levels of welding chamber, or by taking various bearing lengths. The purpose of this study was to optimize layout and heights of baffle plates in the welding chamber in order to balance material flow. First, the extrusion process was simulated by means of HyperXtrude. Due to the large velocity difference in the cross-section of the profile obtained from initial numerical simulation, baffle plates would be adjusted. By several adjustments, an optimal die structure with uniform material flow velocity in the cross-section of the extrudate was obtained and a sound profile produced. Therefore, baffle plates could effectively balance material flow during the extrusion process and this study could provide effective guidance for practical production.

Die Optimal Design for a Large Diameter Thin-Walled Aluminum Profile Extrusion by ALE Algorithm

Extrusion process of a large diameter thin-walled aluminum profile was simulated by Arbitrary Lagrangian Eulerian (ALE) algorithm based on HyperXtrude software. The results show that the material flow velocity in the bearing exit of the initial design die is non-uniform. Three times modifications were performed and simulated. The optimal design with more uniform flow velocity in the bearing exit was obtained.

Effects of flow velocity on electrochemical behavior of seachest 5083-H116 Al alloy for ship

Electrochemical behavior of 5083-H116 Al alloy with flow velocity of seachest material for Al ship was evaluated. To examine the electrochemical characteristics of flow velocity and its effects on the performance of the alloy, experiments were conducted at four flow velocity variables using static state with an agitator. An ultrasonic vibration generator using piezoelectric effect was used in cavitation test according to the requirements of in ASTM-G32. The results show that the corrosion current density and damage were increased by applying the flow velocity compared to static state. Therefore, it is determined that the case of applying flow velocity is weaker to the corrosion.

Three-Dimensioned Extrusion Simulation and Analysis of Bending Aluminum-Alloy Tube Based on Deform Software

In this paper three numerical models , eccentric extrusion method to prepare bending tube ,concentric partial material extrusion method to prepare bending tube, differential velocity extrusion method to prepare bending tube , are built and simulated . Furthermore analyses distribution of material flow velocity filed, load prediction, distribution of simulated tube wall thickness and so on. Though analysis and verification, we can draw the conclusion that three kinds of process methods are feasible, and avoid the quality defect caused by the traditional manufacturing method such as non-uniform wall thickness and wrinkling .They will have practice directive significance for improving bending tube.

Tectonic events, continental intraplate volcanism, and mantle plume activity in northern Arabia: Constraints from geochemistry and Ar‐Ar dating of Syrian lavas

New 40Ar/39Ar ages combined with chemical and Sr, Nd, and Pb isotope data for volcanic rocks from Syria along with published data of Syrian and Arabian lavas constrain the spatiotemporal evolution of volcanism, melting regime, and magmatic sources contributing to the volcanic activity in northern Arabia. Several volcanic phases occurred in different parts of Syria in the last 20 Ma that partly correlate with different tectonic events like displacements along the Dead Sea Fault system or slab break‐off beneath the Bitlis suture zone, although the large volume of magmas and their composition suggest that hot mantle material caused volcanism. Low Ce/Pb (<20), Nb/Th (<10), and Sr, Nd, and Pb isotope variations of Syrian lavas indicate the role of crustal contamination in magma genesis, and contamination of magmas with up to 30% of continental crustal material can explain their 87Sr/86Sr. Fractionation‐corrected major element compositions and REE ratios of uncontaminated lavas suggest a pressure‐controlled melting regime in western Arabia that varies from shallow and high‐degree melt formation in the south to increasingly deeper regions and lower extents of the beginning melting process northward. Temperature estimates of calculated primary, crustally uncontaminated Arabian lavas indicate their formation at elevated mantle temperatures (Texcess ∼ 100–200°C) being characteristic for their generation in a plume mantle region. The Sr, Nd, and Pb isotope systematic of crustally uncontaminated Syrian lavas reveal a sublithospheric and a mantle plume source involvement in their formation, whereas a (hydrous) lithospheric origin of lavas can be excluded on the basis of negative correlations between Ba/La and K/La. The characteristically high 206Pb/204Pb (∼19.5) of the mantle plume source can be explained by material entrainment associated with the Afar mantle plume. The Syrian volcanic rocks are generally younger than lavas from the southern Afro‐Arabian region, indicating a northward progression of the commencing volcanism since the arrival of the Afar mantle plume beneath Ethiopia/Djibouti some 30 Ma ago. The distribution of crustally uncontaminated high 206Pb/204Pb lavas in Arabia indicates a spatial influence of the Afar plume of ∼2600 km in northward direction with an estimated flow velocity of plume material on the order of 22 cm/a.

Re-visiting 1-D hypervelocity penetration

Abstract Classical, one-dimensional theory of hydrodynamic penetration is used as the basis of establishing simplified analytical relationships describing energy, momentum, and power deposition during hypervelocity impact events. A concise overview of the 1-D model is given followed by a select grouping of terms into relationships that offer first-order criteria for making engineering design considerations on relevant applications and assist in the analysis of experimental observations. Momentum, energy, and power deposition are found to be proportional to second, third and fourth power exponents, respectively. These analytical terms are presented for constant velocity gradient, i.e. fixed length, rods as well as linear velocity gradient rods, such as shaped charge jets. The role of penetrator-to-target density ratio is then examined in terms of the backflow, or reverse flow of 1-D penetration. Again, the non-dimensional ratio of penetrator-to-target mass density is used to compare the relative velocity of material flow during penetration. The relationship highlights the role of penetrator materials for achieving desired effects in these hypervelocity, terminal ballistics events. Albeit the relationships are derived on the assumptions for hydrodynamic processes, their generality of form and ease of implementation make them a useful first-order description for engineering insight and application over a broad range of velocities.

Investigation into hydrodynamic deep drawing assisted by radial pressure: Part II. Numerical analysis of the drawing mechanism and the process parameters

A new method, named hydrodynamic deep drawing assisted by radial pressure, is proposed. Different from the conventional hydrodynamic deep drawing process (HDD), a radial pressure is loaded along the blank rim to reduce the drawing force. To explore the internal deformation mechanism, the numerical simulation was used for analyzing the forming process of an Al–Mg–Si aluminum alloy by using explicit dynamic finite element calculations utilizing non-quadratic yield criteria. Firstly, the loading boundary conditions were studied for the purpose of calculating the forming process accurately. The effects of sheet anisotropy on the material flow velocity distribution, the stress distribution, the strain distribution and the sheet thickness distribution were investigated. The optimum parameters were studied so that the flange wrinkling and fracture can be predicted and controlled effectively. The simulated results were in good agreement with the experiment.

The Thickness of Parison Layer Formed in Blow Method

In forming a glass container by the blow-blow method, parison is formed in a blank mold by air blow. It is then blown in a blow mold and inflated to form a bottle. Since the final shape of a bottle is designated from the beginning, the final wall thickness of a bottle is controlled by the shape and the wall thickness of an intermediate product parison. In this way the design of parison is important, but it is difficult to study how parison is formed as glass materials to be formed are extremely hot. With this in mind, the author used silicone oil in place of high-temperature glass and measured temperature at which parison is produced and the wall thickness of parison being produced. The author also studied, from the calculation of glass flow, the relationships between variations in equal temperature distribution and temperature of parison and the wall thickness of parison. In addition, the author studied causes of bottom wall thickness and waved faults and countermeasures to be taken. The result is that we have reached the following observations: (1) The wall thickness of parison from its mouth to gob line is closely related to the flow velocity of glass material and is nearly proportionate to the parison diameter. (2) Variations in the temperature distribution of parison according to glass temperature, mold temperature and the length of time during which glass stays in a blank mold cause the flow velocity of glass material to change which in turn affects the wall thickness of parison. (3) The wall thickness of the bottom below the gob line decreases or increases depending upon the length from the gob line to the bottom of parison (the surface area of glass in contact with the mold).