scholarly journals Modeling of the compaction of powder filter elements during radial isostatic pressing

2020 ◽  
Vol 2020 (1) ◽  
pp. 33-39
Author(s):  
O. Y. Povstyanoy ◽  
◽  
A. O. Mikhailov ◽  
V. D. Rud ◽  
O. V. Mikhailov ◽  
...  
Keyword(s):  
Outer Layer ◽  
Elastic Element ◽  
Deformable Body ◽  
Single Layer ◽  
Steel Powder ◽  
Axial Direction ◽  
Isostatic Pressing ◽  
Multilayer Filters ◽  
Porous Permeable Material ◽  
The Difference

The method of computer simulation was used to study the process of radially isostatic pressing of filter elements made of steel powder BBS15. Powder compaction occurs under the influence of an elastic ele¬ment made of polyurethane. The volume of the deformable body is considered as a continuous medium. To describe the behavior of this medium, the relations of the theory of plasticity of a porous body and the finite element method are used. The patterns of compaction of products of two types are considered (hollow cylinders, including multilayer ones, and filters of complex shape in the form of a bulb). When pressing multilayer filters, the load was removed after compaction of each layer. A new powder was placed in the cavity between the obtained layer and the elastic element, which took its original shape. Further, the pressing process was continued. The porosity distribution in the case of compaction of a single-layer cylindrical filter is uneven. The value of porosity increases with increasing radius. As the degree of deformation increases, the difference between the porosity of the material at the inner and outer surfaces of the filter decreases. The compaction of the outer layer of the two-layer filter occurs in the same way as the preliminary compaction of the first (inner) layer. The denser inner layer deforms slightly and acts as a mandrel. Further, the outer layer is compacted and both layers are deformed. The compaction of the layers of a three-layer filter is similar. The thickness and porosity of the layers can be controlled by changing the initial porosity of the powder, the inner diameter of the elastic element, as well as the pressing load. Two compaction schemes (radial and axial) were considered in the manufacture of complex-shaped filters in the form of a bulb. The distribution of porosity is uneven and depends on the compaction scheme. The material of the filter wall is compacted more intensively in the case of radial pressing. The porosity is higher at the outer surface of the filter wall and lower at its inner surface.The bottom material of the filter is compacted more intensively in the case of axial pressing.The use of the pressing scheme, in which the powder is first compacted in the radial and then in the axial direction, allows to get a more uniform distribution of porosity. Keywords: radial isostatic pressing, porous permeable material, filter, density distribution, porosity.

Shape-driven control of layer height in robotic wire and arc additive manufacturing

2019 ◽  
Vol 25 (10) ◽  
pp. 1637-1646 ◽  
Author(s):  
Bohao Xu ◽  
Xiaodong Tan ◽  
Xizhi Gu ◽  
Donghong Ding ◽  
Yuelin Deng ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Deposition Rate ◽  
Control Method ◽  
Single Layer ◽  
Optimization Method ◽  
Content Type ◽  
Layer Height ◽  
Layer Deposition ◽  
Complex Shapes ◽  
The Difference

Purpose Once an uneven substrate is aligned, traditional control theories and methods can be used on it, so aligning is of great significance for the development of wire and arc additive manufacturing (WAAM). This paper aims to propose a shape-driven control method for aligning a substrate with slopes to expand the application of WAAM. Design/methodology/approach A substrate with slopes must be aligned by depositing weld beads with slopes. First, considering the large height differences of slopes, multi-layer deposition is needed, and the number of layer of weld beads must be ascertained. Second, the change in the deposition rate is controlled as a ramp function to generate weld beads with slopes. Third, the variation of the deposition rate must be fine-tuned to compensate for the deviation between the actual and theoretical layer heights at the deposition of each layer. Finally, the parameters of the ramp functions at the deposition of each layer are determined through an optimization method. Findings First, to model the response function of layer height to deposition rate, the experiments are conducted with the deposition rate jumping from 4 to 8 mm/s and from 8 to 4 mm/s. When the deposition rate jumps from 4 to 8 mm/s and from 8 to 4 mm/s, the difference in the height of each layer decreases as the number of layer increases. Second, the variation of the deposition rate can be fine-tuned based on the deviation between the measured and theoretical layer heights because the variation of the deposition rate is proportional to the layer height when the initial and end deposition rates are near 4 or 8 mm/s, respectively. Third, the experimental results demonstrate that the proposed method is effective for single-layer aligning and aligning a substrate with one or more slopes. Originality/value The proposed method can expand the application of WAAM to an uneven substrate with slopes and lays the foundation for aligning tasks focused on uneven substrates with more complex shapes.

Aerodynamic Data for Two Variants of Root Turbine Blade Sections for a 54″ Turbine Rotor Blade

2014 ◽  
Author(s):  
David Šimurda ◽  
Martin Luxa ◽  
Pavel Šafařík ◽  
Jaroslav Synáč ◽  
Bartoloměj Rudas
Keyword(s):  
Limit Load ◽  
Axial Direction ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Angle Of Incidence ◽  
Flow Angle ◽  
Turbine Rotor Blade ◽  
Blade Cascade ◽  
The Difference ◽  
Kinetic Energy Loss

Aerodynamic investigations were performed on planar blade cascades representing two alternative root sections of rotor blades 54″ in length with straight fir-tree root. Each of the variants was designed for different number of blades in the rotor. This paper presents the results of measurements showing the dependency of the kinetic energy loss coefficient and the exit flow angle on the exit isoentropic Mach number and the angle of incidence. Images of the flow fields are also presented. The experimental data is analyzed to assess and document the difference between the two root section designs. Results show that requirement of straight fir tree root leading to high design incidence angles significantly limit operation range. Also in case of root sections with high exit Mach numbers a limit load conditions are an issue. In order to utilize available pressure drop blade cascade throat/pitch ratios should be kept as high as possible which favorites variant with lower number of blades and higher outlet metal angle (relative to axial direction).

COMPARATIVE ANALYSIS OF THE RESULTS OF MODELING THE DEPRECIATION OF SMALL ARMS WHEN FIRED IN QUASI-STATIC AND DYNAMIC PRODUCTIONS

2020 ◽  
Vol 6 ◽  
pp. 24-28
Author(s):  
V.L. BARANOV ◽  
A.S. LEVIN
Keyword(s):  
Comparative Analysis ◽  
Elastic Element ◽  
Shock Absorber ◽  
Initial Conditions ◽  
Small Arms ◽  
Dynamic Formulation ◽  
The Difference

Various variants of the initial conditions for calculating the dynamics of the elastic element of the shock absorber are considered. A comparative analysis of the influence of initial conditions on the difference in calculations in the quasi-static and dynamic formulation is carried out.

Characterization and Design of Honeycomb Absorbing Materials

2019 ◽  
Vol 294 ◽  
pp. 51-56
Author(s):  
Hui Min Sun ◽  
Le Chen ◽  
Zhao Zhan Gu
Keyword(s):  
Double Layer ◽  
Low Frequency ◽  
Single Layer ◽  
Electromagnetic Parameters ◽  
Honeycomb Sandwich ◽  
Absorbing Materials ◽  
Absorbing Material ◽  
The Difference ◽  
Free Space Method ◽  
Honeycomb Sandwich Structure

Honeycomb absorbing materials are anisotropic structural materials. Depending on the size of honeycomb lattices, the absorbent content of the impregnated layer is different, the thickness of the impregnated layer is different, and the absorbing function of the impregnated honeycomb absorbing materials is also different. For the characterization of electromagnetic parameters of honeycomb absorbing materials, this paper adopts free space method for testing, uses CST software for modeling, and inverts the electromagnetic parameters of honeycomb absorbing structures. The absorbing performance of single-layer and double-layer honeycomb sandwich structures was simulated by RAM Optimizer software. The research shows that the height of the single-layer honeycomb absorbing material is 22mm. When the absorber content is 65%, 75% and 85% respectively, the harmonic peak moves slightly to the low frequency electromagnetic wave with the increase of the absorber content, but the absorbing strength decreases with the increase of the absorber content. For the double-layer honeycomb sandwich structure, the difference of absorber content in the upper and lower honeycomb absorbing materials is smaller, and the absorbing performance is stronger. When the thickness of the wave-transparent panel is thinner, the harmonic peak of the absorbing curve moves slightly to the high frequency.

scholarly journals The Secrets of Beautiful Hair: Why is it Flexible and Elastic?

Cosmetics ◽  
2019 ◽  
Vol 6 (3) ◽  
pp. 40 ◽  
Author(s):  
Mikako Ezure ◽  
Noriyuki Tanji ◽  
Yukari Nishita ◽  
Takashi Mizooku ◽  
Shinobu Nagase ◽  
...  
Keyword(s):  
Physical Properties ◽  
Layered Structure ◽  
Outer Layer ◽  
New Technology ◽  
Selective Reduction ◽  
Cell Distribution ◽  
Cortical Cells ◽  
The Difference ◽  
The Relationship ◽  
Hair Surface

Beautiful hair, so called “SHINAYAKA” hair in Japanese, has a good appearance not only when stationary but also when in motion, and it is a highly desirable hair condition for Japanese consumers. We investigated such SHINAYAKA hair, which was selected by sensory evaluation, for the relationship between physical properties, such as flexibility and elasticity, and hair structure. It has already been reported that human hair cortical cells have two types, similar to wool: the ortho-like cortex and the para-like cortex. Microscopic observation revealed that the ortho-like cortex is distributed in the outer layer of the hair (near the hair surface) and the para-like cortex exists in the inner layer (near the center of the fiber). This cell distribution, a concentric double-layered structure, was deemed to be a characteristic of SHINAYAKA hair. Furthermore, analysis of physical properties showed the difference between the elasticity of the outer layer and inner layer, and that this difference was bigger in SHINAYAKA hair compared to other hair. This phenomenon was observed not only in Japanese hair, but also in Caucasian hair. In addition, we have developed a new technology for creating “SHINAYAKA” hair by treatment with succinic acid. Inflexible and inelastic hair can be changed by this treatment, and its flexibility and elasticity improve by selective reduction of stiffness of the outer layer.

An almost-inviscid geostrophic flow

1962 ◽  
Vol 12 (1) ◽  
pp. 129-134 ◽  
Author(s):  
L. M. Hocking
Keyword(s):  
Reynolds Number ◽  
Fluid Velocity ◽  
Equations Of Motion ◽  
Axial Direction ◽  
Reynolds Numbers ◽  
Rigid Rotation ◽  
Velocity Variation ◽  
Geostrophic Flow ◽  
The Difference ◽  
Streaming Motion

An almost rigid rotation of a viscous fluid is produced by dividing the containing cylinder into two sections and rotating them at slightly different speeds. The fluid velocity can be separated into two parts, a swirl about the axis and a streaming motion in the axial planes. When the difference in the speeds of rotation of the two sections is small, the equations of motion can be linearized. The solution is found for large Reynolds numbers and provides an illustration of the way in which the conditions of geostrophic flow (no velocity variation in the axial direction and an inability to insist on undistrubed flow at infinity) are approached as the Reynolds number tends to infinity.

scholarly journals Development of a novel high straining backward extrusion process

2018 ◽  
Vol 190 ◽  
pp. 06001 ◽  
Author(s):  
Qiang Wang ◽  
Zhimin Zhang ◽  
Xubin Li ◽  
Huifang Zhang
Keyword(s):  
Flow Direction ◽  
Effective Strain ◽  
Fibrous Tissue ◽  
Axial Direction ◽  
Extrusion Process ◽  
Backward Extrusion ◽  
New Process ◽  
Processed Sample ◽  
The Difference ◽  
Low Performance

In this study, a new method of backward extrusion is proposed. In this new process, a punch with a movable mandrel was designed. A hollow billet was firstly backward extruded and subsequently upset with the use of the punch after the mandrel returned. The extrusion and upsetting processes were successively executed in order for a higher effective strain to be imposed and a fibrous tissue flow direction to be controlled. In order for the capability of this process to be investigated, experimental and finite element (FE) methods were used. The effective strain of the final part prepared by both the conventional and the new process were compared along the bottom radial and wall axial direction respectively. In the results, it is shown that the plastic strain applied through the processed sample was approximately higher in twice the value of the sample processed via conventional backward extrusion. Consequently, this may improve the mechanical properties and anisotropy of the final products. The difference of the UTS and the TYS between radial and tangential at the bottom was less than 3%.This new process has proven to be promising for parts with a central hole at the bottom production in order for the parts low performance to be improved.

scholarly journals Seamless Tube-Type Heater with Uniform Thickness and Temperature Distribution Based on Carbon Nanotubes Aligned by Circumferential Shearing

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3283 ◽  
Author(s):  
Yoonchul Sohn ◽  
Dongearn Kim ◽  
Sung-Hoon Park ◽  
Sang-Eui Lee
Keyword(s):  
Temperature Distribution ◽  
Axial Direction ◽  
Circumferential Direction ◽  
Laser Printer ◽  
Seamless Tube ◽  
Uniform Temperature ◽  
Rubber Composite ◽  
Tube Type ◽  
The Difference

The uniform temperature distribution, one of the requirements for long-term durability, is essential for composite heaters. An analytical model for temperature distribution of a tube-type heater was derived, and it revealed that thickness uniformity is one order more important than intrinsic material properties such as density, heat capacity, and electrical conductivity of the heating tube. We introduced a circumferential shearing process to fabricate a flexible, seamless tube-type heating layer of carbon nanotube/silicone rubber composite with outstanding uniform distribution of thickness and temperature, which may be attributed to a shorter characteristic dimension in the circumferential direction than in the axial direction. The temperature uniformity was experimentally verified at various temperatures under heating. The difference in measured thickness and temperature in circumferential direction was within ±1.3~3.0% (for tavg = 352.7 μm) and ±1.1% (for Tavg = 138.8 °C), respectively, all over the heating tube. Therefore, the circumferential shearing process can be effective for cylindrical heaters, like a heating layer of a laser printer, which fuse toners onto papers during printing.

Quasi-Static and Dynamic Axial Crushing of Various Polygonal Tubes

2007 ◽  
Vol 340-341 ◽  
pp. 1399-1404 ◽  
Author(s):  
Minoru Yamashita ◽  
Toshio Hattori ◽  
Naoya Nishimura ◽  
Y. Tange
Keyword(s):  
Circular Tube ◽  
Axial Direction ◽  
Plastic Property ◽  
Absorption Capacity ◽  
Deformation Pattern ◽  
Explicit Finite Element ◽  
Collapse Mode ◽  
The Difference ◽  
Dynamic Loading Conditions ◽  
Crush Strength

Various polygonal tubes were compressed in the axial direction under quasi-static and dynamic loading conditions. The effect of the polygonal shape and the wall thickness on the crush behavior is investigated, in which the cyclic buckling takes place. The numbers of polygonal edges were 3, 4, 5, 6 and 7 in the experiment. A circular tube was also tested for comparison. The tubes were machined from aluminum alloy A5056 bar. Crush strength is estimated as an index of the energy absorption capacity of the tube. It increases with increasing the number of polygonal edges of the tube, although it almost saturates when the number of polygonal edges is more than 6. For the wider variety of polygonal tubes than that in the experiment, numerical simulation is performed using the dynamic explicit finite element code DYNA3D. The computed crush behavior well agrees with the corresponding experimental one, however, the difference in collapse mode arises due to the slight imperfections in experiment. The deformation pattern becomes more irregular for the thinner-walled tube. Further, it is presumed that the large hardening exponent in the plastic property of the material could prevent the buckling switching from the symmetric mode to asymmetric one in the crushing of circular tube.

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