Computer analysis of workpieces auto-heating during surfacing

2020 ◽  
pp. 534-539
Author(s):  
S.S. Poloskov ◽  
V.A. Erofeev ◽  
D.S. Buzorina ◽  
M.A. Sholokhov
Keyword(s):  
Thermal Conductivity ◽  
Nonlinear Equation ◽  
Heating Temperature ◽  
Spherical Surface ◽  
Base Material ◽  
Ball Valve ◽  
The Stability ◽  
Clamping Device ◽  
Develop Program ◽  
Heterogeneous Layer

The method for calculating of the temperature when surfacing of complex-shaped workpiece by solving non-stationary and nonlinear equation of thermal conductivity in heterogeneous layer, which allows taking into account the elements of the clamping device and not describing numerous boundary conditions is presented. Example for calculating of the heating temperature of spherical plug of the ball valve during surfacing on spherical surface via welding deposition with spiral and back-and-forth movement of the heat source is given. The calculated temperature variation in the base material during the surfacing of specifi c workpieces makes it possible to develop program for adjusting of the surfacing mode to ensure the stability of the dimensions and properties of the deposited layer.

An Experimental Investigation on Thermal Conductivity and Viscosity of Graphene doped CNTs /TiO2 Nanofluid

2020 ◽  
Vol 17 (3) ◽  
Author(s):  
A.M. Zetty Akhtar ◽  
M.M. Rahman ◽  
K. Kadirgama ◽  
M.A. Maleque
Keyword(s):  
Thermal Conductivity ◽  
Zeta Potential ◽  
Base Fluid ◽  
Minimum Quantity Lubrication ◽  
Cutting Fluid ◽  
Cutting Zone ◽  
Observation Method ◽  
The Stability ◽  
The Relationship ◽  
Zeta Potential Analysis

This paper presents the findings of the stability, thermal conductivity and viscosity of CNTs (doped with 10 wt% graphene)- TiO2 hybrid nanofluids under various concentrations. While the usage of cutting fluid in machining operation is necessary for removing the heat generated at the cutting zone, the excessive use of it could lead to environmental and health issue to the operators. Therefore, the minimum quantity lubrication (MQL) to replace the conventional flooding was introduced. The MQL method minimises the usage of cutting fluid as a step to achieve a cleaner environment and sustainable machining. However, the low thermal conductivity of the base fluid in the MQL system caused the insufficient removal of heat generated in the cutting zone. Addition of nanoparticles to the base fluid was then introduced to enhance the performance of cutting fluids. The ethylene glycol used as the base fluid, titanium dioxide (TiO2) and carbon nanotubes (CNTs) nanoparticle mixed to produce nanofluids with concentrations of 0.02 to 0.1 wt.% with an interval of 0.02 wt%. The mixing ratio of TiO2: CNTs was 90:10 and ratio of SDBS (surfactant): CNTs was 10:1. The stability of nanofluid checked using observation method and zeta potential analysis. The thermal conductivity and viscosity of suspension were measured at a temperature range between 30˚C to 70˚C (with increment of 10˚C) to determine the relationship between concentration and temperature on nanofluid’s thermal physical properties. Based on the results obtained, zeta potential value for nanofluid range from -50 to -70 mV indicates a good stability of the suspension. Thermal conductivity of nanofluid increases as an increase of temperature and enhancement ratio is within the range of 1.51 to 4.53 compared to the base fluid. Meanwhile, the viscosity of nanofluid shows decrements with an increase of the temperature remarks significant advantage in pumping power. The developed nanofluid in this study found to be stable with enhanced thermal conductivity and decrease in viscosity, which at once make it possible to be use as nanolubricant in machining operation.

An analysis of the transport properties and mechanical stability of rapidly solidified Al-Sb alloy

2015 ◽  
Vol 10 (2) ◽  
pp. 2663-2681
Author(s):  
Rizk El- Sayed ◽  
Mustafa Kamal ◽  
Abu-Bakr El-Bediwi ◽  
Qutaiba Rasheed Solaiman
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Melt Spinning ◽  
Elastic Moduli ◽  
Mechanical Stability ◽  
Microstructural Analysis ◽  
Alloy System ◽  
Antimony Content ◽  
The Stability ◽  
Rapidly Solidified

The structure of a series of AlSb alloys prepared by melt spinning have been studied in the as melt–spun ribbons  as a function of antimony content .The stability  of these structures has  been  related to that of the transport and mechanical properties of the alloy ribbons. Microstructural analysis was performed and it was found that only Al and AlSb phases formed for different composition.  The electrical, thermal and the stability of the mechanical properties are related indirectly through the influence of the antimony content. The results are interpreted in terms of the phase change occurring to alloy system. Electrical resistivity, thermal conductivity, elastic moduli and the values of microhardness are found to be more sensitive than the internal friction to the phase changes. 

Effective thermal conductivity of open-pore metal foams as a function of the base material

2015 ◽  
Vol 57 (10) ◽  
pp. 825-836 ◽  
Author(s):  
Alexander Martin Matz ◽  
Bettina Stefanie Mocker ◽  
Norbert Jost ◽  
Peter Krug
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Base Material ◽  
Metal Foams

scholarly journals Design of Thermal Insulation Materials with Different Geometries of Channels

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2217
Author(s):  
Daniela Șova ◽  
Mariana Domnica Stanciu ◽  
Sergiu Valeriu Georgescu
Keyword(s):  
Thermal Conductivity ◽  
Porous Structure ◽  
Base Material ◽  
Cost Effective ◽  
Heat Radiation ◽  
Average Temperature ◽  
Temperature Regimes ◽  
The Face ◽  
Inclined Channels ◽  
Air Channels

Investigating the large number of various materials now available, some materials scientists promoted a method of combining existing materials with geometric features. By studying natural materials, the performance of simple constituent materials is improved by manipulating their internal geometry; as such, any base material can be used by performing millimeter-scale air channels. The porous structure obtained utilizes the low thermal conductivity of the gas in the pores. At the same time, heat radiation and gas convection is hindered by the solid structure. The solution that was proposed in this research for obtaining a material with porous structure consisted in perforating extruded polystyrene (XPS) panels, as base material. Perforation was performed horizontally and at an angle of 45 degrees related to the face panel. The method is simple and cost-effective. Perforated and simple XPS panels were subjected to three different temperature regimes in order to measure the thermal conductivity. There was an increase in thermal conductivity with the increase in average temperature in all studied cases. The presence of air channels reduced the thermal conductivity of the perforated panels. The reduction was more significant at the panels with inclined channels. The differences between the thermal conductivity of simple XPS and perforated XPS panels are small, but the latter can be improved by increasing the number of channels and the air channels’ diameter. Additionally, the higher the thermal conductivity of the base material, the more significant is the presence of the channels, reducing the effective thermal conductivity. A base material with low emissivity may also reduce the thermal conductivity.

Dissipative instability of the MHD tangential discontinuity in magnetized plasmas with anisotropic viscosity and thermal conductivity

1996 ◽  
Vol 56 (2) ◽  
pp. 285-306 ◽  
Author(s):  
M. S. Ruderman ◽  
E. Verwichte ◽  
R. Erdélyi ◽  
M. Goossens
Keyword(s):  
Thermal Conductivity ◽  
Dispersion Equation ◽  
Viscosity Coefficient ◽  
Tangential Discontinuity ◽  
Stability Criteria ◽  
Threshold Velocity ◽  
Cold Plasmas ◽  
The Difference ◽  
The Stability ◽  
Anisotropic Viscosity

The stability of the MHD tangential discontinuity is studied in compressible plasmas in the presence of anisotropic viscosity and thermal conductivity. The general dispersion equation is derived, and solutions to this dispersion equation and stability criteria are obtained for the limiting cases of incompressible and cold plasmas. In these two limiting cases the effect of thermal conductivity vanishes, and the solutions are only influenced by viscosity. The stability criteria for viscous plasmas are compared with those for ideal plasmas, where stability is determined by the Kelvin—Helmholtz velocity VKH as a threshold for the difference in the equilibrium velocities. Viscosity turns out to have a destabilizing influence when the viscosity coefficient takes different values at the two sides of the discontinuity. Viscosity lowers the threshold velocity V below the ideal Kelvin—Helmholtz velocity VKH, so that there is a range of velocities between V and VKH where the overstability is of a dissipative nature.

Thermal Conductivity Performance Modeling and Characterization of a Novel Anisotropic Conductive Adhesive Used in Lead-Free Electronics Packaging

2012 ◽  
Author(s):  
Matthew J. Combs ◽  
S. Manian Ramkumar ◽  
Satish Kandlikar
Keyword(s):  
Thermal Conductivity ◽  
Base Material ◽  
Bond Line ◽  
Thermal Interface Material ◽  
The Novel ◽  
Conductive Adhesives ◽  
Curing Conditions ◽  
Bond Line Thickness ◽  
Significant Research ◽  
American Society

The continued desire to utilize an alternative to lead-based solder materials for electrical interconnections has led to significant research interest in Anisotropic Conductive Adhesives (ACAs). The use of ACAs in electrical connections creates bonds using a combination of metal particles and epoxies to replace solder. The novel ACA discussed in this paper allows for bonds to be created through aligning columns of conductive particles along the Z-axis. These columns are formed by the application of a magnetic field, during the curing process. The benefit of this novel ACA is that it does not require precise printing of the adhesive on pads and also enables the mass curing without creating shorts in the circuitry. This paper will present the findings of the thermal conductivity performance tests using the novel ACA and its applicability as a thermal interface material and for assembling bottom termination components, power devices, etc. The columns that act as electrical conduction paths also contribute towards the thermal conductivity. The thermal conductivity of the novel ACA was measured utilizing a system that is similar to that in ASTM (American Society of Testing Materials) D5470 standard. The goal was to examine the influence of Bond Line Thickness (BLT), particle loading densities, particle diameters and adhesive matrix curing conditions on the electrical and thermal performance of the novel ACA. This paper will also present a numerical model to describe the thermal behavior of the novel ACA. The novel ACA’s applicability for PCB-level assembly has also been successfully demonstrated by RIT, including base material characterization, effect of process parameters, failures, and long-term reliability. Reliability testing included the investigation of the assembly performance in temperature and humidity aging, thermal aging, air-to-air thermal cycling, and drop testing.

Resistance Welding Process Development and Optimization for Recycled High-Density Polyethylene (HDPE)

2015 ◽  
Author(s):  
Peter F. Baumann ◽  
Lucas Sendrowski
Keyword(s):  
Tensile Strength ◽  
Response Surface ◽  
High Density Polyethylene ◽  
Heating Temperature ◽  
Base Material ◽  
Heating Time ◽  
High Density ◽  
Hot Plate ◽  
Initial Testing ◽  
Hot Plate Welding

Large recycled high-density polyethylene (HDPE) structural members, difficult to manufacture by extrusion processes, have been created by the hot plate welding of simple plastic lumber sections. Hot plate welding generates better joint strength than any other welding method currently employed in plastic manufacturing. However, to achieve the desired temperature of the thick plate to melt the polymer uniformly, the process needs a high amount of heat energy requiring furnace (or resistance) heating of a considerable mass. A new method which could combine the heating element and a thin plate into one source could be more efficient in terms of heat loss and thus energy used. The premise of this investigation is to replace the hot plate with a very thin piece of high resistance nickel-chromium alloy ribbon to localize the application of heat within a plastic weld joint in order to reduce energy loss and its associated costs. This resistance ribbon method uses electrical current to reach an adequate temperature to allow for the welding of the HDPE plastic. The ribbon is only slightly larger than the welding surface and very thin to reduce the loss of excess heat through unused surface area and thick sides. The purpose of this project was to weld recycled high-density polyethylene (HDPE) using resistance welding and to match the tensile strength results considered acceptable in industry for hot plate welding, that is, equal to or greater than 80% of the base material strength. Information obtained through literature review and previous investigations in our laboratories established welding (heating) temperature and time as testing factors. Designed experimentation considered these factors in optimizing the process to maximize the weld tensile strength. A wide-ranging full-factorial experimental design using many levels was created for the initial testing plan. Tensile strengths obtained after welding under the various condition combinations of weld temperature and time revealed a region of higher strength values in the response surface. After the wide-range initial testing, the two control parameters, heating temperature and heating time, were ultimately set up in a focused Face Centered Cubic (FCC) Response Surface Method (RSM) testing design and the tensile strength response was then analyzed using statistical software. The results obtained indicated a strong correlation between heating time and heating temperature with strength. All welded samples in the final testing set exhibited tensile strength of over 90% base material, meeting the goal requirements. A full quadratic equation relationship for tensile strength as a function of welding time and temperature was developed and the maximum tensile strength was achieved when using 280°C for 60 seconds.

scholarly journals CLINICAL AND ANATOMICAL RESTORATION OF THE MASTICATORY GROUP OF TEETH WITH A BURDENED GENERAL STATUS

2019 ◽  
Vol 23 (5) ◽  
pp. 202-207
Author(s):  
E. O Kudasova ◽  
N. I Kagramanova ◽  
Ekaterina Vladimirovna Kochurova ◽  
L. V Gavrushova ◽  
V. N Nikolenko ◽  
...  
Keyword(s):  
Base Material ◽  
Spherical Shape ◽  
Gastrointestinal Diseases ◽  
Secondary Caries ◽  
Dental Examination ◽  
Filling Materials ◽  
Hard Tissues ◽  
The Stability ◽  
Group B ◽  
The Cost

Objective. The chewing group of teeth is intended for equally crusher of food and forming food lump. This group is presented by two kinds of teeth: premolars and molars, and more often affected by caries, because a lot of retention zones are contribute to the active delay of plaque and the appearance of carious cavities. It is happening before 18 years. In the absence of these teeth or badly damaged of the crown part, food is chewed badly and as a result, stomach contain extremely large pieces. But its size is impossible for physiological digestion by the gastrointestinal tract and as a consequence the occurrence of gastrointestinal diseases. According to modern data, to work with lesions of hard tissues of the teeth, namely the chewing group of teeth, it is advisable to use composite light-curing microhybrid materials, which are characterized by particles close to the spherical shape. The aim of this study is determination of the possibility using a budgetary aesthetic composite for restorative restoration of the masticatory group of teeth in patients with a burdened anamnesis. Material and methodology. Was examined 22 people with aesthetic and anatomical disorders of the vestibular and occlusal surface of the hard tissues of the chewing group of teeth (n=154), followed by their recovery. The stability of filling materials was assessed according to Ryge-criteria: color coincidence, discoloration of the marginal segment, marginal adaptation, anatomical shape integrity, restoration surface, secondary caries. Results. Clinical and dental examination showed all the above violations of existing restorations (according to Ryge classification) in patients before restoration manipulations. After 1 week after the restoration, the examination showed that both groups of composites completely restore the anatomical and aesthetic chewing group of teeth and meet all the criteria. After 3 months, the assessmen t of the restoration by the composite of group A and group B did not reveal evidence of secondary caries on the perimeter of the restorations. Clinical and dental examination after 6 months showed minor changes in the restorations of composites of both groups in assessing the stability of color (90.9% and 83.3% in groups A and B) and the stability of surface polishing (89.6% and 81.8%, respectively). Discussion. The main signs of the restoration, which are undergoing changes, are discoloration, as well as the preservation of the smoothness of the surface regardless of the cost and branding of the base material.

scholarly journals Bacteriocin Activity of Lactic Acid Bacteria Isolated from Rumen Fluid of Thin Tail Sheep

2019 ◽  
Vol 43 (3) ◽  
Author(s):  
Okti Widayati ◽  
Zaenal Bachruddin ◽  
Chusnul Hanim ◽  
Lies Mira Yusiati ◽  
Nafiatul Umami
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Ph Value ◽  
Heating Temperature ◽  
Rumen Fluid ◽  
Bacteriocin Activity ◽  
Significant Difference ◽  
Sheep Rumen ◽  
The Stability ◽  
Range Test

The objective of this study was to determine the activity and the stability of bacteriocin from lactic acid bacteria (BAL) isolated from rumen fluid of thin-tail sheep under the temperature (80, 100, and 121°C), pH (3, 7, and 10), and the length of storage (for 2 weeks under the temperature -8, 11, and 29°C). Lactic acid bacteria obtained by isolation, selection, and identification of thin-tailed sheep rumen fluid were used for bacteriocin production. The crude bacteriocin was partially purified using 70% ammonium sulfate, then was dialysis for 12 hours. The obtained bacteriocin then tested its inhibitory activity against E.coli (representing Gram-negative) and S. aureus (representing Gram-positive) under temperature (80, 100, and 121°C), pH (3, 7, and 10), and the length of storage (for 2 weeks under the temperature -8, 11, and 29°C). The data of bacteriocin activity based on pH, temperature, and the length of storage were analyzed with factorial, then when there was a significant difference of variable because treatment was continued with Duncan's Multiple Range Test (DMRT) test. The results showed that the bacteriocin activity of the three types of BAL against S.aureus is greater than E.coli. The highest activity was shown in pH 3, while the lowest activity was shown at pH 10 (P<0.01). The highest activity was shown at a heating temperature of 100°C, while the lowest activity was shown at a heating temperature of 80°C (P<0.01). The activity of bacteriocin produced by BAL 0 A, BAL 1 A, and BAL 4 C tended to be stable to the heating temperature of 80, 100, and 121°C but decreased with increasing pH value (pH 3, 7, and 10). The best of bacteriocin activity was found at pH 3 (acid), heating at 100°C, and stored at -8°C for 14 days.

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