specific load
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2021 ◽  
Vol 2021 (6) ◽  
pp. 5448-5451
Author(s):  
JIRI ZACAL ◽  
◽  
JAN PAVLIK ◽  
IVANA KUNZOVA ◽  
◽  
...  

The area of flange joints with gasket includes many types of pressure vessels, which are mainly defined by the purpose of use and specific load conditions. These differences in definitions caused the existence of many types of pressure vessels with different shell shapes. Calculations of basic shapes are defined by standards. However, in some fields of engineering practice, these shapes are atypical. The article discusses the issue of circular sealed flange joints with a nonstandard shape of the pressure chamber shells. The aim of this article is to describe influence of shape of pressure vessel shell on bolt working load and the final tightness of the sealed joint using FEM.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
József Dobos ◽  
Muammel M. Hanon ◽  
István Oldal

Abstract Three-dimensional (3D) printing settings allow the existence of differently filled sections together within a piece. That means the use of inhomogeneous internal material structure. Knowing the load capacity that 3D printed plastic parts can withstand leads to the reduction of the filling degree, thus the amount of the used material in certain places. This approach has two advantages during production: (i) less material use and (ii) reduced manufacturing time, both being cost-reducing factors. The present research aims to find the optimal proportions for fabricating a bending test piece with varying filling degrees. To achieve this goal, experimental tests were performed for obtaining tensile strength and modulus of elasticity using different pairs of infill density and pattern. This provided a basis for creating a working mechanical model based on accurate and realistic material properties. Hence, a series of virtual bending test experiments were conducted on a sandwich structure specimen employing Ansys Workbench software. By doing so, the optimal thickness (of the sandwich’s inner layer) with the highest specific load capacity for the given filling patterns and densities were determined. To the best of our knowledge, the current procedure of experiments and method of settings optimization were not discussed elsewhere.


2021 ◽  
Author(s):  
Fankai Kong ◽  
Wenbo Cui ◽  
Fei Chen ◽  
Zhenyang Wang ◽  
Zhongchen Zhou

According to the insufficient force analysis of the cable in the process of winch retraction, especially the insufficient research on the flexible cable retraction process such as the UHMWPE cable, the dynamic simulation analysis of the retraction process of the parallel grooved multi-layer drum and UHMWPE cable cable is carried out by using the virtual prototype software ADAMS. The simulation model of the cable is created by using the macro command program, and the virtual prototype model of the cable drum is completed, and the force changes of the cable under different rotating speeds are simulated.The simulation results show that the contact force between the cable and the double winding drum can be quickly stable under the specific load, and with the increase of the rotating speed, the maximum value of the tension change of the cable increases, but it is finally stable at a fixed value. The results can provide some reference for structural strength calculation of cable storage drum, selection of high molecular polyethylene cable and dynamic analysis of cable arranger under load.


2021 ◽  
Vol 08 (04) ◽  
pp. 95-98
Author(s):  
Sevinc Abasova Sevinc Abasova

It is known that the service life of oilfield machines and mechanisms is to a certain extent determined by the operability of friction units, the operation of which, as a rule, occurs under severe conditions (heavy loads, abrasive aqueous medium, etc.). It is also known that the determining parameters in the units of machines and mechanisms (lubricated with water) with polymer elements are specific load, sliding speed and relative clearance. In the field, these factors affect the coefficient of friction together, therefore, the study of their influence [µ = f (p, ʋ, ψ)] on the coefficient of friction is possible only with the use of mathematical modeling. We have studied the nature of the joint influence of the main operating parameters on the performance of the ison thermoplastic elastomer plain bearings. Keywords: Operation, polymer elements, field conditions, bearings, sliding speed.


Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1055
Author(s):  
Takumi Iwata ◽  
Masakuni Oikawa ◽  
Riki Chida ◽  
Daijiro Ishii ◽  
Hidemi Ogihara ◽  
...  

Friction occurring between the crank journal and main bearings accounts for a large share of the mechanical losses of automotive engines. The effects of higher in-cylinder pressures and narrower bearings have raised the specific load applied to bearings, making it essential to secure sufficient seizure resistance as well. For the purpose of meeting both requirements, we have endeavored to reduce friction and improve seizure resistance by applying a diamond-like carbon (DLC) coating to the crank journal. In the present study, a bearing tester was used that has received international standard certification from the International Organization for Standardization for reproducing the sliding behavior occurring between the crank journal and main bearings in actual engines. Test results indicated that a silicon-containing hydrogenated amorphous carbon (a-C:H:Si) DLC-coated journal showed a definite friction reduction and a marked improvement in seizure resistance. An acoustic emission (AE) analysis revealed that an adhesion-induced AE peak observed for a steel journal was not seen for the DLC-coated journal. Additionally, tin and aluminum elements in the bearing material that were transferred to and observed on the sliding surface of the steel journal were not seen on the DLC-coated journal. Accordingly, the low affinity of the DLC coating with these metal elements presumably led to the clear friction reduction and superior seizure resistance displayed by the DLC coating.


Author(s):  
Luis San Andres ◽  
Jing Yang ◽  
Ryan McGowan

Abstract Aerostatic journal bearings with porous tilting pads enable shaft support with minute drag power losses. To date archival information on the static and dynamic load performance of this bearing type is scant. Thus, the paper presents measurements conducted with an air bearing with diameter 102 mm and comprising four tilting pads made of porous carbon-graphite, each with length = 76 mm. At ambient temperature of 21°C, as the air supply pressure into the bearing pads increases, so does the bearing aerostatic specific load that reaches 58% of the pressure difference. With a supply pressure of 7.8 bar(a), the test bearing static stiffness = 13.1 MN/m, is independent of both shaft speed and static load. While operating with shaft speeds = 6 krpm and 9 krpm and under specific loads to 115 kPa and 101 kPa respectively, dynamic load experiments with excitation frequencies up to 342 Hz show the test bearing supplied with air at 7.8 bar(a) has frequency independent stiffness and damping coefficients. For rotor speeds equaling 0, 6 and 9 krpm, the bearing direct stiffnesses range from 13.6 MN/m to 32.7 MN/m as the specific load increases from 0 kPa to 115 kPa. The direct damping coefficients are as large as 5.8 kN·s/m. The test porous gas bearing reached its intended load capacity, demonstrated a dynamically stable operation and produced force coefficients mainly affected by the pads' pivot supports and the magnitude of air supply pressurization.


Author(s):  
Hu Peidong ◽  
Liu Zhiguo ◽  
Ye Zhi ◽  
Liu Xiaoping ◽  
Xie Xiong ◽  
...  

Author(s):  
B. R. Mahesh ◽  
J. Satheesh

Formability of a material is found to be one of the important characteristic of a sheet metal to know the variation of the major and minor strain of a sheet metal, using this value one can predict the forming limit diagram of sheet metal, forming limit diagram gives the behavior of sheet metals under various loads and also helps in the prediction of breakage or necking of the material under specific load and velocity of the punch. Current study is mainly focused on obtaining the forming limit diagram of two different aluminium alloys like Al-5052 H32 and Al-6063 T5 using numerical analysis software PAMSTAMP and the results obtained are validated by conducting experiments, there is a good agreement of results between the experimental and numerical values. The forming limit diagram of the mentioned alloys helps in manufacturing of automobile and electric vehicle parts.


2021 ◽  
Author(s):  
Luis San Andrés ◽  
Rachel Bolen ◽  
Jing Yang ◽  
Ryan McGowan

Abstract Aerostatic journal bearings with porous tilting pads enable shaft support with minute drag power losses. To date archival information on the static and dynamic load performance of this bearing type is scant. Thus, the paper presents measurements conducted with an air lubricated bearing with diameter d = 102 mm and comprising four tilting pads made of porous carbon-graphite, each with length L = 76 mm. Two nested Belleville washers resting on spherical pivots support each pad. At ambient temperature of ∼ 21°C, as the air supply pressure into the bearing pads increases, so does the bearing aerostatic specific load (F/(L·d)) that reaches 58% of the pressure difference, supply minus ambient. With an air supply pressure of 7.8 bar(a), the test bearing static stiffness KS = 13.1 MN/m, is independent of both shaft speed and static load. KS is just 63% of the washers’ stiffness KP = 20.6 MN/m (during loading). While operating with shaft speeds equal to 6 krpm and 9 krpm (150 Hz) and under specific loads to 115 kPa and 101 kPa respectively, dynamic load experiments with excitation frequencies up to 342 Hz show the test bearing supplied with air at 7.8 bar(a) has frequency independent stiffness (K) and damping (C) coefficients. For rotor speeds equaling 0, 6 and 9 krpm, the bearing direct stiffnesses KXX ∼ KYY range from 13.6 MN/m to 32.7 MN/m as the specific load increases from 0 kPa to 115 kPa. The direct damping coefficients CXX ∼ CYY are as large as 5.8 kN·s/m, though having a large experimental uncertainty. Bearing cross-coupled force coefficients are insignificant. The test porous gas bearing reached its intended load capacity, demonstrated a dynamically stable operation and produced force coefficients mainly affected by the pads’ pivot supports and the magnitude of air supply pressurization.


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