scholarly journals Investigation of the Influence of Non-Flatness and Runout of Friction Discs on the Service Life of Machine Clutches

2021 ◽  
Vol 24 (4) ◽  
pp. 45-53
Author(s):  
B.A. Gupalov ◽  
V.V. Zakuraev ◽  
V.Sh. Petrenko
Keyword(s):  
Service Life ◽  
Test Bench ◽  
Flat Surface ◽  
Combined Loading ◽  
Outer Diameter ◽  
Test Results ◽  
Sliding Speed ◽  
Inner Diameter ◽  
Alternating Bending ◽  
Elastic Characteristics

In the manufacture of discs, it is important not only to ensure their specified geometric accuracy and correct shape, but to maintain geometric parameters during operation. The method of testing disks on the IKS-T inertial test bench is described. The main units of the test bench and the loading parameters of the disks are indicated. Research has been carried out on the influence of the runout and non-flatness of friction discs on the service life of the clutches. Bench tests made it possible to determine the optimal runout range of discs up to 0.8 mm, which ensures an increase in the reliability of the clutches by 30 % due to a decrease in the wear of the friction discs. In addition, the test results show that with a decrease in non-flatness from 1.2 mm to 0.3 mm, the service life of the friction discs increases by 16 %, i.e. wear of discs in the running-in mode with distortions in geometry occurs more intensively than for discs with a flat surface. With an out-of-flatness value of 0.3 mm, the discs acquire improved elastic characteristics. It was possible to determine that increased values of disc wear are observed mainly along the outer diameter, due to the runout and higher sliding speed compared to the sliding speed on the inner diameter. Calculated dependences of the limiting number of loading cycles on the beating and non-flatness of discs are presented. It was found that when testing discs with the non-flatness less than 0.3 mm, disc wear appears with the formation of “poppet” disc shape. For the purpose of imparting the correct shape to the products with the exclusion of “poppet” discs, a dynamic straightening with combined loading is proposed. The resulting calculated dependencies will be used in the design of industrial universal installations for cyclic alternating bending of friction discs.

Development of a Test Rig for Multi-Axial Static and Dynamic Loading of Bearings

2011 ◽  
Author(s):  
William Jacobs ◽  
Marco Malago´ ◽  
Rene Boonen ◽  
Paul Sas ◽  
David Moens
Keyword(s):  
Condition Monitoring ◽  
Outer Diameter ◽  
Dynamic Force ◽  
Test Results ◽  
Test Rig ◽  
Major Research ◽  
Different Types ◽  
Inner Diameter ◽  
Static And Dynamic Loading ◽  
Real Machine

Condition monitoring of bearings has been a major research topic for more than five decades. To validate and improve the condition monitoring techniques, this paper focuses on the development of an innovative and versatile bearing test rig. The rig allows applying a fully controlled multi-axial static and dynamic load on different types and sizes of bearings. Easy adjustment to mount bearings with different inner diameter, outer diameter and width is possible, without compromising on performance. Furthermore, the behaviour of the bearing is monitored by accelerometers, proximity probes and thermocouples. During the design of the rig, several techniques were applied to ensure clean measurements, with maximum repeatability, and to reduce errors due to temperature variations. Finally, introducing an additional dynamic force on the bearing makes it possible to load the bearing as if it were built into a real machine, for example a gearbox. At the time this paper is written, results of the test rig were not yet available. However, the authors expect to be able to report on the first test results during the conference.

scholarly journals Confinement effects for rubberised concrete in tubular steel cross-sections under combined loading

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
A. Mujdeci ◽  
D. V. Bompa ◽  
A. Y. Elghazouli
Keyword(s):  
Axial Compression ◽  
Cross Section ◽  
Cross Sections ◽  
Image Correlation ◽  
Combined Loading ◽  
Test Results ◽  
Compression Tests ◽  
Confinement Effects ◽  
Rubber Content ◽  
Dependent Modification

AbstractThis paper describes an experimental investigation into confinement effects provided by circular tubular sections to rubberised concrete materials under combined loading. The tests include specimens with 0%, 30% and 60% rubber replacement of mineral aggregates by volume. After describing the experimental arrangements and specimen details, the results of bending and eccentric compression tests are presented, together with complementary axial compression tests on stub-column samples. Tests on hollow steel specimens are also included for comparison purposes. Particular focus is given to assessing the confinement effects in the infill concrete as well as their influence on the axial–bending cross-section strength interaction. The results show that whilst the capacity is reduced with the increase in the rubber replacement ratio, an enhanced confinement action is obtained for high rubber content concrete compared with conventional materials. Test measurements by means of digital image correlation techniques show that the confinement in axial compression and the neutral axis position under combined loading depend on the rubber content. Analytical procedures for determining the capacity of rubberised concrete infilled cross-sections are also considered based on the test results as well as those from a collated database and then compared with available recommendations. Rubber content-dependent modification factors are proposed to provide more realistic representations of the axial and flexural cross-section capacities. The test results and observations are used, in conjunction with a number of analytical assessments, to highlight the main parameters influencing the behaviour and to propose simplified expressions for determining the cross-section strength under combined compression and bending.

scholarly journals Morphological Changes in Lamellar Macular Holes According to SD-OCT Examination over a Long Observation Period

Diagnostics ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1145
Author(s):  
Magdalena Kal ◽  
Izabela Chojnowska-Ćwiąkała ◽  
Mateusz Winiarczyk ◽  
Monika Jasielska ◽  
Jerzy Mackiewicz
Keyword(s):  
Retinal Thickness ◽  
Morphological Changes ◽  
Outer Diameter ◽  
Corrected Visual Acuity ◽  
Macular Holes ◽  
Kolmogorov Smirnov ◽  
Inner Diameter ◽  
Observation Period ◽  
Sd Oct

Background: The aim of this study was to evaluate the quantitative morphological changes in lamellar macular holes (LMHs) based on SD-OCT examinations and to assess the correlations among minimal retinal thickness (MRT), reading vision (RV), and best corrected visual acuity (BCVA) over a 36-month follow-up period. Methods: A group of 40 patients (44 eyes) with LMH was evaluated, with an average age of 69.87 (SD = 10.14). The quantitative parameters monitored in the follow-up period (at 0, 3, 6, 12, 18, 24, 30, and 36 months) were tested for normality of distribution by Shapiro–Wilk and Kolmogorov–Smirnov tests. Results: The RV and BCVA values were stable, and no significant changes were found at any of the check-ups during the 36-month follow-up period (BCVA p = 0.435 and RV p = 0.0999). The analysis of individual quantitative LMH parameters during the 36-month follow-up period did not demonstrate statistically significant differences: MRT (p = 0.461), Max RT temporal (p = 0.051), Max RT nasal (p = 0.364), inner diameter (ID) (p = 0.089), and outer diameter (OD) (p = 0.985). Conclusions: The observations at 0, 6, 12, 18, 24, 30, and 36 months revealed moderate and significant correlations between RV and MRT. No significant correlation between BCVA and MRT was observed.

Influence of fully submerged permanent magnets in the evaluation of heat transfer and performance analysis of single slope glass solar still

2021 ◽  
pp. 095765092110310
Author(s):  
Ajay Kumar Kaviti ◽  
Akkala Siva Ram ◽  
Amit Kumar Thakur
Keyword(s):  
Heat Transfer ◽  
Permanent Magnets ◽  
Outer Diameter ◽  
Solar Still ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Inner Diameter ◽  
Evaporative Heat Transfer ◽  
And Performance ◽  
Depth Water

In this experimental study, permanent magnets with three different sizes (M-1: 32 mm inner diameter, 70 mm outer diameter and 15 mm thick, M-2: 25 mm inner diameter, 60 mm outer diameter and 10 mm thick, M-3: 22 mm inner diameter, 45 mm outer diameter and 9 mm thick) are fully submerged in the single-slope glass solar still. The performance of magnetic solar stills (MSS) with three different sizes at 2 cm depth water to ensure that magnets are fully submerged is compared with conventional solar still (CSS) at the location 17.3850°N, 78.4867°E. Tiwari model is adapted to calculate the heat transfer coefficients (HTC), internal and exergy efficiencies. MSS with M-1, M-2 and M-3 significantly enhanced the convective, radiative, and evaporative heat transfer rate for the 2 cm depth of water. This is due to the desired magnetic treatment of water, which reduces the surface tension and increases the hydrogen bonds. The MSS's total internal HTC, instantaneous efficiencies led CSS by 25.52%, 28.8%, respectively, with M-1. Having various magnetic fields due to different magnets sizes increases MSS's exergetic efficiency by 33.61% with M-1, 33.76% with M-2, and 42.25% with M-3. Cumulative yield output for MSS with M-1, M-2, and M-3 is 21.66%, 17.64%, 15.78% higher than CSS. The use of permanent magnets of different sizes in the MSS is a viable, economical and straight forward technique to enhance productivity.

Self-Organized, Tubular Hybrid Vascular Tissue Composed of Vascular Cells and Collagen for Low-Pressure-Loaded Venous System

1995 ◽  
Vol 4 (6) ◽  
pp. 597-608 ◽  
Author(s):  
Jiro Hirai ◽  
Takehisa Matsuda
Keyword(s):  
Vascular Tissue ◽  
Venous System ◽  
Seeding Density ◽  
Outer Diameter ◽  
Type I ◽  
Dependent Manner ◽  
Mixed Solution ◽  
Vascular Cells ◽  
Collagen Concentration ◽  
Inner Diameter

A tubular, hierarchically structured hybrid vascular tissue composed of vascular cells and collagen was prepared. First, a cold mixed solution of bovine aortic smooth muscle cells (SMCs) and Type I collagen was poured into a tubular glass mold composed of a mandrel and a sheath (example of dimensions: inner diameter, 1.5 mm; outer diameter, 7 mm; length, 7 cm). Upon incubation at 37°C, an SMC-incorporated collagenous gel was formed. After the sheath was removed, the resulting fragile tissue, when cultured in medium, thinned in a time-dependent manner to form an opaque, dense tissue. Higher SMC seeding density and lower initial collagen concentration induced more rapid and prominent shrinkage of the tissue. Morphologic investigation showed that over time, bipolarly elongated SMCs and collagen fiber bundles became positioned around the mandrel. Both components became circumferentially oriented. When the mandrel was removed, a tubular hybrid medial tissue was formed. A hybrid vascular tissue with a hierarchical structure was constructed by seeding endothelial cells onto the inner surface of the hybrid medial tissue. Prepared tissues tolerated luminal pressures as great as 100 mmHg and mechanical stress applied during an anastomotic procedure. This method allowed us to prepare a tubular hybrid medial tissue of predetermined size (inner diameter, wail thickness, and length) by selecting appropriate mold design, initial collagen concentration, and SMC seeding density. Such hybrid vascular tissues may provide physiological functions when implanted into the venous system.

Preparation Techniques and Property Evaluations of Highly Air Permeable Needle-Punched Geotextiles

2015 ◽  
Vol 749 ◽  
pp. 278-281
Author(s):  
Jia Horng Lin ◽  
Jing Chzi Hsieh ◽  
Jin Mao Chen ◽  
Wen Hao Hsing ◽  
Hsueh Jen Tan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Service Life ◽  
Mechanical Strength ◽  
Pore Structure ◽  
Test Results ◽  
Needle Punching ◽  
Pet Fibers ◽  
Environmental Requirements ◽  
Preparation Techniques

Geotextiles are made of polymers, and their conjunction with different processes and materials can provide geotextiles with desirable characteristics and functions, such as filtration, separation, and drainage, and thereby meets the environmental requirements. Chemical resistant and mechanical strong polymers, including polyester (PET) and polypropylene (PP), are thus used to prolong the service life of the products made by such materials. This study proposes highly air permeable geotextiles that are made with different thicknesses and various needle punching speeds, and the influences of these two variables over the pore structure and mechanical properties are then examined. PET fibers, PP fibers, and recycled Kevlar fibers are blended, followed by being needle punched with differing spaces and speeds to form geotextiles with various thicknesses and porosities. The textiles are then evaluated for their mechanical strength and porosity. The test results show that a thickness of 4.5 cm and 1.5 cm demonstrate an influence on the tensile strength of the geotextiles, which is ascribed to the webs that are incompletely needle punched. However, the excessive needle punching speed corresponding to a thickness of 0.2 cm results in a decrease in tensile strength, but there is also an increase in the porosity of the geotextiles.

Development of an Experimental Device to Study Real Connecting-Rod Bearings Functioning in Severe Conditions

2007 ◽  
Vol 129 (3) ◽  
pp. 647-654 ◽  
Author(s):  
Philippe Michaud ◽  
Aurelian Fatu ◽  
Bernard Villechaise
Keyword(s):  
General Principle ◽  
Test Bench ◽  
Numerical Models ◽  
Experimental Device ◽  
Test Results ◽  
Connecting Rod ◽  
Compression Loading ◽  
Key Points ◽  
Loading System

The paper presents a new experimental device made to analyze the thermoelastohydrodynamic (TEHD) behavior of connecting-rod bearings functioning in severe conditions. First, it focuses on the test bench description. The general principle of the test bench and then the main original technological solutions used with respect to the functional specifications are detailed. Two numerical models are described. They were developed in order to design and to validate two central components of the experimental device. Finally, the paper comments on the test results used to understand and validate the traction∕compression loading system, which is one of the key points in the test bench behavior.

scholarly journals Unbalanced Vibration Identification of Tangential Threshing Cylinder Induced by Rice Threshing Process

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Zhong Tang ◽  
Haotian Zhang ◽  
Yuepeng Zhou
Keyword(s):  
Service Life ◽  
Vibration Amplitude ◽  
Rotation Speed ◽  
Resonance Phenomenon ◽  
Test Results ◽  
Axial Vibration ◽  
Ansys Software ◽  
Cylinder Axis ◽  
Vibration State ◽  
Rice Stalks

Unbalanced vibration of tangential threshing cylinder increased the grain loss, shortened service life of the cylinder, and resulted in structural resonance during the rice threshing process. In this paper, the vibration amplitude and frequency of tangential threshing cylinder shaft were tested, and the vibration state of tangential threshing cylinder was identified. The restricted and working modalities of tangential threshing cylinder were solved by ANSYS software. Then, by comparing the resonance phenomenon between the inherent constraint frequency and the rotation speed frequency, the shaft vibration under the idle condition of tangential threshing cylinder was tested and analyzed. According to the axial vibration and axial trajectory of the cylinder, the inherent properties and characteristics of unbalanced vibration were revealed. Test results showed that when the tangential threshing cylinder was at idling and no-load state, the amplitude of vibration in the feed direction of straw flow was -0.049~0.060 mm, and the average vibration amplitude was 0.013 mm. As rice flowed along the tangential threshing cylinder, the vibration amplitude slightly increased. The trend and phase of each trajectory were similar, although the amplitude of each trajectory was different. The tangential threshing cylinder axis trajectory was flat oval. Unbalanced vibration was induced by the rice stalks in the concave gap.

scholarly journals Evaluation of the Lower Punctum Parameters and Morphology Using Spectral Domain Anterior Segment Optical Coherence Tomography

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Riham S. H. M. Allam ◽  
Rania A. Ahmed
Keyword(s):  
Optical Coherence Tomography ◽  
Anterior Segment ◽  
Normal Subjects ◽  
Cross Sectional Study ◽  
Spectral Domain ◽  
Outer Diameter ◽  
Optical Coherence ◽  
Cross Sectional ◽  
Air Bubble ◽  
Inner Diameter

Purpose. To study features of the lower punctum in normal subjects using spectral domain anterior segment optical coherence tomography (SD AS-OCT).Methods. Observational cross-sectional study that included 147 punctae (76 subjects). Punctae were evaluated clinically for appearance, position, and size. AS-OCT was used to evaluate the punctal shape, contents, and junction with the vertical canaliculus. Inner and outer diameters as well as depth were measured.Results. 24 males and 52 females (mean age44±14.35 y) were included. Lower punctum was perceived by OCT to be an area with an outer diameter (mean412.16±163 μm), inner diameter (mean233.67±138.73 μm), and depth (mean251.7±126.58 μm). The OCT measured outer punctum diameter was significantly less than that measured clinically (P: 0.000). Seven major shapes were identified. The junction with the vertical canaliculus was detectable in 44%. Fluid was detected in 34%, one of which had an air bubble; however, 63% of punctae showed no contents and 4% had debris.Conclusions. AS-OCT can be a useful tool in understanding the anatomy of the punctum and distal lacrimal system as well as tear drainage physiology. Measuring the punctum size may play a role in plugs fitting.

scholarly journals Experimental Study on the Transverse Effective Bending Rigidity of Segmental Lining Structures

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Yong-feng Tang ◽  
Han-cheng Chen ◽  
Zhen-wei Ye ◽  
Ting-jin Liu ◽  
Yu-bing Yang
Keyword(s):  
Regression Equation ◽  
Shield Tunnel ◽  
Outer Diameter ◽  
Test Results ◽  
Bending Rigidity ◽  
Segmental Lining ◽  
Ring Model ◽  
Scale Models ◽  
Elastic Stage

The transverse effective rigidity ratio is a key parameter when the uniform rigidity ring model is adopted to design or numerically analyse segmental lining structures commonly used on a shield-driven tunnel. Traditionally, the transverse effective rigidity ratio η is treated as a constant, which can be evaluated through theoretical analysis and model tests. In this study, scale models were designed and tested to investigate the variation of the transverse effective rigidity ratio in the segmental linings’ flattening deformation process. The test results suggested that in the elastic stage, the transverse effective rigidity ratio fluctuated between 0.667 and 0.734 for the stagger-jointed rings and fluctuated between 0.503 and 0.642 for the straight-jointed rings. When segmental linings were squashed and started to crack at the circumferential joints, the transverse effective rigidity ratio decreases sharply. Then, a regression equation was obtained to fit the variation trend of η with the increase of horizontal convergence to the outer-diameter ratio (ΔD/Dout). Finally, in a case study, the regression equation was adapted to determine the value of η of an operated shield tunnel which was once surcharged accidentally and deformed severely so as to numerically predict the prospective deformation induced by the upcoming adjacent excavation. Numerical results indicated that as the value of η decreases, the horizontal convergences of shield tunnel induced by adjacent excavation increase significantly and even more than doubled in the case study. Comparatively, through taking account of the operating tunnels’ exiting transverse deformation, the predicted deformation tends to be unfavourable.

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