Fuel injector actuators in diesel engines are vital and widely used parts, particularly in hydraulics and fuel injection systems. They largely influence the technical, economic, and environmental ...quality of an engine. Therefore, it is of utmost importance for actuators to be highly reliable during their service life. Actuator reliability is a distinct feature of their mating surface performance. Due to complex operational conditions, increased surface stress, friction, and environmental impact, mating surfaces are exposed to various types of surface damage, wear, erosion, cavitations, and fatigue. Depending on the quality of production and the conditions they are used in, these damages are often generated much earlier than predicted, which is reflected in the reduction of the actuators' expected life span and reliability. In addition to the above, generated damage triggers the occurrence of other problems with fuel injection systems in diesel engines, resulting in increased fuel consumption and incomplete combustion, together with increased exhaust gas emission. The research conducted here analyzes the working performance of fuel injector actuators in diesel engines in heavy duty vehicles. The research is focused on inspecting the causes that lead to premature damage of mating surfaces.
For heavy vehicle systems, within the power transmission chain from the driving machine to the working components (wheels), gears have a large share of application in the form of gearboxes, ...differentials and speed reducers. Their purpose is to achieve the highest possible output torque at the working components. In one heavy-duty truck, the gearbox lost its working capacity due to the failure of its vital parts: a tapered roller bearing and a helical gear. The analysis presented in this paper, conducted on the basis of experimental and analytical methods, showed that, due to inadequate installation of the bearings’ outer ring in the gearbox housing in one intermediate shaft support, the roller bearing performed its elementary function in very unfavorable working conditions of mechanical and thermal nature. Due to the damage accumulation, the roller bearing gradually lost its working capacity. As a result, the intensity of the working conditions of the entire gearbox increased. At the moment when they reached the critical value from the aspect of the gear teeth bending strength, volumetric destruction occurred, i.e fracture of the helical gear tooth, and thus the cessation of gearbox power transmission.
•The importance of proper roller bearing installation on the operation of a complex machine system.•Analytical analysis of the rolling bearing overload model.•Mechanical and geometrical changes in rolling bearing characteristics due to elevated operating temperatures.•The relationship between the gear tooth root fracture and the indirect cause of the fracture (rolling bearing damage).
Complex structure experimental analysis has always been a huge challenge for researchers. Conventional experimental methods (e.g., strain gauges) give only limited data sets regarding measurement on ...critical areas with high geometrical discontinuities. A 3D Digital Image Correlation method is an optical method that overcomes the limitations of conventional methods and enables full-field displacement and strain measurement of geometrically complex structures. System Aramis, based on Digital Image Correlation method, is used for experimental analysis and numerical model verification in this paper. Investigated complex structure is sphere/cylinder junction on globe valve housing subjected to axial loading. The highest experimentally measured von Mises strain values around 0.15% are recorded on cylinder/sphere intersection. Von Mises strain values on cylindrical and spherical part are several times smaller than on intersection itself. It is important to emphasize that, to the authors? best knowledge, this is the first paper showing experimental results of 3D full and strain field of geometrically complex structure (sphere/cylinder intersection) on the intersection itself on pressure equipment. It is proven that 3D Digital Image Correlation method is fast and versatile method for recording strain during loading of complex structures.
How to apply the ERP model for Smart Mining? Majstorovic, Vidosav; Simeunovic, Vladimir; Mitrovic, Radivoje ...
MATEC Web of Conferences,
2022, Letnik:
368
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
For a long time, and especially today, the energy crisis has been a limiting factor for the growth and development of the world economy. On the other hand, improving the reliability and readiness of ...energy production systems is becoming a first class priority for research and development institutions around the world. Therefore, the process of production, transport, distribution and usage of energy is increasingly becoming a very important part of smart systems, whose basic framework is Industry 4.0. Thus, starting from the analogies between industrial manufacturing and mining (i.e. “ore production”), the concept of smart mining is developed. This model has three dimensions: (i) application of advanced digital technologies (Cloud Computing and Internet of Things) with automated Cyber-Physical Systems (CPS), Adaptive Manufacturing Processes (depending on working conditions) and Control of Manufacturing Processes (with optimal resource usage); (ii) Smart Maintenance of CPS (for machinery and equipment); and (iii) Smart Supply Chains (procurement of materials and spare parts / delivery of final products). Deeper analyses have shown that most of the Industry 4.0 elements could be applied with some modifications in mining (there are 45 in total, and analyses have shown that 32 of them can be successfully applied in smart mining) – which was the starting point for the ERP model presented in this paper. The developed ERP model has three main parts: a virtual part based on the Cloud Computing model (SaaS model) and usage of Internet of Things to connect different business processes (procurement, sales, management, finance, warehousing, downtime monitoring etc.), the manufacturing part (coal production in open-pit mine) and the technology process part (monitoring and maintenance of auxiliary machinery). This paper presents the developed and partially implemented ERP model for Industry 4.0 in smart mining at one surface coal mine in the Republic of Serbia.
Fused deposition modeling is one of the most widely used 3-D printing
technologies, among other additive manufacturing processes, because it is
easy to use, can produce parts faster, and the cost of ...the finished part is
low. Printing processes and finished parts are often studied and
characterized using different techniques to collect mechanical, numerical,
thermal and dimensional data, with the aim of improving and optimizing the
result. The first part of this research is based on the observation of
temperature changes with a thermal imaging camera during the fused
deposition modeling printing process and during the cooling process after
printing. Specimens of polylactic acid and polylactic acid-X improved with
second-phase particles were prepared to compare the thermal and dimensional
properties of the two materials. The obtained results determined the
characteristic temperature behavior of the materials. In the second part of
the research, a 3-D optical scanner was used to verify the stability and
accuracy of the printed specimens over time. The proposed measurement period
showed that stabilization of the parameters takes place, and further
follow-up should be performed thereafter.
One of the important tasks of evaluating the integrity of mechanical process
elements and structures is to determine the local mechanical properties. In
this paper, experimental and numerical ...analyses of the mechanical behavior
of an output inter-heater tube, made of 12H1MF heat-resistant steel, was
performed after 200,000 h of exploitation. During exploitation, the tube was
exposed to various mechanisms of damage including gas corrosion. The tube
was cut from a pipe system during reparations of a thermal power plant, and
then cold-deformed by bending to obtain a U-bend tube, which was then used
in the experiment. For this purpose, a specimen holder made of structural
steel S235 was specifically designed to test such a sample. The U-bend tube
was then exposed to the external compressive load during the experiment.
Experimental research was based on the application of the 3D digital image
correlation (DIC), while a finite element method (FEM) was applied in
numerical simulation performed by using the Abaqus software package. The 3D
DIC is an optical and contactless experimental method that allows
measurements of displacement fields and deformations of geometrically
complex structures. The Aramis system was used for the experimental analysis
as well as for verification of the numerical model. During the experiment,
the von Mises strain field was measured at the top of the U-bend tube, in
the tightening zone, as it represents a critical place for crack initiation
and propagation during the work of an inter-heater. Based on the obtained
results and a comparative analysis of experimental and numerical values of
the von Mises strain field at the U-bend tube, deviation of the model
predictions of about 18 % was determined. The FEM predicted smaller values
of the von Mises strain field compared to the DIC method. This is the result
of an incomplete geometry applied in the model due to deformation that
occurred in the bend zone of the U-bend tube, loss of material and the tube
surface damage due to the influence of gas corrosion during 200,000 h of
exploitation. Experimental analysis has confirmed that the U-bend tube,
after 200,000 h of exploitation, can remain in service even if it is damaged
due to the effect of gas corrosion.
nema
Nowadays, two most often used methods for rolling bearings condition monitoring are thermographic inspection and vibrodiagnostic.
However, analysis of the relevant literature has shown that so far ...there is no established correlation between rolling bearings surface temperatures and measured radial vibration intensities. These variables also strongly depend on rolling bearing’s service life and it’s environmental operating conditions, especially in case of open pit coal mine conveyor idler’s rolling bearings; where high concentration of debris particles (such as surface dust, dirt and excavated coal) is present.
Taking into account previously listed facts; the main goal of the presented research results was to establish statistically significant correlation between listed variables: rolling bearings surface temperatures, radial vibration intensities, service life and concentration level of debris particles in bearing grease. In order to achieve this goal, specific experimental methodology was developed and implemented. Obtained results were then processed using standardized statistical software and appropriate correlation was generated and later verified in praxis.
At this moment, developed experimental methodology is applied only to open pit coal mine conveyor idler’s rolling bearings, but its principles are universal, so with minor modifications it could be used for prediction of any of listed variables for different kinds of rolling bearings, operating in different environments.
Strain analysis in the vicinity of the dental implants were the subject of many research papers. In this study, new experimental method was employed for strain determination in the surrounding area ...of the axially loaded dental implant, which was embedded in the resin block. This studies can improve understanding of strain distribution, and its possible effects on the surrounding structure. Dental Implant Branemark with dimensions of 14 x 3.75 mm was immersed into rectangular block of polymethil methacrylate in vertical position. Implant was distanced 2 mm and 4 mm from the block sides, and they were named as the surface 1 and surface 2, respectively. Axial load, in the range of 0 - 500 N, was applied using Universal testing machine Tinius Olsen. Digital Image Correlation method was used for measuring deformation. Results were presented in the form of horizontal and vertical strains. Horizontal strains were mostly tensile, with maximum value of 0.3 % on the bottom of the surface 1. This values decreased in the upper area of the block side. Vertical compressive strain were 2-3 times higher on the surface 1, when compared to the surface 2, with maximum values of 0.7 % located on the bottom of the surface 1, and 0.3 % on the bottom of the surface 2. Resin block models could be used for determination of strain distribution under axially loaded implants. Greatest strain concentration were located under the implants apex, in the bottom area of the block. It was concluded that, in this region, strain values decreased linearly with increase of distance from the implants surface.
The research of the influence of housing material on operation temperature of the idler bearing assembly is presented in this paper. Several radial loads and rotary speeds were applied to the test ...bench to determine the transient temperature field. The results were monitored and recorded for the whole period until the temperature of the assembly reached stationary stage. The FEM model was created where the rolling elements were replaced with the especially designed artificial body, having the shape of irregular ring. It generates heat and connects only those points of the inner and outer ring which are in operating conditions connected with the rolling elements. The experimental results are compared with FEM results. The conclusion is given on suitability of polymer material for this purpose.
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