Maintenance, Reliability and Condition Monitoring
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Hydromount elastic shell dynamic stiffness calculation using finite difference method
Get PDFA preliminary approach to calculate hydromount elastic shell dynamic stiffness using finite difference method is presented in the article. This approach is necessary to calculate and assess maximum shear deformations of hydromount rubber shell needed to further determine the hydromount stiffness and damping coefficients at resonance frequencies. For this reason, finite difference method is applied when assessing maximum shear deformations of hydromount rubber shell, caused by variable loads. It was found that using reduced length and reduced arc dimensions of cut-out hydromount shell segment the equivalent stiffness can be determined. The novelty of the proposed method lies in the possibility of a quick and fairly accurate numerical calculation of the rubber shell stiffness using the values of the rubber modulus of elasticity, its permissible shear stress, and the nominal load (weight). This approach can be used to determine and optimize the geometric dimensions of the mounts shells with a given stiffness
Experimental analysis of cutting force during machining difficult to cut materials under dry, mineral oil, and TiO2 nano-lubricant
Get PDFDifficult-to-machine materials, e.g., Titanium alloys, are highly applicable in diverse industries that yield strength and wear resistance. However, they prove difficult to machine due to high vibration, leading to high cutting forces during the machining process. This vibration occurs from chip discontinuity and thereby leads to high friction between the cutting tool and workpiece. In order to minimize these challenges, lubricants are employed in machining operations to reduce frictional and other unnecessary cutting forces and improve surface finish. This research focuses on studying the nano-lubricant effects in reducing cutting forces in the machining of TI-6AL-4V-ELI alloy. Also, carry out a comparative study of dry, mineral oil, and TiO2 nano-lubricant during face-milling machining for optimal performance. Additionally, the study develops a predictive mathematical model for cutting force using a Taguchi L9 orthogonal array. A two-step approach was employed to develop the nano-lubricant before the machining process. The dynamometer is used to collect the cutting force data at the end of each sample. The Results show that the lubrication conditions play a significant role in the reduction of cutting forces. The mineral oil-based-TiO2 nano-lubricant reduces the cutting force by 19 % compared with the mineral oil during the machining of TI-6AL-4V-ELI alloy. Furthermore, the optimal parameters to reduce cutting forces during face milling of TI-6AL-4V-ELI alloy are cutting speed at 3000 rpm, 200 mm/min feed rate, 0.3 mm depth of cut to obtain the minimum cutting force 30 (N). This study concludes that the application of TiO2 nanoparticles in mineral oil significantly improves the thermal and mechanical properties, which leads to a reduction of cutting force
Stress influence to eddy current control of cracked aeronautical material
Get PDFEddy current testing is widely used for non-destructive evaluation of conductive materials where an induced current created by a variable magnetic field propagate on the material surface and sensed by a special sensor. The main purpose of this paper is to study the influence of the stress field near the crack tip especially in the singular and elaborated zones of aeronautical material aluminium 7075-T6 to eddy current non-destructive testing enhanced with a very particular type of probe to have better stresses sensitivity. This experimental part understands impedance variations due to the stress with high measurement reliability and shows that eddy current control is very sensitive to the stress and produces significant changes in magnetic parameters that mean stress should be considered in mechanical parts inspection
Erratum: Feature-based performance of SVM and KNN classifiers for diagnosis of rolling element bearing faults
Get PDFFailure analysis of gas pipeline in a gas collecting station
Get PDFThe gas collecting line of a gas collecting station failed and had obvious corrosion pits. The failure reasons of the pipeline in this section are studied by means of macroscopic morphology analysis, mechanical property analysis, hardness analysis and microstructure analysis. The results show that the main reason is the mechanical damage caused in the construction process for the damage of the anticorrosive coating on the outer surface of the pipe section. The main reason for the failure of “corrosion pit” inside the pipe section is that the wet gas transported contains CO2, which dissolves in water to generate H2CO3, and the pipe section is corroded in H2CO3 solution by electrochemical corrosion, which gradually develops into a more serious corrosion pit. In order to prevent the occurrence of such failure, 13Cr (martensite) material can be used to meet the corrosion resistance requirements, but also can appropriately increase the gas temperature in the tube to reduce the solubility of CO2 in water to prevent corrosion
Correlations between basal metabolic rate in humans with different age, gender, BMI and local earth magnetic field activity
Get PDFDaily energy expenditure includes resting metabolism (RMR), endogenous thermogenesis (or thermal effects of food), and energy expenditure associated with exercise. RMR depends on body weight, age, gender, genetic factors, medications used and health status. Every living organism is affected by external factors. Fluctuations in magnetic fields can affect almost every biological system more or less, depending on the characteristics of the particular biological system and magnetic fluctuations. Environmental energy phenomena affect psychophysical processes that can affect people in a variety of ways, depending on their sensitivity, health status, and ability to self-regulate. The aim of this study: to investigate the correlations between basal metabolic rate in humans with different age, gender, BMI and local Earth magnetic field activity. Information on gas metabolism during respiration was obtained by indirect calorimetry where the gas flow was continuously analysed. O2 consumption and CO2 emissions were continuously analysed. The best quality 5 min section was selected from the 15 min recording (automatically selected by the computer). The results were analysed and mean resting metabolic rate (M_RMR) was calculated. Investigations of metabolic rate were performed in Lithuanian, Druskininkai, Medical SPA Center ,,UPA”. Power of spectral density of Local Geo Magnetic field (LGMF) was calculated in 0.32 to 36 Hz frequency range from the Lithuanian (GCI003) magnetometer for East – West direction (E-W). 395 persons were investigated: 116 men and 279 women. All participants were divided into two groups according gender. Women and men groups were divided again into two groups according mean age, the mean was 46 years. Was analysed correlations in women younger (≤ 46 years) and older (> 46 years) groups and the same for men younger (≤ 46 years) and older (> 46 years) groups. On the next step all women and all men, then younger women group, older women group, younger men group and older men group was divided according BMI mean (29), with less than ≤ 29 BMI and with more than > 29 BMI. On the basis of obtained results, we can conclude, that correlations between LGMF and basal metabolic rate features are negative. More expressed negative correlations are seen in persons with smaller BMI. With age negative correlations with LGMF decrease in men group and increase in women group. Sensitivity of persons of different gender to LGMF – differ
Structural simulation analysis of high pressure common rail pipe
Get PDFAs one of the key components of the common rail system, the accuracy of pressure field and velocity field analysis of the common rail pipe is related to the service reliability. In order to obtain the velocity and pressure distribution that difficult to be measured in the experiment, this paper considers using three-dimensional modeling and establishing the three-dimensional model of oil flow in the common rail pipe based on the fluid simulation software, and then obtains the velocity field and pressure field distribution of the common rail pipe through numerical simulation. The cone angle at the nozzle structure of common rail pipe is compared and analyzed. Meanwhile the most appropriate cone angle’s processing angle among the commonly used processing cone angles is obtained, which improves the rationality of common rail pipe structure processing. It is great significance to the subsequent rail pressure stabilization analysis of common rail pipe
Research on dynamic characteristic of planetary gear system based on bond graph method
Get PDFThe dynamic characteristics of planetary system directly affect the stable state of the whole transmission system. Firstly, an accurate dynamic model of planetary gear system is established by using bond graph method. Formerly, the state equation of the gear train dynamics is obtained based on the bond graph model. On this basis, the simulation model of the gear system was acquired by using the numerical simulation method, and four dynamic indexes including zero-pole diagram, Bode diagram, Nyquist diagram and Nichols diagram of the gear dynamics system were gained. Finally, the analysis results show that the accurate mathematical model is described by the bond graph method and the dynamic characteristics is comprehended of planetary gear system, while will provide a basis for the stability research of the transmission system
Does Planas’ Equiplan really work in deep bite treatment?
Get PDFDeep bite malocclusion impacts function of the stomatognathic system, patients’ quality of life and self-stem by compromising oral and facial esthetics. The malocclusion can involve teeth and facial skeleton, for such is one of the most challenging malocclusion treatments. The aim of this investigation is to check the clinical belief that Planas’ Equiplan is efficient to treat deep bite malocclusion. Dental overbite was measured in 21 patients submitting to Jaw Functional Orthopedics treatment at post-graduation course. The inclusion criteria were a vertical trespass of the incisal border of the upper incisors covering the vestibular face of the lower incisors more than 3 mm, treatment cooperation and a consent form signed by the patients, or their legal tutor, allowing the use of the data obtained for research and didactic purposes. The initial measurement (T0) and 15 months treatment (T1) was collected to study overbite behavior during treatment with Planas’ Equiplan. The mean overbite of the sample at T0 was 5,02 ± 1,311 mm, at T1 the mean overbite was 2,38 ± 1,026 mm. The difference T1-T0 is –2,65 ± 1,462 mm (p< 0,01). The data presented here supports the efficacy of the use of Planas’ Equiplan in the treatment of Deep bite Malocclusion