Bearing life calculations in rotating and oscillating applications

This paper begins by describing standard bearing life models in continuous rotation before going on to explain how the bearing life can be calculated for roller and ball bearings in oscillatory applications. An oscillation factor a_osc is introduced which accounts for the oscillating and stationary ring. This can be calculated numerically as a function of the oscillation angle θ and load zone parameter ε as well the parameters γ =D·cos(a)/dm and the ball-race osculation factors. Critical angles as used by Rumbarger are also employed at low θ values. Appropriate curve-fitted relationships for both roller and ball bearings are then given for a simple calculation of aosc with an accuracy of approximately 10%. Finally, several methods are suggested for estimating the ε parameter using a real case with a Finite Element Analysis load distribution accounting for structural ring deformation and ball-race contact angle variations. The results derived in this paper allow the lifetime of any arbitrary oscillating ball or roller bearing to be calculated.

use of methods of the biocrystallomics in personification of the treatment with high diluted drugs

Background: One of most important trends in modern medicine is its transformation to personalized diagnostics and treatment. This tendency fully applies to homeopathy, especially considering that this discipline is based on the principles of individual approach to the patient. At the same time, the methods of individualization of treatment in homeopathy are relatively few. Aims: Develop of methodology and methods of application biocrystalloscopic tests to personalize the homeopathic treatment. The proposed technology became previously proposed for ozone therapy practice as biocrystallomics pre-test. It includes study of the result of co-crystallization of a biological liquid of a patient with the intended dose of the drug. At the same time, the character of co-crystallization of biological liquid with several doses of tested drug or different parameters of the action of the studied factor is comparatively estimated for the purpose of individualization. Most appropriate for a particular patient believe the dose that causes optimal structuring in the dried microscopic slides obtained from a mixture of biological fluid and a solution containing a given dose of the drug. The comparison is made with a control sample of biological fluid, which has not been exposed to any effects. The optimal result is a sample that matches the control sample as much as possible. It is most preferably for biocrystallomics pre-test to use blood serum or plasma as an analyzed biological fluid. Methodology: To study the characteristics of the structuring of the semicroscopic slides we use the previously created system of semi-quantitative parameters. They are calculated on a straight four-point scale and include: crystallizability (semi-quantitative indicator of crystallization activity), structure index (complexity criterion for constructing crystal elements of facias), facia destruction degree (indicator of “correctness” of crystal formation) and clearity of facia marginal zone (parameter indicating the amount of native protein in the sample of biological fluid). These indicators comprehensively characterize all the main features of the process of dehydration structurization of biological substrate. Conclusion: It should be noted that the technique described above is universal and can be applied to any liquid or soluble compounds with potential therapeutic activity, including their ultra-high dilutions. The data obtained by us indicate the possibility of using this technology in homeopathy.

Effects of aspect ratio and mushy-zone parameter on melting performance of a thermal energy storage unit filled with phase change material

An intermittent supply of energy from renewable or unconventional resources has resulted in the use of phase change materials (PCM) in thermal energy storage (TES) systems. In this work, melting and heat transfer characteristics in a rectangular enclosure of different aspect ratios (width to height) filled with a phase change material (PCM) have been studied numerically. The n-octadecane has been selected as the PCM (melting temp = 301.35 K, Prandtl number ∼ 60). We considered five different aspect ratios (AR) of the enclosure to delineate the effects of 9-fold variation in the aspect ratio. The simulations were carried out using ANSYS Fluent 19.2. In particular, extensive results have been presented and discussed in terms of the temperature contours, rate of melting and energy storage, and total time required to reach the fully melt condition. Additionally, the effect of the mushy zone parameter (A mush ) on the melting performance has also been investigated. Low values of the A mush were seen to predict the higher rate of melting. At a fixed value of A mush , ∼ 3 times faster melting rate was observed as the value of AR was reduced from 3 to 1/3. Finally, it can be concluded that melting and energy storage rate largely depends on the aspect ratio of the enclosure and the optimal choice of the value of the A mush .

Numerical Analysis of Slag Transfer in the IronArc Process

The IronArc process is a novel approach to ironmaking which aims to reduce the associated $${\hbox {CO}}_{2}$$ CO 2 emissions. By superheating gas using electricity in a plasma generator (PG) the heat required for the process can be supplied without burning of coke. Reduction of hematite and magnetite ores is facilitated by additions of hydrocarbons from liquid natural gas (LNG). The melting and reduction of ore will produce a molten slag containing 90 pct wüstite, which will be corrosive to most refractory materials. A freeze-lining can prevent refractory wear by separating the molten slag from the refractory. This approach is evaluated in CFD simulations by studying the liquid flow and solidification of the slag using the enthalpy–porosity model in two different slag transfer designs. It was found that a fast moving slag causes a high near-wall turbulence, which prevents solidification in the affected areas. The RSM turbulence model was verified against published experimental research on solidification in flows. It was found to accurately predict the freeze-lining thickness when a steady state was reached, but with lacking accuracy for predicting the time required for formation of said freeze-lining. The results were similar when the $$k{-}\omega $$ k - ω SST model was used. A design with a slower flow causes more solidified material on the walls and can protect all areas of the refractory wall from the corrosive slag. A parameter study was done on the effect of viscosity, mushy zone parameter, heat conductivity and mass flow on the amount of solidified material, thickness of solidified material, heat flux, and wall shear stress. In the current geometry, freeze-linings completely protect the refractory for mass flow rates of up to 3 $${\text {kg}} \, {\text {s}}^{-1},$$ kg s - 1 , and are stable for the expected viscosity (0.05 to 0.3 Pa), heat conductivity (2 $${\text {W}}\, {\text {m}}^{-1}\,{\text {K}}^{-1}),$$ W m - 1 K - 1 ) , and used mushy zone parameter (10,000).

Buckling of an Elastic Plate/Layer Along a Rigid Base With Adhesion

An infinitely long elastic plate/layer is under uniaxial compression with its long dimension held by adhesion to a flat rigid base without friction. A prescribed length of the plate/layer is free of adhesion. This configuration is similar to a pre-stressed elastic film for which buckling of an unbonded section is a necessary, but not sufficient, condition for delamination. For that configuration, buckling occurs at the Euler buckling load of a fixed–fixed plate. Although the present study does not include friction or tangential interface stresses, the onset of buckling should be similar for these two cases. For the case of an elastic plate, a cohesive zone is used and it is found that the fixed–fixed buckling load is not attained except for extremely large values of a cohesive zone parameter. For realistic values, the buckling load is about half of that value. For the situation of an elastic layer with adhesion (without a cohesive zone), the buckling load approaches the fixed–fixed value only for very large values of the ratio of the unbonded length to the thickness.

An adaptive robust control scheme for robot manipulators with unknown backlash nonlinearity in gears

This paper presents an adaptive robust control algorithm for the nonlinear dynamics of robot manipulators with unknown backlash in gears. The basic nonlinear model of a serial manipulator robot is used for the controller design, and this is combined with the nonlinear proposed dead zone model, based on the input and output torque. The main idea of providing this model is to achieve a dynamic model of the system considering the backlash of the robot joint gears, and having less complexity such that the developed controller does not need the inverse backlash model. The adaptive robust controller is developed, without using the inverse backlash model. The proposed controller is designed based on an unknown dead zone parameter and it guarantees the stability and path tracking of the robot trajectory with unknown dead zone parameter in the desired range. Numerical simulations are conducted to show the effectiveness of the proposed controller. Finally, the efficiency and capability of the proposed controller in dealing with the unknown backlash nonlinearities in gears of the manipulator are demonstrated by experimental results with a five-bar manipulator.