The authors investigated experimentally and theoretically the friction torque in a modified thrust ball bearing having only 3 balls operating at low axial load and lubricated with NGLI-00 and NGLI-2 greases. The exper...
The authors investigated experimentally and theoretically the friction torque in a modified thrust ball bearing having only 3 balls operating at low axial load and lubricated with NGLI-00 and NGLI-2 greases. The experiments were made by using spin-down methodology and the results were compared with the theoretical values based on Biboulet&Houpert's rolling friction equations. Also, the results were compared with the theoretical values obtained with SKF friction model adapted for 3 balls. A very good correlation between experiments and Biboulet_&_Houpert's predicted results was obtained for the two greases. Also was observed that the theoretical values for the friction torque calculated with SKF model adapted for a thrust ball bearing having only 3 balls are smaller that the experimental values.
In this paper some experimental results related to the Coanda effect are presented. The idea is to use them to build and control a flying vehicle. Our experiments have been done on an laboratory testing device. From t...
In this paper some experimental results related to the Coanda effect are presented. The idea is to use them to build and control a flying vehicle. Our experiments have been done on an laboratory testing device. From the first obtained results we have seen some advantages and disadvantages to applying Coanda effect to a flying vehicle. The advantages are: reducing the pressure near the of the convex surface, protected screw, vertical takeoff and landing. The main disadvantage is the cost of the fuselage and the extra weight that he has. Our conclusion at this time is that this technical solution can bring some benefits through a suited sizing and geometry with vehicle mass.
Thermomechanical wear is a complex phenomenon present in a number of industrial domains, such as rolling bearings, gears, friction wheels, rolling mill rollers. In this type of surface tribological deterioration, both...
Thermomechanical wear is a complex phenomenon present in a number of industrial domains, such as rolling bearings, gears, friction wheels, rolling mill rollers. In this type of surface tribological deterioration, both fundamental and some peculiar wears are combined (abrasive, adhesive, corrosive wear and contact fatigue), with mechanical ant thermal causes. The present paper takes into account the contact fatigue type of deterioration, with both causes in mechanical variable load and the thermal tide action on the contact surface. There are some theories synthetically presented regarding the location of critical stresses in rolling contact fatigue. The Jacq thermal effect is briefly presented with some considerations concerning the temperature gradient in the metallic wall. The connection between the Jacq thermal anomaly and the thermomechanical contact fatigue is considered to be a new approach. Also, the same location for both mechanical and thermal critical stresses gives a strong support for the thermomechanical contact fatigue primary deterioration, according to the results obtained during the author's PhD research.
A design procedure for the optimum distribution of the addendum modification coefficients of spur gear pairs with smaller number of pinion teeth is presented for the case of a fixed centred distance. The geometrical, ...
A design procedure for the optimum distribution of the addendum modification coefficients of spur gear pairs with smaller number of pinion teeth is presented for the case of a fixed centred distance. The geometrical, kinematics and load capacity criteria are considered in the design analysis. The geometric and kinematics criteria are used to prevent the negative phenomena of the generating and engagement processes. The relation between the contact pressure of meshing teeth and specific sliding are analysed in relation with addendum modification coefficients. A dynamic model is developed to simulate the load sharing characteristics through a mesh cycle. The specific phenomenon of contact tooth pairs alternation during mesh cycle is integrated in this dynamic load modelling. A comparative study is included, which shows the effects of the distribution factor of the addendum modification coefficients on the contact surface characteristics of the gear pairs.
This paper presents relevant aspects of the idea of using the digital medicine in cancer, so that to shape a viable strategy for creating and implementing an interactive digital platform, NEO-VIP, that should be the b...
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The normal pressure distribution on contact area and depth distribution of von Mises equivalent stress are of major importance in prediction of various failure phenomena (e.g. rolling contact fatigue, scuffing) of the...
The normal pressure distribution on contact area and depth distribution of von Mises equivalent stress are of major importance in prediction of various failure phenomena (e.g. rolling contact fatigue, scuffing) of the contacting surfaces. The paper reveals the relationship between roughness amplitude and stress state developed in the loaded material. The study was performed on a double rows spherical roller bearing under three levels of radial loading, and three significant values for the surface roughness. The numerical simulation was used to generate Gaussian rough surfaces with imposed values for Ra parameter. A semi-analytical method was used to solve the non-hertzian contact between rough surfaces. For the same loading level, the depth distribution of von Mises stress for rough surfaces is close to the distribution found for smooth surfaces, except the shallow layer close to the contacting surfaces. For medium and especially high loads, the contact between rough surfaces develops, inside this shallow layer, von Mises equivalent stresses higher than the fatigue limit stress.
This paper presents a novel technique for development of data glove with Ionic Polymer Metal Composite (IPMC). IPMC is one of the varieties of Electro Active Polymer (EAPs). The IPMC strips have been used as sensor be...
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This paper presents relevant aspects of the idea of using the digital medicine in cancer, so that to shape a viable strategy for creating and implementing an interactive digital platform, NEO-VIP, that should be the b...
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This paper presents relevant aspects of the idea of using the digital medicine in cancer, so that to shape a viable strategy for creating and implementing an interactive digital platform, NEO-VIP, that should be the basic support to design the strategy for integration of basic, clinical and environmental research on neoplasia progression to cancer. The two main components of the VIPRO Platform are represented by the workstation “engineering Station” for CPS (Cyber Physical System) and “omics” technology and by the “Graphical Station” for the development of a virtual mechatronic system environment and virtual reality for system components' motion. The NEO-VIP Platform will consolidate the collaboration of specialized institutions in IT, medicine, health, life standards so that to enhance their capabilities to work as a consortium. The results lead to the possibility developing NEO-VIP Platform in the IT modelling field, applied on bio-medical data, as a new player alongside with the existing ones. So, new improved methodologies for investigating social implications of machines working with and for people will be applied.
In this paper, we present a study on stability of popular biopolymer poly(lactide acid) (PLA) under degradation process. As a main objective of this study we investigate an influence of polymer decomposition on decrea...
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In this paper, we present a study on stability of popular biopolymer poly(lactide acid) (PLA) under degradation process. As a main objective of this study we investigate an influence of polymer decomposition on decrease of its two physicochemical parameters - dynamic viscosity and molecular mass. To include the molar mass distribution we calculate three various mass averages: the number, the weight and the viscosity molar mass. To simulate the polylactide behavior at the atomic level we use molecular dynamics method in conjunction with reactive force field ReaxFF. To provide degradation conditions similar to human interior system we operate in the MD-NVT conditions at the temperature 310K. Based on reported in literature values of polylactide density we develop computational model of its amorphous structure. We achieve full compliance with expectations - obtained values of PLA viscosity and mass are steadily dropping. Determined trends confirm progressive polymer decomposition resulting in deterioration of polymer durability. The obtained results may be use in a future to predict a lifetime of biomedical polymer implants.
In this paper, we constructed three dimensional (3D) microchannel networks inside gelatin-based hydrogel towards 3D in vitro cell structures. To achieve functional 3D cell structures, vascular networks are important t...
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