Figure 63 – uploaded by Dobre George

See full PDF downloadDownload figure

Figure 6 In order to characterize the stresses, spherical coordinates were used, since the border conditions are expressed versus these coordinates, with the centre of coordinate system in the centre of the void and oriented as seen in Fig. 6.

Related Figures (128)

Figure 3. Contact hertzian elasticity of CARB bearing vs. axial position of toroidal rolls.

Figure 4. Ellipticity factor of CARB bearing vs. axial position of toroidal rolls.

Figure 5. Contact force distribution on the rollers for three different loads

Figure 6. Component x of the contact force between a roller and the outer race for three bearing loads (50kN-curve 1, 100kN-curve 2, and 150kN-curve 3)

Figure 7. Component y of the contact force between a roller and the outer race for three bearing loads (50kN-curve 1, 100kN-curve 2, and 150kN-curve 3)

Figure 8. Component x of the contact force between a roller and the outer race for three positions

Figure 9. Component y of the contact force between a roller and the outer race for three positions (neutral position - curve 1, 0.5° misalignment — curve 2, and 9mm axial displacement — curve 3)

Process of sintering is accompanied by a number phenomena which were fixed by us with the help of various devices and tools. Supervision over these phenomena and over their change under change of technological parameters allows to operate process of sintering in a required direction with the purpose of reception of materials with the set level of the properties providing reception of a product set form and the sizes. Table 1 - Some physicomechanical properties received WC samples

Figure 1: Structural scheme of the optimal choice of diamond-spark grinding conditions

Figure 2: Model of grinding wheel work surface relief. Probability distribution density of real ends of diamond grains in co-ordinate systems connected with end of the most advanced grain: a) with initial (imaginary) end b) with real end

High-rise wheel work surface relief reduces probability of keeping of diamond grains in bond under action of work contact loading, and so the mean number of separate acts of microcutting for every from its reduces also. Therefore, level of diamond wheel relief sharpness, which rise and support are the general physical purpose of grinding combining, can be excessive when wheel work surface real relief height exceeds the depth of real introduction into it on the side of processed material (b,,. > H fig. 2) made conditional on kinematic- max max ? geometrical and physical contact conditions. T Tessie ceo laSéerteees 23° sextet lan «ff aswewkased spflheseeeeoeew 0606 | 6O6felC6UGreeersem el acnl adios: Preliminary wheel correcting quaranteed its work relief start height no lower of this one value of spark gap between surfaces of work part allowance and wheel bond should be preceded to the first technological operation with adjusted productivity of diamond-spark grinding under posterior validity of criterion V,,=V,,,/ im processing, one-pass (when individual production) or multiple (when repetition work), at the last case down to full exhaust of diamond-contained layer during the sum operation time 7=S/V,, represented complete continuous (without intermediate autonomous correcting) wheel resource (S — thickness of diamond-contained layer).

Figure 4: Example of experimental dependences of cutting power (P, kw), processed productivity (Q mm?*/min), specific consumption of diamonds (q,mg/g) and surface roughness (Ra, wm) from grindin; depth (d, pm): 1 —Q, 2—P, 3 — Ra, 4-q. Processed material — chrome-vanadium steel X38; wheel — 1A1 250x15x5 AC6 100/80 M2-01 4; processed regimes — current strength 5a, cutting rate 35 m/s, longitudinal feeding 10 m/s, crosscut feeding 3.3 mm/double stroke It is position of minimization of superhard abrasive expense and maximization of wheel cutting resource simultaneously, increase of energy-conversion efficiency of chip forming work by exclusion of a friction of bond of wheel with work part allowance surface. Developed approach is verified by experience of processing of high-strength plastic materials that are wearproof fused surfacings and coverings, high-speed and stamp steels, other hard-machining materials (fig. 4).

As the theory and practice of diamond-spark grinding shows the extreme indices of processing productivity and bluntion of cutting grains up to falling out from bond of wheel [4] at that the specific consumption of diamonds takes minimum (fig. 5). The same character of change has a dependence “cost price — productivity” that permits to develop and operate really optimum technologies of diamond-spark grinding.

The necessary sizes for the functioning of this type of servo-amplifier are presented in the figure.One of the most important problems regarding the functioning of the mechanical- hydraulic servo-amplifiers is the self-oscillation phenomenon of high frequency. This consists of oscillations with frequencies up to 200Hz and amplitudes of several tenths of millimeters of the operated component. The frequency of these oscillations depends on the dimensions of the servo-amplifier cylinder, on the width of the distributor slots, on the characteristics of the hydraulic fluid and the operated m mass. 1. Scheme of the servo-amplifier and the distributor of different covarages between admission and exposal Keywords: servo-amplifier, self-oscillation, high frequency. Abstract: This paper presents numerical simulations for the mecano-hydraulic servoamplifier with a special kind of distributor. This distributor has different covering for the admission and evacuation flow. The purpose of this kind of distributor is to diminuate the high frequency auto-oscillations of the servoamplifier.

3. The numerical simulation and the obtained results

Fig. 2 Local Cartesian Coordinate System for a Cylindrical Blade Section [1]

Fiabilitate si Durabilitate - Fiability& Durability nr.1/2010 Editura “Academica Brancusi”, Targu Jiu, ISSN 1844 — 640X

Fig.8 Rotor with symmetrical blade distribution Fig. 7 Rotor blade (symmetrical blade distribution)

To settle the coordinates for contact point C; (Figure 2) the following equations results: Deriving (9), (10) and dividing:

Fig. 7. The evolution of X>, Y2, 8, y on a kinematic cycle Fig. 6. Mechanism positioning for extreme value of command angle,

Fig. 8. The evolution of valve lift for various command angle, a

Fig. | The structure of a composite material made of fibres included in a matrix

Measurements and Results The other particulate composites were formed keeping the amounts of Clay and Talc but adding other fillers such: 0,5% CNT for the B type; 1% CNT and 5% Ferrite for the C type: 0.5% CNT, 5% Ferrite for D type; and 0.5% CNT, 2% Ferrite and 5% Wolfram carbide for the E type. The volume fractions for all the components are given in Table 1. EE The particulate composites were formed by molding the filled pre-polymer mixture. For the A type of composite 5% weight ratios for Clay and Talc were used [4]. The amounts of Clay and Talc were mechanically mixed and then added in the main component of the Epoxy system (RE 4020) after mechanical dispersion for 30 minutes the right amount of polymerization agent (the second component of the Epoxy system — DE 4020) was added and the mixture was mechanically homogenized for other 15 minutes before molding (the RE 4020 — DE Epoxy system’s gel time is about 45 minutes). E 4020 | Tha nthar nartieinlata pamnncaitac wrara frarmad lLaaninag tha amnintoa af Mlarz and Tale hAiit

The specific heat was also determined for each material using DSC1 and Stare from Mettler Toledo. During heating (10°C /min) appearance of a peak was observed for all the materials (Fig. 3. - left) but this peak disappears if the heating temperature is over 120°C (for repeated experiments the peak appears always when the final temperature did not exceed the mentioned temperature). That means that around 120°C the polymer structure is irreversibly changed.

The thermal conductivity was determined for each material using DSC1 and Stare both from Mettler Toledo. The method is described in [6] but in this study’s case four materials were used as references for temperature: Palmitic acid (melting temperature 60°C), Stearic acid (melting point 70°C), Naphthalene (melting point 80°C), Indium (melting temperature 157°C). The curves for four different values of sample’s thickness with Stearic acid for reference temperature are presented in Fig. 2. Table 3 contains the values of thermal conductivity for formed materials at references temperatures.

In Table 4. are presented the specific heat values for each material both sides of the peak, in the intervals [40°C - 54°C] and [74°C — 88°C] and for the almost linear parts [80°C - 130°C] (Fig. 3) for both first and second heating. All the values are close to the theoretically predicted ones. The Clay powder used in this study is a cosmetic use one and it contains also organic compounds. When materials are heated over 90°C these organic substances are decomposed with effects on final properties of composites.

Ultraacustic system is the most important part of an equipment or ultrasonic activation as ultrasonic energy transfer and increase in focus on the processing and activation. Ultraacustic system consists of an active element - transducer - one that converts electrical oscillations in ultrasonic and passive elements - Ultrasonic energy concentrator - who lead concentrate and focus ultrasonic energy on the focus’ of processing. Ultraacustic system is calculated and designs so that to work in the resonance regime. [11],[12],[13].

Mesh is shown in Figure 3 pills with previously selected element mesh.

Fig. 7. Linear response function of voltage oscillation amplitude attack pill. Graphical representation of these pairs of values (Fig. 7) shows linear response of the voltage amplitude size pellets attack piezoceramic components

Fiabilitate si Durabilitate - Fiability & Durability nr.1/2010 Editura “Academica Brancusi”, Targu Jiu, ISSN 1844 — 640X Results of analysis regarding the state of deformation of the assembly piezoceramic components are given in table 2. It contains pairs of nodes aplitudine coordinate values elements located generators and radiant reflector blocks and elements Piezoceramic components, the origin of the coordinate system being out of plane reflector.[4],[7].

Figure 9 is represented deformed state / non-deformable in isometric and verticala of all piezoceramic components for resonant frequency of 20 kHz and represented in figure 10 is deformed state / non-deformable in the vertical assembly Piezoceramic components for resonant frequency of 20 kHz.

Figurel12 Generation of assembly geometry concentrator element - cutting tools used for meshing the internal grinding

Fig. 14. Application type load displacement Respecting the physical reality, concentrator of ultrasonic energy is applied as a result of type load displacement input section (area than the head), obtained from analysis of all piezoceramic components (Fig. 14).

Fig. 18. Deformed and non-deformable in the horizontal for effort “ig. 16. Deformed and non-deformable in the isometric for horizontal travel

The figure 19 is shown along the oscillation amplitude changes size of ultrasonic energy concentrator. Fig. 19. Variation in size oscillation amplitude along concentrator

Fig. 4— Tool type choice Fig. 5 — Linked tool choice

A spherical void of radius equal to the contact area radius was considered into the half-space. The stress field was found for the position of the spherical cavity centre at a distance h = 1;2;3mm with respect to the half-space plane boundary. In Fig. 5 the analytical results are presented for the contact parameters of the compact half-space compared to o,, stress value found for “with void” case, when the spherical void is situated at a depth h = Imm. One can notice that the maximum contact pressure is not altered by the void presence. 3.Finding the stress field from a half-space with void In order to characterize the stress field, it is required a size of the meshing element smaller than the contact zone dimensions. This fact is illustrated in Fig. 2a, where the considered contact region dimensions are ten times the dimension of the contact radius a = 0.296mm. The Hertzian contact parameters were computed in MATHCAD and a sequence of the program is given in Fig. 2b. It can be seen that the theoretical value obtained for maximum contact pressure is p, = 5.44-10°Pa and the numerical value being Po = 5.46-1 0° Pa, from FEA, the correct choice of meshing element size is validated. In Fig. 3, the position of a level curve for o, stress in an axial plane is presented comparatively. In Fig. 4 it can be observed the continuous curvature of the contacting surfaces after deformation.

Fig.2. Finding numerical (a) and analytical (b) maximum contact pressure

SMS Sapa etn eV RE Sa aero aN a The aspects revealed above suggests the necessity of evaluation the stress concentrator factor of a spherical void from an elastic half-space with uniaxial tension at infinity, fig. 7. In order to solve the problem numerically, the void is considered placed into a cylinder with much larger dimensions compared to the cavity radius. With the purpose of comparing the present problem to the precedent Hertzian type one, the cylinder is axially loaded with a surface force having the resultant equal to the normal force from previous Hertzian case. In Fig. 8, the equivalent von Mises stress is shown and it can be seen that the maximum is reached on the equator from the plane normal to the traction direction. ‘ig. 7. Spherical cavity from a monoaxially stretched Fig. 8. space

The paper studies the stress concentrator effect of a spherical void from an elastic half- space in Hertzian contact with a normally loaded sphere. In a first stage, the dimensions of the study zone and the mesh element size in order to describe with a superior accuracy the stress field behaviour. To this end, the Hertz problem of a sphere pressed onto an elastic half- plane is analytically and numerically solved.

the design process and reduce the time to market (1 1M). In recent years 3D printing and 3D printers have become financially accessible to small and medium sized business, thereby taking prototyping out of the heavy industry and into the office environment. It is now also possible to simultaneously deposit different types of materials. While rapid prototyping dominates current uses, 3D printers offer tremendous potential for production applications as well. The technology also finds use in the jewellery, footwear, industrial design, architecture, automotive, aerospace, dental and medical industries. Here are some examples of 3D printed parts, from large used goods to elaborated Fig.2 Scale model 1:80 of Dubai apartment building

deo Te BR BEW 8B GENE L NUR BEROCER In both ASCII and binary versions of STL, the facet normal should be a unit vector pointing outwards from the solid object. In most software this may be set to (0,0,0) and the software will automatically calculate a normal based on the order of the triangle vertices using the 'right hand rule’. Some STL loaders (e.g. the STL plugin for Art of Illusion) check that the normal in the file agrees with the normal they calculate using the right hand rule and warn you when it does not. Other software may ignore the facet normal entirely and use only the right hand rule. So in order to be entirely portable one should provide both the facet normal and order the vertices appropriately - even though it is seemingly redundant to do so. Some other software (e.g. SolidWorks) use the normal for shading effects, so the "normals" listed in the file are not the true facets' normals. a — -— kw 4 ak lam a Nay; oc 4 ag ei 3. General characteristics and limitations of .STL file format

Here are some examples of 3D Prints (via .STL) from industrial design to architecture, automotive, dental and medical industries:

Fig 9. Examples of use of .STL in architecture and medical 3D Prints Fig 8. Examples of use of .STL in industrial 3D Prints

A first opportunity to calculate the regression curve for the reliability field data is the software CurveExpert (version 1.3 or 1.4), a comprehensive curve fitting system for Windows. It employs a large number of regression models (both linear and nonlinear) as well as various interpolation schemes to represent data. In addition, the user may define any customized model desired for use in a regression analysis [2]. An illustrative example is presented in fig. 2, for the polinomial model: Af{x) =a bx tex? 4+ dx? (2)

Structure [1 1512] is illustrated in fig.5.

PE A Le a LT EN TS A ! A ee eo Sn eee eee aE, Serene ee We consider the general case when the plate is of a x b x h, simply supported on the contour line, normally loaded with p(x,y) varying on both directions. The system of axes is like in Figure 1. It is developed the normal load p(x,y) in double Fourier’s series: 2.1 The analytical resolution of differential equations by double trigonometrically series

Fiabilitate si Durabilitate - Fiability& Durability nr.1/2010 Editura “Academica Brancusi”, Targu Jiu, ISSN 1844 — 640X The parameters pmn are determined by Euler’s method and become:

Fiabilitate si Durabilitate - Fiability& Durability nr.1/2010 Editura “Academica Brancusi”, Targu Jiu, ISSN 1844 — 640X The expressions of shearing forces become:

Figure 2. The rectangular orthotropic plate loaded with a normal load uniformly distributed:

Figure 3.The plate simply supported loaded with p(x) varying on the direction. For the plate in the Figure 3 we take the form:

2.3 Resolution of differential equation by Ritz method The expression of total potential energy is:

We easily see that these coefficients are in fact, the coefficients of double trigonometrically series. The deflection will have the following form:

The moments and the shearing forces can be calculated and the numerical results are listed in Table 1.

2. Equivalent mechanism. Mechanism positions We left from the mechanism given in [1], consisting of a planetary gear, which is formed by gears 3 and 2, port satellite arm 1 and a RRP dyad. One point of the satellite wheel generates hypocycloids. If a branch of one hypocycloid is approximated by an arc, then, when the tracer point is on that branch, the 4 plunger is stationary. Such a mechanism may be used, for example, to plastic injection presses, where a little pause is required after pressing.

They are derived, in relation with time, relations from positions, resulting in: The piston course is shown in fig. 7; it is observed the approximately constant portior around the value of @=180 degrees, meaning at the F end of the race from left (fig. 2), wher Errors occur becaus¢ the tracer point goes through the hypocycloid are from the left (fig. 4). ] of discrepancies between the hypocycloid arc and the circle arc that approximates it. Thes« errors can be compensated by introducing a compensation arc in the piston area. In fig. 8 are shown the mechanism positions in the area of interest

Fiabilitate si Durabilitate - Fiability& Durability nr.1/2010 Editura “Academica Brancusi”, Targu Jiu, ISSN 1844 — 640X piston speed is approximately zero.

values in the transition from one hypocycloid branch to another one. In the area around the

Fig.l. The fundamental scheme of processing through complex erosion In case the specific power introduced within the working area is low and the drawing takes place especially based on the anodic dissolving, the productivity is reduced, but the precision of processing and ruggedness of the surface are of superior levels. In increasing the specific power, the erosion of the material is owed almost exclusively to the thermal effect of electrical discharges. In this case a drawing of material takes place, which is owed to the anodic dissolving, simultaneously with the drawing of electrical impulses, but outside the surface affected by these discharges.

The electric contact, as a thermal source in the process of processing through complex electric erosion, starts the moment when the physical contact is realized between the most prominent micro- asperities, one of them pertaining to the processed object (OP), and the other to the transferred object (OT) (figure 1). The contact is realized in a kinetic way by the relative velocity between the two bodies, by the pressure of contact, as well as by the depth of processing. Due to the interaction of the dissociated elements with the smelted metal, on the surface of the semi- finished product (figure no. 2.b) and the electrode, a film of oxide will be formed. Consequently, electrical discharges in impulse may take place, caused by the easy penetration of the oxide film (figure 2.d) with low dielectric rigidity, or of the areas with impurities. The cnecial literatire ectimatec that far the nrocecano thranoh ecamniley electric erncan semi- finished product, also wi charges in motion (electrons and h a larger section(figure no. 2 a); the kinetic energy of the ions) in the discharging channel of the un-stationary electrical resort, suddenly given way at the surface of the semi-finished product and electrode (figure no. 2.c). Together with the therma processes, which have the greatest share in the drawing of material, as we have already mentioned, concurrently some mechanical actions determined by the relative movement between he electrode and the semi- finished product take place, as well as some chemical processes of decomposing of the working environment. i a ae a ey i ee i ee ne eS .

Table 1. Sizes field of nominal values and their tolerances. ——_—O << eee Table 2 presents the information on this problem. The safety ring (A) and the two bearings (C) and (G) assembled on the axle are purchased parts, therefore their tolerances are fixed and cannot be changed during the tolerances allocation process. The other parts are processed in the factory. Depending on parts role and importance, during their design process, tolerances values are initially given for parts B, D, E and F.

Tab. 2. Description of initial tolerances These tolerances are initially selected from table 1, supposing a value that is at the middle of the tolerance field they are part of. The compensation that will appear will be represented by the clearance between the axle and the bearing support ring which is determined with the tolerance accumulation in the assembly.

Tab. 4. Minimal real cost. Therefore, the total adopted cost also includes a part of the assembly cost. The total cost is adjusted in order for a part of it to include the cost of assembly waste. Anyway, it does not include some parts that can be recovered or the cost of waste parts as individual component parts.

Fig. 2. Comparison of the results between tolerance and cost

Fig. 2: Various Drive Trains with Alternating Loads Over many decades engineering design practice and standardization have led to an enormous amount of technical knowledge. Formulas, tables, diagrams und text have been put down on several hundred thousand pages, mostly unstructured and untraceable. In MDESIGN, a digital engineering handbook, a substantial part of this content was converted into design and simulation tools for mechanical engineering. More than hundred programs help to dimension mechanical components with respect to safety and reliability (Fig.1). Results you can also achieve with MDESIGN are material consumption, energy efficiency and total cost of ownership.

fils. 4. AVLALOLULV CULCULULLOTE SUL, 2.1 General Machine Element Calculations

Fig. 4: Integrated Drive Train Development with MDESIGN Platform

Fig.1. Kinematical scheme of planetary precessional transmissior By the end of the 70s Prof. Ion Bostan designed a new type of gears, new in principle, - precessional planetary gears with multiple gearing (Bostan, 1991). Over 20 years, research was carried out comprising the total range of problems from the idea to the implementation: fundamental theory of the precessional gear-engineering calculation procedures-Know-How manufacturing technologies-applications. The research results have been published in over 450 scientific ic papers, in 1 about 150 patents, in 3 monographs and i in one design guidebook. 1 +,° 4e pf a4hnnRNnYS r 1

Fiabilitate si Durabilitate - Fiability& Durability nr.1/2010 Editura “Academica Brancusi”, Targu Jiu, ISSN 1844 — 640X es eR Dynamic processes in planetary precessional transmission derive, to a great extent, from the interaction of conical rollers of the satellite crowns with generating surfaces of central wheel teeth. The bearing capacity defined by gear forces (static and dynamic), the noise emission and the transmission vibroactivity, depend on the gear dynamic processes on the whole. With account of these important factors in the elaboration of 3D model of the initial precessional gearing, the linear contour of central wheel teeth profile (fig. 3, a) were designed applying parametric equations:

Figure 63 – uploaded by Dobre George

Related Figures (128)

Connect with 287M+ leading minds in your field