Torque calculations

These oscillatory torques are approximately symmetrical about the torque calculated form the simple equivalent circuit and decay to zero as the rotor accelerates. 

According to boundary conditions x=0 then torsion angle cp O, x=L then torsion angle (p=0, can obtain wire rope torque M and integration constant B from formula (10), the torque calculation formula of hoisting wire rope is ... 

Thus, there is a choice as to whether the peel torque calculated included the contribution needed to bend the flexible member. Circumstances will determine which is the more appropriate. 

Stepper Motor — Stepper motors can be used in simple open-loop control systems and are generally suited for systems operated at low acceleration and static load. Closed-loop control may be needed for high dynamic loads, particulariy when loads vary. If a stepper motor in an open-loop control system is overtorqued, all knovdedge of rotor position is lost and the system must be reinitialized. To prevent this, the torque capacity of the stepper motor must not exceed the maximum running torque calculated from ... 

Ljii.iiitiJtTi mechanical calculation on this molecule used 1000 basis functions). However, dis-nilnited multipole models have not yet been widely incorporated into force fields, not least because of the additional computational effort required. It can be complicated to calculate llic atomic forces with the distributed multipole model in particular, multipoles that are lull located on atoms generate torques, which must be analysed further to determine the roi es on the nuclei. 

I liis simulation provides the quantitative measures required for evaluation of the extent of deviation from a perfect viscometric flow. Specifically, the finite element model results can be used to calculate the torque corresponding to a given set of experimentally determined material parameters as... 

Power. There are two main ways to measure the power deUvered by the driver to the pump. The first method is to install a torque meter between the pump and the driver. A torque meter is a rotating bat having a strain gauge to measure shear deformation of a torqued shaft. Discussion of the principle of torque meter operation is available (16). The benefit of this method is direct and accurate measurements. The power deUveted to the pump from the driver is calculated from torque, T, and speed (tpm) in units of brake horsepower, ie, BHP (eq. 4a) when Tis in lbs-ft, and kW (eq. 4b) when T is N-m. 

The equations and methods for determining viscosity vary greatly with the type of instmment, but in many cases calculations may be greatly simplified by calibration of the viscometer with a standard fluid, the viscosity of which is known for the conditions involved. General procedures for calibration measurement are given in ASTM D2196. The constant thus obtained is used with stress and shear rate terms to determine viscosity by equation 25, where the stress term may be torque, load, or deflection, and the shear rate may be in rpm, revolutions per second (rps), or s F... 

Therefore, the viscosity can be determined from the torque and angular velocity. However, the viscosity is usually calculated from the shear rate and shear stress, which can be obtained from the Margules equation. The shear rate is given by equation 27, where r is any given radius. 

The shear rate and shear stress can be calculated for any radius r from these equations. In most cases the radius used is R because the shear stress and shear rate of interest are at the inner, torque-sensing cylinder. Thus equations 27 and 28 become... 

In most rotational viscometers the rate of shear varies with the distance from a wall or the axis of rotation. However, in a cone—plate viscometer the rate of shear across the conical gap is essentially constant because the linear velocity and the gap between the cone and the plate both increase with increasing distance from the axis. No tedious correction calculations are required for non-Newtonian fluids. The relevant equations for viscosity, shear stress, and shear rate at small angles a of Newtonian fluids are equations 29, 30, and 31, respectively, where M is the torque, R the radius of the cone, v the linear velocity, and rthe distance from the axis. 

Drive motors should be of the high-starting-torque type and selected for 1.33 times maximum rotational speed. For two- or three-diameter Idlns, the brake horsepower for the several diameters should be calculated separately and summed. Auxiliaiy drives should be provided to maintain shell rotation in the event of power failure. These are usually gasohne or diesel engines. 

Belt Presses Belt presses were fiiUy described in the section on filtration. The description here is intended to cover only the parts and designs that apply expression pressure by a mechanism in adchtion to the normal compression obtained from tensioning the belts and pulling them over rollers of smaller and smaller diameters. The tension on the belt produces a squeezing pressure on the filter cake proportional to the diameter of the rollers. Normally, that static pressure is calculated as P = 2T/D, where P is the pressure (psi), T is the tension on the belts (Ib/hnear in), and D is the roller diameter. This calculation results in values about one-half as great as the measured values because it ignores pressure created by drive torque and some other forces [Laros, Advances in Filtration and Separation Technology, 7 (System Approach to Separation and Filtration Process Equipment), pp. 505-510 (1993)]. 

To determine the exact accelerating torque, measure the ordinates of torque as shown at different speeds and calculate the average torque as follows ... 

When the torque is determined by the above method, the voltage during the test should be so adjusted that the locked rotor current is approximately equal to the full load current. After the locked rotor test, the resistance of the stator windings should be measured and may also be considered for calculating the I R losses. 

Due to smaller output and torque, the slip would rise and add to the rotor s losses (mainly iron losses) (see Figure 12.3). The voltage unbalance can be calculated as follows ... 

The voltage drop during starting should be calculated using the speed current data, locked rotor power factor, and the distribution system con stants. Speed-torque values at this reduced voltage can be calculated, assuming that the torque varies as the voltage squared. These values are compared to driven equipment curves. 

Since u and 6 are functions of time, they are written u t) and 6 t). The constant a could be calculated if the following vehicle data for engine torque T, wheel traction force F, aerodynamic drag D were available ... 

In this apparatus the polymer melt is sheared between concentric cylinders. The torque required to rotate the inner cylinder over a range of speeds is recorded so that viscosity and strain rates may be calculated. 

The heat run will he equivalent load method. Efficiency at full, and V2 load and power factor at full, /4 and V2 load and breakdown torque will be determined by equivalent circuit calculation (IEEE 112,... 

The calculations lor recommended makeup torque assume the use ol a thread compound containing 40% to 60% by weight of linety powdered metallic zinc, or 60% by weight of finely powdered metallic lead, applied thoroughly to all threads and shoulders the use of the modified jackscrew formula as shown in the lAOC Drilling Manual and the API Spec RP 7G (latest addition) and a unit stress of 62,500 psi in the box or whichever is weaker. 

Calculations for the minimum performance properties of drill pipe are based on formulas given in Appendix A of API RP 7G. It must be remembered that numbers in Tables 4-80-4-83 have been obtained for the uniaxial state of stress, e.g., torsion only or tension only, etc. The tensile stress resistance is decreased when the drill string is subjected to both axial tension and torque a collapse... 

Calculate the maximum value of a rotary torque that may be applied to the drill pipe as specified in Example 5 if the actual working tension load P = 300,000 lb. (For instance, pulling and trying to rotate a differentially stuck drill string.)... 

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