What is viscous damping in motor?
Table of Contents
In Part 1 we defined a viscous damper as a fundamental component to create durability and efficiency in a powertrain system by reducing torsional vibration. Torsional vibration is the speed fluctuation of a rotating shaft.
How do you find the coefficient of viscous friction?
The ratio of the shearing stress to the velocity gradient is a measure of the viscosity of the fluid and is called the coefficient of viscosity η, or η=Fx/Av. The cgs unit for measuring the coefficient of viscosity is the poise.
What is motor damping?
When the shaft of the motor is rotated by a human user, it causes a current to flow through the armature of the motor producing a damping force which opposes the force exerted by the user. The energy input into the system by the human user is now dissipated in the armature resistance by the current produced.
What is the formula used to calculate viscous damping force?
r n = q n 2 − i ω ρ 0 μ . p ( 0 ) = − 8 μ h R 2 r 4 w ( d ) . B T ≡ F 0 w d = B S − 8 π μ h R 4 r 4 . The formula (10) gives the damping coefficient for small values of frequency where compressibility effects are weak.
How do you calculate the viscous damping coefficient of a motor?
You can calculate the coefficient from other motor parameters. To find the viscous damping torque at a given RPM you must convert from RPM to radians/second so a factor of 2π60 (about 0.105) is involved. Then multiply the angular velocity is s^-1 by the coefficient to get torque (Nm).
How do you calculate the damping coefficient of a motor?
Short-circuit damping When the terminals of the motor are shorted together, you get a viscous damping torque T opposing the shaft angular velocity ω, satisfying the equation T = −Bω, where B > 0. The damping B can be calculated from the torque constant and terminal resistance.
What does viscous friction mean?
Viscous friction. The resistive force between surfaces in relative motion through a fluid (liquids & gases). Air resistance or aerodynamic drag is a type of viscous friction.
What is the difference between friction viscosity and viscous dissipation?
The main difference between friction and viscosity is that friction is used to refer to forces that resist relative motion, in general, whereas viscosity refers specifically to resistive forces that occur between layers of a fluid when fluids attempt to flow.
How do you calculate damping coefficient?
You may use this formula: critical damping coefficient Cc=2*sqrt(km). For calculating actual damping coefficient ‘c’, you must have to perform either simulation with proper material properties or experiments. From there you can find the natural frequency and damping ratio.
What is the equivalent damping coefficient?
The equivalent damping coefficient is defined as the exponential value of the logarithmic mean shown in Figure 6. As mentioned earlier, a constant 5% viscous damping ratio was used in the simulations. The effective viscous damping ratio is estimated using Equation (3).
How do you calculate viscous damping of a BLDC motor?
To find the viscous damping torque at a given RPM you must convert from RPM to radians/second so a factor of 2π60 (about 0.105) is involved. Then multiply the angular velocity is s^-1 by the coefficient to get torque (Nm).
How do you calculate damping ratio?
What is Damping Ratio?
- Definition: The damping ratio is defined as the number of oscillations in a system that can decay or restrain after an interruption and it is a dimensionless measurement.
- ζ = C/Cc.
- m d^2x/dt^2 + c dx/dt + kx = 0.
- Cc = 2 √km (or) Cc = 2m √(k/m) = 2mωn.
- y(t) = A.
- ζ = C/Cc = C/2√mk.
What is the viscose damping coefficient?
viscose damping coefficient is the constant of proportionality associated to the effect Show activity on this post. Ideally, for viscous damping the force (torque in your case) is a constant times the (angular in your case) velocity. You can calculate the coefficient from other motor parameters.
How to calculate viscous damping torque?
Ideally, for viscous damping the force (torque in your case) is a constant times the (angular in your case) velocity. You can calculate the coefficient from other motor parameters. To find the viscous damping torque at a given RPM you must convert from RPM to radians/second so a factor of 2 π 60 (about 0.105) is involved.
How to measure damping coefficient of a spring?
The combined effect can be measured (and tested) with a log decrement method. Hit the spring hard and measure the amplitude as a function of time. If you count the relative decrease and the # of cycles you can use that to calculate and overall effective damping coefficient.
How does the speed of a spring depend on its viscosity?
If it is a spring in air, then it is likely to be proportional both to the viscosity of the air and to the relevant area of the the spring leading to the damping. For low speeds in air you can probably use Stokes’ approximation.