Electromechanics - Science topic

Me simulate the B-H curves to V-I of different magnetic materials used in transformers to study the inrush patterns in transformers, could refer my paper “ Laboratory methods to generate inrush current patterns of power transformers “….

Refer to IEEE standards on piezoelectricity,

Nurhan Onar Çamlıbel The CHI660E electrochemical workstation is specialist equipment for electrochemical research and testing. It is often used to characterize the electromechanical performance of piezoresistive pressure sensors, as well as a number of other electrochemical tests.

You may get additional information about using the CHI660E workstation by searching online for user manuals, technical documentation, and application notes for this instrument. The manufacturer's website, academic research papers, publications, and internet forums or discussion groups devoted to electrochemical measurement and testing are all viable sources of information.

Contacting the manufacturer directly may also be beneficial, as they may have more extensive information and resources regarding utilizing the CHI660E workstation for piezoresistive pressure sensor characterization. They may be able to provide you with more advice, technical assistance, and references to get you started with your measurements.

Dear Naveed Mazhar , yes you can use the parametrization method to tune PID controller, please see the following:

Book: Quantitative process control theory. Vol. 45. CRC press, 2011.

Hi Swatantra Singh Chauhan

Please have a look at these articles which can give you some idea on the question you are asking:

Each physics can run respectively, how can I couple the two physics together? I have tried to add two studies. Disable the laminar flow and run the solid mechanics using study 1, then disable solid mechanics and run laminar flow using study 2. In study 2, use "Initial value of variables solved for" "study 1".

Thanks you so much Mohamed Azab, your answer helped me a lot.

Hi, I initially face a same problem in my research. It solved :)

Kindly refer my publication attached.

Both methods could be very sensitive. It depends on the frequency. However, ultrasonic guided wave are able to monitore surfaces. The impedance measurements are (to my knowledge) monitore effects next to the sensor.

What system you choose depends on the problem you want to solve or monitore.

Your order is in the lubricant centers of interest to you

In principle the smoothness of a curve is defined with the mesh size. In Ansys I have the possibility to define the fineness by mesh operations. I don't know if Comsol has this feature.

Additionally, Ansys has an energy-difference sensitive refinement iteration build in. I can define how precision the entire solution (and electric field distribution) must be. This is a rougher method because it "waste" a lot of computing power.

Muhamad arif ashraf abd satar ..... Good question… Please check references below.. hope it will be helpful for you…

Regards…

I have seen 0-3 PZT/PvDF composites in the past.

I found this:

I am glad I could be of some help. Please let me know if I can help you further. Thanks.

Dear Chandra,

Thank you very much for such information.

The maximum torque is inversely proportional to the D-axis synchronous inductance. If you are able to make the air gap longer or reduce the number of turns you can decrease the D-axis synchronous inductance value. Reducing the stator leakage helps also a bit. Another alternative is to drive the machine with increased voltage (if there is room for extra flux in the magnetic circuit and efficient enough cooling).

Saif,

The original poster requires an actuator that can shoulder a load of 7kN for a significant fraction of the stroke. Parker makes no ETT actuators with that ability.

I doubt that any linear electrical actuator will have this combination of speed and strength. Other methods have merit.

(a huge solenoid? a pneumatic ram?)

I think these will help you.

Thanks Luis,

My problem was for Hydropower plants and not for chemical plants.

In general case, electro_mechanical torque is the torque that is specified in motors, that is when u give a electrical energy it is converted to the rotational force for this rotational force a torque is produced this torque is called electromechanical torque. in simpler words the torque produced in mechanical parts by the electrical source then it is called as electro mechanical torque.so the generator is not related with this electro mechanical torque hence it is nothing but a torque required to the generator produced by the wind. 

Hello Jay,

It's better to refer to the datasheet of the specific gyro that you are using. It must have been specified by the manufacturer. It varies from device to device (the sensors).

Alternately, first evaluate what is the signal range of (estimated) your mechanical system and then choose a gyro to accommodate this range.

I hope this will be helpful to you.

Thanks and best wishes!

-Prasanna Waichal

Dear Uma, 

i advice you to see this video:

Hi Michiko,

Many thanks for your message.

The presence of an optimal (as in Fig. 9) rubbing frequency is attributed to two reasons. First,  the helical robot is swimming against flow rate of 10 ml/hr. Therefore, at low frequencies it does not generate enough propulsive force to overcome the flow and the rubbing is not effective. Second, at high frequency the damping increases and result in a decrease in the removal rate.

As to the contact, our model takes the contact force into consideration (Eq. 4). We have also characterized the frequency response of the robot during contact with the channel but without rubbing, and the relation is almost linear (Fig. 9). The step out frequency is beyond the range we studied.

Do not hesitate to contact  any of the co-authors if you have any questions :-))

Islam

Thanks for the answer Mr.Tao....Please explain why??

Dear Zhongmou Li

Yes also i think so that difficulty is because all the actuated joints are in the same leg.

Actually, there is little research on (model and control) the parallel robot with one leg.  

However, here are some attached files that interest from near or far the subject.

Best regards

Thank you Prasanna Waichal

Hello, 

You can take a look at our paper on measuring g31 coefficient of PVDF during stretching. I hope it can help.

Boris

Situ Rani is there any calculations/formula to find out geometric ratio and spacing factor or we have to choose it randomly? Suppose i want to design it for (400-5800) MHz then how i'll do all the calculations?

All so speechless?

We speak of ECM, and the work gap is defined by tool, electrolyte path and workpiece. Electrically, these are the two double layers between the electrodes and the electrolyte (resistance in parallel of the double layer capacitance) and the ohmic resistance of the electrolyte (electrical flow field). Therefore, if the working gap is to be kept constant, the voltage drop across the electrolyte must be constant. Since this distance is increased by the removal, this distance must be adjusted back to the desired degree.

Have you tried matched filter?

A well regulated source should not change its voltage one change in load. 

Disclaimer first: I invented the DiSCmini and the partector, and sell the partector, so I have a conflict of interest here.

Dear Oliver,

you would first have to define "vibration" and "mechanical shock" to get a definite answer. I have often taken DiSCmini or partector devices with me when walking, cycling and, infrequently, in cars. We have had long-term deployments (2 years each) of DiSCmini and Partector devices on Trams and Buses of public transport. I have never seen any real issue with the performance of the devices. A bit more quantitatively, I once took a DiSCmini in a backpack with me while riding a bicycle and put a filter on the inlet and simply recorded the electrometer signal, and analyzed the noise in the end, which was identical (+-10%) of what I got in stationary testing. 

That said, in all these modes of transportation the devices only see weak accelerations. If I drop a partector or a DiSCmini from a few cm on a hard surface (table, floor), I usually see a spike in the electrometer, so in principle there could be effects if the accelerations are too great. For normal operation, I don't think it's relevant, but to answer your question in more detail one would have to really measure the accelerations quantitatively along with the electrometer signals. 

I have heard that the TSI FMPS is sensitive to vibrations (the PSI group had to mount it very carefully in their mobile lab, with shock absorbers etc.). I once put an electrical diffusion battery (which uses similar technologies) in the same mobile lab for comparison with the FMPS and we didn't have to do anything regarding the mounting, it just worked fine. I'm not sure where this difference comes from; my hypothesis is that since the FMPS is a much larger device, the insulators will see much larger forces during accelerations - because F = m*a and m is much larger so for the same acceleration larger forces are applied. Insulators can exhibit piezoelectric and/or triboelectric effects which I would suspect are at work here. By keeping m low, such effects can be minimized. One more good reason for building miniature devices :-)

If you are at ETH conference next week we can do some experiments at our booth where we squeeze, shake and drop partectors and watch the signal in real time on a PC.

best regards

  Martin

PZT actuators can be actuated using a voltage amplifier or a charge amplifier. Charge amplifier will reduce the hysteresis of the PZT. Chose the amplifier based on your piezo specifications and voltage ratings. 

Normally a PZT actuator has a very high bandwidth >20kHz, therefore creating different frequencies is possible below the bandwidth of the actuator.  You can use any real time interface(eg. simulink real time with dSpace/ speedgoat IO boards) to generate your frequency signals and feed into the amplifier. 

I used a Speedgoat IO104 FPGA with simulink real time to generate signals. 

If you do not enable non-linear geometry under your Study node, you essentially have zero displacement between the plates, no matter the body load. Perhaps you would fine some inspiration in the "bk 4134 microphone" under Application Library.

-René

Biaxial pre-strech can eliminate the instability of dielectric elastomer actuator to avoid electrical breakdown. The actuation strain highly depend on how you apply the forces, biaxial or uniaixal.

You may refer to the following publicastion:

There is a lot of encoders out there. Starting with encoder pickups (e.g. avagotech.com) and ending with encoders with digital interfaces transmitting angle and number of revolutions (e.g. heidenhain.com).

Searching for "rotary encoder" will reveal more hits than you can ever check.

Another term would be "angular sensor"/"angular position sensor". These are typically some kind of magnetic sensor (GMR, AMR, TMR) - delivering sin/cos signals. (Just like the AS5048 Ron Reiser described above.)

Last but not least: if you've got a toothed wheel with many, many teeth, you can use a hall sensor that will deliver one or two pulses per tooth.

The most important thing may be to have measurement periods >> 1 s as all these sensors have practical limits at about 5000 inpulses per revolution. Or to use a gearbox, rotating the sensor pickup at a higher speed than the machine itself.

There are many ways to do it. It is up to you to assess what's applicable in your environment.

It is always a good practice to check the d33 measurements on both sides.

your measured d33 values should be approximately the same, but opposite in sign, this indicates effective poling treatment given to your samples.

K. Sreenivas

In physics simulation you can try different maximum angles and compute the forces in the joints and check the smoothness of overall locomotion. By utilising genetic algorithms or reinforcement learning methods of your preference. Then you should easily find appropriate parameters.

You can also have a look here: 

Hello friends,

I'm a little shocked at the answers Murugesh received.

Let's talk of  WEDM and the best Ra values. Whence such values as 0.8 µm to come; or 3 µm; or µm?

Of course I can reach such values, if I let a strong influence on surface and through lead wire EDM with pulse durations of 20 to 200 µs.

First of all it must be clarified what kind of material to be cut. The next question is what Ra values are to be achieved. Can the machining with a main section made or must be re-cuts.

With reputable WEDM equipment you should come without problems less than 1 µm (Ra) in a productive main section. Today, it is also not a problem with a main section under 0.5 microns (Ra) to come. With appropriate after cuts Ra values are 0.2 µm feasible.

Basically, we need to re-discuss with the W-EDM of hard metals and ceramics.

Best regards

Hans-Peter

Laser Doppler Vibrometer (LDV) are also used by some to measure the displacement of thin film AlN.

In order to control a piezoelectric stage, you don't need to extract all of mechanical properties of your stage, so I propose some steps:

1. Specify your important points: You have some important points in your mechanical stage, for example maybe your stage is a table and then roll and pitch angles are important.

2. Excite model's actuators: Excite piezoelectric elements one-by-one and record the movement of each important point.

3. Build the stiffness matrix: Now you can build the stiffness matrix easily.

4. Mass matrix: For the mass matrix you can use modal analysis in ANSYS and with the calculated natural frequencies and the known stiffness matrix, it can be easily computed.

5. Damping matrix: You can build damping matrix directly from K and M by mechanical properties that you entered in ANSYS material definition.

Dear Leonid,

I’m a member of a research group which deals with high-performance motion control systems. We develop special purpose identification algorithms for flexible electromechanical systems based on the estimation of plant frequency response. We also work on the problem of model-based controller design for the automatic commissioning of electric drive systems. You can find some of the results in the research papers published on my RG profile. Feel free to contact me, I’m open to any kind of cooperation on this topic.

The electromechanical time constant is the time needed for servo to speed up from zero to a nominal no load speed, with stall torque acting and no load torque present on the shaft.

The mechanical time constant is the time needed for servo to speed up from zero to a nominal speed, with nominal torque acting and no load torque present on the shaft.

The electrical or armature time constant is the ratio of armature inductance L and resistance R, and it is not directly related to electromechanical or mechanical time constant.

Hello Mahdi,

What you need to do is to add two study steps, "Stationary" and "Eigenfrequency". "Stationary" study should perform the stress analysis. Results from this study need to be passed to "Eigenfrequency" study for successful implementation. 

This can be done automatically by selecting "Prestressed Analysis, Eigenfrequency" study. A few such examples with this study type are also present in COMSOL Model Library.

The key concept is variable gap permeance.  For an off-center rotor, the closer gap has a greater permeance and the further gap has a lesser permeance.  The permeance varies around the rotor circumference.  For a given excitation current, the permeance determines the magnetic field,  which means it is not the same for each pole. The rotor force is the surface integral of the magnetic stress: Fx = Integr(sigma*R*L*cos(q)*dq,0,2*pi); sigma=B^2/2*mu_knot; B=mu_knot*N*I/(g-x*cos(q)).  q is angle from 0 to 2*pi.  So your force integral is: Fx=B0^2*R*L*integr(cos(q)*dq/(g-x*cos(q))^2/2*mu_knot,0 2*pi), where B0=mu_knot*N*I/g.  The integral is difficult, but you can expand the integral in a Taylor series for small x.  After some algebra, the reference equation 2.72 is achieved with the second term approximated as (x/g).  [Math is hard to write when limited to text.]

Hi

I'm not sure about what exactly is the problem.

Do you require info on using the PID controller in the PLC. If this is the case then you should consult the manual or look online.

Do you require to tune the device? Then you should consider using tuning methods like ZN or any other of the popular methods.

Besides the above answer, optimisation of turbine speed using echocardiography guidance should be also performed. Some patients may develop VTs that could be ablated in an expert center. The implant is only the first step, most of the care is required after...

Hi

I am not in any way an expert on this topic so please treat my thoughts on the matter with caution.

Electrodynamic shakers usually are used for frequencies higher than 5 Hz as their mass-spring resonance is this ballpark or higher frequency.

Piezoelectric actuators are stiff, can take lots of load cycks and some may generate the force required but they tend to be hard to drive as their load is reactive, i.e. you would need a serious amplifier to drive them. In any case, they are worth considering and a good place to start looking may be here http://www.physikinstrumente.com/products/integrated-piezo-actuators.html

The other way to go would be to consider servohydraulic excitation. Again, this is not cheap and the premier supplier would be MTS (http://www.mts.com). Hydraulic excitation can easily do the loads you require, MTS shakers are fatigue rated and can take the load cycles you specify. The main limitation would be minimum displacement amplitude which is limited by internal stick.slip effects in the shakers. The MTS shaker I have toyed with managed to go down to the ball park 1-0.5 micrometer. Other limitations will be on velocity and governed by flow rates in control servos. The suggested frequency 5 Hz should be easy for a hydraulic shaker.

If you are on a tight budget, you may want to consider resonant excitation, i.e. you design a simple, e.g. mass-spring type, system to be at resonance at 5 Hz. You should then be able to find a low cost way of driving this system and use the resonance to amplify your loading.

Last, one should not bang one's own drum but, if you want to determine structural properties during your test, you may, or may not, have use of looking at this reference to study the effects of massloading of combined force/moment excitation. https://www.researchgate.net/publication/256801180_Direct_measurement_of_moment_mobility_Part_I_A_theoretical_study?ev=prf_pub

Sincerely

Claes

InsyAllah I will explain in detail soon.

Dear Mihail AIGNATOAIE,

You look this site. There can be you will find the answer of your question.

Best regards, Shafagat

Hi,

Instead of linearizing your system from PID tuner, define you linarization input/output points in the simulink model (search for linio in MATLAB help) and  then linearize your simulink system for the defined input and output points using the command (search for linearize in MATLAB help). Then check if the linearized model is stable or not and see whether or not you can stabilize the linearized model using PI controller. You may have to design different controller.

By the way, after linearizing your system, if the order of the linearized model was high, you can reduce the order of the linearized model (I recommend Hankel singular value based model order reduction: search for reduce in MATLAB help) . The reduced order model can help you in the controller design stage.

Regards,

If you advise me of the size of the tube, I may be able to help. If the diameter is reasonably large, you can measure the velocity profile inside, estimate the mean velocity and multiply it with the cross-sectional area - you will get the volume flow rate.