Harmonic Analysis - Science topic

What are the most effective methods to measure and calculate the harmonic contribution from both the utility and the customers at the PCC? Which methods are commonly used in industries and power systems, and could you suggest useful references on this topic?

In trigonometry we know that frequency and amplitude are independent because they have independent variables.

Then frequency and amplitude do not have the same equation of motion.

But according to Newtonian determinism, all of the motion of a system is determined an equation that depends only on the initial state of the string, being the totality of points on string and their velocities. The initial velocity is zero.

In a closed system, all of the movement must include both frequency and amplitude. That is, frequency and amplitude have the same equation of motion.

On the elastic string, the false assumption the string wave is trigonometric by itself implies amplitude and frequency have independent equations. Indeed, in the literature when mathematicians and physicists want the standing wave to stand down, they just add another arbitrary real-valued function. The frequency and amplitude are parameterized by sine wave and exponential functions, and each has its own time variable. Frequency and amplitude do not map on to the same interval of time.

But under one degree of freedom the standing wave never stands down because it is a surface defined by the potential energy. The surface being precisely those lines of motion along which energy is conserved.

So please tell why are two equations better than one? Why are two degrees of freedom better than one? Some even say the string has infinite degrees of freedom as if the string is not subject holonomic constraint.

You guy’s think the frequency is a velocity, but it's not. Frequency is a potential. Constant velocity and constant potential are both measure by a time unit.

Apparently, physicists and mathematicians think the velocity of the string is constant right up to the point in time when the string stops moving. Because the frequency is constant. That is, you think dv/dt = df/dt = 0. Then you write a partial differential equation that has the form of a sine wave. But your equation in the form u(x. t) is parameterized by time but contain coefficients that are not determined by the initial condition of the string. And it is not continuous on the lower limit.

That is to say the trigonometric string cannot map onto the string at rest. The trigonomtric string has no natural vector field.

Furthermore, the assumption of a continuous trig function implies that you are not required to have a lower semi-continuous boundary, without which it is not possible to formulate the law of string motion in terms of a minimum principle. (See Critical Point Theory by Mawhin and Willem)

There is a stumbling block here because it may seem that it is obvious that amplitude is dependent on time, since it occupies an interval of time. In fact, it is independent of time because decay always consumes the same amount of time regardless of amplitude magnitude.

the rate of amplitude decay da/dt2 = 0 is constant just like the frequency. They have the same Hamiltonian minimizing functions.

The equation da/dt2 = 0 is possible mathematically if the external derivative of amplitude decay is a tautochrone formed by the cycloidal involution of the cycloidal string manifold.

On a tautochrone, a rolling ball always arrives at the bottom of the curve at the same time regardless of how high the ball in dropped from.

This shows that frequency and amplitude are subject to the same holonomic restraint imposed by energy conservation.

When you give up your false assumption frequency is a velocity and change to frequency is a potential, you should see energy conservation is equivalent to volume preservation according to the principle of Liouville integration.

In attached diagrams I show the string manifold and amplitude decay manifold are both minimal surfaces of revolution and they have the same submanifold in Liouville integration except that amplitude is the involution of the cycloid at constant volume. Both manifolds uniform rectilinear motion. The frequency and amplitude run on the same time interval and clearly are not independent.

The trigonometric law of frequency/amplitude independence is not a natural Newtonian law, it is just an illusion that results from the assumption that frequency itself is sinusoidal.

But potential energy is a real number. You guys are just assuming frequency is real (so continuity seems to demand a trigonometric form).

Finally, if the moving string keeps moving until external force stops it, what force stops the string? Clearly not gravity, friction, or viscosity.

The answer is that the motion of the string is quasi-periodic meaning that perturbation involves only the loss of kinetic energy. Potential and kinetic energy do not alternate like a pendulum. When the string is deformed, the potential increases, but quickly the excess goes to kinetic energy and never returns to potential energy. Amplitude decay is simply the loss of kinetic energy doing work against the inertial mass of the string. Since it must be true that potential and kinetic energy have the same Hamiltonian equation, they cannot be independent.

Fig 1 The string manifold and amplitude decay manifold have the same submanifold

Fig 2 Amplitude Decay Manifold

Fig 3 Path of a Cycloidal Pendulum

Fig 4 Amplitude decay is the cycloidal involution of the Cycloidal Manifold.

Fig 5 Volume-preserving Liouville Integration

Fig 6 Constructing a cycloid geometrically using a horocycle give the string a constant radius of curvature.

I am trying to do some harmonic analysis , I have to select the most effective natural modes. I have the modal matrix (natural modes eigen vectors), but I am confused between many techniques. some techniques depend on selection of modes based on orthogonality of modes. while some techniques depend on independency of the modes like (Modal Independence Factor (MIF), Modal Independence Index (MII), and Modal Assurance Criterion (MAC)).

Are there any other techniques ? and which of them consider the most effective and feasible technique ? and if it is possible to include a literature for such method ?

while adding rotating force in harmonic analysis in ansys for a rotor, following error is there:"Selected Remote Point location is different from hit point location." i am ading rotating force by using remote point. any help??

Hello everyone! I have some problems with ANSYS APDL Harmonic analysis.

In general, I have found that using these two methods produces different consequences in ANSYS harmonic analysis.

1. Stepped loads get larger results, and ramped loads get smaller results. The gap between the two was even close to 10 times at one point (e.g. according to the simulation conducted at: https://www.youtube.com/watch?v=SFSnu6fUFeI, and changing the loading method). So I'm wondering exactly why this is. What is the difference between these two methods in ANSYS harmonic analysis? and which value is accurate?

2. Under Stepped load, the amplitude of the same structure at the same frequency point will not change with the frequency range of harmonic analysis. But under the ramped load, the amplitude at the same frequency point will change, and the multiple is regular (for example, if the frequency range is doubled, the amplitude at this point will be reduced by half). In theory, this is impossible. So I'm wondering, why is there such a result?

I am doing ANSYS APDL simulation related to the piezoelectric actuator. I have attached some pictures.

Any help will be appreciated! Thank you very much!

I got interest in the field of Quantum Harmonic Analysis and would like to work on this field. For that I would like to know the recent trends in this field in mathematical point of view.

I want to use the syncrosqueezed transform for analise 1-D and 2-D signal. I am wondering if you could recommend me some good texts on syncrosqueezed transform. Knowing if some code is available in Python or Matlab would be helpful. Thanks a lot!

I am working on design wavelet frames to detect specific patterns in 1-D signals. I wondering if you could recommend mesome good texts on wavelet frames construction. Knowing if some code is available in Python or Matlab would be helpful. Thanks a lot!

As we know, in many references (Farmer et al., 1975; Schmidt et al., 2018; Austin, 2019), the harmonic analysis on the individual thermistor temperature records was applied, especially for the high-frequency water temperature data. I think this method is helpful for water temperature analysis, but I still do not fully understand the physical significance of this method. Can anyone make a clear explanation for this?

After a harmonic analysis, we can obtain a signal. It is easy to understand that the magnitude of the signal decreases with water depth. But some researchers assume that it can be fitted with an offset exponential equation (Austin, 2019). In this way, I can not understand. Hope some warm-hearted can help to explain it.

Thanks very much!

Reference:

[1] Farmer D M. Penetrative convection in the absence of mean shear[J]. Quarterly Journal of the Royal Meteorological Society, 1975, 101(430): 869-891.

[2] Austin J A. Observations of radiatively driven convection in a deep lake[J]. Limnology and Oceanography, 2019, 64(5): 2152-2160.

[3] Schmidt S R, Gerten D, Hintze T, et al. Temporal and spatial scales of water temperature variability as an indicator for mixing in a polymictic lake[J]. Inland Waters, 2018, 8(1): 82-95.

In kalman filter for state variable estimation we take initial zeros but in ensemble especially for harmonic analysis, which values to take ?

Using Python, I would like to convert PSD (G²/Hz vs Frequency) diagrams to Acceleration vs Time diagrams. Would someone be able to provide some insight into this matter, because I would like to know first whether or not this can be accomplished and if so, how?

Dear all,

I am trying to perform harmonic analysis with the forcing term which is not harmonic but periodic. I converted the forcing term to harmonic series of sine and cosine. Now the problem arises when I have to incorporate this force in ANSYS analysis.

Is there any way to input non harmonic forcing term, or the another way to input series of sine and cosine term ??

hello everyone,

what is the criteria to decide the position of an acoustic black hole (ABH)?

I don not address beams which ABH is usually considered as a tapered edge. I am addressing plate and shell structures with a wide design space.

I think the criteria could be maximum normal nodal speed which is directly relevant to radiated noise.

Let me know you ideas, engineers :)

Hello, I am doing a harmonic analysis in 2D on Ansys APDL. I have a disc (mass element + plane182 elements linked to the mass element with rigid constraints) confined in a fluid29. I want to impose a circumferential mean flow effect to my fluid, using BF,,VMEN,,U. But once I run the simulation no frequency appear in the Fourier spectrum, as if no force was applied. However it works when I apply a force with the F command, so I think the problem is with the BF command which is not taken into account. can someone help me ?

How to get the frequency response in terms of voltage from the piezoelectric patch using the ANSYS workbench? Like in this paper,

Hello everyone, I am analyzing the harmonic response of a beam in a frequency range [0-50 Hz] but I noticed that the results for the 0 Hz frequency are not provided by ANSYS workbench. would like to know is there a possibility to have the amplitude of the displacement of the beam for the frequency 0Hz?

Although adopted by few scholars, Kinetic energy minimization could be a helpful approach to isolate vibration.

Suppose we have a plate under harmonic loading and vibration reduction with the help of an absorber is of interest. Personally speaking, I don't like vector quantities for this purpose. Having a positive or negative direction on a large number of nodes, these quantities cannot accurately determine the level of vibration. Because, the designer may use an average or RMS evaluation of a lot of nodal vector quantities which of each has some approximation error.

Thus, I am eager to get some feedback from the community of NVH engineers for considering Kinetic energy as the criterion to be minimized for vibration reduction (instead of vector quantities such as force, velocity or displacement).

Looking forward to your valuable comments!

Hello,

I am doing a harmonic analysis. I am dealing with force reaction, or simply speaking force output. ANSYS gives maximum amplitude but not RMS value.

Is there any way to get the RMS value directly from ANSYS?

Thanks for your attention :)

Hello,

I detached a component from its mother structure. Now, I should define right boundary condition at the cutting boundaries. (I use ANSYS)

I think I should define semi-stiff boundary conditions... I have written the constraint equations... But, I need to discuss it with an expert...

Thanks,

hi,

Similarly to the problem addressed in this topic :

I would like to reduce the size of the .rst file as much as possible in order to minimize the time requires for the simulations. The OUTRES function allowed me to significantly reduce the size of the files with the following commands :

OUTRES,erase

OUTRES,ALL,NONE,

OUTRES,NSOL,ALL,

However, I would like to reduce the size even further. A possibility would be to save solution associated to a restricted number of nodes only. The solutions related to the other nodes may be not saved since they are not used. So I tried the following commands (where 'nxtrnl' is the name of the component grouping the nodes of interest):

OUTRES,erase

OUTRES,all,none

OUTRES,nsol,all,nxtrnl

But the results are very different from what I usually get (magnitude 1e6 larger).

So, would you know if is it possible to save into the .rst file only the solution for a restricted number of nodes ?

Thanks a lot !

Simon

This is an openzmeter capturing the voltage of my house (Almería - Spain). It should be 230V - 50Hz with a more or less sinusoidal wave, but instead, I have a lot of PQ events like in the photo attached. What is happening in the grid??

Hi all, I am using PZT to excite the beam structure and measure the impedance using dynamic signal analyzer. And I also build the finite element model in ANSYS to do harmonic analysis and get the impedance data. My current work is to update the simulation model based on experimental measurements. I read some papers, but all use trial-and-error method. I am wondering if there is an efficient method to conduct model updating.

If make the whole FE model in an optimization loop, the harmonic analysis takes really long time for each iteration. On the other hand, there are too many parameters, and most of them have influence on impedance curve. So the parameters to be updates are also undetermined.

Any suggestions or references are appreciated, thanks.

Hello,

I have a question regarding the zero-sequence voltage injection in three-phase SSTs with bypassed modules in a failure case. I investigated some literature and it is clear that only the fundamental harmonic can shift power between the 3 arms (for power balance).

A 3rd harmonic is often used to reduce the peak arm voltages (-13.4%). However, I investigated asymmetrical fault cases and a 5th and 7th harmonic can help tofurther reduce the arm voltage by a small percentage like 5% (so less redundant modules are needed):

My question is: Do you know other methods to handle asymmetrical fault conditions in cascaded H-bridges or SSTs? Can I handle grid-imbalances like module faults, since the modules in the phase with an over-voltage have to transmit more power (if no zero-voltage injection takes place)?

I thank you for your suggestions and ideas.

my project is power quality and harmonic analysis ubder balancee load conditions under 0-2 Khz.

i was asked to measure each harmonic up to 2 kHz at different power levels and THD. i made a multidrive system upto 20 drives using Dipde rectifier and nonlinear loads

Change the grid impedance (1%, 5% and 15% base impedance) and see the differences.

so what frequency should i take my source and grid impedance values?

What does upto 2khz mean??

Do i keep my source at 2 khz ?

The monochord page in Wikipedia implies that the diatonic scale is determined by the monochord instrument to be ratios defined by the position of a movable fulcrum.

However, on musical strings found on instruments such as the guitar or violin, the string is not a monochord because the detainment of the string allows the fundamental mode to resonate between only two points, and not three.

It follow then that the fundamental of the monochord has a wavelength 2L while the musical string has a fundamental which is 1.

Significantly the musical string does not depend in any way on the length, tension, mass, or composition (within a bound range useful for harmonic oscillations) because the only requirement is the 12th fret is placed at the string midpoint and then one half the string is divided into 12 equal frequency units using the 12th root of 2.  This is the geometric equivalent of the construction of the square root of 2 by the unit square.

My question is whether the monochord and the musical string are in fact the same because it seems the monochord overtones are multiples of 2L and the musical string does not depend on L at all because it is normalized for length.

The string is 1.  It is one thing, always the same, a constant. It is not 1L. Its just 1. It always has the same shape, which is detained in a concatenation.  So the idea that the string is the sum of all the possible modes of vibration is wrong.  There is only one mode and that is the fundamental.  This means the natural overtones are not the defined mutliples of the fundamental.  The multiples are the octave, and any subset of the octave is also a multiple.  You have a ruler and then 12 equal subunits.

The monochord investigates the effect of changing the wavelength and frequency as continiuous variables, but the music string (which is formed by the union of the pitch value and string position sets on the fundamental) are constants that cannot be continuous because the fundamental is a standing wave.

If multiples of the fundamental are defined by the frets that detain the fundamental, then the definition of the overtones is mathematically distinct from the monochord overtones which are degenerate (that is not nondegenerate) forms based on a lower mode of vibration than actually exists.

Doesn't this mean the string under the square root of 2 is always tempered and the problem tempering the piano results because the strings on piano have different lengths?

Is there a way to input wave speed in a complex form on ANSYS? The wave speed I need to assign a material is 325(1+0.11i) however I have been unable to do this thus far.

Failing that, is there any way around this?

Thank you,

Callum.

Hi all, I have conducted modal and harmonic analysis for the PZT transducer in ANSYS or ABAQUS with Open and Short circuit respectively. The following is the key process (ANSYS):

——Solid45 and Solid 5 elements, and Circu94 for circuit

——Coupling surface nodes of PZT to two coupling nodes as electrodes ( shown in the figure1 )

——For Open circuit, I connect a resistor between the two electrodes of PZT with 10e-20 ohm

——For Short circuit, I connect a resistor between the two electrodes of PZT with 10e20 ohm

——The whole analysis process, the bottom electrode is set with a zero voltage as ground

I, respectively, conduct modal and harmonic analysis. For modal analysis, I get the first natural frequency is 30.732 Hz for OC, and 30.721 Hz for SC.

For harmonic analysis, the sweeping force is applied at the tip of the cantilever beam and measure the voltage at the top electrode. The responses are plotted as in the attached figure 2.

My purpose is to calculate the electromechanical coupling coefficient:

ksi = sqrt (1- w_SC²/w_OC²).

So I can only get the ksi with value of 0.03. The structure and parameters are used from the literature [Active-passive hybrid piezoelectric networks for vibration control: comparisons and improvement]; In this paper, the coupling coefficient is 0.1167. There is a huge difference. I read many papers about related analysis, but I can't figure out where my analysis steps are wrong.

In one conference paper I read, it indeed has a large coupling effects. It uses ANSYS to conduct the same analysis, and its results are really good, as shown in figure 3. I nearly use the same analysis steps, so I know I am now approaching to the correct answer now but there is still some details that I may not set correctly. So I am writing to hope someone familiar with the related analysis could help to figure out my issues. Thanks.

Good day,

I design the rail-wheel geometry and the harmonic frequency ranges between 20-10kHz with 500Hz solution intervals and the results makes sense. Most of the time on the related literatures they use 10 or 20 Hz solution intervals. I want to know how to correctly make a choice of number of solution intervals when performing harmonic analysis?

I have modelled a unit-cell of an anechoic structure using ANSYS. The layer is silicone and has been assigned as an acoustics physics region, with an air cavity inside (the air has been modelled and also assigned as an acoustics physics region). There is a steel backplate as well that is structural. In order to simulate the water closure on the silicone layer face I have applied an impedance boundary condition, assigned a port to this front surface and used the body of the same layer to assign the inside surface bodies. A planar wave has been applied using a 'port in duct' excitation condition (with 10000 Pa) and the acoustic absorbance is calculated.

I have used the same material parameters that I have seen in many papers, however I am getting very different results and wondered if anybody could please highlight where I have modelled it incorrectly or explain the observed behaviour? I have included an image of the absorption coefficient with regards to frequency in a 0-6000 kHz range.

Thank you for any help.

I am a final year university student and for my honours project I am studying the effects of the size of air-filled cavities in an anechoic layer. The layer is made of silicone and has a steel plate backing. It is surrounded by a water enclosure, the surfaces in the x and y planes of the anechoic layer have a frictionless support applied to them to stop displacement in the normal directions. I am however having trouble with the remainder of the boundary conditions, namely the mesh sizing and whether I have to use commands to apply specific nodal values (using FLUID 30?).

Any help would be greatly appreciated. Thank you.

Whether the model parameters such as property or geometry could be tuned to obtain desired frequency response by performing harmonic analysis coupled with direct optimization module of ANSYS workbench?

How to prove or where to find the radii of Starlikeness and Convexity of functions in Dunkl and q-Dunkl setting and what are the difficulties to meet in this subject?

In fact, I am interested in this question.

I've been trying to simulate the force transmissibility experiment based on the setup shown in the attached diagram where the transmissibility is defined as the ratio of transmitted force (measured by bottom force sensor) to the exerted force (measured by top force sensor).

I've used a fixed support boundary condition (BC) on the lower face of the bottom force distribution plate and a remote displacement/displacement BC to the upper face of the top force distribution plate. I used these BCs as I believed they are the closest to the real experimental conditions used.

to measure the force, I used force reaction probes on these boundary conditions. Then, I manually plotted the transmissibility ratio ( force reaction measured from the bottom to top plates).

However, the graphs obtained are nowhere near the normal transmissibility curves.

I also tried this way by using frequency response for the top and bottom plates and used the generated amplitudes to manually plotted the transmissibility ratio, however, I did not manage to do this as the frequency response from the top plate is zero (shown in attached figures).

I am doing dynamic analysis of water tank using ansys workbench. While choosing the fluid elements from engineering data, it  shows error message. So I have to give properties of water as Modulus of elasticity and poisson's ratio. I think it does not represent actual behaviour of water. At the same time, using acoustic extension, I can define water as Acoustic body. But the input properties are not bulk modulus and boundary admittance.

Please anybody help me to know how to input  fluid property from the engineering data in modal/ harmonic analysis.

Dear researchers,

I am going to estimate the main four tidal constituents (M2, S2, K1, & O1) as well as shallow water corrective terms (f4 & f6) from hourly sea-level observations in a shallow water station based on the Admiralty method. Do you know any open-source package in this regard?

Most of the available packages e.g. t_tide and Utide works based on Foreman (IOS) method and do not provide the mentioned corrective terms.

Thanks

Here the problem is, we cannot able to create uniform mesh for both exponential cantilever beam and rectangular piezoelectric patch. Is there any problem for this analysis?

Taylor described harmonic motion on the string using Newtonian physics as a smooth manifold. This is absolutely unequivocal in Incremental Methods Direct and Indirect. The string field is uniform, tangent-cotangent bundles are (almost) everywhere perpendicular to the string. The curvature of the string is constant because the string always follows the shortest path.

As the first to describe the equation of harmonic motion, Taylor should get credit for the principle of least action but Euler wrote the formal integral.

But Euler said No, the curve of the string can be any continuous curve. To prove this Euler wrote a series of functions, presumably with the string modes on the monochord (kanon, or measuring rod in Greek) in mind. The use of a transcendental series is similar to Fourier harmonic analysis.

Euler and Bernoulli apparently disagreed on whether the number of terms in the series was infinite. They may have thought the series added up to 1, but Cantor showed the series in not coherent because it does not converge.

Show the question I have here is whether the string manifold is smooth or merely continuous.

First, there is no addition function on the monochord which allow two modes to add. They cannot add because they have different critical points and a point cannot be critical and not critical at the same time.

Second, if the string curve is a combination of waves with different frequency, and therefore different energy levels then those waves on the string that have higher energy will simply minimize on the fundamental.

On Research Gate and Stack-exchange (where I am an outlaw banned for life, like the Jesuits opposed to infinitesimals), I have asked perhaps a hundred questions that have never been answered.

I mean, come on! Of course Taylor was correct. It is easy to see the string manifold is smooth because manifolds cannot exist without smooth functions!

I'd like to hear from John M Lee, Pavel Grinfeld, Liviu Nicolaescu, Marco Marzzucchelli, Giuseppe Buttazzo. People who know a smooth manifold when they see one.

Just as Euler's idea became Fourier (useful but just not in music), Taylor's principle later became the Lagrangian, later Hamiltonian principle.

The string is fundamental to science so if physics and mathematicians do not understand it, what else do they have wrong?

The questions you cannot answer are the best ones.

I have attached Taylor's diagrams showing how he analyzed string motion. Even in Latin the words "cycloid" and "constant curvature" are clear.

I tried to use LDREAD command to take results from a static analysis into the harmonic analysis, but it fails to read the file. I've been using it as LDREAD,REAC,LAST,,,,'structural','rst',' '. Are there other way to take results from different analysis into another?

I was wondering if there are some references available on harmonics analysis (especially for power systems) from a control theory perspective.

I was using ansys workbench to analyze the cantilever energy harvester via harmonic analysis. I don't know why the vibration pattern is a curve.

I am doing dynamic analysis of PIPE contained with fluid using ansys workbench. While choosing the fluid elements from engineering data, it  shows error message. I think it does not represent actual behaviour of water Please anybody help me to know how to input  fluid property from the engineering data in modal/ harmonic analysis.

I am doing harmonic analysis over a beam, I need to single and continuous load over the beam that will transverse the beam with certain speed. The load represents gross axle of a car. I need to know any source, reference, example, or feature that can help me simulating this in ANSYS. Also please if I require to write a script let me know about sources that can benefits me

Thanks.

A new paper in "Constructive Mathematical Analysis" by Prof. Michele Campiti.

You can download the paper for free:

https://dergipark.org.tr/cma/issue/47453/574194

I have done modal analysis in ANSYS APDL. Some warning is coming after finish the coupling part. Getting some sort of error in the value of results summary. But i have done the same model in ANSYS workbench, the frequency range is coming correctly. Due to this problem in ANSYS APDL, i cannot able to do harmonic analysis for the model to get the frequency response.

Kindly tell me your suggestions regarding that.

Hi,

iam doing project on Pzt energy harvesting analysis in ANSYS APDL.

I have done MODAL ANALYSIS.

1. I want to do harmonic and iam not getting steps to do .

2. how to insert an resistor & get voltage output.

if possible share to sheshadri1342@gmail.com

Hello,

A structure is tested for a Random Vibration (say Z axis, 0.1PSD, 20-3000Hz), where I obtained response acceleration from measurement system. Now I wanted to obtain same output(amplitude of modes) by giving Harmonic(sine) sweep as input(in Frequency domain) to Shaker machine. I read some on-line papers explaining conversion/equivalence from PSD to harmonic but none of them are actually working. Can someone please refer some good source?

Thank you,

I wish to know if in a harmonic analysis in Ansys (or any other FEA software) we can apply two different loads with phase difference between them.

At first, model is prepared with appropriate material properties. After that, how to couple the electrical potentials of the two electrodes contacted to the phosphor bronze layer?

To get open global frequency, how to do the bottom electrode of the PEH is grounded and the voltage DOF on the top surface is coupled?

To get short global frequency, how to do bot the top and bottom electrode of the PEH are grounded?

Finally, how to do harmonic analysis for that model to get steady state voltage output.

Dear All This is Suman from IIT Kharagpur, India. I have a very silly query which described as follows. Any sort of insight is will be appreciated. Harmonic analysis is a basic mathematical technique used in various branches. In the field of meteorology and atmospheric sciences, we regularly use harmonic analysis for the elimination of annual (1st harmonic) and semi-annual (2nd harmonic) variation from different data. From the earlier literature it is noticed in most of the cases long term series of monthly data is used for that purpose. For example if there is a complete series of 30 (1951-1980) years monthly data (30*12=360 months), then to eliminate seasonal variability of the original data 1st, 2nd and sometime 3rd harmonics will be subtracted considering a Fourier series of 12 harmonics (for 12 months). Please make me correct it I am wrong. In my case, it is something similar but I don't have whole data as I am interested in seasonal study (Indian Summer Monsoon). I have also 30 years of data having only June, July, August and September. It means the data I have June, July, August of 1951, June, July, August of 1952 June, July, August of 1953 and so on. Now if I want to eliminate the seasonal harmonics then what to do? As I don't have data for all months, it is unscientific to use the above procedure for my data. Is the idea is only applicable for complete data (I mean having all months data)? Please help. Suman Maity Ph.D student IIT Kharagpur India.

please suggest me proper methodology to study the nonlinear vibraition behaviour of the system shown in the figure.

I am doing an axisymmetric harmonic analysis using FLUID29 and SHELL63 elements of a cylinder. I want a plot of velocity variation with frequency at one node. In APDL, it seems only pressure variation option is there. While in Workbench velocity can be evaluated at one frequency only, and it has to be repeatedly evaluated for each frequency value of interest. So, how to get velocity variation with frequency?

I conducted harmonic analysis using ANSYS workbench with memes and piezoelectric ACT extension trying to get an understanding of the behavior of the piezo material as the displacement varies harmonically. My question is about the term voltage frequency plot term mentioned in the results tab and what does it mean, and is the resulting plot represents the frequency spectrum of the output voltage that corresponds to the frequency spectrum of the input harmonic force and the resulting frequency spectrum of the displacement?

need help please to clarify things and any help regarding the piezo material simulation is also welcomed.

Hello, I have been having receiving a strange error when performing Harmonic Analysis in ANSYS Mechanical. When I try to perform a Harmonic Response for more than one frequency, I receive an error message saying "forrtl: severe (153): allocatable array or pointer is not allocated."

I have read through the output files and found something that is maybe relevant, but maybe not. "The maximum number of substeps (NSBMX = 1) is less than the initial value for the number of substeps (NSBSTP = 2)." Is it possible that this could cause a data corruption error?

Other than this, I do not have any ideas. I am having no issues performing Static Structural or Modal Analyses at the moment, and just on Friday I was able to perform a similar Harmonic Analysis without issue. I've also tried to rebuild the model from scratch and that resulted in the same outcome.

Has anyone seen this before and if so how did you solve the issue?

Thanks,

Ben

Hi, I have what I think is a simple question that I cannot find the solution to. I am modelling a piezoelectric actuator with a stack system (PZ disc, electrode, PZ disc, electrode, etc.), but I am unable to figure out how to properly apply the sinusoidal voltage to the system.

I would like to apply a sinusoidal voltage (let's say 100V to -100V) to half of my electrodes and keep the others as my ground at a frequency which I previously identified through modal analysis.

Could someone assist me with this? Thanks as this is my first piezoelectric simulation.

Hello Everyone!!

I am working on Non linear vibration analysis of a simply supported beam in ansys apdl.

I am wondering how can possibly i do the non linear harmonic ansys in apdl.

If it is not possible to do Non linear harmonic analysis what other alternative do i have to do this non linear analysis of beam.

Any help/suggestion will be highly appreciated.

Thank you for your time!!

Hello Everyone!!

I am working on harmonic vibration analysis in ansys apdl.

I am using 1D idealization of 3D structure in ansys apd (Preprocessor > Sections > Beam > Common Section).

I am wondering if it is possible to do the analysis in ansys workbench using 1D element which has 3D idelization.

Any help/suggestion will be highly appreciated.

Thank you for your time!!

I want to do Harmonic analysis of a system containing spring and dash pot as stiffness and damping element.The input to the system is base excitation(acceleration or displacement). what method and solver should be used to solve the problem in ANSYS workbench and how should I apply it.Also I want to know that how to perform QR Damped mode superposition harmonic analysis in ANSYS workbench ?

The sound envelope is observed as a change in sound amplitude over time when a musical string is plucked. The sound envelope has a sharp upswing called the attack followed by exponential volume decay. The shape of the sound envelop is characteristic.

The shape of the vibrating string during the decay is fusiform, sort of cigar-like, but when the string is pulled taut it forms a triangle so the up-sweep of the attack phase represents the relaxation of string perturbation during which time the string is returning to the boundary condition 0 1 0 imposed by the fixed string endpoints.

The attack phase seems to have a higher frequency content than the decay phase which seems to have a simple mathematic form.

So my question is if the decay of the sound envelop is the result of dampened harmonic oscillation, the decay is frequency dependent, right? Then isn’t it true that if the string is vibrating in many different modes at the same time, the decay would not be exponential?

Or am I wrong, it is possible the decay phase is the summation of many difference string modes whose decay is none-the-less exponential?

Is there an equation for the sound envelop that can be used to understand the frequency spectrum content of the sound?

My interest here is to show that the musical string topology is in fact not understood in modern literature.

It is clear that there are two competing theories for the topology of the musical string. The standard theory is the string vibrates in many modes. This is absurd because it requires us to believe that points on the string can be fixed and not fixed at the same time. The competing theory is there is only one mode possible at a time but the string boundary can be briefly perturbed by vibrations that are not multiples of the string fundamental (that is, not overtones). It seems to me that there should be a simple experiment which can clarify which theory is correct.

I have attached some theoretical notes which include diagrams and string boundary condition theory in more detail.

Eddington [1] was one of the few who tried to answer the above question, for the case of the decomposition of white light by a prism; however, his answer is ambiguous. Burgers [2] reportedly (see Ref.[3]) reportedly also refers to this case, but his interest lies in the phenomenon of turbulence, where Fourier analysis and other methods of decomposition are employed. Also, Hinze [3], just before mentioning the Burgers paper, says: "... Though a harmonic analysis of the velocity fluctuations [in a turbulent fluid] can be carried out, this fact is no proof that, conversely, the turbulent fuctuations are composed of these harmonics. Compare the similar problem in the case of sound, where one may distinguish between noise (turbulent) and note (composed of a number of harmonics)."

This problem could conceivably appesr in every domain of physics. Is there an unambiguous abnswer to Eddington's dilemma: "discovery or manufacture?"

[1] Eddington, A.S.: "The philosophy of physical science". Ann Arbor, Ann Arbor Press, 1978. Chapter VII, section I.

[2] Burgers, J. M.: Proc. Koninkl. Akad. Wetenschap. vol.51, p. 1073 (1948).

[3]Hinze, O.: "Turbulence". Mc Graw-Hill, 1975, Ch. 1, pp. 7-8.

A three phase source connected with three phase load through a transformer is simulated in Matlab platform. Value of THD for each phase differs from each other having different fundamental voltages.

In the article "Tight wavelet frames on local fields", the author states that "Theorem 3.1 is an easy consequence of lemmas 3.2-3.4". How?

Indeed, we must prove that : || f ||²₌ ∑_g∈X(Ψ)|<f,g>|²      for all f∈L²(K)

Harmonic analysis - Is it a good method for identification of aquifer type for all types of terrains? How this analysis is conducted?