Author Topic: Woodward's effect  (Read 418007 times)

Offline Bob012345

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Re: Woodward's effect
« Reply #1220 on: 12/24/2017 02:23 PM »
Dr. Fearn stated that damping is critical to making the mass fluctuations not just energy oscillations.

Offline dustinthewind

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Re: Woodward's effect
« Reply #1221 on: 12/24/2017 08:02 PM »
@WarpTech

I see.
I think Woodward, Fearn at al. will be interested in your findings, since your design has some improvements they wanted to implement.



@sanman

Quote
As I understand it, Woodward/Mach effect is the alleged propulsive effect that arises from selectively varying a mass while linearly oscillating it. So the mass is higher in value on the upstroke and lower in value on the downstroke.

From the infos I have available (book, papers, etc.) that's not quite accurate. Wikipedia page definition seems consistent with what I found in the other sources:

Quote
The hypothesis states that transient mass fluctuations arise in any object that absorbs internal energy while undergoing a proper acceleration.

So technically one can have a Woodward/Mach effect without any generation of thrust.
Simply accelerating an object while changing its internal energy produces a transient fluctuation, but if you don't push and pull at the right moment there's no "momentum flux" and the center of mass stays put.
That's the reason why Woodward uses two frequencies for driving the device, one for generating the mass fluctuation by accelerating and changing the internal energy at the same time and the other, double of the first one, for pushing and pulling.


Quote
Okay, fair enough - so perhaps a conventional chemical reaction isn't the best candidate - but has anyone comparatively looked at all the possible candidates for physical changes that correspond to change in internal energy? Correct me if I'm wrong, but it seems like the first candidate was the electricity flow in and out of a capacitor, and then later it was purely about mechanical oscillation through piezos.

In Woodward's book it is said that at first the importance of the requirement of "bulk acceleration" was not understood, so initially part of trials consisted in simply charging and discharging a capacitor while pushing and pulling it, or using schemes such as the MLT (Mach-Lorentz thruster). These test often resulted in dubious or inconclusive results.

When this requirement was acknowledged it was determined that the best design between those tried before was the piezoelectric disk type.
These disks provide the acceleration and, when stacked, they also behave like capacitors, so that their internal energy can be changed. So in a way it was never about "pure" mechanical oscillation.

Tajmar paper, posted some pages ago, claims that the "internal energy" that appears in Woodward's equation is actually only the internal mechanical energy of the excited pzt stacks. In this way the predicted thrust seems to fit the data point obtained much better than the previous models.

I'm only aware of one other test using a device with a different concept.
It was suggested by Buldrini in 2011, and it consisted of a ferromagnetic mass that was accelerated through a magnetic field, kinda like in a coilgun, while its internal energy was changing due to the induced magnetostrictive stresses.
Any mass fluctuation would have resulted in a difference between the predicted and measured final displacement or velocity.

I'm not completely sure this test was actually performed. If so, the results seems to have never been published anywhere.
Here's the paper detailing the proposal.

http://www.sciencedirect.com/science/article/pii/S187538921100575X 


Quote
Are we sure that mechanical oscillation is the best way to achieve internal energy fluctuation (aka. mass fluctuation) for Mach Effect purposes?

See above, in the context of this effect fluctuating the internal energy alone (like charging and discharging a capacitor) doesn't cause the sought transient mass fluctuation.
Beside this, the problem is really what this "internal energy" means here. If only the internal mechanical energy (causally linked with the force responsible for the acceleration) is the "right" internal energy then a lot of alternatives won't work.

Quote
Do you see what I'm saying?

Maybe, but I'm not sure why you think that "cross-section contamination" is a problem here.
If you are still referring to mass fluctuation as the effect that comes out of m=E/c^2 then there is no way to use this in a isolated system for propulsion.

How to push on the Vacuum, or create friction with the Vacuum using Radiation Reaction.

I think the Woodward effect can be modeled this way, but please note that this is a work in progress. Not a paper for review. I'm hoping to give us something to discuss and make the conversation a little more productive.  8)






Edit: pardon my earlier mistake of thinking it was a saw tooth wave form.  Just realized this isn't the case.  I think an actual saw form would give a null result.

If I understand it right, using WarpTech's equation relating rate of change in acceleration to change in mass then at some set acceleration there is some set effective mass.  This acceleration sets the devices effective mass via coupling with the vacuum giving damping to acceleration, pulling the vacuum in the direction of acceleration and pushing the object in the opposite direction (conservation of momentum).  The change in mass being related to going from zero acceleration to max acceleration at the peak to zero acceleration again.  After this you want a different rate of acceleration in the opposite direction to change direction, taking more time.  The larger acceleration results in more change in mass. 

The mention of 2 frequencies reminds me of a Fourier transform.  I suspect that as a result it's possible to include 3 or more frequencies.  The objective being to give two rates of acceleration at opposite ends.  See attached image. 

https://en.wikipedia.org/wiki/Fourier_transform

I think this rate of change in acceleration giving a change in mass is just a consideration of the mechanical acceleration.  Something similar happens to the effective mass of objects immersed in gravitational fields via an external viewer. 

The mach effects using magnetism article is interesting.  I haven't quite digested it. 
« Last Edit: 12/25/2017 02:08 AM by dustinthewind »

Offline WarpTech

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Re: Woodward's effect
« Reply #1222 on: 12/25/2017 03:26 AM »
Merry Christmas!
« Last Edit: 12/25/2017 03:27 AM by WarpTech »

Offline Bob012345

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Re: Woodward's effect
« Reply #1223 on: 12/25/2017 04:29 PM »
Merry Christmas!

Merry Christmas to you also!

I'm not sure what you are saying here. The accelerated objects in Woodward's formula are bulk objects and have no net charge.

Offline WarpTech

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Re: Woodward's effect
« Reply #1224 on: 12/25/2017 06:28 PM »
Merry Christmas!

Merry Christmas to you also!

I'm not sure what you are saying here. The accelerated objects in Woodward's formula are bulk objects and have no net charge.

Since the charge is squared, I am assuming Free charge, not NET charge. If I assume 1 free electron per atom, the result is at the same order of magnitude, to what is measured by Fearn & Woodward. Classically, radiation reaction is modelled as the charged particle interfering with itself. We assume it is interfering with the fields of everything else in the universe.

Offline Bob012345

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Re: Woodward's effect
« Reply #1225 on: 12/26/2017 05:02 PM »
Merry Christmas!

Merry Christmas to you also!

I'm not sure what you are saying here. The accelerated objects in Woodward's formula are bulk objects and have no net charge.

Since the charge is squared, I am assuming Free charge, not NET charge. If I assume 1 free electron per atom, the result is at the same order of magnitude, to what is measured by Fearn & Woodward. Classically, radiation reaction is modelled as the charged particle interfering with itself. We assume it is interfering with the fields of everything else in the universe.

Thanks. But aren't you essentially saying that in your model the Mach effect is a missing part of EM theory (or a bridge between EM and Gravity)? If that were true then a clever redesign of some electrical machines would greatly enhance our current technology. Or is that going a bit too far?
« Last Edit: 12/26/2017 05:04 PM by Bob012345 »

Offline WarpTech

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Re: Woodward's effect
« Reply #1226 on: 12/26/2017 05:46 PM »
Merry Christmas!

Merry Christmas to you also!

I'm not sure what you are saying here. The accelerated objects in Woodward's formula are bulk objects and have no net charge.

Since the charge is squared, I am assuming Free charge, not NET charge. If I assume 1 free electron per atom, the result is at the same order of magnitude, to what is measured by Fearn & Woodward. Classically, radiation reaction is modelled as the charged particle interfering with itself. We assume it is interfering with the fields of everything else in the universe.

Thanks. But aren't you essentially saying that in your model the Mach effect is a missing part of EM theory (or a bridge between EM and Gravity)? If that were true then a clever redesign of some electrical machines would greatly enhance our current technology. Or is that going a bit too far?

Not missing. Misinterpreted or misunderstood would be a better description. Hard to tell yet if there is a significant advantage or not. These equations imply the resulting force is no better than a photon rocket. It's simply a matter of numbers, that if all atoms take part in the process, such as; stimulated emission due to vibration, then it's still just a photon rocket. This is an electromagnetic process, not a gravitaitonal one. I'm still trying to comprehend the gravitational effect and determine if it is stronger or weaker than the EM effect described above.

Offline Bob012345

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Re: Woodward's effect
« Reply #1227 on: 12/26/2017 06:01 PM »
Merry Christmas!

Merry Christmas to you also!

I'm not sure what you are saying here. The accelerated objects in Woodward's formula are bulk objects and have no net charge.

Since the charge is squared, I am assuming Free charge, not NET charge. If I assume 1 free electron per atom, the result is at the same order of magnitude, to what is measured by Fearn & Woodward. Classically, radiation reaction is modelled as the charged particle interfering with itself. We assume it is interfering with the fields of everything else in the universe.

Thanks. But aren't you essentially saying that in your model the Mach effect is a missing part of EM theory (or a bridge between EM and Gravity)? If that were true then a clever redesign of some electrical machines would greatly enhance our current technology. Or is that going a bit too far?

Not missing. Misinterpreted or misunderstood would be a better description. Hard to tell yet if there is a significant advantage or not. These equations imply the resulting force is no better than a photon rocket. It's simply a matter of numbers, that if all atoms take part in the process, such as; stimulated emission due to vibration, then it's still just a photon rocket. This is an electromagnetic process, not a gravitaitonal one. I'm still trying to comprehend the gravitational effect and determine if it is stronger or weaker than the EM effect described above.

??????The reported thrust from the Woodward team under development is already far beyond a photon rocket and projected to be a lot larger still. If your model only gives a photon rocket why bother with the complexity when you can just use a laser?

Offline WarpTech

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Re: Woodward's effect
« Reply #1228 on: 12/26/2017 06:15 PM »
Merry Christmas!

Merry Christmas to you also!

I'm not sure what you are saying here. The accelerated objects in Woodward's formula are bulk objects and have no net charge.

Since the charge is squared, I am assuming Free charge, not NET charge. If I assume 1 free electron per atom, the result is at the same order of magnitude, to what is measured by Fearn & Woodward. Classically, radiation reaction is modelled as the charged particle interfering with itself. We assume it is interfering with the fields of everything else in the universe.

Thanks. But aren't you essentially saying that in your model the Mach effect is a missing part of EM theory (or a bridge between EM and Gravity)? If that were true then a clever redesign of some electrical machines would greatly enhance our current technology. Or is that going a bit too far?

Not missing. Misinterpreted or misunderstood would be a better description. Hard to tell yet if there is a significant advantage or not. These equations imply the resulting force is no better than a photon rocket. It's simply a matter of numbers, that if all atoms take part in the process, such as; stimulated emission due to vibration, then it's still just a photon rocket. This is an electromagnetic process, not a gravitaitonal one. I'm still trying to comprehend the gravitational effect and determine if it is stronger or weaker than the EM effect described above.

??????The reported thrust from the Woodward team under development is already far beyond a photon rocket and projected to be a lot larger still. If your model only gives a photon rocket why bother with the complexity when you can just use a laser?

The latest data demonstraighting V4 scaling, only shows results that are 4X to 7X better than a photon rocket. That's not even 1 order of magnitude. It is better than a photon rocket but not what I would call "far beyond", and this is why I'm still contemplating the gravitational aspects of this device.

IMO however, the device is dirt-simple compared to designing a laser of equal power and efficiency, on a large scale.

Offline WarpTech

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Re: Woodward's effect
« Reply #1229 on: 12/31/2017 04:06 AM »
My "lab" is coming along nicely. I have 2 MEGA's. MEGA-2 has all 4 disks “electrically" in parallel, stacked in series. MEGA-1 has 2 disks electrically in series and the two pairs in parallel.

MEGA-1:  + - + - - + - +
MEGA-2:  + - - + + - - +

I just got the dual 400W amplifier that operates on 12VDC, but I have not finished hooking it up yet. So far, what I've done is learn how to use my O'scope as a cheap VNA. :)

The plots are from 0 to 700kHz, 50kHz/Div.
« Last Edit: 12/31/2017 04:08 AM by WarpTech »

Offline flux_capacitor

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Re: Woodward's effect
« Reply #1230 on: 01/01/2018 11:25 AM »
Happy new year everyone!

Quote
Are we sure that mechanical oscillation is the best way to achieve internal energy fluctuation (aka. mass fluctuation) for Mach Effect purposes?

See above, in the context of this effect fluctuating the internal energy alone (like charging and discharging a capacitor) doesn't cause the sought transient mass fluctuation.
Beside this, the problem is really what this "internal energy" means here. If only the internal mechanical energy (causally linked with the force responsible for the acceleration) is the "right" internal energy then a lot of alternatives won't work.

This is Nembo Buldrini's Bulk Acceleration Conjecture:

Quote from:  James F. Woodward (in Making Starship and Stargates, page 132)
What [Nembo Buldrini] pointed out was that given the way the transient terms of the Mach effect equation are written in terms of the time-derivatives of the proper energy density it is easy to lose sight of the requirement in the derivation that the object in which the mass fluctuations occur must be accelerating at the same time. In some of the experimental cases, no provision for such "bulk" acceleration was made.15 As an example, the capacitors affixed to the tines of the tuning fork in the Cramer and the students' experiments made no provision for such an acceleration. Had the tuning fork been separately excited and an electric field applied to the capacitor(s) been properly phased, an effect might have been seen. But to simply apply a voltage to the capacitors and then look for a response in the tuning fork should not have been expected to produce a compelling result.

Other examples could be cited and discussed. Suffice it to say, though, that after Nembo focused attention in the issue of bulk accelerations in the production of Mach effects, the design and execution of experiments changed. The transition to that work, and recent results of experiments presently in progress, are addressed in the next chapter.

15 By "bulk" acceleration we are referring to the fact that the conditions of the derivation include that the object be both accelerated and experience internal energy changes. The acceleration of ions in the material of a capacitor, for example, does not meet this condition. The capacitor as a whole must be accelerated in bulk while it is being polarized.

This would discard prior designs based on an electromagnetic coil (instead of vibrating PZT discs). Unlike METs (Mach Effect Thrusters, now called MEGA drives), MLTs (Mach-Lorentz Thrusters) didn't used any mechanical motion. In an MLT, a Lorentz force, cross product between an electric field and the magnetic field produced by a coil, appears and acts upon the ions inside the capacitor dielectric. According to Buldrini, there is no bulk acceleration in this kind of device, which cannot work. Woodward agrees with him.


Woodward's 2006 MLT design

BTW, Sonny White's first QVPT (Quantum Vacuum Plasma Thruster, or Q-thruster) at Eagleworks was a shameless theft of the MLT design without crediting Woodward for the invention. Whereas the Woodward effect required AC and proper phase sync, White was pushing his own QFV conjecture instead of Mach effects so he was persuaded the device could work on HV DC like an MHD drive with a real ionized gas, except White thought his device could trigger a "virtual plasma" with e-p pairs quickly popping in and out of existence due to quantum vacuum fluctuations, and he thought he could push upon them with Lorentz forces. As it is now considered the MLT was a flawed design, it could not even run with AC, even less so with DC. White later dropped the MLT design and switched the embodiment of the QVTP (which is not a single design of a precise apparatus, rather some application of a theoretical concept) to the EmDrive. First QVPT based on the MLT (circa 2010-2012) below.
« Last Edit: 01/01/2018 12:05 PM by flux_capacitor »

Offline WarpTech

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Re: Woodward's effect
« Reply #1231 on: 01/03/2018 05:52 PM »
My "lab" is coming along nicely. I have 2 MEGA's. MEGA-2 has all 4 disks “electrically" in parallel, stacked in series. MEGA-1 has 2 disks electrically in series and the two pairs in parallel.

MEGA-1:  + - + - - + - +
MEGA-2:  + - - + + - - +

I just got the dual 400W amplifier that operates on 12VDC, but I have not finished hooking it up yet. So far, what I've done is learn how to use my O'scope as a cheap VNA. :)

The plots are from 0 to 700kHz, 50kHz/Div.

On MEGA-2, I zoomed in and determined the 1st strong resonance is at 44kHz, and it has an impedance of 100 Ohms at this frequency. I also noticed that the PZT stack behaves like a capacitor, not an RLC circuit. Once charged, it doesn't ring and discharges very slowly. The impedance of a 1M-Ohm O'scope probe is enough to cause it to discharge, but without the probe attached, it stays charged for a relatively long time.

I have an idea to parallel an inductor with the stack, to cause it to ring, and tune the inductor so that it rings at 44kHz. Then if temperature causes the resonance to change due to capacitance change, the circuit should naturally track that change in frequency. I have some Ferrite cores and wire, but I need to lookup the specs and determine how many turns I need. I estimate 360uH will do it, but that size inductor may require a larger powdered iron core.

Regarding thrust. I've worked out the conservation of energy and momentum now. I can see why it "appears" to thrust better than a photon rocket, even though it is still just a photon rocket. The stack excited at a constant frequency w, will be damped by Larmor radiation emitted in both directions. It is proportional to acceleration squared, ~ a2, which oscillates at the highest amplitude at the light-weight end of the stack.

By applying a 2nd frequency at 2w, the emission in one direction is amplified, while emission in the other direction is suppressed. Having emission in one direction only, causes thrust in the opposite direction, conserving energy and momentum just like a photon rocket.

I see that the "peak" power radiated is much higher than the average power consumed because of the small duty-cycle. A slow response thrust balance cannot respond fast enough, so it acts like a "peak detector". It only measures the peak thrust as an impulse, and then does not relax fast enough to average it out. Therefore, it gives the appearance of being 5 or 6 times better performance than a photon rocket when it fact, it is just a photon rocket.

While the process occurring is similar to my model of quantum gravitation, there is no time dilation occurring, so it's not really gravity at all pulling it forward. I looked at the time dilation and relativistic doppler shift, but these are down by a factor 10-9, and as such are negligible effects.

As I see it, there is no external field required, and unless Larmor radiation is somehow controversial, I don't see any controversy on whether or not this should work. It doesn't require the quantum vacuum to push against, however the thrust can be modeled as an asymmetrical friction, due to an asymmetrical "velocity x jerk" product. Friction however, still results in simply emitting photons.

I'm about to the point where I can start a write-up of the theory of operation, but I'm still working on designing a MOSFET dual-driver circuit. I purchased a BOSS dual-channel audio amplifier and a 40A, 12V power supply (cheap) on Amazon. It is good for driving it the way Dr. Fearn and Prof. Woodward do, but the output voltage is too low for a 100 Ohm impedance. My MOSFET driver will not have this issue.

« Last Edit: 01/03/2018 05:57 PM by WarpTech »

Offline ThinkerX

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Re: Woodward's effect
« Reply #1232 on: 01/04/2018 01:24 AM »
Ok, Warp Tech.  I'm trying to wrap my mind around this:

Quote
On MEGA-2, I zoomed in and determined the 1st strong resonance is at 44kHz, and it has an impedance of 100 Ohms at this frequency. I also noticed that the PZT stack behaves like a capacitor, not an RLC circuit. Once charged, it doesn't ring and discharges very slowly. The impedance of a 1M-Ohm O'scope probe is enough to cause it to discharge, but without the probe attached, it stays charged for a relatively long time.

Are you saying that this device is like a 'turbo-charged' photon rocket because it's also a capacitor?

If so, wouldn't the 'extra thrust' gained during the discharge effect be lost while the device was charging?

And...heading out on a limb here...

way back in the first few EM Drive threads, repeated mention was made by electrical engineers that the EM Drive device was 'capacitor-like.'  Possibly your explanation applies to the EM Drive as well?  Or is the degree of thrust between this and the EM Drive too far apart?

Offline WarpTech

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Re: Woodward's effect
« Reply #1233 on: 01/04/2018 02:27 AM »
Ok, Warp Tech.  I'm trying to wrap my mind around this:

Quote
On MEGA-2, I zoomed in and determined the 1st strong resonance is at 44kHz, and it has an impedance of 100 Ohms at this frequency. I also noticed that the PZT stack behaves like a capacitor, not an RLC circuit. Once charged, it doesn't ring and discharges very slowly. The impedance of a 1M-Ohm O'scope probe is enough to cause it to discharge, but without the probe attached, it stays charged for a relatively long time.

Are you saying that this device is like a 'turbo-charged' photon rocket because it's also a capacitor?

It is like a "turbo-charged photon rocket", but not because it's a capacitor. I'm just surprised that it behaves like a capacitor and not a resistor or inductor. It is an "open circuit" when there is nothing connected to it to complete the circuit, therefore it can store charge and stay charged over long times. Believe me, I got a helluva shock when I took the disks out of the oven and tried to pick one up after it sat there for over an hour, cooling.

If so, wouldn't the 'extra thrust' gained during the discharge effect be lost while the device was charging?
It charges from the amplifier and discharges into the vacuum. If there were only one frequency, it would radiate in both directions equally. But when the 2nd harmonic is added, the output is amplified and rectified, so that it only radiates out one side. The MEGA thrusts the other way to conserve momentum. Direction depends on phase.

And...heading out on a limb here...

way back in the first few EM Drive threads, repeated mention was made by electrical engineers that the EM Drive device was 'capacitor-like.'  Possibly your explanation applies to the EM Drive as well?  Or is the degree of thrust between this and the EM Drive too far apart?

I haven't found the connection to EM Drive yet. I haven't given it much thought, but if the EM Drive conserves momentum, it should be the same in principle.

Offline sanman

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Re: Woodward's effect
« Reply #1234 on: 01/05/2018 08:35 PM »
Are you saying that this device is like a 'turbo-charged' photon rocket because it's also a capacitor?

It is like a "turbo-charged photon rocket", but not because it's a capacitor.


I really like your "turbo-charged" analogy, because a turbo-charger works by creating a higher-pressure equilibrium state (a zone of higher energy potential) to extract more energy from the combustion process. Likewise, analogously, the resonance cavity is creating a zone of higher energy potential with its traveling and standing waves, to perhaps facilitate more efficient momentum extraction from the resonant photons.

Your "capacitor" analogy touches on the idea that the resonant cavity is a well of elevated potential.


Offline WarpTech

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Re: Woodward's effect
« Reply #1235 on: 01/08/2018 02:11 AM »
I have completely rebuilt my MEGA based on the mathematical model. I am still using the same SM-111 material, with the 50mm x 2.1mm disks. The diagram below shows the complete assembly. I have two stacks of 4 disks, that allow me to either combine them together into an 8 disk stack or keep them separated and apply 2 frequencies, as shown.  The last 2 disks are used to measure the displacement, it provides an output signal so I can quantitatively measure what is going on. Dr Woodward refers to this as an accelerometer, but it can only measure displacement.

The plots below have a center frequency at 45kHz, 5kHz/div, from 20kHz to 70kHz.

Compare images TOP3 to BOT3. The Bottom stack being the one resting on the copper reaction mass. The Top stack is the 4 disks in the middle, and the output in purple is measured at the output of the displacement sensor.

1. You can see how very different each of the 4 disk stacks behaves. I don't know why but this will need more investigation. Perhaps I need to buy a lot of disks and compare stacks and find two that are well matched.

2. From these two, I want to select the frequency to drive each stack, such that the two frequencies are the 1st and 2nd harmonics. I found several pairs of frequencies that work. 21.5/43kHz, 45/90kHz, 63/126kHz. Of the 3 pairs, the lowest frequency has the highest amplitude by a wide margin. The response is not there at high frequency, it will require much larger electric fields to drive the stacks at higher frequencies.

3. In the image BOTH3, both were combined into an 8 disk stack, driven by 1 source. Notice that around 21kHz, the purple trace is asymmetrical. This is how we can spot where the Electrostriction is occurring. Without applying the 2nd harmonic, at around 21.5kHz the stack will provide its own 2nd harmonic from the electrostriction effect of the stack. The problem is, the stack heats up rather quickly and as it does, the electrostriction goes away, or is no longer at the right phase relationship relative to the 1st harmonic.

4. When I apply 2 sources as shown in the diagram, heat doesn't cause it to drift as long as the driving frequency is in the bandwidth where the amplitude of the displacement sensor is large.

I still haven't started working on a driving circuit because first I need to quantify what is needed to drive it properly.


« Last Edit: 01/08/2018 04:26 AM by WarpTech »

Offline ThinkerX

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Re: Woodward's effect
« Reply #1236 on: 01/08/2018 03:13 AM »
Warp Tech, are you missing an image or three from your last post?  Or are they just unlabeled?

Offline dustinthewind

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Re: Woodward's effect
« Reply #1237 on: 01/10/2018 01:10 AM »
I have completely rebuilt my MEGA based on the mathematical model. I am still using the same SM-111 material, with the 50mm x 2.1mm disks. The diagram below shows the complete assembly. I have two stacks of 4 disks, that allow me to either combine them together into an 8 disk stack or keep them separated and apply 2 frequencies, as shown.  The last 2 disks are used to measure the displacement, it provides an output signal so I can quantitatively measure what is going on. Dr Woodward refers to this as an accelerometer, but it can only measure displacement.

The plots below have a center frequency at 45kHz, 5kHz/div, from 20kHz to 70kHz.

Compare images TOP3 to BOT3. The Bottom stack being the one resting on the copper reaction mass. The Top stack is the 4 disks in the middle, and the output in purple is measured at the output of the displacement sensor.

1. You can see how very different each of the 4 disk stacks behaves. I don't know why but this will need more investigation. Perhaps I need to buy a lot of disks and compare stacks and find two that are well matched.

2. From these two, I want to select the frequency to drive each stack, such that the two frequencies are the 1st and 2nd harmonics. I found several pairs of frequencies that work. 21.5/43kHz, 45/90kHz, 63/126kHz. Of the 3 pairs, the lowest frequency has the highest amplitude by a wide margin. The response is not there at high frequency, it will require much larger electric fields to drive the stacks at higher frequencies.

3. In the image BOTH3, both were combined into an 8 disk stack, driven by 1 source. Notice that around 21kHz, the purple trace is asymmetrical. This is how we can spot where the Electrostriction is occurring. Without applying the 2nd harmonic, at around 21.5kHz the stack will provide its own 2nd harmonic from the electrostriction effect of the stack. The problem is, the stack heats up rather quickly and as it does, the electrostriction goes away, or is no longer at the right phase relationship relative to the 1st harmonic.

4. When I apply 2 sources as shown in the diagram, heat doesn't cause it to drift as long as the driving frequency is in the bandwidth where the amplitude of the displacement sensor is large.

I still haven't started working on a driving circuit because first I need to quantify what is needed to drive it properly.
I am not sure this will help but I noticed your signal looked very similar to the displacement signal I was supposing might contribute to the mach effect.  I circled the signal in red and it is the purple signal. 

In the image of my plot (blue displacement signal) I added in the original signal but I have found if you modify the 2nd and successive signal terms, (here I use 5 signals) it amplifies displacement/acceleration at the top, and minimize deceleration/displacement below.  Successive terms seem to approach max 2 top and 1/2 bottom.  Probably some other series that would accomplish even more drastic effects.

The red plot is of a simple sin wave. 

Not really sure how useful this will be as it seems you suggest the material is responsible for the 2nd wave introduced via electrostriction.  Isn't maximizing electrostriction in a material maximizing its expansion on application of an electric field?  So the objective is to maximize displacement per applied electric field?  Am I wrong in suspecting the heavier mass provides an anchor mass that is less accelerated while the other mass is more accelerated?  The more accelerated (aluminum) mass takes the brunt of the effect of asymmetric acceleration providing the actual mach effect?

What would happen if you just introduced your own mix of frequencies for physical displacement via each individual disk (5 disks 5 separate frequencies).   - would you be combating the electrostriction effect or would there be a way to make it work?

with each signal being out of phase pi/2 or 90 degrees it some how seems familiar to a phased array but I don't quite see how. 
« Last Edit: 01/10/2018 01:22 AM by dustinthewind »

Offline WarpTech

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Re: Woodward's effect
« Reply #1238 on: 01/10/2018 03:02 AM »
I am not sure this will help but I noticed your signal looked very similar to the displacement signal I was supposing might contribute to the mach effect.  I circled the signal in red and it is the purple signal. 

In the image of my plot (blue displacement signal) I added in the original signal but I have found if you modify the 2nd and successive signal terms, (here I use 5 signals) it amplifies displacement/acceleration at the top, and minimize deceleration/displacement below.  Successive terms seem to approach max 2 top and 1/2 bottom.  Probably some other series that would accomplish even more drastic effects.

The red plot is of a simple sin wave. 

Not really sure how useful this will be as it seems you suggest the material is responsible for the 2nd wave introduced via electrostriction.  Isn't maximizing electrostriction in a material maximizing its expansion on application of an electric field?  So the objective is to maximize displacement per applied electric field?  Am I wrong in suspecting the heavier mass provides an anchor mass that is less accelerated while the other mass is more accelerated?  The more accelerated (aluminum) mass takes the brunt of the effect of asymmetric acceleration providing the actual mach effect?

What would happen if you just introduced your own mix of frequencies for physical displacement via each individual disk (5 disks 5 separate frequencies).   - would you be combating the electrostriction effect or would there be a way to make it work?

with each signal being out of phase pi/2 or 90 degrees it some how seems familiar to a phased array but I don't quite see how.

Your waveform is very interesting. That looks like the ideal "output" displacement, but I don't know that this is what we will get for output if that waveform was used as the input. In my oscillogram, the yellow trace is the input current. You can see the sinewave is collapsing at the top because my amplifier + transformer are maxed out. I have some heavier wire and a current sensor coming next week so I can maximize the power to the MEGA. In the end, I hope to apply nearly 800W of power.

You are correct, that the material is providing the 2nd harmonic. The electrostriction is depending on the electric field squared, E2, where the piezoelectric effect only depends on E. This makes the response of the PZT disk asymmetrical, as required for the Mach effect. The material is not going to provide all those other harmonics you are using.

Your other ideas are correct. The mass difference makes lightweight side dissipate more power. Power flow is asymmetrical.

IMO, applying multiple frequencies to multiple stacks probably has some advantages. The electrostriction effect seems to go away when it gets hot.





Offline dustinthewind

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Re: Woodward's effect
« Reply #1239 on: 01/10/2018 04:14 AM »
I am not sure this will help but I noticed your signal looked very similar to the displacement signal I was supposing might contribute to the mach effect.  I circled the signal in red and it is the purple signal. 

In the image of my plot (blue displacement signal) I added in the original signal but I have found if you modify the 2nd and successive signal terms, (here I use 5 signals) it amplifies displacement/acceleration at the top, and minimize deceleration/displacement below.  Successive terms seem to approach max 2 top and 1/2 bottom.  Probably some other series that would accomplish even more drastic effects.

The red plot is of a simple sin wave. 

Not really sure how useful this will be as it seems you suggest the material is responsible for the 2nd wave introduced via electrostriction.  Isn't maximizing electrostriction in a material maximizing its expansion on application of an electric field?  So the objective is to maximize displacement per applied electric field?  Am I wrong in suspecting the heavier mass provides an anchor mass that is less accelerated while the other mass is more accelerated?  The more accelerated (aluminum) mass takes the brunt of the effect of asymmetric acceleration providing the actual mach effect?

What would happen if you just introduced your own mix of frequencies for physical displacement via each individual disk (5 disks 5 separate frequencies).   - would you be combating the electrostriction effect or would there be a way to make it work?

with each signal being out of phase pi/2 or 90 degrees it some how seems familiar to a phased array but I don't quite see how.

Your waveform is very interesting. That looks like the ideal "output" displacement, but I don't know that this is what we will get for output if that waveform was used as the input. In my oscillogram, the yellow trace is the input current. You can see the sinewave is collapsing at the top because my amplifier + transformer are maxed out. I have some heavier wire and a current sensor coming next week so I can maximize the power to the MEGA. In the end, I hope to apply nearly 800W of power.

You are correct, that the material is providing the 2nd harmonic. The electrostriction is depending on the electric field squared, E2, where the piezoelectric effect only depends on E. This makes the response of the PZT disk asymmetrical, as required for the Mach effect. The material is not going to provide all those other harmonics you are using.

Your other ideas are correct. The mass difference makes lightweight side dissipate more power. Power flow is asymmetrical.

IMO, applying multiple frequencies to multiple stacks probably has some advantages. The electrostriction effect seems to go away when it gets hot.
If I understand your correctly, you tried 2 methods. 

method 1 is you apply a single sinusoidal voltage to the entire stack and the electrostriction provides the 2nd harmonic but you are encountering rapid heating which destroys the phase of the 2nd harmonic. 

method 2 or (4.) is you ignore the overheating of the electrostriction effect (let it heat up - go out of phase) and directly put in the 2 harmonic to force at 2f so that it has the desired displacement wave form, regardless of over heating. 

If this is true then when you get your 2nd frequency just right with the phase adjustment signal at 2f, if you introduce a 3rd harmonic frequency at about 3*f where f is the original frequency then the stack might provide the 4th frequency at 6f also?  (not sure this would work.)  might need a 4th signal at 6f to adjust the phase also. 

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