Questions tagged [frequency-response]

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Changing the relative equilibrium position for a 2-mass spring-mass system

I am trying to solve a double spring-mass system that is positioned vertically (I currently have the pendulum at an angle of 0 in my code below). I derived the system of ODE's required, and I get this ...
remusconnor's user avatar
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1 answer
58 views

How does frequency-response and lead-lag compensators fit in with PID or State Space control

I am new to control theory, as my background is in statistics. In watching a wonderful set of lectures by John Rossiter, and am feeling pretty comfortable with my understanding of the basic concepts ...
krishnab's user avatar
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Topology optimization issue (or not an issue, which is the issue)

I am currently doing some work in topology optimization regarding optimizing for the dynamic compliance of a beam structure but I am running into some issues. Well actually I am not running into some ...
DVL's user avatar
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1 vote
1 answer
705 views

What is the bandwidth for a 2nd order system?

I know that for a first-order system, the bandwidth can be computed known the time constant, tau, where the bandwidth is equal to 1/τ. Is there an equivalent formulation for a second-order system, ...
rhody's user avatar
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How to push apart the first two natural frequencies of a cantilever beam

We have first two natural frequencies of a composite Cantilever Beam obtained through experiment and analytical calculation. Experiment gives 31 and 250 Hz whereas formulae give 30 and 200 Hz. ANSYS ...
Rehan Jamshed's user avatar
1 vote
3 answers
109 views

Do sound waves caused by a vibrating machines correlate to the vibration waves of the machine itself?

I'm a computer engineer, so please excuse my lack of mechanical knowledge :). We have a machine that has large electrical motors causing massive amounts of vibrations, the machine also consists of ...
Rikus Coetzee's user avatar
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1 answer
83 views

Fundamental Frequency values for Rexnord ZA-2115 bearing

I am having difficulty coming to terms with the Rexnord ZA-2115 bearing technical specifications. This bearing is used in the NASA Bearing Dataset where the Rexnord bearings are tested at 2000 RPM ...
Daniel J. Greenhoe's user avatar
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1 answer
26 views

Failure of component due to natural frequency vs stress

lets take a component like a fan blade as an example. Is it right to conclude that it will fail even when the stress is within permissible limits but its operating frequency is close (close enough ...
AJAY SARAF's user avatar
1 vote
1 answer
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why Type III systems has at least two gain margins?

I heard the following statement https://engineering.stackexchange.com/a/54322/40848 if we have a type III system, or one that has three or more low-frequency poles that we're closing around, then we ...
zymaster's user avatar
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2 answers
91 views

Why are the phase indicators different between the open loop bode plot and the closed loop bode plot?

I have an open-loop transfer function G num=105*conv([1 1],[1 2 43.25]); den=conv([2 0 0],conv([1 2 82],[1 2 101])); G=tf(num,den); and a closed-loop function of G/(1+G). Here are the open-loop bode ...
zymaster's user avatar
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3 answers
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How simultaneous can we trigger multiple cameras' frame acquisition

Say we have ten cameras surrounding an object. The object changes its color with a certain frequency (or any information other than color, such as a text on it). The point is if all cameras are ...
Alejandro's user avatar
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1 answer
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Contradiction of bandwidth and damping

I am studying control theory and mechanical vibrations. From control theory aspect, I know that bandwidth and response time is inversely proportional, which means bandwidth and damping as well. But in ...
Tym's user avatar
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1 answer
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Forced vibration single degree of freedom system

so for the Single Degree of freedom system, I obtained the equation in blue, where I think the equation below in black is missing the ‘m*a’ from F=ma? So I see that there is one ‘m*a’, but is that ...
Batsova's user avatar
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2 answers
337 views

Modeling a second order system in time and frequency domain

For school I was asked to model the transfer function $H(s)=\frac{3}{(s+4)(s+5)}$ in both the time and frequency domains using initial conditions $y(0)=2,y'(0)=3$, a step input, and Simulink. I would ...
Red's user avatar
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Area under Frequency response function (amplitude vs frequency)

Recently, I was plotting frequency responses of multi-degree spring-mass systems and I was wondering what does the area under the FRF (amplitude vs frequency) (or in general FFT) mean? Does it have ...
Thorongil's user avatar
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2 answers
111 views

How can I find the right resonant frequency of a chassis?

Structures have infinite DOFs, so it possess infinite mode shapes. How can we find the right resonant frequency out of the infinite resonant frequencies so that we can save our structure? For example, ...
Ibrahim Omer's user avatar
1 vote
1 answer
436 views

How to find out the sampling rate of an acceleration sensor?

In the sensor catalogs, I cannot find this field. They only depict the frequency response range. For example, Bently Nevada's sensors. How we can find out their maximum sampling rate?
Ali Hosseinli's user avatar
4 votes
1 answer
184 views

How to determine the dynamic response of a spring-mass system?

The Problem I have the following system for which I would like to determine its dynamic response, taken from these lecture notes pg.20: where the forcing functions are $u_1 = 1-U(t - t_0)$, $u_2=0$, ...
kostas1335's user avatar
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1 answer
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Controls System experiment

We performed an experiment in which we turned a bicycle on its side and placed a piece of green tap on one of the spokes. We spun the wheel and recorded the wheel spinning until it came to a complete ...
user15588486's user avatar
2 votes
1 answer
135 views

How do I study the frequency response of a physical system with Arduino?

I am a control engineering student and I am studying the frequency response of a system, so the Laplace domain, the Bode plot, poles, zeros,etc. ... I have clear grasp of their meaning, but if I think ...
dcr's user avatar
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Transforming a Wireless Computer Mouse into a Wireless Switch [closed]

With no computer involved whatsoever, I want to be able to read oscillator outputs from my wireless mouse and switch an LED on a left click AND off on a right click. I have taken my mouse apart to try ...
Smartsav10's user avatar
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420 views

Boundary Conditions of a Stepped Beam

I would like to ask about the boundary conditions to be considered in a stepped beam. For a cantilever beam wherein the one end is fixed while the other end is free to oscillate along the z-axis, we ...
p.laine's user avatar
1 vote
0 answers
32 views

Finding force distribution using accelerometer data

The team I'm currently working for is trying to compare bushings with different durometer ratings in the front suspension using single axis(z) accelerometer data during curb impacts. The current ...
MajorMajorMajorMajor's user avatar
1 vote
0 answers
47 views

Where do I start with learning how to transfer data via RF

So I literally have no idea where to start but I know what I want to make. The goal is to somehow transmit 25mb/s of data across 15km with high penetration. Acceptable for reaching through trees and ...
Karekin_FPV's user avatar
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0 answers
24 views

What do the rectangular components of the complex frequency (s) in Laplace transform stand for?

I tried doing a quick search on this question and was very surprised that this information feels very obscure as if it is almost never discussed. Complex frequencies appear in many mathematical ...
AndroidV11's user avatar
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1 answer
2k views

Deflection Equation of a Stepped Beam

Help out a college student. How do you derive the deflection equation y(x) of the shown stepped cantilever beam in the figure? Each segment has a unique Young's modulus and moment of inertia. The ...
p.laine's user avatar
1 vote
0 answers
312 views

Z - transform of white noise

I am taking a graduate course in Digital signal processing with no prior knowledge in DSP. So I am struggling because I don't have the foundational knowledge. Please I need help with the following. ...
Tee's user avatar
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0 votes
2 answers
129 views

How to calculate frequency response of the system? and find missing values [duplicate]

I can convert the H(s) into the frequency response which is: 𝐻(𝑗𝜔) = 𝜇(𝑗𝜔/(1+ 𝑗𝜔𝜏)) and the output in the steady state is: 𝑦(𝑡) = |𝐻(𝑗2)|sin(2𝑡 + ⟨𝐻(𝑗2)) The phase: ⟨𝐻(𝑗2), has to ...
Barlos's user avatar
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-1 votes
1 answer
582 views

Phase shift of transfer function using MATLAB

I'm trying to compute the phase shift of a transfer function (accelerance) in MATLAB, but I'm having issues. The transfer function was computed by dividing the magnitude of the system output by the ...
hopper19's user avatar
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3 votes
0 answers
123 views

Getting the damping ratio from a frequency response function v.s. transfer function

I'm trying to find the damping values of a specimen, based on sweeping the forcing frequency from 0-10 kHz. As shown in the diagram, I measure the input force from the shaker, and the subsequent ...
hopper19's user avatar
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0 votes
1 answer
375 views

Could Tesla have REALLY shaken a building with a little oscillator?

I came across this story while reading about Nikola Tesla ground-power scheme. Supposedly, he created a little oscillator that could be plugged into the ground, tuned to the right (resonant) frequency,...
Palbitt's user avatar
  • 239
4 votes
1 answer
101 views

What is the frequncy range of seismic vibrations?

I'm working on a structure which needs to sustain common seismic vibrations due to earthquakes. So I want to do some modal analysis to find natural frequencies of the structure and make sure they are ...
Foad's user avatar
  • 249
1 vote
1 answer
587 views

Physical interpretation of a Bode plot

I have a few questions regarding the physical interpretation of the information presented on a Bode plot. I believe it is one of those cases where I "don't know what I don't know", so please bear with ...
Richard E.'s user avatar
1 vote
2 answers
5k views

Why phase margin and gain margin should be positive?

In many textbooks it's given that gain margin (in db) and phase margin of the system needs to be positive for the system to be stable. I could not find the reason behind this. Could someone explain ...
Cris waran's user avatar
3 votes
2 answers
1k views

Relation between natural frequency and the thickness

If I have a solid material, let's say two bricks, one of which is thicker and I do modal/vibration testing. What would be the relation between thickness and natural frequency of any of them, is there ...
elluthfi's user avatar
-1 votes
1 answer
37 views

Construct "Modal Coordinates Time History" from transfer function and test accel-time data

I have a query regarding the calculation of the so called “Modal Participation Factor time signal” from a combination of a) transfer functions (amplitude and phase for each eigenmode) obtained from "...
shoggananna's user avatar
1 vote
0 answers
31 views

Mobile Frequency and Carrier Frequency not Matching

I am using a Google Nexus 6 Mobile in India with Airtel as Network Provider. Recently Airtel has upgraded their Network to 2300 Mhz 4G. Whereas Google Nexus 6 Operates on Band 3 (1800Mhz) LTE. When ...
Mitesh Manani's user avatar
0 votes
1 answer
161 views

How do I verify the reaction forces of an FE model due to a response spectrum

In the case of a static calculation of a structural model, one can verify the model by checking the applied and reacting forces to be equal zero. I would like to adapt the same principle for a ...
shoggananna's user avatar
0 votes
1 answer
377 views

Nastran / Frequency Response / Free-Free

There are examples of using SOL 108 and SOL 111 to create a frequency response. In Siemens Simcenter (NX Nastran), the examples focus on a tower with a seismic mass. The model drives the mass with ...
user3533030's user avatar
2 votes
3 answers
347 views

Do internal / external stresses affect modal frequency?

Imagine a cantilevered beam, fixed on one end and with a tension line connecting the other end to ground (e.g. perpendicular to the length of the beam). If I increase the tension, does the modal ...
user3533030's user avatar
3 votes
5 answers
3k views

What can be the reason of the constant 50 Hz sound in my home?

I am suffering from a strange hum in my home. I have just bought my home and living in 3 months. A month ago I've started to hear a humming noise. Then, I recorded the sound and looked at its ...
Ufuk's user avatar
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0 votes
0 answers
35 views

Frequency domain analysis of steering system of a car

Can anyone share the equations involved, or some relevant theory material for frquency domain analysis of steering rack and pinion using bode plot?
anshul suri's user avatar
1 vote
0 answers
38 views

What's the best way to get an ultrasonic sensor that can vary its operating frequency

Long story short I'm looking to build an ultrasonic sensor that can also be used to communicate with a seperate sensor. (So it must be able to send out a pitch around ~42kHz, but also alter the pitch ...
haxonek's user avatar
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0 votes
1 answer
153 views

Base Driven Tuning Fork Mechanical Response Spectrum

I am new to vibration analysis/simulation etc. so I may be missing something very basic here so please forgive me if I'm explaining things poorly or not making sense. To familiarize myself with ...
Jagerber48's user avatar
0 votes
1 answer
62 views

Fourier series with frequency response

I have seen many times that people gets the frequency response function using DTFT. Can I use the Fourier series, and when I do that?
Laur155 155's user avatar
1 vote
1 answer
73 views

MIMO control: static inverse plant decoupling

I am using techniques explained in the book of Skogestag, Multivariable feedback control, for feedback control of a MIMO plant. In this book they explain the phenomena of static inverse plant ...
T.van de Wiel's user avatar
6 votes
1 answer
352 views

Elastic (Young's) Modulus relation to the Eigenfrequency

I would like to compare the shape of the frequency spectrum of a plastic and aluminium component. Now if we assume that the plastic and aluminium component only differ in the material, while the mass ...
mcluka's user avatar
  • 81
2 votes
2 answers
314 views

How the amount of bolt's preload in a single lap joint can change the natural frequencies?

Few days ago someone told me that the amount of bolt's preload in a single lap joint can influence the natural frequency of the beam. So to test that out I modeled a 3D single lap joint in ABAQUS and ...
Omid Fadaei's user avatar
3 votes
1 answer
200 views

Eigenfreuency of beam

How would you calculate the eigenfrequency of such a cantilever?
james's user avatar
  • 268
2 votes
1 answer
247 views

Modal Testing and Frequency Response Interpretation

I'm studying vibrations in a gearhead, for which I have a general dynamic model of 12 degrees of freedom (only translational coordinates) and I have calculated its natural frequencies. Now I want to ...
spe4ker's user avatar
  • 409