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Questions tagged [dynamics]

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1answer
29 views

In equilibrium is engine torque zero? Vehicle dynamics

Consider following equations for a driving wheel in a car. $$ J\dot{\omega} = T - F_x R - F_r R \\ m\dot{v} = F_x + F_r $$ where $J$, $\omega$, $T$, $F_x$, $R$, $F_r$, $m$, and $v$ are wheel inertia, ...
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14 views

mass on rope attached to a rotating bar

is the linear momentum of the ball conserved in the $e_3'$ direction? I figure since there is no force on this direction, but the direction is changing, the linear momentum will not be conserved. is ...
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0answers
12 views

Absolute motion of cable pulley problem dynamics

So this problem stumped me. I solved the simple parts but then it asks to find the absolute velocity of the point C on a cable. In my mind they are asking for the velocity of the cable.(prob 215) My ...
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1answer
37 views

Two Dimensional Kinematics

Attempting this kinematics question but not really understanding if what I'm doing is right or completely wrong. Should I be starting by finding Vp? Any help appreciated. Not an assignment, just ...
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0answers
34 views

How are all LTI systems also dynamical systems?

How are all LTI systems also dynamical systems? I understand that LTI systems are linear and time invariant and that dynamical systems describe how one state develops into another, but how would this ...
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1answer
35 views

Fluid dynamics of a valve

I am new to fluid mechanics and am trying to understand the fluid mechanics of a simple valve. Let's assume we have a simple tube, which is supplied with a constant stream of liquid using a pump. At ...
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0answers
14 views

Combining response spectra

I have a question regarding response spectra and its use within dynamic analysis. Assume that a load combination that a component is subject to is the result of two events: A and B. If each event, A ...
2
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1answer
47 views

Vertical component of force for rigid wheel hitting a step

My question relates to finding the vertical component of force due to a rigid wheel hitting a rigid step. I know the details of the step and I know the horizontal velocity of the wheel. I'm using the ...
4
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2answers
56 views

Power decreases as the diameter increases

I have a question about the use of a servo motor. I need to lift a load of $130\ kg$ with two servo motors with $13\ Nm$. The diameter of the shaft is $Ø40\ mm$, ie, $r=\ 20mm$. $1\ N = 1\ Kg\ *\ 1\...
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3answers
28 views

Damage differences in frontal collision of two vehicles and their speed

Please check this newspaper article and its pictures and the video in it: Article It contains photos and a video of a frontal crash between two vehicles of a trolley line. From the photos, it seems ...
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1answer
35 views

Mechanical vibrations: kinetics of kinematics?

In books of dynamics, I normally see topics in kinematics and then in kinetics, and finally a last chapter on mechanical vibrations dealing with SDOF and MDOF systems. But I do not see any book ...
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2answers
81 views

Finding out torque in a viscosimeter

I am solving problems through Fox and McDonald.Here is the problem I tried by finding out the torque due to viscous forces which is $$\tau_1=\mu(2\pi Rh)\frac{R\omega}{a}$$ and the torque due to ...
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60 views

Why do cornering vehicles need yaw motion to turn when facts prove otherwise?

Considering what we know about rotation, laws of motion and using a few examples below, is yaw motion even needed for the cornering vehicle to turn? Vehicle dynamics claims the need for yaw motion ...
1
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1answer
24 views

Linearly Damped Harmonic Motion with Sliding Friction

In Problem 2/54, I have come up with a solution only one decimal place off from the books results. I am posting to see if someone can look over my solution to see if it is correct. To begin the ...
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2answers
31 views

Damped harmonic motion with dry friction

So I'm a hobbiest who loves doing and learning about different subjects. Often I run into difficult problems that I normally can find solutions to however this one stumped me, I have reviewed many ...
0
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2answers
53 views

How would I calculate the torque need to move the trailer?

I want to find out how much torque will be needed from my motor if I want to pull a mass. So imagine a car towing a trailer.How would I calculate the torque need to move the trailer? I found the ...
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0answers
33 views

Abaqus implicit dynamic vs custom script

I'm trying to validate results from a custom code written with Matlab by comparing the results with Abaqus. I'm doing an implicit dynamic analysis using direct integration and, as done in Abaqus, I'm ...
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0answers
58 views

Can a 'Point on Curve Joint' (ANSYS Rigid Body Dynamics) be applied to a 3D curve?

I am looking to simulate a cylindrical barrel with a track cut into it, that a pin slides along - essentially transfering rotational motion of the barrel to linear motion of the follower pin. ...
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0answers
24 views

dynamic analysis of an inversed slider-crank linkage

So, I have been struggling with this mechanism for a week now. But I think I am still forgetting something. a brief explanation into the mechanism: the model (seen above schematically) has 3 ...
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2answers
41 views

How to calculate the max torque due to angular momentum of a beam given motor specs

I have non-rigid beam attached to a gearbox and motor assembly. The gearbox outputs $1000 N \cdot m$ at the shaft. The beam is rotated at $3000 RPM$ around it's center. If the motor is switched off ...
0
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1answer
48 views

Isolating vibrations originating from my machine

I'm developing a machine with a reciprocating motion (mass: 50-100 kg, period: 1.35 s, accelerations: 1 g). This machine is part of a process line, and I don't want the resulting "shaking" to ...
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2answers
45 views

I want to know the water flow rate from a certain height knowing the flow rate at near the ground level

I used a bucket to find out that at 1 feet high (a garden faucet) the flow rate from an half inch pipe is 1 gallon in 26 seconds At 3 feet high (face basin) the flow rate is 1 gallon in 30 seconds at ...
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0answers
47 views

What constructive solid geometry CAD programs can accurately model and simulate structural rope, cable, pulleys, and dynamic motion elements?

It seems that flexible objects just don't model well in many popular constructive solid geometry (CSG) CAD programs. Most CSG modelers seem to assume exclusively rigid bodies with sharply defined and ...
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0answers
22 views

How to control an underactuated platform with a single servo

What's the best way to control the following type of platform so that it remains balanced and upright? It's a box supported by a single leg that can pivot at the foot (F) and at the hip (H). The foot ...
1
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1answer
29 views

the possibility of a breakwater/seawall preventing the beginnings of a landslide-formed tsunami [closed]

. . A thought recently crossed my mind which I cant seem to find any studied material on. It occurred while hearing a story about a potential future landslide in Kauai causing a large tsunami aimed at ...
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0answers
41 views

Question regarding notation and wording of rigid body dynamics questions

I'm confused about the notation and wording we use when working with rigid body dynamics (e.g. "with respect to this ref. frame", "relative to point B" etc.) I was wondering if anyone on here could ...
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0answers
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Dynamics chain question

I was wondering if anyone can explain to me how we work out this type of question. Thank you. A chain of total length 2l with a mass ρ per unit length is hanging in the equilibrium position shown. If ...
5
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1answer
88 views

System Dynamics Modeling

I am trying to model this system but am having difficulties in setting up the equations of motion. This is a simplified model of a motorcycle suspension system, where P is the ground in the image ...
2
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1answer
53 views

Torque and angular acceleration

I have got 19.6 as the answer for (a) but the book tells 14 is the answer. Can someone tell what mistake I have done or is there in the book.
4
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0answers
68 views

Questions regarding Cornering Stiffness for RC Car

I am a bachelor's level student tasked with modeling the vehicle dynamics of an RC Car that will be made to drive autonomously. I lack prior experience or particularly specific education with vehicle ...
5
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1answer
80 views

Would a partial space elevator work? [closed]

Background The normal space elevator (that reaches from the Earth's surface to a counterweight beyond geostationary) needs a material that's strength/weight ratio is better than any material we have ...
1
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1answer
45 views

Relation between ride frequency and wheel deflection of a car

I am not able to understand the relation between ride frequency and wheel deflection of a car, as per given in Race car vehicle dynamics book by milliken. Is it something to relate with harmonic ...
4
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1answer
98 views

How to design the right input to obtain a desired output for a linear system?

If I have a state-space model, so that the A, B, C and D matrices are known, how can I design the right input u, so that y is a custom signal, for example, a sine wave with constant amplitude? $\dot{...
0
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1answer
28 views

Power needed to accelerate metal powder through two spinning wheels

I have a wheel which has a radius of 0.1m that needs to spin at 10000RPM. The outer surface of this wheel is pressed up against another free spinning wheel like a football or tennis ball launcher. I ...
4
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2answers
75 views

Linearization of dynamic equations/transfer function in control theory

I've gone through a control theory course, and after looking back at what we covered and how the subject was taught to us, I still have quite a few questions (which I unfortunately did not ask in ...
0
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1answer
40 views

How to determine the degrees of freedom for ball and beam system such as shown in pic below

Since, motion of the ball on the beam depends on the beam angle alpha, shouldn't this system have a single degree of freedom?
1
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1answer
40 views

What is slippage velocity?

I’m trying to understand the effects of a bike’s trail on its steering stability. There, however, is a concept of slippage velocity of the tires during steering of which I cannot make heads or tails ...
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2answers
68 views

Magnetic Entrapped Storage at 0 gravity

I understand this is a multifaceted question and I apologize . All of it is relevant to be understood. On Earth Fly wheel storage devices are used as an alternative to batteries. Even with magnetic ...
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0answers
19 views

Elbow Manipulator Parameter vector Θ - how to assign the components of the parameter vector?

In the Robot Modeling and Control book there is a worked example of a two-link elbow manipulator, shown by Figure 1. I have derived the inertia matrix, $D(q)$ using a symbolic software, Maple. The ...
2
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0answers
24 views

Plot zero-pole from frequency response matrix

I've represented with Matlab a system with three degrees of freedom. I'm trying to plot a pole-zero map from my Frequency Response Matrix H(w) in the case of Damped-...
0
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2answers
128 views

Pivot joint of pendulum with no yaw

I have a conceptual design that I've been evaluating which can be summarized as a simple pendulum extended to 3D (i.e. swing not limited to x-z plane). If I want to actually build the conceptual ...
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0answers
154 views

How to use VBA on Aspen Hysys? [closed]

I am trying to write a program on Aspen Hysys. Hysys has a script manager to write scripts using Visual Basics for Applications syntax. Having no background in VBA, I'd like some help to: Import the ...
2
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3answers
327 views

How to determine the compressor power in a refrigeration system?

The picture below represents a refrigeration unit In order to calculate the power produced by the motor, two quantities must be measured Angular speed of the motor. This parameter can be observed ...
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0answers
84 views

Maximum slope of the road for a car pulling a trailer

I have a five meter long, 2.40 meter wide, 200 kg portable catamaran I've built at home. To transport, I bought a semi-finished trailer, just the running chassis; and built the upper structure, namely ...
0
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1answer
42 views

hydraulic diameter

QUESTION: I needed help here, I tried solving but still can't prove or arrive at the conclusion. my working:
3
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1answer
119 views

How can I absorb shock on an existing steel structure?

I'm currently trying to extend the shock-absorbing capabilities of a welded steel structure that is shown in the following image. It is a structure that supports a slat conveyor. A load is to fall ...
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0answers
150 views

Beam-to-Column-Stiffness ratio

This parameter defines the structural behavior, defining shear or flexure behavior of the structure. How do I use this parameter to define the stiffness matrix of the structure to perform dynamic ...
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0answers
102 views

Vehicle Yaw angle from course map

Is it possible to determine a vehicle's yaw angles during its journey through a predefined course layout? I am interested in this for aerodynamics related inquires only, specifically I need to ...
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1answer
55 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 ...
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0answers
45 views

How can I estimate the impact force of multiple objects falling at the same time from a given height?

I'm trying to model what impact forces a structure endures from multiple cylinders falling on it at the same time. I know the approximate geometry and density of the individual cylinders. I also know ...