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Questions tagged [dynamics]

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Deriving the equations of motion for free-floating spacecraft with a single link robot arm

Note: I had previously posted this question on the Space and Robotics SE sites, but received little/no response. So I've deleted the previous posts and repasted my question here in the hope of ...
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Why is it recommended to place the new car tires on the rear axle? [migrated]

When buying a pair of new tires for a car, it is presumed they are better than the (worn) tires being replaced. Isn't steering better when you put them on the front? Why is it recommended to put the ...
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29 views

Batter Hitting a Ball

Consider a batter hitting a ball. The ball exibits elastic deformation and rigid body translation. When will it happen that whole of the energy supplied by the batter is consumed in Structural ...
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16 views

Inertia relief in ANSYS - rotating model

I'm trying to use ANSYS to solve statically a dynamic problem. As shown in the image below, there is an orange bar that is constraint to slide horizontally only and attached to another bar (pink) ...
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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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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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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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40 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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1answer
48 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
42 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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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 ...
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2answers
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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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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
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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
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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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1answer
28 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
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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 ...
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2answers
85 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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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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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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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 ...
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1answer
49 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
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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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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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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 ...
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1answer
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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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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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31 views

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 ...
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1answer
100 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 ...
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1answer
55 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.
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1answer
85 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 ...
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1answer
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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 ...
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1answer
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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 ...
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1answer
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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{...
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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 ...
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2answers
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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 ...
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1answer
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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?
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1answer
47 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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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-...
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2answers
177 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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186 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 ...
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3answers
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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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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 ...
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1answer
46 views

hydraulic diameter

QUESTION: I needed help here, I tried solving but still can't prove or arrive at the conclusion. my working:
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1answer
127 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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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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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
62 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 ...