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Questions tagged [applied-mechanics]

Questions about using applied mechanics to model engineering problems.

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28 views

Free pre-processor for Nastran?

I want to do a non-linear analysis (possibly SOL 400) on Nastran. I used PyNastran (python module) to set-up the BDF file for a Linear buckling analysis (sol 105). However I feel like it might be too ...
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40 views

what is the physical interpretation of poles and zeros of a mechanical system?

what is the physical interpretation of poles and zeros of a mechanical system? I'm asking things like the meaning if I have only 0 or only complex numbers. And about the number of the poles and zeros, ...
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How could I get the coordinates of the circumscribed circle giving the 3 points coords?

I have the coordinates of 3 points thrgouh which, a circle should pass . Having the coordinates of the points in 3D, how could I have the coordinates of the center of circumscribed circle ? also : if ...
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1answer
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Would an orthotropic cylinder subjected to torsion have warping?

The situation I'm imagining is the one shown above, which is the cross section of a cylinder made of alternating layers of material. The material axes are shown where 1 and 2 are in the same plane and ...
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Understanding compatibility of strains

In mechanics, we have the so called compatibility conditions, which quarantee that when a body deforms, the strains are "compatible" in such a way to no discontinuities or gaps for inside the body as ...
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1answer
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Latch Mechanics

I want to make a sprung latch mechanism which keeps a door in place until a certain force is applied to the door. In the diagram attached, the force the door must release at is Fd, and the latch ...
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1answer
34 views

Door functional or not? [closed]

Hello I am building a door and I have taken a large rectangle piece of wood for the base. At the top-right point of the rectangle I am planning to connect it with the top right point of a large ...
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1answer
21 views

If a driver gear has larger radius than a driven gear, will a larger gear ratio result in more torque supplied to the driven gear?

Suppose a driver gear has larger radius than a driven gear. For example, we have a pinion with a main disk, where the main disk is larger than the pinion and the pinion is a follower. This is the case ...
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1answer
67 views

Driving Gearbox in Reverse

https://www.maxongroup.com/maxon/view/product/251601 https://www.maxongroup.com/maxon/view/product/gear/spur/gs45/301171 Consider that this motor-gearbox combination is backdriven so that the motor ...
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1answer
41 views

Impact of Gearbox on Motor Inertia

If you consider a motor attached to a spur gearbox with a reduction ratio of say $r=50:1$ which is then back-driven so that the motor acts as a generator, what would be the effective moment of inertia ...
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Is a Geodesic Dome (fuller dome) that floats possible? What material or engineering effort would it take?

Buckminster Fuller has popularized Geodesic Domes (invented by Dr. Walther Bauersfeld who based it on the use of convex polyhedrons), and thus, making buildings with a very large roofs that don't ...
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2answers
36 views

2nd Moment of Area of a ring

This is my first question here. I am having trouble finding the 2nd moment of area of a ring with a thickness 't' and radius 'r'. I seem to be a factor of 2 out. What I do is I consider an area like ...
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Position vector to Velocity vector

Is it possible to derive velocity vector form position vector without unknown such as: position vector of A = (0.8)i + (1.2)j?
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1answer
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Normal Force distribution of Prism

On the image below there is a regular prism which is angled by $\alpha$. The (black) mass m1 applies a torque $M_k$. The mass m2, which is the rest of the Body applies the torque $M_s$ In the ...
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1answer
36 views

Unit of Angular velocity of Precession [duplicate]

Since the Equation for the Angular velocity of Precession of a Spinning Disk is: $$\omega _{p}=\frac{m*g*r}{I*\omega _{spin}}$$ Where, m -> Mass of the spinning Disk. [$kg$] g -> ...
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small gearbox for experimental wind mill

The gear box will have little torque as I am only using a 12 by 18" wing which rotates. The two shafts I am using are 1/4 ", one form the wing and the other going the to pivot for the wing to circle, ...
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1answer
46 views

Alternatives to sawstop technology

Sawstop table saw braking system works by putting a low voltage on the blade, and when it detects that voltage shorted to ground, the blade is retracted and slammed into an aluminum block. The claim ...
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1answer
34 views

Break loose torque calculation of lock nut against rotating/acceleating bolts?

I have a Scenario where my lock nut is tightend using a prevailing torque of 14 Nm (as mentioned by the manufacturer) on to the rotor placed between bearings (But the tightening direction and the ...
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2answers
60 views

Cascaded ball bearings

Around where I live there's these soapbox/gravity kart races (google "carros de rolamentos") in which the wheels are built simply from ball bearings. As I was building my own, I began wondering how I ...
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1answer
26 views

Low-Flow Nozzles for Corrosion Spray Testing

So, for a cyclic corrosion test system, I need a nozzle or arrangement of nozzles that provides a flow rate of 45ml-140ml of salt solution per hour to an area 60cm square. All commercial nozzles I've ...
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2answers
52 views

How are the location of Gausian points determined in Finite element theory?

From the finite element theory, what is remained a bit unclear for me, is that how do we know the location of gausian points where the integration is done for each specific type of element ? it is not ...
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1answer
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What is the Source of the 10% Trailer Tongue Weight Recommendaton?

Throughout the trailer, hitch, and tow vehicle industry a recommendation of 10% tongue weight for a tow-behind trailer and 15% for a 5th wheel trailer seem universal. They have even been changed to 10%...
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How can I develop the displacement imposed frequency response function?

in theoretical vibration books , almost all of them to my knowledge, the FRF function is always developed for a system of SDOF or MDOF being excited with a unit force. but in FEM softwares there is ...
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2answers
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From a mechanical point of view(Physics/Engineering) why are Front-Load washers said to clean/wash better than Top-Load washers on average?

Which cleans better? Is it just marketing or do they really clean/wash better due to some physical property or the way they work, I am asking how do they if they do? N.B I do not intend to indicate ...
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1answer
27 views

Temperature logging of li-ion cells

I'm looking to measure and log the surface temperature of lithium ion cells (cylindrical and pouch). I tried using LM35 sensors with an Arduino, but, the drift was too much somehow. Any suggestions on ...
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1answer
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Ball and Socket Wheel Concept

I am sure you all remember those prehistoric computer mouses that had a ball under it. I'm looking for any points and tips on how to create a ball and socket wheel that has an almost frictionless ...
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1answer
21 views

Mass inertia tensor for rod non-symmetric regarding coordinate system origin

I want to express the inertia tensor of a rotating rod (total length $L_1$) to use it in Lagrange mechanics for expressing the kinetic energy associated to the rotation with angular velocity $\dot{\...
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35 views

How to calculate traction force w.r.t. rotational speed of a shaft mounted at a certain angle on a surface?

I am designing a new mobile robot platform and i need a generic solution for the robot in order to establish a proper mathematical modeling. My question is about calculation of the traction force of ...
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1answer
41 views

Do concealed door closers exacerbate wear on a door's hinges?

Not being of an engineering background, I was first inclined to think that a door closer would reduce horizontal load on all hinges and not contribute any support in the vertical dimension. However, ...
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1answer
30 views

Measuring Torque in a bicycle [closed]

How to measure torque in a bicycle? how much newtons will produce by the pedal of the cycle ?
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Parallel Axis Theorem for x and y Shift

I have a quick question about the parallel axis theorem. Let's say I have a box-like object rotated about the following pivot point I was wondering, by applying the parallel axis theorem, would the ...
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1answer
30 views

Stopping Force of Irregularly Shaped Object

I have a quick question about the force needed to accelerate/decelerate an irregular object. Lets say I have a 3D object with the following general shape, This system is in general a gripper (gray) ...
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How is the slip calculated in Abaqus small-sliding interaction?

I’m doing research on the sliding of 2 fracture surfaces. To do that, I’m trying to understand the Small-sliding deformable interaction in the Abaqus (2018), and I use the Node-to-surface ...
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Equation for the spring constant of an orthotropic, rectangular wire spring

I hope I can get some help with this problem as I've been struggling with it for a long time. I have a helical tension spring with radius $R$ and a square wire cross section and made of orthotropic ...
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1answer
60 views

Locations of max stresses in a circular beam?

If a torque and axial force is applied to a beam with a circular cross section, where along the cross section of the circular beam is the location of the max shear stress, max bending moment, max ...
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3answers
216 views

Moments of Fixed-Fixed Beam

I have a quick question related to the topic of mechanics of materials. If I were to have a beam that is fixed at both ends and has a central point force, do moments develop at the fixed supports? e....
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Are these force components right?

Would you also decompose the centrifugal force this way? $m_{tot}$ is the total mass of the Hyperloop. $a_c $ is the centripetal acceleration. $\beta_a$ is the angle formed by the air bearings with ...
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Viscoplastic model of solder alloys

I have found some data of viscoplastic Anand model for the SAC305 solder joint of electronic devices in the literature. Does this data depend on the thickness, length and width of the joint? I mean ...
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49 views

Derive a Transfer Function from first principles (PID, system identification, statics)

I want to derive a transfer function of my system so I can plug it into MATLAB and use the PID tuner tool. My system is a balancing beam with a motor on each end of the beam. My first principles ...
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38 views

Pendulum-like effect

In modeling a wing with the finite element method, I am asked to consider an engine (approximated as a lumped force and moment) and it's mass, inertia, prestress and gravity contributions. So the ...
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1answer
45 views

Calculate Rolling Resistance Experimentally

I am trying to calculate the exact rolling resistance ($F_{rr}$) of my car. The approach I am going with is a coastdown test at a low speed so no drag slows down the car. From there I am going to ...
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Acceleration of the rotation of three gears

Hello, I am trying to solve the question shown in the image but having some doubts in resolving the motion into its different components. To my knowledge, the problem should be split into 3 or 4 ...
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1answer
73 views

Finite Element Code: Convergence issues

I am trying to code a simple FEM problem. A bar is fixed at the bottom edge, and a displacement is applied at the top. I want to apply the displacement gradually , so I have divided it into a number ...
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28 views

Stopping a tall structure from being blown away by a strong wind [duplicate]

I have a 1.5-meter satellite dish, and I wish to have it point directly upwards. Here is what the dish looks like with the feed in place (ignore the wobbliness of the feed, we increased its backplate ...
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24 views

Solving Hertz Impact ODE with Simulink

I have a question about modelling a nonlinear 2nd order ODE for an impact of a sphere on a thin plate in Simulink. Depending on the solver and solver options, my results in Matlab vary a lot. Some are ...
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45 views

Need help with FEA bar analysis problem

I'm trying to solve this which is to find the total deformation of the bar. I'm trying to implement the finite element approach, but I am getting way too large of numbers. Here is what I did in ...
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Distance travelled at articulation point of turning vehicle

Problem outline: I'm trying to figure out the distance travelled at the articulation point of a turning vehicle with 4 driven wheels (each wheel houses a motor and can all rotate at different RPMs). ...
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2answers
172 views

Statically indeterminate fixed-pinned beam problem

F=32KN; Mf1=60KN-m; Mf2=-58KN-m; g=30KN/m I need to solve this using Force method. Find the reaction at the pinned end.
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1answer
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FEA: Newton-Raphson algorithm for Dirichlet BC non-linear static analysis

I have a standard non-linear static problem to solve with FEA. I am applying displacement boundary conditions only, no external force. The equation to solve look like these: $K(u)u=R(u)$ Eq(1) The ...
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Stopping metallic construction held by a threaded rod from wobbling

I am working on a 1.5m satellite dish with a custom feed. The problem is that the feed is being very wobbly once slightly pushed, as shown here: https://www.youtube.com/watch?v=rAFGbEhhDZ8 (it swings ...