Questions tagged [applied-mechanics]

Questions about using applied mechanics to model engineering problems.

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135 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
76 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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66 views

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
72 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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2answers
41 views

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
34 views

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
56 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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27 views

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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180 views

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
83 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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2answers
63 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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2answers
77 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
42 views

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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50 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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0answers
55 views

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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1answer
67 views

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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2answers
96 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
249 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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2answers
132 views

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
36 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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0answers
72 views

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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3answers
3k 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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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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4answers
884 views

Plastic modulus

Are there some general guidelines for approximating the plastic modulus of steel under tension so that a bilinear stress strain curve can be defined for Loading beyond the elastic region?
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121 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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2answers
217 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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41 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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67 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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0answers
66 views

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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1answer
128 views

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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3answers
1k views

Compound gear system ratio

This might be a stupid question, but I'm new to mechanics, so please bear with me. Suppose I have a compound gearing system defined in the image below (not to scale). The green gear is the driving ...
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32 views

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 ...
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1answer
651 views

How to simulate the simply supported boundary condition in experiments?

I want to do some experiments on the dynamic behavior of the beam, plate and so on. Four boundary conditions I want to simulate: Free Clamped Simply supported For free boundary condition, I can use ...
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1answer
104 views

Stopping/reducing wobbliness in threaded rod

I am working on a 1.5-meter satellite dish with a custom receiver cantenna-like feed. The dish didn't come with feed arms, so I need a way to hold the feed into place. What I tried was using a 1-meter ...
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33 views

How to slide 2 small pieces of metal into each other

I'm trying to build a keyboard addon for my smartphone (https://gitlab.com/xengi/mkbd65). The last challenge I'm facing is how the two pieces, namely the smartphone and the keyboard should slide back ...
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1answer
543 views

How to transfer rotational energy into lateral energy only when rotating one way?

Is there a general way to convert rotational energy from a gear or something into lateral motion toward or away from the gear? I could use a piston type construction, but I only want the lateral ...
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1answer
62 views

Soil mechanics-Geotechnical engineering [closed]

Which is more economical to improve or change the soil that is used to build a structure? my answer is that it depends on each case, but I would like to get more information, or where to search about ...
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3answers
9k views

Are the points of inflection and contraflexure the same?

In theory of bending of beams, often these terms are used. There are no clear definition present. Most of them contradicting. Which of the property(bending moment and shear force) is zero in which ...
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1answer
115 views

Moment of Inertia of a Rotor System

I need to settle a discussion on the following question: Part A: Find the equivalent spring constant for springs in series Use equations of motion, sum of torques to find natural frequency of the ...
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2answers
333 views

Rotary to linear motion - how to make upside down “hammer” mechanism?

I’m not an engineer, however I think this place is the best one to find an answer to my question. So my problem is as follows: I need to create a mechanism, preferably driven by a dc motor, that will ...
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1answer
115 views

Could a spinning permanent magnet's interaction with the Earth's magnetic field propel a boat through the water?

I am wondering if a spinning permanent magnet's interaction with the Earth's magnetic field will produce a propelling force strong enough to propel a toy boat through the water. This propelling force ...
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1answer
3k views

Principle of Virtual Work vs Castigliano's (Second) Theorem

I had a look online and into some literature however I did not seem to find a good comparison for the two different methods. They are both used for determining displacements and slopes (rotation by ...
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1answer
79 views

Calculate surface area and outward normal of each face(non-planar) for a irregular hexahedron.

I am using the vector cross product to calculate each surface area and thus the outward normal. However, this approach fails when the surfaces are non-planar. So what is the best approach to calculate ...
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0answers
80 views

How can I do engineering projects for money at home? [closed]

I am a M.Sc. graduate in mechanical engineering and I have experience with engineering software, like MATLAB, CATIA, and ABAQUS. I want to know how I can find industrial projects like finite element ...
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1answer
2k views

A way to calculate the magnitude of the moment

In my engineering textbook, I didnt understand the example given to explain the magnitude of the moment. It asks to calculate the magnitude of the moment about the base point O of the 600-N force in ...
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1answer
65 views

Approach to solve a frictional problem?

I am having a bar and surface (made of aluminum). I need to attach some material to the end of the bar so that, if I apply any force (25 N-sideways) to bar it has to stick with the surface. Force ...
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1answer
32 views

Creep / cold flow SS304 vs A514/T1

I made a pallet lift table out of 1/4" SS304 and now have about 5x the deflection that beam calculations predict. I noticed that the machine was shipped supporting a 500lb pallet. I thinking a few ...
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2answers
2k views

Is strain energy the same as potential energy, or something differen?

Sorry for this stupid, basic question. But I got hung up on it. We know from Clapeyron's theorem that the strain(internal) energy of an elastically deformed body is equal to half the work $$ U=\...
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1answer
52 views

Curve-linear vs. Cartesian coordinate systems: linear-elastic & isotropic elasticity tensor

For shell elements, is the elasticity tensor for linear-elastic & isotropic materials the same in a local curve-linear (convected) system vs. a local Cartesian system? I wonder because ...
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0answers
42 views

Virtual work method for a disk with axisymmetric distributed and concentrated loads

I'm trying to determine all forces/reactions on a disk with a hole in the center. The disk is loaded with a (known) uniform distributed load from A to C (all around the disk), a concentrated (known) ...