Questions tagged [applied-mechanics]

Questions about using applied mechanics to model engineering problems.

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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
26 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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7 views

How slip is calculated in the 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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22 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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1answer
34 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
55 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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45 views

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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10 views

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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36 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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36 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
35 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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17 views

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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36 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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27 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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17 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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35 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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23 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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2answers
132 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
76 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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31 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
28 views

Polarity of a relative angle - Knee joint angle

I'm wondering if it's correct to write: $$ \alpha = \theta_{lg} - \theta_{th} $$ EDIT: the theta angles are defined positive in counter-clock direcction, instead alpha in clockwise direction. My ...
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42 views

Need help picking motor to wind a spool

The application is a motor attached to a spool to wind/unwind window blinds. I would like to operate the motor at $v=0.2\text{ m/s}$, with a max load of 1.5 kg. I need to know the ideal diameter ...
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1answer
68 views

Installing satellite dish to point to local zenith

After receiving help on my previous post (Stopping/reducing wobbliness in threaded rod), I've decided to come back and ask another question: how can I actually hold the satellite dish into place? I ...
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1answer
91 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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29 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
34 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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1answer
57 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
171 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
83 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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0answers
61 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
39 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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1answer
124 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
63 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
28 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
184 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
32 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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24 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) ...
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2answers
82 views

Why do we use simple bending equation when bending moment is caused due to shear force?

Simple bending equation is derived assuming pure bending(when a couple is applied onto a beam with no shear stress).We tend to use the above derived equation when moment is caused due to shear stress?...
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1answer
80 views

FBD of folding table leg

I've drawn an FBD of one leg of the table the picture. I've a feeling I'm missing something. Am I?
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1answer
69 views

Reynolds transport theorem and eulerian material derivative

The problem as well as my work so far are in the image. I begin with equation (2.23) and use the divergence theorem to express the second term as the surface integral part of the problem equation. ...
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1answer
102 views

Eulerian and Lagrangian descriptions of velocity

I feel as if I understand the conceptual difference between Lagrangian and Eulerian descriptions. But I can't seem to follow the math. I have one example that I would greatly appreciate an explanation ...
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1answer
98 views

Difference in Diameter calculation using Solidworks and manually

When I try to create a flat form of a archimedes screw using Solidworks it gives me a diameter different from what is calculated manually basically using a Pythagoras Theorem. Can anyone explain the ...
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2answers
53 views

Polyurethane mix-on-the-spot system

3d printing is a slow process and for my solution I need fast printing. So I print with no infill and I fill inside with a two part, 10 min drying polyurethane resin. I mix them in a disposable cup ...
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0answers
125 views

How to calculate bearing loads in a two stage helical gear box?

Here P, Q, R, S are the bearings and G1, G2, G3, G4 are four helical gears. The gear forces tangential(Kp), Axial(Ka), Radial(Kn) are known. All the distances are known. The forces acting on bearing ...
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1answer
113 views

LS DYNA Material Model 163, Modified Crushable Foam

Question is on the meaning of input variable TID within material model 163 of LS-Dyna 971. Definition of TID variable. TID: Table ID defining yield stress versus volumetric strain at different ...
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2answers
42 views

What should be the density of a compressed gas while measuring the flow rate using Rotameter?

Say we have a required mass flow rate, in order to have equivalent volume flow rate, we need to consider density of the operating fluid (compressible fluid). To measure the volume flow rate in LPM, ...
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3answers
186 views

What components are needed to reverse the direction of a belt conveyor using one reversible motor, and how do they change the tension on the belt?

On regular conveyor belts, motors are usually placed on the head shaft where material is discharged, and tension is highest at the entrance of this head shaft. However, if the motor were to be simply ...
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1answer
106 views

Calculate the torque needed to turn a rod it's own axis [closed]

If a rod is turned around it's own axis, force/torque is needed. Let's assume the rod it self has a diameter $d$, a length $l$, the mass $m$ and should be turned by a motor on one side. The other ...
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1answer
61 views

Analytic expressions of the kinetic and potential energy [closed]

A homogeneous rigid circular disc (radius R, mass ms, center point S) rolls without a slip on a plain with a small angle of inclination alpha against the horizontal. A point mass MG is fixed on the ...
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120 views

press fit ball joint

I enjoy creating mechanical designs but I am not a trained mechanical engineer. I have a technical issue with a joint design that needs to be permanently retained using a press (snap) fit. Any idea ...