Questions tagged [applied-mechanics]

Questions about using applied mechanics to model engineering problems.

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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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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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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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1answer
202 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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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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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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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
65 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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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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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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65 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
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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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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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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3answers
272 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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1answer
101 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
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
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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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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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
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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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) ...
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2answers
444 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
184 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
196 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
289 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
121 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
62 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
288 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
220 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
52 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
1k 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
218 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
66 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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1answer
323 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 ...
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1answer
981 views

Calculating the torque requirements of the motor for a specific case

I want to use a DC 12/24V motor to rotate an assembly of glass tubes(image attached) through a hollow shaft of 25mm OD and 22mm ID, the shaft is supported on bearings on both the sides(assume minimum ...
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1answer
52 views

Structural mechanics

Ques: I have a question regarding solid mechanics and plate theory,is 2 layer plate means laminated plate or simply refers to as a plate?
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516 views

What is the maximum deflection and bending moment of a hinged hinged beam? [closed]

It is not a simply supported beam with one end hinged the other end with roller support. I am working on both the ends hinged beam. i.e at the two ends only rotation about z axis is allowed and all ...
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1answer
23 views

A sealed ball is not connected to anything externally, but can have any complex mechanism inside. Can the mass change? [closed]

A sealed ball is not connected to anything externally, but can have any complex mechanism inside (mechanical, chemical, or any other). Can a wireless trigger from a remote or any other wireless ...
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1answer
100 views

Cantilever beam with disc at end (structural mechanics)

I am trying to figure out how I can assemble multiple finite elements to obtain the system mass matrix $\boldsymbol{M}$ and the stiffness matrix $\boldsymbol{K}$. The situation is depicted in a ...
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1answer
80 views

Rayleigh damping in structural mechanics

In structural mechanics, we often approximate a partial differential equation by a system of ordinary differential equations in matrix form $$\boldsymbol{M}\ddot{\boldsymbol{q}}(t)+\boldsymbol{B}\dot{...