Questions tagged [applied-mechanics]
Questions about using applied mechanics to model engineering problems.
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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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22 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
26 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
49 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
42 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
72 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
58 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
30 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
55 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
59 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
27 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
50 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
28 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
20 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
55 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
60 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
44 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
81 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
82 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
48 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
60 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
74 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
38 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
57 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
76 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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72 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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0answers
17 views
Slip efficiency with optimal control inputs
I have developed an equal slip controller in order to maximize the slip efficiency of a tire. Slip efficiency is a component to traction efficiency that is formulated as followes:
$$\eta_t =\frac{F_x ...
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55 views
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1answer
78 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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58 views
Mechanical engineering
I am from electronic field and I have a question regarding solid mechanics.I have to do modeling and analysis of a capacitive sensor under normal force measurement using finite element method. I will ...
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1answer
38 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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66 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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How is the response curve of ShockWatch Label obtained?
I'm now trying to understand the characteristic of ShockWatch Label activation.
Specifically, I need to know how the response curve of ShockWatch Label is obtained through lab test(see page 6 to 8 in ...
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1answer
21 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
53 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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22 views
Names for pressure and traction using projected area
Normal force per unit area is called pressure.
Force in some general direction per unit area is called traction.
What are names for:
A) Normal force per unit projected area
B) Force in per unit ...
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1answer
50 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
$$\boldsymbol{M}\ddot{\boldsymbol{q}}(t)+\boldsymbol{B}\dot{...
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323 views
How does Abaqus calculate reaction force?
I wrote a UEL for one element and compared to a reference UEL (FEM), where the results agreed satisfactorily, except the reaction force. The stress, strain, strain energy all were pretty accurate.
I ...
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79 views
Determining Elastic Equation of Beam with Linearly Distributed Load
I'm trying to solve this question, but I'm not sure where to start.
Typically, to solve this type of problem, I would find the vertical support reaction at R $\left(\dfrac{w_0 L}{24}\right)$, then ...
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1answer
48 views
Hinge or similar that breaks at a certain change in acceleration?
Suppose I have a rope that is capable of lifting 100 Kg without breaking. But I would like the rope to break if it is exposed to a sudden change in acceleration (jerk). So if the rope was lifting 10 ...
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2answers
59 views
Cutting tool for hollow tubes [closed]
We have steel hollow tubes of 80 mm length and 0.5 mm cross section, that we need to cut in smaller pieces of 10.1 and 10.5 mm length. We have been using utility knifes with very poor results.
I am ...
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0answers
45 views
Boundary Conditions for a circular clamped plate
I've been trying to find the boundary conditions for a fourth order DE equation for a bending circular plate. I'm assuming angular symmetry and an even pressure distribution.
Displacement Equation
$$...
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Free fluid flow during orbit in response to the differential gravity vector encountered
In a satellite in orbit, in a temperature-controlled, but NOT pressure-controlled environment, what will a slick fluid in one end of a short internally slick tube, that is kept aligned with the vector ...
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2answers
120 views
How much torque will I need to pull a 2250Kg load?
I need to use this to find a motor that will be able to pull at most 2250 kg at a 1.5 m/s pace. At peak acceleration, I would like this to accelerate at 0.5 m/s2. The area that the load ...
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1answer
41 views
does payload weight distribution affect rolling resistance?
Recently came across the following 2-minute YouTube video that claims A Balanced Rig Saves Fuel
While nicely done, it is a marketing video. Does anyone know of any unbiased studies that support the ...
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63 views
How can I transfer water quickly from one tank to another?
I have an aqua treadmill which is used to exercise dogs after they have had surgery.
To fill it using water from a government tap takes an hour, which is far too long. So I have an external tank ...
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1answer
71 views
Shaft Size design / replacement
does anyone have any idea what standard shaft size / adapter this is?
the motor is NEMA 56C and the socket size it self is 27.8 mm in diameter and 32 overall with the key.
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3answers
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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
142 views
Do outer fillets|chamfers also reduce stress as inner ones do?
I kind of have an intuition or at least imagination about how fillet|chamfer of inner edges|vertexes reduce stress (concentration).
But does that apply to outer edges|vertexes aswell? Maybe to a ...
