Questions tagged [applied-mechanics]
Questions about using applied mechanics to model engineering problems.
239
questions
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Calculating time derivatives of stress (σ ) in the constitutive equation of a viscoelastic model without explicitly remembering the prior stress?
I am trying to understand how to work with viscoelastic models. There are numerous simple viscoelastic models (described at that link). In each, there is a "constitutive relationship" ...
1
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1answer
70 views
Determine the reactions on supports A and C and write the functions of the internal forces for the beam sections AB
The figure shows a metallic structure composed of two beams $AB$ and $BC$ connected to each other by a pin in $B$, the structure being supported in A and C through fixed supports. In the AB beam, a ...
1
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1answer
35 views
Reinforce foldable table legs
I'm trying to build a table with 4 swivel legs that can be locked into arbitrary angles so that it can stand over one to three rows of storage crates in my garage:
As you can see, the legs aren't ...
1
vote
1answer
32 views
What's the best FEA software if you want reliable data [closed]
What's the best FEA software if you want reliable data and are a beginner?
So, I've never used FEA software before so I want to learn one that is powerful and relatively approachable. I am most ...
0
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1answer
58 views
formula for M(x) - Shear Force and Bending Moment Diagrams
I've watched the video "Understanding Shear Force and Bending Moment Diagrams" from "The efficient engineer" and i got a doubt in this exercise
For $4<x<7$ I arrive to $V=-6x+...
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2answers
40 views
How to calculate the force required to lift this deck?
I want to build a folding deck. both sides are on wheels.
Trying to wind my head around how to calculate the required force for the hydraulic piston to be able to pull the deck into a folded position.....
1
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1answer
40 views
How to mechanically attach a compression spring to a flat surface
I am working on a new project right now and I was wondering if anyone had any ideas on how to keep a spring fixed and connected to this flat plastic piece [image shown below].
Our goal is to keep the ...
0
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1answer
26 views
How could an absorbent material be emptied?
I have been thinking about this for quite some time: Given a foam or other absorbent material saturated with a solvent, how could you draw all the solvent to the top of the foam (basically how could ...
2
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1answer
42 views
Calculate thickness of a 1 square meter window made of acrylic in a submarine to endure 100meters
This question would have two parts:
1 - How to calculate thickness of a 1 square meter window made of acrylic in a submarine to endure 100meters of deepness in salt water?
I don't remember the ...
1
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0answers
23 views
Pully size, imagine 2 systems A,B both transmitting power, both 1:1 but if OD of pulley is 50mm on A and 100mm on B, How do we choose optimal size?
All searches resulted in ratio calculations, which makes sense, my question relates to creating a servo driven spindle with 1:1 ratio with timing belt. Is increased belt surface engagement important ...
3
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2answers
91 views
How high will a flywheel catapult launch a payload?
First off, this is not a homework question or anything like that. I'm trying to build a catapult to launch a payload using a flywheel as an energy device!
It goes like this:
The flywheel spins up to ...
3
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2answers
58 views
Can you use an accelerometer to measure beam deflection under static loading?
With an appropriately collocated accelerometer is it possible to retrieve lateral deflection of a beam under static loading.
The beam will be loaded and then deflect until it reaches equilibrium with ...
0
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0answers
21 views
how to obtain solution of this bessel equation using Frobenius method
Given this equation:
$$
\frac{1}{r}\frac{d}{dr}\bigg(r \frac{dT}{dr} \bigg) - \bigg(\frac{2h}{bk} \bigg)(T-T_a) = 0
$$
I can let $x=r\sqrt{(2h/bk)}$ and $z=T-T_a$ to obtain the bessel equation using ...
2
votes
1answer
27 views
Pressure-force limiting blocks or relief mechanism for avoiding excessive pressure over a piece
I am looking for some device that can be used for blocking a sheet of glass or other materials in position. On one side of the glass (blue sheet in the diagram) is applied a force if the force is ...
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1answer
44 views
Deriving equation of motion of a 1 degree of freedom system
Before solving this system, note that the rigid bars $\mathrm{\overline{OA}}$ and $\mathrm{\overline{OB}}$ are rotating about point $\mathrm{O}$, not their respective CGs. To account for this two ...
2
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0answers
40 views
Why funnelling air in order to increase the velocity is a bad idea when generating power
Disclaimer: I’m not trying to violate the conservation of energy here; I know that’s impossible for us mortals. I think I’m either wrong or not considering something, I just want someone to point it ...
1
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1answer
38 views
Differential Equation for: Locking a laser's frequency with a PI controller
I think I have a good understanding of differential equations, so I would like to first try to understand my system in terms of differential equations before transforming my system into the more ...
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2answers
93 views
Does a change in specimen dimension affect the measured yield strength and tensile strength?
I am having a hard time trying to understand the effect of geometry on a specimen's yield and tensile strength or if there even is one.
If there is an effect or not, why is it so?
Thanks in advanced!
0
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1answer
72 views
Would this air amplifier attachment increase a leaf blower's effectiveness?
With the start of the leaf raking/blowing season just a month away, I have been thinking of a way in which I could make my old leaf blower more effective so I can spend less time doing leaf blowing. I ...
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1answer
50 views
What theories solve the problem of weight dispersion to minimize damage?
I assume there's some simple link to give me to answer this, but I don't know the terminology for it and so haven't been able to solve this.
The use case it to avoid having my TV put divots into my ...
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5answers
2k views
Would a centrifugal flyweight governor system slow down the descent of an object that is free falling down to the Earth's surface? (Revised design) [closed]
I am wondering if rotating flyweights would slow down the descent of a object that is free falling down to the Earth's surface.
Please reference the conceptual drawing below:
This drawing is showing ...
1
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3answers
75 views
Torque required to rotate object around axis using Stepper Motor for Kinetic Machine
Hey all,
I'm creating a machine to rotate a socket wrench using an arm attached to a motor shaft in order to make clicking sounds from the object therefore I'm trying to choose an appropriate stepper ...
1
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1answer
54 views
What causes an inflated spherical cap to look more like a mountain?
I'm working with bulge tests of materials using biaxial loading (applying pressure from one side through a circular aperture).
The materials are clamped on the edges.
The diameter of the aperture is &...
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0answers
30 views
Is a pyramid considered axisymmetric? Why so?
I read a source, I will not reference the source on this platform.
They stated a pyramid is axisymmetric. Can you explain why if yes?
2
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1answer
50 views
Is there a way to convert a short throw in one direction into a long throw in two directions
I have a motor that I have created a simple adapter for; this lets us attach any parts we might design to solve the final problem:
I would like to convert the motors motion to oscillating motion in ...
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2answers
34 views
How to design internal wall separation in the PVC tube to use it as a water tanker
I am working on design of the column which contains the water tanker and the pump + electronics at the bottom.
I have tried different solutions and they failed. I would like to know your advice on ...
1
vote
0answers
18 views
Deformation gradient tensor from particle displacements in an inflating material
I don't have a mechanics background, but am trying very hard to read and understand how to approach this problem. I am struggling with understanding what's "correct" or the basic process of going from ...
1
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2answers
67 views
Fixed-Free End Column Design
I am currently working on a problem where I have to design a column. The structure I am currently designing currently takes the following form,
When designing the column, I know that I have to ...
1
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1answer
50 views
Solving for stiffness matrix numerically by a set of measurements
Is it in general possible when you have a mechanical structure (in this case I am referring to the structure in this post) and you want to determine the global stiffness matrix of this structure, to ...
0
votes
1answer
45 views
Calculate forces/ torques on a parallel spring array
I am stuck on the calculation of forces on a certain system involving parallel springs.
The schematic of the system is as follows:
The lower plane is fixed and the upper plane movable. There is a ...
1
vote
2answers
129 views
How do you find the resultant hydrostatic force on a curved surface which is not exactly semicircle
Assuming this is a pressurized chamber with hydro-static force acting on a semi circle stuck in a surface:
To find the resultant force, I would first divide the semicircle into half. Pressure on ...
0
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2answers
62 views
Boundary conditions for this beam deflection problem
consider the diagram above. I know that deflection is described by the equation
$$EI\frac{d^4y}{dx^4}=p(x)$$
where $L$ is the length of the beam, $E$ is the Young's module, $I$ is the moment of ...
2
votes
1answer
60 views
Generating Linear Velocity Movement?
In preparation for a Fluid Mechanics experiment, I am looking for a simple commercial ready made
apparatus to generate a linear velocity trend to prove a new theory:
https://aip.scitation.org/doi/abs/...
-1
votes
1answer
55 views
Equation governing relative motion between aircraft and store
I am reading a paper titled Conditions for safe separation of external stores by EE Covert [Link]. In Section 1 Introduction of the paper, the author has given an expression for $d$, the relative ...
2
votes
2answers
45 views
Converting Newton's Second Law Differential Form to Integral Form and Integration Limits
I am reading a report titled ``Definition of safe separation criteria for external store and pilot escape capsules'' in which the author uses following expressions.
From Newton's second law:
$$ z \...
3
votes
3answers
40 views
How to make pivoting arms move symmetrically towards each other?
I have a basic design of two arms which need to be brought together. But I tried the design using a test setup and it did not work successfully. Here is a diagram of my design -
What I observed is ...
1
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2answers
36 views
Dimensioning of beam pressed by screw in assembly
I need help dimensioning a screw-beam system of a press. I built one prototype but the beam is bending too much.
Below is a sketch of my press. In the middle it has a fixing screw which presses ...
0
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1answer
18 views
Effect of speed of turbo fan in bypass jet engine
Why do we keep speed of turbofan of turbofan jet engine, low.
And what is the maximum thrust a turbofan jet engine., how much can thrust a turbofan jet engine produce with just compressed air.
1
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1answer
31 views
calculation of tension in curved chain for chain fountain (Mould effect)
https://royalsocietypublishing.org/doi/10.1098/rspa.2013.0689
A chain of some sort goes upwards, turns in a half circle (according to the drawn diagram), and goes back down.
Focusing on the half ...
1
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1answer
229 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 ...
3
votes
1answer
101 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, ...
1
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1answer
46 views
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 ...
2
votes
1answer
23 views
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 ...
1
vote
0answers
50 views
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 ...
2
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1answer
86 views
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
35 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 ...
1
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1answer
52 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 ...
1
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1answer
113 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 ...
0
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1answer
63 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 ...
2
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0answers
58 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 ...
