Questions tagged [applied-mechanics]
Questions about using applied mechanics to model engineering problems.
206
questions
0
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1answer
28 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 ...
2
votes
1answer
40 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
vote
1answer
41 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
17 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
12 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
votes
1answer
52 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 ...
-1
votes
1answer
34 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
vote
1answer
21 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
vote
1answer
67 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
votes
1answer
41 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
39 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 ...
1
vote
2answers
36 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 ...
0
votes
2answers
31 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?
0
votes
1answer
26 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 ...
1
vote
1answer
36 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 -> ...
0
votes
1answer
26 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, ...
0
votes
1answer
46 views
Alternatives to sawstop technology
Sawstop table saw braking system works by putting a low voltage on the blade, and when it detects that voltage shorted to ground, the blade is retracted and slammed into an aluminum block. The claim ...
0
votes
1answer
34 views
Break loose torque calculation of lock nut against rotating/acceleating bolts?
I have a Scenario where my lock nut is tightend using a prevailing torque of 14 Nm (as mentioned by the manufacturer) on to the rotor placed between bearings (But the tightening direction and the ...
1
vote
2answers
60 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 ...
0
votes
1answer
26 views
Low-Flow Nozzles for Corrosion Spray Testing
So, for a cyclic corrosion test system, I need a nozzle or arrangement of nozzles that provides a flow rate of 45ml-140ml of salt solution per hour to an area 60cm square. All commercial nozzles I've ...
0
votes
2answers
52 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 ...
2
votes
1answer
36 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%...
0
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0answers
18 views
How can I develop the displacement imposed frequency response function?
in theoretical vibration books , almost all of them to my knowledge, the FRF function is always developed for a system of SDOF or MDOF being excited with a unit force.
but in FEM softwares there is ...
-1
votes
2answers
110 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 ...
0
votes
1answer
25 views
Temperature logging of li-ion cells
I'm looking to measure and log the surface temperature of lithium ion cells (cylindrical and pouch). I tried using LM35 sensors with an Arduino, but, the drift was too much somehow. Any suggestions on ...
0
votes
1answer
40 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 ...
0
votes
1answer
21 views
Mass inertia tensor for rod non-symmetric regarding coordinate system origin
I want to express the inertia tensor of a rotating rod (total length $L_1$) to use it in Lagrange mechanics for expressing the kinetic energy associated to the rotation with angular velocity $\dot{\...
0
votes
2answers
35 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 ...
0
votes
1answer
41 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, ...
0
votes
1answer
30 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 ?
1
vote
2answers
41 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 ...
0
votes
1answer
30 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) ...
1
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0answers
15 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 ...
4
votes
0answers
39 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 ...
1
vote
1answer
59 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 ...
3
votes
3answers
208 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....
0
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0answers
46 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 ...
0
votes
0answers
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 ...
0
votes
0answers
49 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 ...
0
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0answers
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 ...
0
votes
1answer
42 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 ...
0
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0answers
18 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 ...
0
votes
1answer
73 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 ...
0
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0answers
28 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 ...
0
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0answers
24 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 ...
0
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0answers
45 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 ...
1
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0answers
33 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). ...
0
votes
2answers
171 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.
1
vote
1answer
84 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 ...
0
votes
0answers
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 ...
