Questions tagged [applied-mechanics]

Questions about using applied mechanics to model engineering problems.

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0answers
108 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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2answers
582 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
95 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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1answer
80 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
11k views

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
496 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 ...
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2answers
121 views

How to make a clamp for this motor to move it in two directions?

I'm working on a disc brake balancing machine, as shown below this is a belt pulley drive and for alignment purposes I want motor to be able to move vertically as well as inwards outwards (to tighten ...
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4answers
1k views

Plastic modulus

Are there some general guidelines for approximating the plastic modulus of steel under tension so that a bilinear stress strain curve can be defined for Loading beyond the elastic region?
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1answer
80 views

What kind of positioning holding Hinges do Laptops & Notebook Computers use?

What kind of positioning holding Hinges do Laptops & Notebook Computers use? Is there a set of Mech/ Engineering terms for hinges similar to these and are there a category of them that I can ...
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0answers
31 views

vibrate a floating microbody [duplicate]

I have a tiny plastic disc of dia 1cm submerged inside water in a container in the halfway. I have to make the disc to oscillate sinusoidal with a frequency(1Hz to 10Hz) and amplitude (1 cm to 5 cm). ...
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2answers
262 views

Thin walled pressure vessel

What is the NORMAL STRESS in a thin walled pressure vessel? I am aware of only 2 types of stresses in thin walled pressure vessels: Longitudinal & Tangential. Is any one of these 2 is ...
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1answer
45 views

Standard bicycle monorail design considerations

I have been thinking of a design for a standard bicycle monorail. I don't have the resources to prototype it right now so I would like to bounce the design off the community. Basically thinking of a ...
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1answer
44 views

Is it possible to use a vehicles own carbon emissions to shield it from wind drag?

Let's say a cargo ship uses a large amount of fuel while on a voyage. Could you direct the exhaust i.e. Carbon dioxide into a chamber utilising a check valve so the emissions don't backflow into the ...
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2answers
381 views

Pivot joint of pendulum with no yaw

I have a conceptual design that I've been evaluating which can be summarized as a simple pendulum extended to 3D (i.e. swing not limited to x-z plane). If I want to actually build the conceptual ...
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1answer
219 views

Type of hinge I should use [closed]

Can you please suggest what kind (type) of hinge / pins I should use to make the mechanism in the attached file. I was considering to use the pins shown in the second image. But I am not sure if it ...
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0answers
62 views

Engineering mechanics of cutting blades

There are several machines that have (rotating) cutting blades. For example the kitchen aid Vorwerk Thermomix can cut pieces of Food in hundreds of pieces within a few seconds. But why it is so? If ...
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2answers
2k views

Difference between maximum shear stress and absolute shear stress

What is the difference between maximum and absolute shear stress in multi axial stress system?
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2answers
342 views

Applications of simple spring harmonic oscillator

For pedagogic reasons I am looking for applications in engineering for the simple spring harmonic oscillator, i.e. something like this ("harmonic" implies in particular "without damping"): . The ...
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1answer
858 views

polar moment of inertia for compound shape

I have a shape that I'd like to calculate the polar moment of inertia for: the diameter is 600mm; the hexagon in the middle sides are 70mm each; the holes around the hexagon are 130mm from the center ...
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0answers
211 views

Nonlinear simulation in ANSYS workbench

I'm trying to conduct a thermo-mechanical analysis in ansys workbench, I've been able to obtain some results using the transient thermal and static structural modules, however, I would like to perform ...
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2answers
2k views

Maximum torsion shear stress in cylinder

I am trying to figure out am I doing this calculation correctly. To get the maximum shear stress for a solid cylindrical pipe I need two formulas: Moment of inertia = pi/2*r^4 Not sure what this ...
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2answers
14k views

Failure in torsion

Why does a ductile rod in torsion fail at an angle perpendicular to its axis? I know the reason for brittle material failing in pure shear but I don't understand the reason for ductile material.
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2answers
1k views

Projected area in hoop's stress structural mechanics

While calculating hoop's stress we consider projected area. Infact in bearing stress from pins in a truss something similar is applicable.Can you explain why we are taking something like this instead ...
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4answers
341 views

Is radians a dimensionless quantity?

Quite often while calculating angular velocity we come across the quantity radians per second. How do I treat radian dimensionally?
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2answers
8k views

What is Saint Venant Principle?

I am having problem with the application of Saint Venant principle.I have heard that quite often we use that knowingly or unknowingly.I would be very greatful to anyone who would explain this very ...
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0answers
84 views

Is there a way to construct a self-centering axle?

Suppose I have a flat plate of arbitrary but connected shape. If I try to connect an axle perpendicular to the plate it is very difficult to align it with the centre of mass, creating wobble when ...
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2answers
1k views

Why does a vehicle under crosswind need corrective steering?

If we consider a stationary car, a moderate wind hitting it broadside might tilt it a bit, but not move it otherwise. Now, consider the car moving perpendicular to that wind (e.g., driving straight ...
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1answer
320 views

Length of a seconds pendulum

I would like to construct a seconds pendulum. The length of a 1/2 Hz pendulum is 994 mm. My question, is that length the distance to the center of mass? And how does the density of the arm effect the ...
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1answer
2k views

How to Calculate the Minimum Radius a Rod Can Can Be Bent Staying in the Elastic Range?

I am wondering if there is a formula (or how to derive one) for calculating the minimum radius a rod (with a given radius/diameter) can be bent around while staying in the elastic range. Obviously, ...
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1answer
538 views

I need to determine the RPM of a rotating cylinder over which a silk thread is wound and is moving along in the fashion of a screw.

Recently I visited a sericulture facility in India and I saw that people there 'degummed' (https://www.youtube.com/watch?v=h13fctiTylI) silk in a batch process. As a Chemical Engineer, I thought of ...
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1answer
334 views

How to calculate bending of shell

I'm an electrical engineer, so please bear with me :). I came across this situation and I tried to find some equations to solve it, but all I could find was some Finite Element Theory, and I was ...
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0answers
202 views

Worm Drive Calculation

I have this setup: -Pully with a mass attached. -Worm gear drive to lower the mass with a constant speed. (Section A-A) Now if we look at the cross-section A-A, we can see the worm gear drive: ...
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1answer
258 views

How does friction help a car to turn?

I know that friction helps car to move forward. The engine of the car turns the wheels, and the tyres have to grip the road in order for the car to start moving forward. If there is no friction, tyres ...
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2answers
3k views

Help with a simple calculation of the required mass for a counter-weight for a horizontal hatch

Hello fellow engineers, A friend is part-way building an outside storage chest. For whatever reason, the materials and size of storage that he is going for means that the door is heavy to lift and ...
5
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2answers
157 views

Longitudinal impact of steel rod on a steel plate to verify the contact duration

So I'm doing an experiment to verify the contact duration when a steel rod (Material: Mild Steel) is allowed to free fall longitudinally on a steel plate. The arrangement is real simple: The rod is ...
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1answer
299 views

Two-way pulley system considering inertia of pulleys

This is the following question. [![This is how i tried, but I know it is wrong.][2]][2] This is our attempt but We can't seem to solve it with inertia.
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2answers
154 views

Can buckling failure at the first critical load be avoided by "instantaneous" loading?

Previously, I was told by someone I trust well that a column can avoid buckling at the first critical load by applying the load "instantaneously" with a magnitude between the first and second critical ...
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2answers
1k views

Design a trolley with four casters

I need design a trolley with four casters, the four casters are installed on the four corners of a 460mmX405mm metal plane. And the load will be a cubic 380mmX225mmX350mm (Height is 350mm), weight ...
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1answer
62 views

How I can compute cutting processes with continuum mechanics?

In YouTube I have seen various videos where someone cut with a sword into hard objects and has cut that into pieces. For example: https://www.youtube.com/watch?v=EVCWGwvctt4 Given the mass, the ...
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1answer
621 views

Reaction forces in a structure

I have the following structure, in which I am failing to calculate the two reactions: Cz (apparently vertical) and Dz, in the roller support of the beam. The beam length is 7.5 m, the reactions Az, Cx,...
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1answer
474 views

Reaction force on a beam

I have the following problem most of which I have calculated but have a difficulty with the beam under angle. The angle is 56,30 degress. I just cannot figure out how the forces there are acting - the ...
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1answer
3k views

Principle of Virtual Work vs Castigliano's (Second) Theorem

I had a look online and into some literature however I did not seem to find a good comparison for the two different methods. They are both used for determining displacements and slopes (rotation by ...
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3answers
165 views

Compound gear system: Finding velocity

In the figure below we have that the gear $A$ is has an fixed axis and has the radius of $R_a = 0,1m$ and, in the instant represented in the figure spins clock-wise with angular velocity $\omega_a = 4\...
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2answers
58 views

How to pump same amount of paste every time?

I am not sure if I am on the right site for this, but here it goes. I have a friend who makes a hot sauce for a company he runs. It is very pasty (made of pepper flakes in an oil). The problem is, ...
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1answer
79 views

Improvised weighing machine from broomstick and 1kg counterweight [closed]

Let's say I want to measure the weight of a bag of clothes (or some other object), in a situation where I don't have a weighing machine ("scales"?) available. Objects that are available: A broom. ...
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2answers
5k views

Force required to rotate an object on a plane - moment of inertia?

I have a rectangular shape with uniform mass, approx 6m x 1m. It rotates around an axis in the centre of its width but 1m from one end. The axis has some friction but this is not known. What I need ...
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3answers
132 views

Finding downward force of lever bar

I am working on a DIY project, I am trying to replicate a bar compressor which for some reason is only sold in Europe so I thought it would be fun to make my own without having to waste so much ...
5
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1answer
162 views

Poisson ratio boundary condition

Let's say I have a large isotropic body in uniaxial tension, onto which a small rectangular piece of film is applied. Think of a strain gage on a big body, but the 'strain gage' is one single ...
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1answer
370 views

Gear ratio and motor power

I have a small drum that will be immersed half way in a water bath (drag). The drum will contain some 500ml of photo chemicals (weight). The questions: is there an easy way to calculate the gear ...
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0answers
641 views

IV drip/flow rate controller design

I have a question about intravenous flow rate controllers, which are controlled using microprocessors. For example: I want to control the IV flow rate, the flow is in range from 0 to 300. So, I just ...

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