Questions tagged [applied-mechanics]

Questions about using applied mechanics to model engineering problems.

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158 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, ...
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2answers
69 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 ...
3
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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
653 views

How to simulate the simply supported boundary condition in experiments?

I want to do some experiments on the dynamic behavior of the beam, plate and so on. Four boundary conditions I want to simulate: Free Clamped Simply supported For free boundary condition, I can use ...
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2answers
293 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 ...
3
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1answer
97 views

Calculating the Motion of a Particle on a Moving Surface Due to the Friction Between Them

The Basics: I am trying to come up with an equation describing the motion of a particle resting on a non-stationary surface, given the motion of the surface. Imagine setting a coin on a board and then ...
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2answers
2k views

Pneumatic cylinder force output and impact energy

I'm designing a little tester for a project which uses a pneumatic cylinder. The pneumatic cylinder's purpose is to apply an impact on a hard surface to test for deflection of the surface. When I ...
3
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2answers
2k views

How to draw the velocity and acceleration diagrams if there is no connecting rod between the pins?

From the previous examples I've seen, there is a connection rod, for example, between a and c and then another rod from c to one of the pins. However, in this case, the rod ac is directly connected to ...
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2answers
5k views

How do you find the kinematic degrees of freedom of a mechanism?

In the above mechanism it is required to find the generalized coordinates to write equation of motion of the MDOF system. I just want to ask how do we actually approach such a problem? How to identify ...
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2answers
53 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 \...
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1answer
70 views

Glass panel engineering at work

We are designing a button panel at work, made out of glass and are running into some issues. Glass, of course, can shatter. But we noticed that when dropping a steel ball in the center of the glass it ...
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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 ...
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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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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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2answers
12k 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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1answer
303 views

Isotropic materials and levels of stress

I was wondering if I was to have two objects both made of isotropic materials such as steel and aluminum and the two objects were the same geometry and I was to apply the same load and boundary ...
2
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1answer
47 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 ...
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1answer
30 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 ...
2
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2answers
446 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
81 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{...
2
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1answer
86 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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2answers
666 views

Solid mechanics: Deflection of a rectangular elastic membrane

I am trying to solve for the deflection $w$ of a rectangular membrane with tension $T$ acting on two opposite edges. These two edges are fixed i.e. $w = 0$. The other two opposite edges are free. The ...
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1answer
227 views

Block and Tackle with Ramp - stopping rope drag

I am designing a block and tackle system to haul wood up a ramp onto my porch. The issue I am having is that the rope seems like it will rub against the top of the ramp and cause it to fray. How can I ...
2
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1answer
33 views

Firing a bullet on wooden block and then finding the average resistive force by block?

For a Q in which we are firing a bullet of 0.04kg onto a wooden block which is stopped after a distance of 60cm after penetrating inside it. It’s u=90m/s. For this Q , we can find a=-6750m/s^2. Using$ ...
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1answer
65 views

To stop or to go around?

Let us we are moving in a car. There is a wall in front of us, we need to decide can we go around it or not. It is known that width of the wall is $w$ and our speed is $v = const$. What is a simple ...
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1answer
51 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
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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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
288 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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1answer
451 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
6k views

Derivation if the formula for the surface moment of inertia of an isosceles triangle

For a isosceles triangle with base b and height h the surface moment of inertia around tbe z axis is $\frac{bh^3}{36}$ (considering that our coordinate system has z in the horizontal and y in the ...
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1answer
4k views

Finding Neutral Axis of a simple shape undergoing axial load

I know that the neutral axis occurs where the sum of stresses (bending + axial) is equal to 0. I have found the stresses and drawn a diagram to represent forces. How do I determine the neutral axis?
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1answer
2k views

How to rate a davit beam?

What forces are relevant when it comes to a davit lifting arm with a support? I'm not sure how to take the weight of the davit into account or how to calculate the max stress/strain on the system. ...
2
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1answer
27 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 ...
2
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1answer
105 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 ...
2
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1answer
42 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%...
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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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1answer
50 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
526 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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0answers
71 views

Calculating the bending moment ($M$) of a beam as it relates to stress ($σ$) and strain ($ε$)?

I am trying to learn how to work out the bending moment for progressively complex systems to model a beam. I am assuming only one axis of motion (transverse = $y$). For the basic equations of motion, $...
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0answers
45 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 ...
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1answer
71 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/...
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66 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 ...
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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) ...
2
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1answer
324 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 ...
2
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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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592 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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175 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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590 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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0answers
109 views

Mathematic modeling of an overshot water wheel [closed]

We're working on a project that require some mechanical engineering and electronics engineering. In this project we've to model this overshot water wheel (so the water comes from the left top side and ...