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Questions tagged [applied-mechanics]

Questions about using applied mechanics to model engineering problems.

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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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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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38 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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Nut clamp force on a crankshaft

I want to find the clamp force of a nut on a crankshaft holding a sprocket & a spacer which are mount on it using a key. I would like to know the equation which is required to go about the problem....
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45 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
34 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
53 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
65 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
42 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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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
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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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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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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
44 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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Finding equilibrium positions (All)

I have tried to calculate the Kinetic and Potential energy of the given mechanism. I would be glad if somebody could have a look and confirm if it's correct. One of the equilibrium positions would ...
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Finding constraint condition + Kinetic and Potential Energy

I am trying to find the Kinetic and Potential energy of the slider-crank mechanism shown in the fig. I am not sure what I have calculated is correct or not. I would be glad if somebody could confirm ...
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1answer
58 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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52 views

Eigen-Modes for a homogenous, non-conservative mechanical system

$$ M\,\ddot{y}+D\,\dot{y}+K\,y=0\\ y=\begin{bmatrix} y_1&y_2&\cdots&y_f \end{bmatrix}^\top\\ M=M^\top>0,\quad D=D^\top,\quad K=K^\top\geq0 $$ Equations show a homogeneous non-...
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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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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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43 views

Basic Mechanics, Determine reaction at a point

This is what I have attempted so far.
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1answer
43 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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53 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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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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1answer
53 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
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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
44 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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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
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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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238 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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48 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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57 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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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
78 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
35 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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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
67 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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2answers
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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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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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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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2answers
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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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Where to get data for tensile tests of various materials?

I'm asked to plot various values of force vs elongation and graph the resulted curve, as dull of an assignment as it is, I found no where to get elongation vs load values and all there was was max ...
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36 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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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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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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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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Slipping ball on table (two dimensional motion)

Suppose i have a horizontal table. Choose a standard cartesian coordinate such that the $x-y$ plane coincise with the table. Assume that the table is not smooth. Suppose i have a solid ball with ...