Questions about using applied mechanics to model engineering problems.
0
votes
1answer
23 views
Calculate the torque needed to turn a rod it's own axis
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 ...
0
votes
0answers
30 views
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 ...
0
votes
0answers
38 views
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 ...
0
votes
1answer
57 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 ...
0
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0answers
51 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-...
1
vote
0answers
33 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 ...
0
votes
0answers
17 views
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 ...
0
votes
0answers
41 views
2
votes
1answer
38 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 ...
0
votes
0answers
52 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 ...
2
votes
1answer
37 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?
0
votes
1answer
51 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 ...
0
votes
0answers
15 views
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 ...
-1
votes
1answer
21 views
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 ...
1
vote
1answer
40 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 ...
0
votes
0answers
19 views
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 ...
2
votes
1answer
43 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{...
1
vote
0answers
115 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 ...
0
votes
0answers
37 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 ...
2
votes
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 ...
0
votes
2answers
55 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 ...
1
vote
0answers
23 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
$$...
0
votes
0answers
15 views
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 ...
2
votes
2answers
73 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 ...
2
votes
1answer
34 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 ...
0
votes
0answers
59 views
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 ...
0
votes
1answer
65 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.
2
votes
2answers
256 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 ...
6
votes
1answer
88 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 ...
0
votes
2answers
32 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 ...
3
votes
2answers
49 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?
0
votes
0answers
29 views
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 ...
0
votes
1answer
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 ...
1
vote
0answers
28 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).
...
1
vote
1answer
50 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 ...
0
votes
1answer
41 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 ...
0
votes
0answers
21 views
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 ...
0
votes
1answer
37 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 ...
0
votes
2answers
104 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 ...
1
vote
1answer
60 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 ...
1
vote
0answers
50 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 ...
1
vote
2answers
206 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?
3
votes
2answers
127 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 ...
0
votes
0answers
18 views
Leadscrew connection for 4 DOF apparatus
I have a 25kg apparatus that sits on 3 elevation screws. The rear elevation screw is in a fixed location, and the other two slide along an arc, +/- 2 inches, shown here in green, to change the angle ...
1
vote
1answer
197 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 ...
1
vote
0answers
44 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 ...
1
vote
1answer
105 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 ...
2
votes
2answers
1k 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.
2
votes
2answers
285 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 ...
5
votes
4answers
144 views
Is radians dimensionless quantity?
Quite often while calculating angular velocity we come across the quantity radians per second. Dimensionally how do i treat radian as?Explain vividly.
