Questions tagged [moments]
The moments tag has no usage guidance.
53
questions
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3answers
93 views
Statically determinate structure by adding moment
I'm considering the problem below.
It's a setup with a roller joint and a pinned joint with a hinge between the two rigid links.
Since there are now 3 unknowns for 3 equations and a zero moment at the ...
2
votes
0answers
28 views
Optimization: Most efficient way for multiple people to move boxes
We are moving house in a few weeks and have a couple of people helping moving the boxes. My previous experience from moving is of queues building up in small hallways and people getting tired from ...
0
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0answers
42 views
External moment over an hinge
I want to find the moments around points A and B in the following figure.
Suppose the structure is fixed at the point where $F_{ax}$ and $F_{ay}$ are located.
I consider A and B to be hinges so that ...
0
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2answers
45 views
How can I find deflection in a member that doesn't have a constant area moment of inertia?
I'm trying to calculate the maximum deflection in a simply supported member with a uniformly distributed load. The trouble is this member does not have a constant area moment of inertia. I've drawn a ...
0
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2answers
104 views
Maximum induced bending stress within the beam
The Maximum induced bending stress within the beam.
Given that:
$$\frac{My}{I}$$
The beam depth is 300mm, the width is 150mm. The beam is an I section beam with a 5mm wall thickness.
My ...
-1
votes
2answers
29 views
How to determine the new position of a support if the beam is shortened (moments question)?
I am having trouble with this moments question:
A force F balances a 6m long, 100kg uniform beam at A. The beam will be shortened in length by 2.5m at B. Determine the new position of support A that ...
0
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0answers
29 views
Finding transformation of forces and moments
I have two sets of forces and moments, measured by two 6 DOF force/torque sensors at position A and B on a robot arm (B at end effector). My goal is to use this measurements to relate the forces/...
0
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1answer
95 views
Calculate deflection of a beam with an arbitrary shape
I have a beam with rectangular cross section, but rather an strange shape in the length wise direction as seen below:
So I have taken out the symmetry part of it:
And it actually has some nice ...
0
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2answers
61 views
Resultant force coordinate for parallel 3d forces acting on a slab
Apologies if I have done something wrong, first time posting on a stack exchange website.
Four forces act perpendicular to the surface of a circular slab (assume mass of slab is 0 and middle of slab ...
0
votes
1answer
36 views
Are there different moments of inertia for shapes and bodies?
I'm confused by this. There is a moment of inertia for a shape, let's say circle:
But if you make it 3D, you have a new moment of inertia:
Is there any connection between these two?
0
votes
1answer
382 views
Problem while solving for the moment of a cantilever beam
As in the first image,
Moment at any point between C and B should be 0.
But when I try to solve it by substituting equal and opposite forces at end C so that anti-clockwise moment of $F(l-a)$ and ...
2
votes
1answer
43 views
Why is the bending moment equation for a uniformly distributed load (w) across a length x on a structure given by w(x)(x/2)?
So for any structure, simply supported beam, three hinge frame, cantilever etc. where there is a uniformly distributed load. For example, for a simply supported beam with uniform load of w along the ...
1
vote
2answers
55 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 ...
1
vote
3answers
78 views
Is there a 6th equilibrium equation for a static beam?
For a scholarship exam I'm taking, it takes simple enough ideas and then messes with them in crazy ways. In this question four of the equilibrium equations I'd use to solve this are linearly dependent....
0
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0answers
94 views
Finding Tension in cable in 3D Equilibrium
In a typical 3D Equilibrium problem.
Assume you have two cables points supporting a mass. The two cables are K distance above origin and form a quadratic triangle with the mass which is a the same ...
0
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2answers
181 views
Resolving moments and forces
The calculations for a design I am doing are making me go round in circles. I have simulated the design but I cannot seem to resolve this mathematically and it is really bugging me!
Below is an ...
1
vote
1answer
61 views
Is there a moment at a point between two connected sliders, when one is subjected to a force? (schematic shown)
Background: I'm designing a machine that uses an actuator to push an object. The connecting component may not take certain bending forces, therefore I'm trying to evaluate the system with a free body ...
0
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1answer
44 views
Sign convention-moment
I am having a hard time taking care of signs. Whether weāve made the cut at right or at left. Whether should we make the rotation according to axis x, y or z.
In this case, they assumed that P was ...
1
vote
2answers
1k views
The internal normal force, shear force and moment
How do I determine the internal normal force, shear force and moment at the point C?
$V_c = 0$, $N_c = 0$ and $M_c=3.75 kN/m$
I have already done this:
Where is the problem?
0
votes
2answers
1k views
Shear force and bending moment for continuous span
It's given that L1 = 5m, L2 and L3= 7.5m, w = 8.9kN/m , I am asked to find the bending moment using these coefficient.. Prior to this , i need to have the value of shear force first.Shear force = ...
3
votes
1answer
772 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 ...
2
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0answers
31 views
Most efficient way for finding the rotation angles after moment distribution (Cross method)?
First of all, I have taken a look at the Grinter's method, which is similar to Cross, but balancing angles instead of moments. My question assumes that we are using the Cross method, and not the ...
0
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1answer
64 views
How to solve for moment with uniform distributed load
How do we get the moment when there's a distributed load?
For example, the picture below has 9[(60)(18)]. I get that 60 is the distributed load and 18 is the total length of the load, my question is ...
1
vote
1answer
99 views
Shear force and bending diagram un-uniformly distributed load
I already got great help on this topic, but I'd like to make sure that I get it.
For example, take a beam of length 6 meters, left side fixed support and right side rolled support. There is a load of ...
1
vote
3answers
2k views
Transfering moment through internal hinge
My professor says, the internal hinge can not transfer moment:
But can we calculate $\Sigma M_A=0$ for whole beam ( without cutting it or something) this way?:
$\Sigma M_A=0 ===\Rightarrow M_A+(D_y ...
2
votes
0answers
18 views
Shift of joint in kinematically indeterminate system
Given ist the following system:
$$EI=100000\frac{\text{kN}}{\text{m}^2}$$
$$EA\to \infty$$
I'm suppossed to find the horizontal and vertical shift of joint g. My first approach was to use the ...
3
votes
1answer
129 views
Skewing of joints using virtual work
Given ist the following framework:
$$E=210 \frac{\text{kN}}{\text{mm}^2}$$
$$ EA \to \infty $$
$$ I_1 = 80000\text{cm}^4 $$
$$ \frac{I_1}{I_2} = \frac{3}{4} $$
$$ I_3=I_1 $$
Using the principle of ...
7
votes
3answers
828 views
Calculating moment of inertia for a hollow discontinuous circle?
This is a pretty simple problem, but I'm just not sure how to go about it. I want to find the moment of inertia of a discontinuous hollow circle. But since the shape is so irregular, I'm not sure how ...
2
votes
2answers
4k views
Transfer of moments in beams with internal hinges
We have a beam with 1 internal hinge just like the picture. We know the internal hinge can not transfer moments between AB and BD. We know the 30 kN force makes some moments on BD & AB. If B (...
1
vote
0answers
42 views
Pin, Slot, and Spring Equilibrium
I am checking to see if this is done correctly, the slot is a little confusing for me.
B is a pin in a slot, solve for the spring constant (k) so the 50 lb force applied does not move pin B
Solving ...
4
votes
3answers
2k views
is bending moment on roller supports at beams zero?
isn't the bending moment supposed to be zero on roller supports at beams?
then why isn't it zero here in this picture at x=2?
0
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3answers
755 views
Second Moment of Area for slanted triangle?
Consider this triangle with its centroid at $C$:
Then this is how I believe we can calculate the Second Moment of Area along the $x_{C}$ and $y_{C}$ axis:
$$\begin{align}
I_{xc} &= \frac{bh^3}{...
0
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1answer
83 views
Plastic Hinge by Skyciv
Is it possible to determine plastic hinge location of a frame in SkyCiv? Is it also possible determine moment -curvature relationship curve in SkyCiv? If yes, how?
2
votes
1answer
2k views
Sheet Metal Bending: stuck on calculating the minimum radius required
I'm used to calculate the minimum radius required for bending operations on both aluminum and steel sheets, given the following parameters: https://imgur.com/a/7akHC
Problem statement:
For a sheet ...
2
votes
4answers
233 views
Moment and Torque at a Single Point
As far as I know, moments/torques occur when forces applied are not in line. However, I often see moments/torques being applied at a single point in free body diagrams.
How can moment/torque be ...
0
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2answers
186 views
Finding the force in a cable of a rigid system
QUESTION (see attached image file):
I got stuck when trying to find tension for part A; see my working below.
and help me solve.
0
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1answer
2k views
Determine the reactions at A and C, knowing that Ī± = 30º [closed]
QUESTION(see image attached):
Really need help here can someone help me show how we get the solution as shown in the image file attached above.
okay since I was asked by one of the users ...
1
vote
1answer
354 views
Is radius of gyration same for both types of moment of inertia?
We know that moment of inertia is commonly known as second moment of area. Which is $\int_{}{} y^2 dA$.
However there another moment of inertia called as mass moment of inertia given by $\int_{}{} r^...
1
vote
1answer
597 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
2answers
1k 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 ...
0
votes
2answers
84 views
moment of inertia forces and torque
I did some calculations to find out the moment of inertia and physical qualities of some metal.
I am using typical medium carbon steel.
I'll use a density of 7.8 g/m^3 until I get better numbers.
...
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2answers
494 views
Moment of force or torque [closed]
Is the moment of force taken in a clockwise and anticlockwise fashion? Why then do we curl our fingers and check it?Explain the equivalence or similarity between the two.
1
vote
2answers
269 views
Moments of inertia, rods mechanism
I need some assistance understanding moments of inertia. I am doing some review for an upcoming exam, however I am slightly stumped by this question. I have already tried googling "moments of inertia" ...
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votes
2answers
2k views
Fluid mechanics- Force required to keep the gate closed
I have to answer the following question which is (image shown above)
"what is the force to keep the rectangular gate closed? in N/M"
This is all the information I have to solve the question. I ...
2
votes
1answer
174 views
Structural mechanics - computing bending moment
I am having difficulties trying to work out one problem. I've attached a picture explaining the situation - the task is to determine internal forces in C but the bending moment M(x) doesn't seem to ...
2
votes
1answer
287 views
What are the principles (if there are any) behind the conservation of bending moment in frame analysis?
I notice from this question that the moments at joint connection are somehow "conserved", or being "transferred" from one element to the others. In other words, there are no "missing moment".
Note ...
1
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2answers
4k 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 ...
-1
votes
1answer
2k views
Calculating the moments due to reaction forces on a bent beam
I am trying to solve the following problem:
EXAMPLE 2.10
Determine the reactions on the beam in Fig. 2ā30a. Assume $B$
is a pin and the support at $B$ is a roller (smooth surface).
...
1
vote
2answers
534 views
Flexural modulus for a beam fixed at one end
For a beam supported at both ends with a mass in the middle, the flexural modulus is given by:
$$E_b = \frac{F L^3}{48I d}$$
with I as the area moment
$$I = \frac{1}{12}wh^3$$
How does the ...
0
votes
1answer
83 views
Shear Stress / Flexure Stress Formulas / Tables
Is there something similar to the Section Modulus in the Flexure Formula
$$\rho_{max} = \dfrac{M_{max}}{S}$$
where $S = \dfrac{I}{c}$ for shear stress formula?
So in
$$\tau_{max} = \dfrac{VQ}{IT}$$...
