Questions tagged [stresses]
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228
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Why is the yield strength of steel assumed to be less for a thicker element?
The above image is part of table 3.1 of Eurocode steel design standard. Looking for example at the first row (steel grade S 235), we see that there are two values for yield strength $f_y$, one for ...
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3answers
52 views
Calculating Load On Winch From a Distributed Load?
I am in the process of building an antenna mast that can tilt from horizontal (down) to vertical (up). The mast (arm) is 360" and weighs a total of 105 lbs. I need to calculate the amount of ...
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12 views
How to calculate minimum and maximum cross-section of a compression clip
I am trying to design and 3D a custom snap in fastener, and I am having a hard time figuring out what cross section it needs to have so that it does not break when compressed, but also isn't so that ...
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17 views
Why doesn't the Stress Power in the theorem of the expended mechanical power contribute to the kinetic energy?
The following is the formula of the expended mechanical power:
$P(t)$ $=$ $\frac{d}{dt}$ $\int \frac{1}{2} \rho\ v^2 dV$ $+$ $\int \sigma \colon d\ dV$
where $P(t)$ is the mechanical power entering ...
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How to solve stress/strain constitutive equation for system of springs and dampers with a Coulomb friction element added in?
I am attempting to solve the stress/strain constitutive equation for a system of springs, dampers, and a Coulomb friction element. Basic examples for such constitutive equations can be found in this ...
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1answer
106 views
Why is the Stress vs strain diagram preferable to the Load vs displacement diagram?
I’m really unsure what is the difference between stress vs. strain and load vs displacement graphs and why stress-strain is better.
I know that the units are different:
stress is in MPa and the load ...
2
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3answers
75 views
Shelf Reinforcements
Hi I know this is a little bit of a strange one, but I’ve got a relatively cheap shelving rack that I bought to make good use of garage space.
I have included a pic, It’s footprint is 1220mm x 610mm ...
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1answer
46 views
Is it possible to use Plain Cement Concrete post for fencing?
I am in need of around 700-800 posts to fence my farm in a semi-arid area in TN state, India. In my place granite posts mined from quarries are normally used. It costs around Rs 300-400 per post(6-7ft)...
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71 views
Why is it said that the flange of an I beam carries most of the moment?
It is often said for I beams that the flange carries most of the moment subjected to the beam, while the web carries most of the shear force. The latter is obvious from pictures like above, showing ...
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1answer
27 views
If an airfoil underwent horizontal loading, would it stiffen the airfoil? [closed]
I am designing a wing for a Vertical Takeoff and Landing aircraft. I am trying to choose a wingtip winglet for my aircraft. One of the option is a aft-swept wingtip winglet. However, this structure ...
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29 views
What are the limits of small 3D printed gears?
How much tangential force should I expect a 10~20mm pitch diameter/1.5mm gear module 3D printed rack and pinion system to support without breaking nor sliding?
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Is there a mode of failure criterion for a valid unconfined uniaxial compressive strength test for intact rock core specimens?
I have read the latest revision of the ASTM D7012 standard, which includes the test procedure for determining the unconfined uniaxial compressive strength of intact rock core specimens. There, I do ...
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16 views
Stress Tensor components
Given an equivalent stress vector(or Traction vector) in a plane stress state, how can one determine the 3 components of the 2*2 Tensor matrix, i.e. sigma_x, sigma_y and tau_xy?
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30 views
Stress Transformations
In plane stress state:
How can one comment about the state of stress for the given condition?
I am not sure but I guess that we can use the principle of superposition. Though I do not know how can I ...
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41 views
How do I calculate the strength to weight ratio of this object?
I have an object that weighs approximately 10 grams = 0.022 pounds. I know it can hold at least 45.1 pounds without breaking. It's a cube-like object so I placed many books on top of it and weighed ...
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2answers
42 views
Why do I see stresses on the fixed support face of a solid body in FEA?
Below, I have shared pictures of a simple model in FEA. As it can be seen that the face onto which the fixed support is applied, there exists Von-Mises stresses. I cannot comprehend why. Since the ...
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9 views
Finding the Shear Center for a Beam with 1 Axis of Symmetry
I am trying to solve this problem of finding the shear center for the given beam and I have found that e = 35.94 mm, however the solution that was shared with me, had the answer of 39.17 mm.
My method ...
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1answer
61 views
deformable object squeezing
I have the problem following. There is a deformable sphere with radius r. It goes inside a constriction channel with d*d cross section. Assuming that the sphere volume is constant and the sphere shape ...
2
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1answer
43 views
How to calculate the adhesion I need to keep a 3D printed bending part straight?
3D printed parts cool down during printing, resulting in thermal contraction which causes a bending moment and separation from the printing bed.
The issue is solved by increasing adhesion to the ...
1
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1answer
39 views
Poisson relationship between area and length of electric wire
I was given the following formula to relate the change of area against the change of length of an electric wire with a Poisson ratio:
$ {\Delta A \over A} = -2 \nu {\Delta L \over L} $
where $ \Delta ...
2
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0answers
70 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, $...
1
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1answer
62 views
What exactly is Hooke's law defined for?
I used to think that Hooke's law was a relationship between how much a bar under uniaxial loading deformed and the internal force (per unit area) that developed within that bar. But this clearly isn't ...
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2answers
60 views
Shearing Stress at the Boundaries of two infinite Planes
This is a worked example on a book I am reading (Fundamentals of fluid Mechanics).
He then asks
"Can you explain the change in sign? [Hint: Sketch a sheared fluid particle adjacent to the top ...
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0answers
50 views
Is Viscosity = Slope?
studying fluid mechanics, I see that viscosity relates shear stress to shear rate, like a slope. However, on graphs I see that they draw a triangle, and where I would expect to see $\Delta \tau $, I ...
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1answer
40 views
Reinforce foldable table legs
I'm trying to build a table with 4 swivel legs that can be locked into arbitrary angles so that it can stand over one to three rows of storage crates in my garage:
As you can see, the legs aren't ...
1
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1answer
84 views
How can I decrease strip tension with bridle rolls in tension leveller? How can I find total elongation after the strip exits initial bridle rolls?
I'm working on a tension leveller design which consists of 3 main sections. These are
Input Bridle Rolls Zone: Increase the strip tension coming out of the decoiler.
Leveller Zone: Strip goes through ...
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1answer
30 views
Where does the equation for shear stress of a rectangular beam (3/2 V/A) come from?
I am writing a report and need to reference every equation used. I am using the equation for shear stress in a rectangular beam of
tau = 3/2 * V/A
but am not sure where it came from or what textbook ...
5
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1answer
77 views
“Heavy-duty” or not, can my drawer slides really support this weight?
Okay, so recently I got a Dewalt 735 Thickness Planer.
It's great at what it does. (It even LOOKS like it's ready to consume the tender flesh of lumber, like some twisted Victorian lumberjack... ...
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1answer
48 views
Stress Concentration Factor – Why a Specific Range?
I was trying to find the stress concentration factor for a specific situation and I found two different resources for it.
Ref: Shigley's mechanical engineering design
Ref: Roark's Formulas for ...
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1answer
39 views
Struggling to find solution: question 1 (Finding the maximum length possible of a rod with specific stresses in action)
Could someone please help with the problem below?
Edit 1:My guess on this question is: when I plot in the formulas, the stress rooting from the bending moment overcomes greatly over the other ...
5
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1answer
103 views
Yield properties of plastic material
What is meant by yield of isotropic plastic material?
How is yield of Isotropic plastic material different from the term normal yield which is referred as transition from elastic behaviour to plastic....
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13 views
Finite element welding simulation with commercial software? [closed]
I am looking forward some libraries/add-ons to perform welding simulation (thermomechanical coupling, steel alloys) using commercial software, like Ansys or Abaqus. My aim is to determine better ...
1
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3answers
92 views
Buckling of Parallel rods
I am trying to calculate critical force $P$, if two rods (same diameter and length - rigid fiberglass sandwiched on two steel plates) are parallel to each other.
$$
P = \frac{\pi^2 EI}{(KL)^2}
$$
I ...
2
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3answers
65 views
The behavior of the stress-strain curve of metal, containing a void
Let's assume that in a metal sample without any dislocation, there is a void. Then we conduct a uniaxial tensile test.
0
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1answer
429 views
What's the best way to design a joint with two fasteners?
When you're trying to design a relatively long joint with only two fasteners, what's the best way to arrange them? Since fasteners effectively radiate a circle of clamping force around them, what's ...
2
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2answers
78 views
Why is the thin-walled cylinder more likely to experience failure along its axis than along its hoop/circumference?
I was watching a YouTube video to understand the concepts of hoop/circumferential stress and axial/longitudinal stress in thin-walled cylinders and their formula derivation.
So the formula of the ...
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0answers
16 views
Should I use ST or LT values for extruded rod?
In MMPDS for AA7075-73511 (extruded rod) the Table 3.7.10.0(g3) show both ST and LT values for transverse directions. For a rod with circular cross section there is really no Short and Long transverse ...
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19 views
Limit state design/ LRFD of short steel columns
Why do we use the yield strength as the limiting strength in short column design when using limit state design.
Why is the full capacity of the material not utilized (as is the case with beams when we ...
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2answers
45 views
Other than yielding, what type of stress you check for ASD?
ASIC 360-16, in page pdf 330, it says
"For any single element, there may be a number of different allowable stresses that must be checked."
I can think of yielding. What else?
Rupture for ...
2
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1answer
74 views
Shock loading stresses due to falling: what strength to use for acceptance criteria?
We are evaluating a design in which a fall-arresting safeguard would be subject to a shock load in the event of a catastrophic failure of a different component, which is required to meet compliance ...
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2answers
46 views
Calculate elastic modulus of titanium [closed]
I would like to work out the elastic modulus of a specific grade of titanium.
Further to this I would like to learn how to calculate the maximum tensile strength of that metal in relation to its cross-...
4
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1answer
259 views
Why is fillet weld assumed to be in a state of pure shear stress?
According to Building codes, when calculating the maximum load a fillet weld can take, one checks only that the stress in pure shear is below the maximum shear strength. We know that shear yielding ...
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1answer
50 views
simply supported beam with a midspan load
First off non-engineer apologies,
A plate of 5251 Aluminium is used to support the load of a centrally seated human I estimate a load of 1 kilonewton.
The beam measures a length of 1000mm, 100mm wide.
...
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3answers
94 views
Beginners material science for handling a load
I’ve got a reasonably strong grasp of Newtonian mechanics, but as far as material science goes I don’t know which of the many material properties I need to use to solve my problem:
I’m trying to mount ...
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2answers
50 views
Reduce stress on holes
I have an aluminium bearing holder attached to one end of an aluminium plate as follows:
The bearing holder is attached to the plate by two bolts on the bottom. The intended setup is to attach a ...
1
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1answer
31 views
Assess bearing force ratings [closed]
Suppose that a ball bearing has axial and radial force ratings of 300N. If the bearing is to hold a 1m long shaft in its bore with a 1kg load on the end of the shaft, will the ratings be exceeded? The ...
2
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1answer
72 views
Strength of bolts
I was wondering if it'd be a good idea to attach a 10kg load to the end of a movable steel rod by fastening it with just one M5 bolt. Looking at Misumi's datasheet, M5 (Class 10.9) has an allowable ...
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1answer
45 views
Hook's law - beginner's question
Under Hooke's law, we know that sigma stresses are responsible for volumetric strain, while shear stresses are responsible for the formation of form strains. In a lecture at my university it was shown ...
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0answers
57 views
Is having a keyway in aluminium for 30Nm a bad idea?
I'm designing an aluminium shaft hub for a 16mm keyed shaft with a maximum torque of 30Nm. However, stress analysis tells me that the keyway can suffer too much stress:
If my understanding is correct,...
5
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1answer
107 views
Rover Wheels: Convex or Flat?
I was comparing the wheels of the Curiosity rover and the Perseverance rover and noticed that the latter had a very flat cylindrical design as compared to the former.
This got me thinking about which ...
