Questions tagged [stresses]
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209
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Calculating time derivatives of stress (σ ) in the constitutive equation of a viscoelastic model without explicitly remembering the prior stress?
I am trying to understand how to work with viscoelastic models. There are numerous simple viscoelastic models (described at that link). In each, there is a "constitutive relationship" ...
1
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1answer
45 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 ...
0
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2answers
46 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 ...
2
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0answers
28 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 ...
1
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1answer
35 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 ...
2
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1answer
56 views
How can I decrease strip tension with bridle rolls in tension leveller?
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 ...
0
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1answer
19 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
70 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
44 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
29 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
90 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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0answers
12 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
81 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
56 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
423 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
72 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 ...
1
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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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0answers
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
43 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
71 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 ...
-1
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2answers
45 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
107 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
43 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.
...
2
votes
3answers
90 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 ...
1
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2answers
48 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
70 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 ...
1
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1answer
41 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 ...
2
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0answers
36 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
votes
1answer
91 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 ...
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0answers
45 views
Shear and normal stress in rivets
Hello everyone :) This is my first post here so please excuse any of my mistakes.
I’m having some difficulty with solving the following problem. Let us have a thin-walled square pipe exposed to ...
0
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1answer
45 views
Analytical solution of thermal stress in a bi-metallic cylinder
As a side project I have looked to solve using Python an analytical solution for one-dimensional transient heat transfer in a thick cylinder with cladding on the inside surface, wherein the fluid in ...
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1answer
38 views
Stress Analysis University Report Help
I'm working on a final report for the mechanics of material course, and the project was to choose a structure or mechanical element and carry out stress analysis using solidworks and then confirm ...
2
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1answer
120 views
Bending behavior of built-up C-Channel
I am analyzing a built-up C-channel for bending purposes (2 point loads of 1200 N each @ 30 cm symmetrically from the CL). The flanges are made of a different material than the web, they are also of a ...
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1answer
25 views
Deformation and stress in moment of hit (Ansys)
This how task goes: i need to find deformation and stress of piston in moment of hit between piston and tool (tool is stationary). Velocity of a piston is (5-7 m/s) and forces are in picture below.
I ...
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0answers
24 views
WEC linear inputs
I have seen some designs being made for linear generators for WEC(wave energy) applications. A buoy driving a shaft. But what if the shaft inside was a rack and pinion? If you converted the ...
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2answers
86 views
Stress Concentration Factor
Looking through texts such as Shigley's Mechanical Engineering Design, you come across tables of the stress concentration factor (defined as $K=\sigma_{max}/\sigma_{avg}$) such as the following:
This ...
3
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1answer
48 views
Calculate whether a polycarbonate plate can withstand a certain force
I need to calculate whether a polycarbonate sheet can withstand a certain maximum force. The force is an impact force on any one point of the sheet at any given time. All I have are the Young's ...
1
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1answer
51 views
Why does fatigue crack growth require unloading?
When a crack has been initiated in a material, further loading of the material causes stress concentrations at the crack tip. This high stress causes the material to break at the tip and the crack ...
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2answers
59 views
Bending moment in Euler-Bernoulli finite Element
I'm trying to calculate the bending moment distribution on a fixed-fixed Euler-Bernoulli beam. It is known that interelement nodes show different values for the bending moment. What is customary to do ...
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0answers
37 views
Unexpected stress concentration results
I've run some stress simulations but I keep getting some unexpected results. I have 3 parts connected using 4 bolts as follows:
A torque of 1N is applied to the hole on the right to simulate a hung ...
2
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0answers
129 views
Why do we use the strain-controlled test for the compressive strength of concrete?
As you all now, a typical stress-strain curve for concrete under compression can be seen in any reinforced concrete design textbook. The decreasing part of the curve (post-peak) can be obtained by ...
4
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2answers
53 views
Is it feasible to mount a 40kg shelf on a rotating and sliding pole?
I want to build a shelf that can I can place near a wall and still be able to rotate it around 180 degrees. I therefore would want to mount the shelf on a rotating pole and to reduce the needed ...
1
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1answer
33 views
Physical Significance of Max Shear Stress in a Rod in Compression
For a rod in compression, the max shear stress at a point is $\pm\sigma_x/2$, i.e. half the compressive stress applied at either end.
This value is obtained using the equation for $\sigma_\theta$, ...
3
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0answers
179 views
Double Shear Stress butt joint
A double shear butt joint is shown below in the diagram 4 plates are held together by two bolts. The applied force is 42KN. Determine the shear stress within the joint
$$\begin{align}
a &= 2 \...
1
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1answer
328 views
Determine Bolt dia from Shear stress and force
The Diagram below shows a lap joint where two plates are held together by a bolt. The applied force (F) is $42~\text{kN}$ and the shear stress is $593~\frac{\text{N}}{\text{m}^2}$ Assuming that the ...
2
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1answer
70 views
Twist “buckling” critical load
I have a very long beam which is subjected to a torque (I have the moments and shear forces with respect to X along the beam). I can calculate the critical load when the beam would bend if it was ...
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2answers
104 views
Maximum stress point
I want to determine the point where the maximum stress is located. Also, I want to know how this kind of questions is answered.
2
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2answers
97 views
How do I determine what hardness to change the bearing or the track?
We have a project that requires us to use a qty of 4, Ø2" yoke roller bearings mounted two per side on a trolley that roll on a steel track. The maximum total weight that we estimate on the track at ...
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0answers
50 views
Understanding compatibility of strains
In mechanics, we have the so called compatibility conditions, which quarantee that when a body deforms, the strains are "compatible" in such a way to no discontinuities or gaps for inside the body as ...
