Engineering Stack Exchange
Engineering Stack Exchange

Questions tagged [stresses]

383 questions
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How do ball bearings not crack from a load concentrated on an infinitesimally small point?

How do ball bearings last? Most bearings in a standard hub (bottom of the image) are not actually taking a load. Only the single ball that happens to be at a particular location while spinning takes 100% of the load. If the bearings were cylindrical…
Sam7919
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Why exactly does a washer help distribute the stress around a bolt?

Usually the reason for having a washer under a bolt head is stated to be that it helps to evenly distribute the stress to the clamped material surface. But why is this? I would understand if the washer was significantly larger than the bolt head.…
S. Rotos
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Why do we even use engineering stress?

Surprisingly this hasn't been asked before, so I must be missing something simple. We use engineering stress and engineering strain in this eq. Stress = (Young's modulus) × (strain). This eq. is used in analysis of bending beams, twisting shafts…
Jessica
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Why does prestressing in trees make them stronger?

In "Structures: or Why Things Don't Fall Down" James Gordon talks about trees being prestressed with the outside in tension and the inside in compression. Why does it make a tree stronger to have it in tension on the surface and compression at the…
Voltron
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What is the difference between the Polar Moment of Inertia, $ I_P $ and the torsional constant, $ J_T $ of a cross section?

This question is so fundamentally basic that I am almost embarrassed to ask but it came up at work the other day and and nearly no one in the office could give me a good answer. I was calculating the shear stress in a member using the equation,…
William S. Godfrey- S.E.
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What is the difference between pressure and stress?

Since the units are the same ($\frac{N}{m^2}$), what's the difference between pressure and stress?
user133
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Strength of a welded steel gate with vertical bars vs. crossed diagonal bars

Looking for some hints on how to create a rough estimate for the following problem. Given two steel gates with the same dimensions, same material - e.g. everything is the same. The only difference is that the middle parts have different…
kobame
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How do you select the correct area to consiser for first moment of area calculations?

I have just begun studying mechanics of materials and I am struggling to understand intuitively how to select the area in first moment of area calculations. I was hoping someone has a relatively easy explanation. The problem arises when calculating…
Akitirija
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Interpretation of shear flow/shear center of L-profile

I have calculated the shear flows and center of an L shaped profile. I assume they are correctly calculated (I followed the same steps as during the lectures for an I shaped profile). However, I have some problems with the interpretation of the…
Simon
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How can I calculate the stresses and limits for the physical lowering of in-service pipelines?

Sometimes underground pipelines are exposed due to vertical scour or lateral migration of streams (or other erosion). One option is to lower the (in-service) pipeline to a new depth that provides sufficient ground cover. How can I determine the…
JustInTheWoods
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Why do stress concentrations really occur?

From doing some research I've learned that internal stresses inside an object can "concentrate" on sharp edges, as shown in the above picture. For that reason we often make fillets so that the change in diameter is smoother and we get a smaller…
S. Rotos
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How do large turbines deal with asymmetry and beat arising from those?

A large turbine used in an electric plant can easily have 10+ meters in diameter and rotate at 70+ RPM. Should any asymmetry occur the rotating turbine will produce beat which will sooner or later destroy the plant. Crafting a turbine that large and…
sharptooth
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Principle of Virtual Work vs Castigliano's (Second) Theorem

I had a look online and into some literature however I did not seem to find a good comparison for the two different methods. They are both used for determining displacements and slopes (rotation by theta) at a point in a continuum. Former uses a…
thephysicsguy
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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. I am bit confused of term Yield of Isotropic…
John
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Is a distributed load in two parts equal to a full distributed load?

I have a structure like such: Due to my lack of knowledge of ANSYS, I have made the singular distributed loading (GI) represented as two distributed loadings (GH and HI). Would this be an accurate model? I feel like there should be some bending in…
General Stubbs
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