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14 votes
Accepted

Is radians a dimensionless quantity?

radian is a derived unit, defined as the ratio of arc length to radius. As the ratio of two lengths it is dimensionless.
agentp's user avatar
  • 949
9 votes

What is Saint Venant Principle?

The intuitive meaning of Saint Venant's principle is that "if two different sets of applied loads are statically equivalent, then the differences between the two stress patterns they create are only ...
alephzero's user avatar
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8 votes
Accepted

Strength of a Vertical Round Aluminum Tube with load cantilevered off it?

I'm going to run with this assuming the arm looks like the following diagram (I'm ignoring the 11.4 pounds of the bar for now to make the concepts easier to explain - that can be added later by ...
Mark's user avatar
  • 5,333
8 votes

What is Saint Venant Principle?

To add to @alephzero's answer, here's an layman's explanation of Saint-Venant's Principle: far enough away from the load's point of application, equivalent loads can be treated as identical. For ...
Wasabi's user avatar
  • 13.1k
6 votes

Why don't car engine piston-rods (or similar parts) fail as often as other car parts?

The main reason from a designer's point of view is the consequence of a failure. Almost always, something like battery failure or a puncture doesn't cause any collateral damage - you just replace the ...
alephzero's user avatar
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5 votes

Switch at the back of a battery eliminator

It's difficult to be certain, but I suspect what you have is commonly known as a spring speaker clip. Using those terms in your search engine to find one that has listing for maximum and voltage. My ...
fred_dot_u's user avatar
  • 7,132
5 votes

Can anyone verify this wall thickness of a pressure cooker?

Those figures are about right for the bare minimum wall thickness for the walls of a cylinder however, as you say, this would be inadequate in practice for a number of reasons. Safety concerns ...
Chris Johns's user avatar
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5 votes
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Failure in torsion

As a rule of thumb: When brittle materials are subjected to torsion they fail in the plane, where tension is at its highest, i.e. at a 45° angle. Ductile materials on the other hand fail in the plane ...
Andrew's user avatar
  • 1,166
4 votes

Difference between Precipitation Hardening and Tempered Martensite

Summary: Both processes depend on relative solubility of solute between high and low temperature solvent phases. How each process proceeds at sub-microscopic scale is very different. Precipitation ...
do-the-thing-please's user avatar
4 votes

Buckling vs. Yielding Failure of Columns

The basic Euler buckling formula is unrealistic because it implies perfect geometry and perfect alignment of the loads. Therefore a large empirical safety factor is required. It is also a potentially ...
alephzero's user avatar
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4 votes
Accepted

Do yielded columns buckle?

When a column is stressed beyond yield, the strain increases rapidly with small changes in stress, at this stage, the stress-strain curve is no longer linear, and the tangent modulus decreases. The ...
r13's user avatar
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3 votes
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Hardening and Brittleness

Brittleness describes the inability of a material to absorb a considerable amount of plastic deformation. Thus, the material fails without a lot of deformation. Hardening, on the other hand is the ...
Andrew's user avatar
  • 1,166
3 votes

What is the difference between tau = VQ/It and tau = V/A?

As mentioned, the formula $\tau_{avg}=\frac{V}{A}$ is called average shear stress. In some calculations it might suffice to calculate $\tau_{avg}$ for a widely used cross-section (let's say a ...
Andrew's user avatar
  • 1,166
3 votes

Moment of force or torque

A moment has a direction, which you can imagine when you look at the direction of the force and the axis you're calculating the moment from. Depending on which direction you're looking at it from, ...
Andrew Elliott's user avatar
3 votes

Is radians a dimensionless quantity?

TL/DR As the other answers have stated, radians are dimensionless. Cycles and Turns This is a question that seems to come up often, and from many different quarters; not only from students and lay ...
Rick's user avatar
  • 1,166
3 votes

Buckling vs. Yielding Failure of Columns

Yes, it is better to design for yield than buckling because Euler buckling is a result of instability as opposed to overloading force. Gamma f is determined from Eurocodes which are from extensive ...
Rhodie's user avatar
  • 974
3 votes
Accepted

Does a change in specimen dimension affect the measured yield strength and tensile strength?

Usually no. However, yes in a manner of speaking. No: Primarily both properties are material specific. Therefore, no there shouldn't be an effect of the geometry on either the yield or the tensile ...
NMech's user avatar
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3 votes
Accepted

Why is the thin-walled cylinder more likely to experience failure along its axis than along its hoop/circumference?

Actually, the pressure inside the vessel is uniform and constant everywhere. What happens is that geometry results in reduced stresses in one direction and not in the other. There may be some ...
NMech's user avatar
  • 24.3k
2 votes

Would engineering bricks explode if used to build an oven?

Engineering bricks (solid) are fired at 1200 degrees in a kiln so don't worry about your complicated mathematics , your pizza oven will never get to that temp.if it did or even if it got much much ...
dave's user avatar
  • 21
2 votes

Can buckling failure at the first critical load be avoided by "instantaneous" loading?

This is just wrong. The notion of a "critical load" in Euler buckling is a very simplified mathematical idealization of the situation. In the real world, buckling behaviour always involved nonlinear ...
alephzero's user avatar
  • 12.5k
2 votes

Actual amount of reinforcement gained by adding gusset to welded steel tube construction

This answer is from the riding/cycling side, not an engineering view. If you think of the forces involved on a head tube, then the "static" force ( while it is standing still) is upward through the ...
Criggie's user avatar
  • 430
2 votes

Behavior of materials on application of tension

Yes. In a perfectly elastoplastic material (where the stress-strain relationship is perfectly linear until the yield point and is then constant and equal to the yield point), the material will ...
Wasabi's user avatar
  • 13.1k
2 votes
Accepted

How to prevent screw from loosening?

to prevent the nut from unscrewing, you must use either 1) a thread-locking compound (Loctite or equivalent) on the threads during assembly, 2) split lock washers, 3) an aircraft-grade castellated nut-...
niels nielsen's user avatar
2 votes

DOE analysis or root cause analysis?

Let assume a leak has been reported in the following pump system. As a result there is 1 inch of water on the floor. To identify the failure a root cause analysis (RCA) needs to be performed. To ...
Mahendra Gunawardena's user avatar
2 votes

Why is the thin-walled cylinder more likely to experience failure along its axis than along its hoop/circumference?

In the old days we used the formula- Stress = PD/2t , and the hoop stress was twice the axial /longitudinal stress . Pressure vessel heads were usually half the thickness of the walls because of the ...
blacksmith37's user avatar
  • 6,134
2 votes

What is the best time interval in condition monitoring programs for checking rolling bearings?

I know of no global standards for vibration monitoring. Like all preventive/predictive maintenance items, these things need to be equipment-specific. These are the same considerations you would apply ...
Tiger Guy's user avatar
  • 6,901
2 votes

What is the reason for forbidding liquids for cooling in drilling on cfrp/Al or cfrp/Ti stacks?

According to this article: A Phased Approach to Optimized Robotic Assembly for the 777X drilling multi-material composites does require some special trickery, especially when automated assembly is ...
Jpe61's user avatar
  • 150
2 votes
Accepted

What does it mean for an item's tensile strength to be "rated"?

"Rated" means it has been proof-tested by an independent lab (like UL or CSA) according to a published standardized test protocol invented by a standards organization (like ASTM) and ...
niels nielsen's user avatar
1 vote

Hollow Steel Tubing: Critical Load for Sidewall Buckling

I am not sure if I understand your question correctly but to determine whether your steel sections compression flange will buckle before it will fail by some other mechanism it might be helpful to ...
J.J.'s user avatar
  • 11
1 vote

Ductile,Brittle and Malleable

Ductile ("able to be drawn out into a thin wire") makes sense as the failure method, because the test is stretching the sample. Malleable ("able to be hammered or pressed into shape without breaking ...
Jonathan R Swift's user avatar

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