New answers tagged stresses
1
For engineering stress-strain curve, the only region where you would see basically two discrete strain values for one single value of stress is the necking, i.e. the region beyond Ultimate point on the curve. What happens there? The structure looses its stiffness and load bearing capacity, and just keeps on shrinking (in the necking area) without taking a ...
3
The stress-strain curve isn't created using a incremental load.
Instead what most standards for tensile testing nowadays require a constant displacement rate. I.e. you have a setup similar to the following (it may vary of course)
Figure: Tensile test setup (source engineeringarchives)
The crosshead (horizontal bar that the load cell is attacheds) moves at a ...
1
Because (to my understanding your problem is more in the interpretation of derivatives rather structural mechanics) I will try to explain it in parallel example. Hopefully it will make sense.
Imagine a car accelerating with $a [m/s^2]$, and at some point in time t suddenly decelerating at $- a [m/s^2]$.
The acceleration in time t will abruplty change from ...
1
The reason the convention picks the shear positive when on a differential element it tries to rotate clockwise is that this rotation will produce a positive conventional moment, bending the beam into a smile.
This convention makes the calculation easy and because conventionally a horizontal beam is analyzed from left to right and the positive shear direction ...
1
"The author has taken shear force as positive if it tries to rotate the element clockwise,..."
This sign convention indicates the positive direction of force is up, and the couple produces a CW rotation about the center of the small element. "q" is assumed to have the same direction of $V_2$ (pointing down) as shown in the first ...
1
Poisson's ratio is defined in the case of uniaxial tensile testing. As such the x axis is in the direction of the loading, while the y and z axis are transverse.
In isotropic materials it doesn't make any difference which axis the material is tested.
However for anisotropic (i.e material that don't behave in the same way in all directions), there are ...
0
The definitions below ar quite clear:
https://www.mechanical.in/what-is-stress-and-types-of-stress/
0
Example: You provide confinement reinforcing to a column. That is passive confinement, which will automatically activate and provide confining stress, if there is the need, after a certain amount of strain. But if you applied that confinement force actually yourself, instead of the confining reinforcing, then that would be active confinement. You would be ...
2
First of all, the body should always be in equilibrium. This means that the load applied by the support on the body should be equal but in the opposite direction to that what is applied to the body by you. Opposite is important, not the sign or direction. You can assign upwards as positive or downwards as positive, it doesn't matter. If you apply (+) load, ...
3
The way I manage these types of problems in my head (as an engineer that likes math) is the following:
At
$x= 0^-$ the shear force is 0
$x= 0^+$ the shear force is -W
$x=0$ is a singularity point and both and none are strictly correct
Where the notation
$a^-$ is for a number close to $a$ approaching from minus infinity.
$a^+$ is for a number close to $a$ ...
2
Ductility-- of the ball, the race, and the cone-- is indeed a key to the ball not cracking. My experience with bicycle bearings is of having the ball, the race, or the cone show some pitting, and/or for the race to show spalling or cracking. Usually during a repack I found that the balls were in flawless condition. From all this I came to the belief that (a) ...
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