- #1

richard9678

- 79

- 4

I understand that if you glue together two pieces of a bar together at an incline, and apply an axial tensile force (normal) to the bar, that as far as the layer of glue is concerned, the force applied to it is partly normal (normal to the surface of the glue layer) and shear (perpendicular to the normal force).

Okay, now let's just consider a bar that is perfectly homogeneous and prismatic. Are there any shear forces within the bar? I know bars often fracture at an angle, that is, not exactly perpendicular to the length of the bar, but in a perfect bar there should be no shear forces inside the bar, at least that is what I understand.

But I read "To obtain a complete picture of the stresses in a bar, we must consider the stresses acting on an "inclined" (as opposed to a "normal") section of the bar". That sort of seems to hint that even in a perfect bar there are shear forces. But, that seems contrary to what I've previously believed.

So, are there only normal stresses in a bar that is only subject to normal stress? Just a plain straight bar. Not glued together or whatever. Thanks.

P.S. Only if there is some defect in a bar, can I imagine a shearing stress. in a straight bar entirely under uniaxial normal stress.

Okay, now let's just consider a bar that is perfectly homogeneous and prismatic. Are there any shear forces within the bar? I know bars often fracture at an angle, that is, not exactly perpendicular to the length of the bar, but in a perfect bar there should be no shear forces inside the bar, at least that is what I understand.

But I read "To obtain a complete picture of the stresses in a bar, we must consider the stresses acting on an "inclined" (as opposed to a "normal") section of the bar". That sort of seems to hint that even in a perfect bar there are shear forces. But, that seems contrary to what I've previously believed.

So, are there only normal stresses in a bar that is only subject to normal stress? Just a plain straight bar. Not glued together or whatever. Thanks.

P.S. Only if there is some defect in a bar, can I imagine a shearing stress. in a straight bar entirely under uniaxial normal stress.

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