tensions and loads in the tree under conditions of non-balance

[alequatt]

Good evening to all, in the courses of ing. mechanical stresses and distributions of loads are studied for usually isostatic or hyperstatic structures. When we talk, for example, of a rotational shaft with angular acceleration, nothing like the speech of tensions and loads? we take for example a moment of inertia tree compared to its negligible rotation axis. If at this tree I imprison a couple c, instinctively I think that there is no load nor inertia to win, the state of tension due to the couple is null. Is it correct, instead, if at the extreme opposite to which the couple is applied there is a j inertia to win what happens? Are tangential tensions due to the couple as in equilibrium conditions? or these tensions are proportional to the j to be won? of course I neglected the weight of the shaft and the reactions of the bearings, not that the tensions due to vibration and centrifugal force.
thanks for the attention.

 

[Stan9411]

Well I would say you make a somewhat unrealistic example .... I stick a pair to a tree because I expect that along the tree there are one or more couples whose combination is exactly the same and contrary to the pair I am applying. therefore at the end the state of torsion stress to which the tree is subjected is always uniformly distributed from the point of application of the drive to the point of application of the resistant torque.

n.b: the strong couple can be very inertial (accelerating a flywheel. . )

 

[alequatt]

the condition that you describe is of balance, I speak of the transient to get there. where the resulting pair is different from zero. I was interested in knowing what torque value to use for the calculation of torque tensions in that situation.

 

[Stan9411]

excuse me... but in the universe the resulting torque is always zero ... transitory or balance that both power balances are always valid .. or win a load at constant speed or accelerate an inertia, but at the other end of the tree you are still downloading all the torque that you erode ... otherwise the torque where it goes? according to principle of dynamic

 

[Stan9411]

net of friction

 

[alequatt]

You're perfectly right, a resumption of applied mechanics would only do me well. Thanks for the answers.

 

[Stan9411]

Don't worry.
I read now that you're a student. my mechanical prof applied to the machines always told us that, even if you really don't remember a c*zzo of how the dynamics of the systems work, starting from f=m*a is always a good start

 

[alequatt]

banally I didn't consider the product \[ J\alpha \] like the inertial couple.

 

[meccanicamg]

as my colleagues told you the contribution on a tree can be due to a mechanical context, friction or simply acceleration of an inertial mass. in the practical field, the machines that have behaved fast and must have high impact strength are studied in two conditions: maximum force to be applied and maximum acceleration of position. then overlap the effects according to the phase of operations.