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## 29 thoughts on “HOMEWORK H29.A”

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When calculating the shear stress, does the sign of the torque matter or is it only the magnitude of the torque that determines the stress?

I don't think the sign of the torque matters when calculating the shear stress because the tau_max is a scalar quantity so you just want the magnitude.

However, when finding the torque that you need to use in that shear stress equation, it's important to recognize that the applied torques are opposite signs when calculating the internal reactions for member 1.

Good explanation, Zach

For part B, I calculated the shear stress for segment 1 and 2 and found the max between the two. My questions is, does this shear stress act on the whole segment or will the most likely to shear off at a point (like B or A)?

The shear stress would act on the whole segment but I am not sure what happens at the ends of the segment (like B or A)

I think the assumption is that the connector won't fail, which means that the segments will stay connected at B and A. So, individual segments will shear off.

So, for the "location of the maximum stress", you can say the outer surface of either component 1 or component 2 based on what you get.

Since the torques at acting at points along the shaft, the shear stress along each segment will be constant, so I think the shaft would be most likely to shear off at any point on the segment.

Good question, Jessika. The shear stress is acting on the segment. As far as I understand, that means that the segment could shear off at some point in the middle of that segment instead of points such as A and B.

Since point B is a rigid connector, does that mean there will be a reaction torque on the shaft due to that connector?

You can consider the external torques to be acting on the connector. Then the torque on the shafts could be interpreted as the reaction torque due to the connectors.

I find it easier to separate out each segments with the reaction forces for future calculations

You will have to consider the reaction forces on the other shaft and like sum or substract depending on which one to find the net torque on that one.

Do we need to include units in our answers?

Since no units are mentioned anywhere in the problem statement, I'm pretty sure that no units are expected in our answers.

No units are required as you have to leave your answer in terms of T and d

Would the sheer stress act along a member up until a rigid connector or would it also include the connector?

You are only calculating the shear stress on the shaft. So it won't include the connectors.

I'm working on finding the max shear stress and am confused on if I need to take into account the ends of each segment piece?

I think finding the max shear stress only needs to compare the shear stress of two members and decide the max one.

Bowen is right

We do not consider C to be another connector right? it will only have the torque given in the problem right?

I believe so. If I have understood your question correctly, the torque at C would just be T.

Do we have to find the torque at the fixed support?

I think so. What I did was found the torque at each end (CB and BA - both sides) and then found the torque load on each component

Are we gonna find torque ilustrated as a double arrow all the time? and do signs matter on torque or is it an absolute value?

The signs do matter when describing the amount of torque on each segment. However, when the shear stress is calculated, you use the absolute value, so the sign would not matter there.

This is such an easy mistake that I've made in the past, thank you for the clarification!

Thank you for the help on this problem!