Moment for bending materials test

[scotty03]

Homework Statement

I have to do the following practical, but I am unsure of how to calculate one of the variables.

We are doing this test

and we are given this information to calculate E.

I have equations on how to calculate R and I, but I am not sure how to calculate M. It's obviously something to do with the mass of the weights on the end and the distance from them, but this information isn't included in the prac sheet.

Does anyone have any ideas?

 

[pongo38]

In the 400 mm length, M is constant. Are you able to calculate the reactions, where the little triangles are?

 

[scotty03]

They both = W from sum of forces in Y direction.

The idea of the test was to see how much the material deflected upwards in the middle. I am just not sure if the applied moment is W*100mm or W*100mm*2 or W*300 or W*300*2

 

[pongo38]

One definition of Moment at a section is: The sum of the moments on one side (or the other) of the section. So, at the point of application of the load at the end, you should find the moment is zero. In the central section it is W*300. You should check this by considering a section distance x from the left hand support, going to the right.

 

[rezeew]

Thank you for sharing your question with us. The moment for bending materials test is an important practical that helps us understand the behavior of materials under different loads. In order to calculate the value of E, or Young's modulus, we need to have accurate values for the variables R, I, and M. As you mentioned, R and I can be calculated using specific equations, but M is a bit more complex.

In order to calculate M, we need to know the distance from the weights to the center of the material being tested, as well as the mass of the weights themselves. This information may not be explicitly stated in the practical sheet, but it is important to have in order to accurately calculate E.

One way to determine the distance from the weights to the center of the material is to measure it directly using a ruler or measuring tape. As for the mass of the weights, you can either weigh them using a scale or refer to the manufacturer's specifications if they are pre-made weights.

Once you have all the necessary information, you can use the equation M = Fd, where F is the force applied by the weights and d is the distance from the weights to the center of the material. With this value for M, you can then proceed to calculate E using the equation E = (F*L^3)/(4*W*I), where L is the length of the material being tested and W is the width.

I hope this helps clarify the process of calculating E for your bending materials test. It is always important to have accurate and complete information in order to obtain reliable results in any scientific experiment. If you have any further questions, please do not hesitate to ask. Good luck with your practical!