Properties of materials like rubber bands

[shk]

Homework Statement

The question has been attached here .

Relevant Equations

The question does not need any equations. It requires to know some definitions.
For example:
Rubber bands provide an interesting contrast to springs. On stretching, they do not obey Hooke’s law very precisely. On unloading, they show hysteresis.

I appreciate some helps with this question.
I understand that soft noodles is not as strong as calamari squid and breaks easily . I also know that that calamari squid does not have elastic behaviour since behaves like rubber band and it goes back to it's original shape after reloading. But I'm still very confused about answering this question.

 

[berkeman]

Rubber bands provide an interesting contrast to springs. On stretching, they do not obey Hooke’s law very precisely. On unloading, they show hysteresis.

I think you are on the right track with this statement. Can you say more about how the behavior of rubber bands is different from springs? Also, chewing squid is a compressive motion -- does rubber also behave differently from metal springs in the compression direction? How so?

 

[Merlin3189]

That's an "interesting" question!
I think I'd use a diagram (a graph) to help me. You can use a lot of the "correct technical terms" by labelling.

 

[shk]

That's an "interesting" question!
I think I'd use a diagram (a graph) to help me. You can use a lot of the "correct technical terms" by labelling.

Thank you for the reply.
I understand how the force extention graphs for rubber band and spring are.
I've attached them here.
I know that reloading spring is different before and after it passes the linear part.
But I cannot still answer the question.

 

[berkeman]

You are still not addressing the question. Contrast the compressive properties of rubber versus metal springs. Please do that now.

Also, the question asks about a material that is not springy at all. What are your thoughts about that part?

 

[shk]

You are still not addressing the question. Contrast the compressive properties of rubber versus metal springs. Please do that now.

Also, the question asks about a material that is not springy at all. What are your thoughts about that part?

View attachment 274251

In this question we need to compare calamari squid with soft noodles.
Calamari behaves like rubber band so after chewing and let's say reloading, it will come back to its original shape , unless the pressure from chewing is a lot and exceeds a certain point so it breaks.
Soft noodles behaves very similarly but that limit is much lower so it breaks with a very smaller force.
This is all I can say.

 

[berkeman]

In this question we need to compare calamari squid with soft noodles.
Calamari behaves like rubber band so after chewing and let's say reloading, it will come back to its original shape , unless the pressure from chewing is a lot and exceeds a certain point so it breaks.
Soft noodles behaves very similarly but that limit is much lower so it breaks with a very smaller force.
This is all I can say.

That works for me. All that you need to add for the problem is some analysis using technical terms. What can you say about any Stress/Strain analysis of the noodles versus rubber bands or squid? The noodles break down with a lot less force, no?

 

[shk]

That works for me. All that you need to add for the problem is some analysis using technical terms. What can you say about any Stress/Strain analysis of the noodles versus rubber bands or squid? The noodles break down with a lot less force, no?

I would say the noodles break with a lot less force which means the stress strain graph is much lower . For both graphs we have the same shape that we have for rubber band which is a none linear graph. I've attached the loading reloading graph for you. Both soft noodles and calamari squid have similar shape graph as rubber band.
Am I correct ?

 

[haruspex]

For both graphs we have the same shape that we have for rubber band

For the calamari, that is sort of right, but you are supposed to be considering biting into it, not pulling it, so the axis should be compression, not extension. Also, it is important to show the failure trajectory, where the bite does irreparable damage to the morsel. What happens to the resistive force in this case?

For the soft noodles, one key difference is that the elastic range is so short as to be almost nonexistent. Another is how the resistance varies (or doesn't) once plastic phase is reached.

 

[shk]

Thanks for the reply. Do you think what I'd said about the graphs was ok then ?
in the terms of failure trajectory, I would say that the Calamari has more plastic deformation in compare with soft noodles. not sure what else I can say.
I'm not sure what you mean but resistive force though. I think I only need to compare the properties of these and say which is for example tough or whatever else.
I appreciate it if you can help a bit more.

I'm still not sure how to answer this question .

 

[haruspex]

Thanks for the reply. Do you think what I'd said about the graphs was ok then ?
in the terms of failure trajectory, I would say that the Calamari has more plastic deformation in compare with soft noodles. not sure what else I can say.
I'm not sure what you mean but resistive force though. I think I only need to compare the properties of these and say which is for example tough or whatever else.
I appreciate it if you can help a bit more.

I'm still not sure how to answer this question .

I'd need to see your actual graphs to comment on them.
The rubberiness of calamari means it has a greater elastic range of deformation.
But the other distinction I would make is in regards to what happens once it starts to yield. As you bite into calamari, does the resistance rise to a maximum and stay there? What about soft noodles?

 

[Delta2]

This thread opened my apetite. I am hungry now !

 

[shk]

I'd need to see your actual graphs to comment on them.
The rubberiness of calamari means it has a greater elastic range of deformation.
But the other distinction I would make is in regards to what happens once it starts to yield. As you bite into calamari, does the resistance rise to a maximum and stay there? What about soft noodles?

I think for the soft noodles , reaches to a maximum and then quickly breaks. for the calamari reaches to a maximum but it will still carry on deforming since it has plastic deformation. I am not very sure about the graphs though. I have attached what i think should be close.
I also need the answer for today please.
Thank you

 

[Merlin3189]

My comment that the question is "interesting" was based on the proverbial curse, "may you live in interesting times!" It is interesting, but rather like turbulence supposedly was for Einstein.

I do not know what the properties of soft noodles are, as I've never done the experiments. I did find someone had done a relevant(tongue in cheek?) experiment on pasta. Calamari is even less familiar, though I do have plenty of rubber bands to chew on.
So I can't really tell you what the properties of the materials are and, I think, whoever set the question probably did not expect you to have much more than a general notion about it yourself. What IMO they are looking for is your understanding of material properties and its nomenclature. So if you describe your relevant beliefs about calamari, noodles and perhaps rubber, either in words or in graphs, then apply the appropriate technical terms to show you understand what they mean, I think you'll succeed even with little accurate knowledge of the materials themselves.

 

[haruspex]

I think for the soft noodles , reaches to a maximum and then quickly breaks. for the calamari reaches to a maximum but it will still carry on deforming since it has plastic deformation. I am not very sure about the graphs though. I have attached what i think should be close.
I also need the answer for today please.
Thank you

I would have said the resistance from soft noodles quickly reaches a (low) maximum and stays there. Its deformation is plastic almost from the start, so the force it exerts on your teeth drops to zero as soon as you stop biting.
The calamari has a much longer elastic phase, but once your teeth have started to go through it I believe it will break quite quickly, the resistance falling away.

 

[shk]

I would have said the resistance from soft noodles quickly reaches a (low) maximum and stays there. Its deformation is plastic almost from the start, so the force it exerts on your teeth drops to zero as soon as you stop biting.
The calamari has a much longer elastic phase, but once your teeth have started to go through it I believe it will break quite quickly, the resistance falling away.

Thank you very much.
So in a few words I can say that the behaviour of soft noodles is plastic whereas the behaviour of Calamari is elastic. Plus calamari is strong but soft noodles are weak . Is this corect ? Or should I use other terms instead of strong and weak?

Can I also say

 

[haruspex]

Thank you very much.
So in a few words I can say that the behaviour of soft noodles is plastic whereas the behaviour of Calamari is elastic. Plus calamari is strong but soft noodles are weak . Is this corect ? Or should I use other terms instead of strong and weak?

Can I also say

That is all reasonable.

 

[shk]

That is all reasonable.

Thank you very much.
You have been very patient with me and answered all my questions.
I think I now understand this question very well.