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LosAngeles
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| Posted: 13 November 2006 at 11:04am | IP Logged
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Hi people,
How can I assign hardness to material in Pro Mechanica?
What can i set are young's modulus are poisson's ratio.
Are those enough?
Thanks
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LosAngeles
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| Posted: 13 November 2006 at 12:58pm | IP Logged
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What is the relation between hardness and young's modulus?
Can i use young's modulus for part that works under pressing?
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MichailS
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| Posted: 13 November 2006 at 1:18pm | IP Logged
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You are asking a bit too wide. A bit like "How do I write in french?"
The relationship between stiffness and hardness is complex and it doesn't help that nobody ever really made a good definition of what "hardness" really is. They're all a bunch of made-up scales of how deep some object will go into another given some certain force.
Hardness is really dependant on stiffness, strength AND ductility, so it is no mean feat to find a good representation.
What is it that you are trying to compute?
Edited by MichailS on 13 November 2006 at 1:19pm
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LosAngeles
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| Posted: 13 November 2006 at 1:24pm | IP Logged
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I am trying simulate human's foot. I fix heel and apply force to toe.
I need to minimize localized stresses by varying hardness of components.
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MichailS
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| Posted: 14 November 2006 at 4:06am | IP Logged
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If it is bone vs. flesh you are modeling, then it is the stiffness (Young's modulus) you need to change rather than hardness (Rockwell, Vickers, etc).
Poissons ratio should be about 0.3 for crystalline materials, but I have no idea what it should be for a bag of water like flesh. 1.0 sounds right but I don't know really.
Flesh is viscoelastic, so you ought to compare it to some sort of soft rubber. Incidentally, rubber also has a "hardness" index named Shore.
You can find a lot of material data on www.efunda.com and www.matweb.com .
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Israr
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| Posted: 14 November 2006 at 5:37am | IP Logged
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You can change or assign hardness properties by editing material inside Mechanica in Wildfire 3.0
Israr
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paoloz
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| Posted: 14 November 2006 at 8:18am | IP Logged
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1- Poisson ratio cannot be greater than 0.5 (rubber is about 0.49);
2- Hardness has a rude relation with Ultimate tensile strength for steel. I don't know for bones;
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LosAngeles
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| Posted: 14 November 2006 at 12:02pm | IP Logged
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I am trying to model foot as beam which made of some kind of plastic (nylon, polyurethane).
I tried to set hardness in ProMech 3.0 but it is likely to has no influence to my model.
So, i will vary young's modulus.
Thanks to all!
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Topic: How can I vary hardness for material?
