# Re: 300% Modulus

• posted

Perhaps they are talking about elongation?

I've been reading about rubber lately and have run across data for "300% > modulus" frequently. What is this? If I'm not mistaken, where rubber is > concerned the shear modulus is typically somewhere around 1/3 of Young's > modulus. Is there a connection there or does this 300% modulus refer to > something else? > > Thanks! > > Todd Wasson > Racing Software >
My car sim >
• posted

Could it be the secant or tangent modulus at 300% elongation?

• posted

• posted

Youngs (tensile) modulus can be described as the pressure to extend a section 100% so that it ends up twice as long as it started. For many materials, this is a theoretical construct, because they waist and or fracture between 1 and 5% elongation. For rubber however, it is entirely conservative, because some rubbers can extend to 7X their starting length.

Brian Whatcott Altus OK

• posted

Thanks for your responses, everyone. I'm working on an RC car simulator for Serpent Model Cars and due to a lack of tire test data, I'm trying a different approach for a new tire model. The tires are foam rubber, very high friction coefficient, and I've found some formulae that theoretically give friction coefficient of soft, deformable materials given Young's modulus and surface roughness, which is fantastic because we're trying to find how stiffness and grip should change given different shore ratings. I've also read that Young's modulus isn't what you really want to be dealing with when it comes to rubber. Seems that different sources have different thinking on this subject.. Surprise surprise...

Just to make sure I'm understanding this correctly: Young's modulus (and shear modulus too, I presume, which is important for this too) are not constant, but instead change with deformation, right?

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Wasson Racing Software

• posted

Great, thanks Mr. Whatcott.

Todd Wasson Racing Software