How a material with hardness can be created in Creo/Simulte, is there any method?

[ptc-6722761]

Hi

I am involved in FE analysis of an assembly in which one of the component is made out of C45 hardened to 50 HRC, Now I struck with creating a material with hardness properties to it. I strongly feel this will have a strong effect on the results. Can anyone help me in fixingthis, is there anyway to define hardness to that component?

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[unickque]

You hardening is presumably done by heat treatment.

This only changes the material strength.

It does not change the Youngs modulus nor Poissons ratio.

Most of the time you will be doing elastic analyses in Creo, so the results are only affected by Youngs modulus and Poissons ratio. The resulting stress is then checked against yield stress (or ultimate stress, or fatigue strength) to see if your component is sufficiently strong to withstand the applied loadings.

So you probably do not need to do anything with hardness in your model. You just need to figure out what the strength is of your hardened material, so you can check if the calculated stresses are below allowed values.

Unless you are doing something special in your analysis...

[mlindqvist]

Pramodh,

As Patrick mentioned, hardening does not affect Young's modulus or Poisson's ration. But it does affect the non-linear portion of the stress-strain curve. The yield stress as well as ultimate tenisle strength usually becomes higher upon hardening, and the material becomes more brittle, i.e. the strain at which fracture occurs is smaller. Obviously a nonlinear analusis is required to capture the difference between hardened and non-hardened material. It might be a challenge if its a case hardened component, since the transition between the two material types is probably smooth. In addition, case hardening usually introduces residual stresses in the component, and this is a desired effect. Case hardening results in compressive residual stresses that are beneficial for the fatigue strenght of the component.

/Mats L

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[ptc-6722761]

Thanks for your replies!!

I am actually analyzing a fixture assembly in which I am interested to know how the fixture and its components behaves for the given load conditions, in doing so I have components that were hardened & also it comes in loading path. I feel the hardened part in loading path will have an effect. how to model this condition in Creo/Simulate.

[gkoch]

The material properties allow to define hardness, but it doesn't look as if it is used for calculation.

There is one article that says it has an effect on damping (which should be used with Mechanism) - maybe this is what you are looking for:

CS125269: Information on damping in 3D contacts for Mechanism in Creo Elements/Pro 5.0

[JonathanHodgson]

Compare your calculated stresses with the yield stress for the hardened material. If the stresses are below the yield stress, then a linear analysis is valid and increasing the hardness will make no difference.

If the stresses are above the yield stress, then either a) your parts will yield, and you could do an analysis with non-linear material to see the effects; or b) you should increase the hardness (or decrease the stresses) to make the yield higher than the stresses.

People often "feel" that hardness should influence the elastic behaviour (stiffness) of a steel, but it doesn't, certainly not at a macro level.

http://imechanica.org/node/2285

"There are no apparent changes in elastic modulus in metals that have undergone different hardening treatments"

Hardness varies with Young's Modulus, but YM does not change with hardness for a given material - "Elastic modulus is an intrinsic material property and fundamentally related to atomic bonding. Hardness is an engineering property and for some materials it can be related to yield strength."