Turn off Nonlinear effect in linear elastic analysis?
Turn off Nonlinear effect in linear elastic analysis?
(OP)
Dear members,
I use Ansys for Elastic analysis of a part according to ASME VIII-2 Part5 and i have 2 questions:
1- Should i turn of "Nonlinear effects" in Geometry material properties or it automatically use linear analysis if we didn't assign a nonlinear properties (such as Tangent modulus) to the material's specification?
2- As you know, CONTACTS convert our analysis to nonlinear. Is there any problem to use contacts in Elastic Analysis and make Stress linearization according to part5?
Thanks.
I use Ansys for Elastic analysis of a part according to ASME VIII-2 Part5 and i have 2 questions:
1- Should i turn of "Nonlinear effects" in Geometry material properties or it automatically use linear analysis if we didn't assign a nonlinear properties (such as Tangent modulus) to the material's specification?
2- As you know, CONTACTS convert our analysis to nonlinear. Is there any problem to use contacts in Elastic Analysis and make Stress linearization according to part5?
Thanks.





RE: Turn off Nonlinear effect in linear elastic analysis?
But it may have changed now. As far as nonlinear material goes I do not think you can use it in linear analysis.
It will simply take the slope of the first part of the curve and go along that curve.
It is very uncommon in aerospace in general to use a nonlinear material, we prefer to be in the linear part.
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RE: Turn off Nonlinear effect in linear elastic analysis?
RE: Turn off Nonlinear effect in linear elastic analysis?
Maybe it was better to post it in ASME forum.
Regards
RE: Turn off Nonlinear effect in linear elastic analysis?
RE: Turn off Nonlinear effect in linear elastic analysis?
a) A stress-strain plot that is NOT a straight line within the elastic limit does NOT automatically mean the stress-strain relationship is NONLINEAR. A straight line is only a special case of linearity.
Nonlinearity has a precise mathematical meaning in that if the superposition principle does NOT apply, then the mapping is nonlinear. So, for instance, if a AND b both are solutions to a linear differential equation, then a (linear) combination of a and b is also a solution to the said differential equation.
b) Nonlinearity does NOT arise only by material relationship being nonlinear. There are multiple sources of nonlinearity (large deformation, contact, and large rotation).
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RE: Turn off Nonlinear effect in linear elastic analysis?
Can you provide a practical example where the superposition principle does apply for materials that have a stress-strain relationship that is not a straight line?
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: Turn off Nonlinear effect in linear elastic analysis?
Are you new to this forum? If so, please read these FAQ:
http://www.eng-tips.com/faqs.cfm?fid=376
http://www.eng-tips.com/faqs.cfm?fid=1083
RE: Turn off Nonlinear effect in linear elastic analysis?
Are you just saying that parts of a non-straight stress-strain relationship can be straight over a limited range?
If not, can you give more details.
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: Turn off Nonlinear effect in linear elastic analysis?
Are you new to this forum? If so, please read these FAQ:
http://www.eng-tips.com/faqs.cfm?fid=376
http://www.eng-tips.com/faqs.cfm?fid=1083
RE: Turn off Nonlinear effect in linear elastic analysis?
Can you give us an example or two?
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: Turn off Nonlinear effect in linear elastic analysis?
Are you new to this forum? If so, please read these FAQ:
http://www.eng-tips.com/faqs.cfm?fid=376
http://www.eng-tips.com/faqs.cfm?fid=1083
RE: Turn off Nonlinear effect in linear elastic analysis?
I am trying to understand what your point is, and I was hoping that a technical paper might make it clear, with some examples of how non-linear stress-strain behaviours combine in a linear way, other than as a rough approximation.
Or perhaps you just mean that assuming linear behaviour can often be a useful approximation to highly non-linear behaviour, which (I hope) no-one would dispute.
At the moment, I just don't know.
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: Turn off Nonlinear effect in linear elastic analysis?
To be sure, I believe we are in agreement.
Are you new to this forum? If so, please read these FAQ:
http://www.eng-tips.com/faqs.cfm?fid=376
http://www.eng-tips.com/faqs.cfm?fid=1083
RE: Turn off Nonlinear effect in linear elastic analysis?
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/