Creation of a stress-strain curve for FE analysis with the Ramberg-Osgood Equation
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- Опубліковано 9 вер 2024
- Ramberg-Osgood Equation - Describes the nonlinear relationship between stress and strain. It is special applicable to metals that harden under plastic deformation.
This relationship was proposed to describe the stress-strain curve using three parameters by Walter Ramberg and William R. Osgood from National Advisory Committee for Aeronautics, 1943.
Excel tool to create a stress-strain curve:
docs.google.co...
References
- Ramberg, W., & Osgood, W. R. (1943). Description of stress-strain curves by three parameters. Technical Note No. 902, National Advisory Committee For Aeronautics, Washington DC; ntrs.nasa.gov/...
- Getting Started with ABAQUS 10.2 Plasticity in ductile metals
Master Andrea, sincerely grateful to you. Few people share information, but you, for example, share. Thank you.
Thank you so much!
Master Andrea, I congratulate you for the tutorial and the explanation in this one. Please, can you tell me that, once I do the stress-strain curve approximation: Ramber-Osgood, what value I should take as a coefficient since I define the value of n (exponent) prior to analyzing the curve.
Excuse me, I clarify, these data, n-exponent and K-coefficient, are taken in the offpipe and orca flex programs. I want to know, if you guide me, on the graph, what coefficient value I should take.
Hi Alcides Garcia,
in OrcaFlex the relationship between stress and strain can be specified using either Ramberg-Osgood or a stress-strain table.
You can use my Excel tool to define the stress-strain table or you can convert to Ramberg-Osgood using the parameters K and n (K, n - constants that depend on the material).
For K, n you need two equations. Example S355, two points from the curve:
Point 1 with stress = 355 and strain_eng=0.00369
Point 2 with stress = 470; strain_eng = 0.2
Formula [1] from point 1: 0.00369 = 355/210000 + K*(355/210000)^n
Formula [1] from point 2: 0.2 = 470/210000 + K*(470/210000)^n
Isolate K and solve n >>> n = ln 0.01011 / ln 0.7553191 = 16.37089
then with formula from point 1 or point 2 >>> K = 4.79731E+42
After you can then compare curves - for further details see Excel:
docs.google.com/spreadsheets/d/1RVna6O0ZFjtK8PN_rqyjKN34XVOzXWAs/edit?usp=sharing&ouid=106721331533058990532&rtpof=true&sd=true