Linear to True Stress-Strain

The following analysis produces an estimated local stress and strain from an elastic point stress using Neuber, Glinka, and Unified Expression methods. This is useful in predicting a peak stress and strain in a high gradient area from a linear finite element (FE) analysis. This method allows an estimate of an true stress and strain at a stress concentration without having to run a material nonlinear FE analysis.

  • Used for calculating effect stress concentration factors in notches - inelastic strains

  • Uses Neuber (upper bound), Glinka (lower bound), and Unified Expression methods

  • Iterative method solves for true stress using Newton's method

  • True stress is calculated using a modified Ramberg-Osgood equation

Point Stress and Material Properties Inputs


Unit System: /

Three-dimensional Stress State






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Neuber Method

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Glinka Method

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Unified Expression Method

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References

Primary References - Neuber and Glinka Methods

Neuber, H. (1961). Theory of Stress Concentration for Shear-Strained Prismatical Bodies With Arbitrary Nonlinear Stress-Strain Law. Journal of Applied Mechanics, 28(4), 544-550. [Original development of Neuber's rule]

Molski, K., & Glinka, G. (1981). A Method of Elastic-Plastic Stress and Strain Calculation at a Notch Root. Materials Science and Engineering, 50(1), 93-100. [Original Glinka equivalent strain energy density (ESED) method]

Glinka, G. (1985). Energy Density Approach to Calculation of Inelastic Strain-Stress Near Notches and Cracks. Engineering Fracture Mechanics, 22(3), 485-508. [Extended development of ESED method for cracks]

Textbooks and General References

Dowling, N. E. (2013). Mechanical Behavior of Materials: Engineering Methods for Deformation, Fracture, and Fatigue (4th ed.). Pearson Education, Upper Saddle River, NJ. [Comprehensive coverage of Neuber and Glinka methods with practical examples]

Stephens, R. I., Fatemi, A., Stephens, R. R., & Fuchs, H. O. (2001). Metal Fatigue in Engineering (2nd ed.). John Wiley & Sons, New York, NY. [Notch analysis and fatigue life prediction methods]

Bannantine, J. A., Comer, J. J., & Handrock, J. L. (1990). Fundamentals of Metal Fatigue Analysis. Prentice Hall, Englewood Cliffs, NJ. [Stress concentration and local strain approaches]

Unified Expression Method

Ye, D., Hertel, O., & Vormwald, M. (2008). A Unified Expression of Elastic-Plastic Notch Stress-Strain Calculation in Bodies Subjected to Multiaxial Cyclic Loading. International Journal of Solids and Structures, 45(24), 6177-6189. [Unified expression with alpha parameter generalizing Neuber and Glinka methods based on thermodynamic analysis; achieves <5% error vs. FEA]

Comparative Studies and Applications

Hoffman, M., & Seeger, T. (1985). A Generalized Method for Estimating Multiaxial Elastic-Plastic Notch Stresses and Strains, Part 1: Theory. Journal of Engineering Materials and Technology, 107(4), 250-254. [Extension of Neuber and Glinka to multiaxial loading]

Moftakhar, A., Buczynski, A., & Glinka, G. (1995). Calculation of Elasto-Plastic Strains and Stresses in Notches Under Multiaxial Loading. International Journal of Fracture, 70(4), 357-373. [Multiaxial extensions of ESED method]

Ramberg-Osgood Material Model

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. [Original Ramberg-Osgood formulation]

Metallic Materials Properties Development and Standardization (MMPDS) (Current Edition). Metallic Materials Properties Development and Standardization. Battelle Memorial Institute, Columbus, OH. [Material property data including Ramberg-Osgood parameters]

Finite Element Implementation

Conle, A., & Chu, C. C. (1997). Fatigue Analysis and the Local Stress-Strain Approach in Complex Vehicular Structures. International Journal of Fatigue, 19(1), S317-S323. [FEA post-processing with Neuber/Glinka methods]

Amstutz, B. E., Kardomateas, G. A., & Taggart, D. G. (1997). Further Investigation of Neuber's Rule and the Equivalent Strain Energy Density (ESED) Method. International Journal of Fatigue, 19(8-9), 721-727. [Comparative accuracy study]


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