Skip to Main content Skip to Navigation
Conference papers

LOCAL EVALUATION OF THE HARDENING LAW OF A MATERIAL THROUGH SPHERICAL INDENTATION: DEFINITION OF AN AVERAGE REPRESENTATIVE STRAIN AND A CONFIDENCE DOMAIN

Abstract : The indentation test is widely used for the determination of the stress-strain curve of materials. One of the advantages of this technique is that it is local and can be applied to materials in some conditions for which the classic tensile test cannot be done. One of the disadvantages of the indentation test is that the field of strain in the deformed sample is not homogenous which makes it difficult to identify the hardening law of the material from an indentation curve. The application of the concept of the representative strain can significantly simplify the analysis of the indentation response and has often been used in the stress-strain curve determination from the indentation test. In the present work, a new method based on the definition of an "average representative strain", εaR, is developed for the determination of the hardening law using the load displacement curve, F-h, of a spherical indentation test. This method consists to calculate the error between an experimental indentation curve and a number of FE simulation curves. For the smaller values of these errors, the error distribution shape is a valley, which is defined with an analytical equation. In the bottom of the valley, all the stress-strain curves that intersect at a point of abscissa εaR lead to very similar indentation curves. Thus, the average representative strain indicates the part of the hardening law that is identified with the highest precision for a given penetration depth. Hence, considering multiple penetration depths, several values of εaR are determined. The hardening law is precisely constructed using these values of εaR and their corresponding values of stresses, σaR . This way, no assumption on the mathematical form of the hardening law of the studied material is made. Since the indentation test is local, material heterogeneity lead to different indentation curves for the same material and under the same conditions. The proposed method leads to the determination of a "confidence domain" that takes into account the experimental imprecision and the material heterogeneity using several indentation curves. The results obtained for a 20MnB5 steel alloy show that the identified hardening law (and confidence domain) is in agreement with the tensile test curve
Document type :
Conference papers
Complete list of metadatas

https://hal-univ-rennes1.archives-ouvertes.fr/hal-00994658
Contributor : Olivier Bartier <>
Submitted on : Wednesday, May 21, 2014 - 6:48:31 PM
Last modification on : Monday, January 20, 2020 - 2:44:02 PM

Identifiers

  • HAL Id : hal-00994658, version 1

Citation

Charbel Moussa, Xavier Hernot, Olivier Bartier, Gerard Mauvoisin, Guillaume Delattre. LOCAL EVALUATION OF THE HARDENING LAW OF A MATERIAL THROUGH SPHERICAL INDENTATION: DEFINITION OF AN AVERAGE REPRESENTATIVE STRAIN AND A CONFIDENCE DOMAIN. 10th International Conference of Local Mechanical Properties, Nov 2013, Kutna Hora, Czech Republic. ⟨hal-00994658⟩

Share

Metrics

Record views

65