Determining Plastic Properties of Material Through Instrumented Indentation Approach (original) (raw)
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Journal of Mechanical Engineering and Sciences, 2021
Instrumented indentation technique gives the possibility to determine the mechanical properties for small specimens and material in service. Several researchers have attempted to evaluate this approach experimentally and investigated the factors that affect it by using different indenter’s geometries for different engineering materials. In this work, the instrumented indentation technique was used to evaluate the mechanical properties experimentally and numerically using finite element simulation to understand the contact mechanics between the indenter surface and the substrate for two types of steel alloys namely ASTM516-G70 and AISI1010 steel. Two shapes of indenters, blunt (spherical) and sharp (Vickers) were used. The results were then compared with the experimental results extracted from the instrumented indentation test. The results have demonstrated a good agreement between the experimental and the finite element simulation results with error bound a ±5 % for young’s modulus ...
MATERIAL CHARACTERIZATION BASED ON INSTRUMENTED AND SIMULATED INDENTATION TESTS
This paper reviews various techniques to characterize material by interpreting load-displacement data from instrumented indentation tests. Scaling and dimensionless analysis was used to generalize the universal relationships between the characteristics of indentation curves and their material properties. The dimensionless functions were numerically calibrated via extensive finite element analysis. The interpretation of load-displacement curves from the established relationships was thus carried out by either solving higher order functions iteratively or employing neural networks. In this study, the advantages and disadvantages of these techniques are highlighted. Several issues in an instrumented indentation test such as friction, size effect and uniqueness of reverse analysis algorithms are discussed. In this study, a new reverse algorithm via neural network models to extract the mechanical properties by dual Berkovich and spherical indentation tests is introduced. The predicted material properties based on the proposed neural network models agree well with the numerical input data.
Acta Materialia, 2003
Indentation testing is a common method to assess the mechanical properties of materials near their surface. The elasto-plastic properties may be determined from the force penetration curves measured in indentation using inverse methods. In this spirit, Dao et al. [1] (Acta Materialia, 49, 2001) have established a forward and a reverse analysis for engineering metals using the equivalent conical indenter of the Berkovich and the Vickers pyramids, which has an included angle q of 70.3°. Extending Dao's approach, we studied, based on a finite element analysis on elasto-plastic materials, the influence of the included angle of conical indenters (q = 70.3, 60, 50 and 42.3°) and the friction coefficient on the force penetration curves. Based on this analysis, we suggest a more general method for determining the plastic properties of metals. The mechanical behaviour is modeled with the Young's modulus, E, the yield strength, s y , and the strain hardening exponent, n. We have shown that friction has a significant effect on the normal force measured on tips having included angles lower or equal to 50°. We have constructed, for each indenter geometry, a dimensionless function relating the characteristic parameters of the loading curve in indentation to the elasto-plastic parameters of metals. These functions have been generalized for any included angle. We show that the use of a second indenter with an included angle lower than q = 70.3°allows us to determine the strain hardening exponent with greater accuracy. Moreover, the sharper the indenter, the better the accuracy.
International Journal of Materials, Mechanics and Manufacturing
The deformation of spot welded joints is challenging research problem due to the complex nature of the structure. One major problem is to characterize the materials properties. The elastic-plastic material parameters and the fracture parameters of materials can be readily determined when standard specimens are available, however, for a spot welded joint, standard testing is not applicable to characterize the HAZ and nugget due to their complex structure and small size. This has opened up the possibility to characterize the material properties based a dual indenter method to inversely characterize the parameters of the constitutive material laws for the nugget, HAZ and the base metals. In numerical-experimental approach Finite Element (FE) model which simulates the geometry and boundary conditions of the experiment using input data load and displacement experiment results. With indentation tests, the local plastic properties can be calculated by solving the inverse problem via finite element analysis by incrementally varying properties in 3D modeling to find a similar simulated load-displacement curve as compared with experimental one. The approach will then be used to test different welding zones and the material parameters thus predicted used to simulate the deformation of spot welded joints under complex loading conditions including tensile shear and drop weight impact tests.
Experimental Mechanics, 2006
In this article, we focus our attention on the relation between instrumented indentation tests and the prediction by means of finite element calculations. To this end, a finite strain viscoplasticity model of Perzyna-type with non-linear isotropic and kinematic hardening is calibrated at experimental data of steel S690QL. A particular concept for conducting uniaxial tensile and compression tests is taken up in order to represent the basic rate-dependent material behavior. In this respect, an algorithmic framework of material parameter identification using finite elements is proposed leading to a two-stage procedure in the case of the underlying rate-dependent constitutive model. On the basis of the termination points of relaxation the rate-independent equilibrium stress state can be identified and all viscous parts of the model are obtained using rate-dependent loading paths. Finally, use is made of finite elements for predicting indentation experiments, which results in a critical view on modeling and parameter identification on the basis of experimental results occurring in instrumented indentation tests.
2019
A new technique that can determine the elastic-plastic properties of metallic materials using an instrumented indentation testing and iterative finite element (FE) simulations is proposed. This non-destructive technique can be applied to isotropic, additively manufactured, and/or surface treated metallic components of various scale. Currently, the measurement of material properties using the instrumented microor nanoindentation test is limited to the elastic modulus and surface hardness. A number of experimental and numerical approaches have been suggested for prediction of monotonic properties of metallic materials including yield strength, strain hardening parameters, ultimate strength, and fracture toughness. However, the past efforts to measure the stress-strain behavior using a single instrumented indentation test were not successful because there is no straightforward correlation between forcedisplacement relation and the elastic-plastic relation. In this study, both experimen...
Mechanical testing shows an important role in finding the fundamental properties of engineering materials as well as in generating new materials and in managing the quality of materials for use in design and construction. If a material is used as a part of an engineering structure, it is important to know that the material is strong and rigid enough to overcome the loads that it will experience in service. As a result, engineers have developed a number of experimental techniques for mechanical testing of engineering materials. Instrumented indentation test is one of them. It is introduced as a method that finds hardness, modulus of elasticity, yield stress and extracted the stress-strain curve, instead of traditional tensile test. Whereas it gives a possibility to determine the mechanical properties for small specimens, and material under operation in the field. Several researchers have attempted to evaluate this method experimentally and to investigate the factors affecting it by using different shape of indenters. In the same regard, this research work is conducted to evaluate by finite element simulation methods. One type of industrially significant steel was selected; it is namely AISI1010 steel; and two shapes of indenters, blunt and sharp (Spherical, and Vickers) were used. The finite element simulation has been performed by the finite element ABAQUS simulation program, and its results were then compared with the experimental test results that extracted from Nanovea instrumented indentation test machine. The results obtained have demonstrated that good agreement between the experimental and the finite element simulation results within 5 % difference for young's module and 2.3 % for yield strength. Whereas excellent agreement is observed at the elastic region and the beginning of the plastic region for engineering stress-strain curve. Finally, it is to be emphasized that the obtained results are more applicable for the tested materials, and further research is recommended to accommodate other materials as well and to confirm the generality of this method.
2019
In this paper, a methodology, for calculating the stress level of monotonic plastically pre-hardened materials, using the instrumented indentation technique (IIT) coupled to the inverse analysis technique (IAT) is presented. In this methodology, the Voce work-hardening law is always considered as the work hardening law of the studied material. This methodology has shown a very good efficiency in determining the stress levels and the plastic strains undergone by two pre-hardened pseudo-materials. That was encouraging for applying this methodology on real metal sheets. Three metal sheets were studied (DC01 and DP600 steels and aluminum alloy 2017). In the case of the as-received sheets, the identified laws show precise results for plastic strains between 3 % and 6 % which correspond approximately to the representative strain in the case of spherical indentation. Tensile samples were then pre-hardened by imposing a monotonic plastic strain. Three levels of plastic pre-strains were impo...
Procedia Manufacturing, 2015
Significantly advantage in the use of indentation testing its use for the characterization of materials is simple and requires only a small sample. In material characterization by indentation, the material behaviour is represented by the load (P)-depth (h) in the P-h curve. However, despite the breadth of use of indentation in the evaluation of the behaviour of the material has not been able to explicitly relate the behaviour of materials with constitutive material properties. This encourages further research to be able to predict the P-h curves and hardness and indentation resistance of the constitutive parameters of the material, it is also very important for research and practical use to explore the potential for using indentation data for predicting the constitutive properties of a material. This could potentially provide a faster way for identification of material parameters and applied in situations where a standard specimen is not available. In this research, the relationship between the constitutive parameters of the material (represented by the yield stress (σy) and work hardening coefficient (n)) of elasto-plastic materials, Indentation P-h curve, and Hardness value with dual indenters have been systematically investigated by combining the representative stress (σr) analysis and FE modelling using steel as a system materials. FE model of Vickers and Spherical indentation has been developed and validated. Validation conducted on the feasibility of the FE models to investigate approaches to the material system, and establishing factors affecting the accuracy and robustness of the approach finite element programs used. A new approach for predicting the hardness values are developed based on the 3D relationship between hardness, yield stress (σy) and strain hardening coefficient (n). The prediction proposed method has been successfully used to produce hardness values of various material properties and is used to establish the relationship between the hardness values with representative stress. Prediction process of the material parameters based on the intersection between the indentations curves of the material properties of both the dual indenter Vickers and spherical indentation. It provides a useful tool to evaluate the feasibility of using a hardness value in predicting the constitutive material parameters with respect to the accuracy and uniqueness by mapping through all the range of potential materials.
AL-MUKHTAR JOURNAL OF SCIENCES, 2019
Instrumented indentation technique at micro-scales has become more popular to determine mechanical properties of materials like hardness, modulus of elasticity, and yield strength. It is introduced as a method that finds the stress-strain curve, instead of the traditional tensile test. Furthermore, it gives a possibility to determine the mechanical properties for small specimens and material under operation in the field. Several researchers have attempted to evaluate this method experimentally and to investigate the factors affecting it by using a different shape of indenters, and different types of materials. In the same regard, this research work is conducted to evaluate this method experimentally and by finite element simulation methods. Two types of industrially significant steels were selected; they are namely ASTM516-G70, AISI1010 steel; and two shapes of indenters, blunt and sharp (Spherical, and Vickers) were used. The finite element simulation has been performed by ABAQUS s...