Experiments and Material Parameter Identification Using Finite Elements. Uniaxial Tests and Validation Using Instrumented Indentation Tests (original) (raw)
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Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications, 2013
Conventional indentation tests do not provide an accurate estimation of viscoplastic material properties. In this work, a combined finite element analysis and optimization approach is developed for the determination of elastic–plastic and creep material properties using only a single indentation loading–unloading curve based on a two-layer viscoplasticity model. Utilizing the indentation loading–unloading curve obtained from a finite element-simulated experiment with a spherical and a conical indenter, a set of six key material properties (Young’s modulus, yield stress, work hardening exponent and three creep parameters) can be determined. Non-linear optimization algorithms are used with different sets of initial material properties, leading to good agreements with the numerically simulated target loading–unloading curves.
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...
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 ...
Computational Materials Science, 2009
We proposed an application of inverse approach to experimental indentation data in order to determine combined hardening models parameters. It was shown that the use of a model combining isotropic and kinematic hardening allows a better description of cyclic indentation than isotropic hardening models. It was also shown that inverse analysis applied to experimental cyclic indentation curves can give a quite good approximation of the monotonic stress-strain curve and the beginning of cyclic tensile test. However, it appeared that the combined hardening model, used in this paper, is not sufficient to take into account all phenomenons coming in the steels behaviour under cyclic indentation.
International Journal of Solids and Structures, 2019
Ti 2 AlNb intermetallic alloy is a relatively newly developed high-temperature-resistant structural material, which is expected to replace nickel-based super alloys for thermally and mechanically stressed components in aeronautic and automotive engines due to its excellent mechanical properties and high strength retention at elevated temperature. The aim of this work is to present a fast and reliable methodology of inverse identification of constitutive model parameters directly from cutting experiments. FE-machining simulations implemented with a modified Johnson-Cook (TANH) constitutive model are performed to establish the robust link between observables and constitutive parameters. A series of orthogonal cutting experiments with varied cutting parameters is carried out to allow an exact comparison to the 2D FE-simulations. A cooperative particle swarm optimization algorithm is developed and implemented into the Matlab programs to identify the enormous constitutive parameters. Results show that the simulation observables (i.e., cutting forces, chip morphologies, cutting temperature) implemented with the identified optimal material constants have high consistency with those obtained from experiments, which illustrates that the FE-machining models using the identified parameters obtained from the proposed methodology could be predicted in a close agreement to the experiments. Considering the wide range of the applied unknown parameters number, the proposed inverse methodology of identifying constitutive equations shows excellent prospect, and it can be used for other newly developed metal materials.
Acta Materialia, 2012
Two different definitions of indentation strain and two different definitions of contact radius are being used in the current literature, leading to inconsistent estimates of mechanical properties (especially plastic properties). In this paper, we critically evaluate the validity of the different definitions of both the indentation strain and the contact radius by applying the protocols on datasets generated from a finite element simulation of spherical indentation. The finite element models allow assignment of a wide range of elastic-plastic properties to the sample while circumventing many of the uncertainties faced in experimental investigations, and thereby offer unique opportunities for critical validation of the different data analysis procedures. In particular, we are able to establish important connections between the indentation stress-strain curves and the conventional uniaxial stress-strain curves.
Determining Plastic Properties of Material Through Instrumented Indentation Approach
INTERNATIONAL JOURNAL OF ADVANCED RESEARCH IN ENGINEERING & TECHNOLOGY, 2019
One significant advantage of indentation tests is that this test only requires a small amount of test material, this makes it very attractive for material characterization with gradient properties where standard specimens are not available such as in situ or in vivo. Regarding tests for spot welded joints, standardized testing does not apply to characterize HAZ and nuggets because of their complex structure and small size. This has opened the possibility to characterize material properties based on the Indentation method to characterize inverse parameters of constitutive material laws for nuggets, HAZ and base metals. The numerical approach based on the Finite Element (FE) model has been developed and validated. The established formulation is used for reverse (inverse) prediction of the nature of constitutive material (ie yield stress (σy), strain hardening coefficient (n)) for the welded joint zone namely the nugget, HAZ and parent metals (base). Then able to predict the effect of the nugget size and the thickness of the sheet metal on the strength of the spot welded joint with dissimilar material.
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.
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...
Journal of Materials Research, 2001
This paper describes a novel technique for determining the constitutive equation of elastic–plastic materials by the indentation technique using plural indenters with different apex angles. Finite element method (FEM) analyses were carried out to evaluate the effects of yield stress, work hardening coefficient, work hardening exponent, and the apex angle of indenter on the load–depth curve obtained from the indentation test. As a result, the characterized curves describing the relationship among the yield stress, work hardening coefficient, and the work hardening exponent were established. Identification of the constants of a constitutive equation was made on the basis of the relationship between the characterized curves and the hardness given by the load–depth curve. This technique was validated through experiments on Inconel 600 and aluminum alloy. The determined constitutive equation was applied to the FEM analyses to simulate the deformation including necking behavior under unia...