Non-destructive evaluation of local mechanical properties of Al die cast large components by means of FIMEC indentation test (original) (raw)
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Mechanical characterization of FDM parts through instrumented flat indentation
Evaluating local mechanical properties of parts made by Additive Manufacturing processes can improve the deposition conditions. This study proposes a non-destructive characterization test to determine the mechanical behavior of fused deposition modeling (FDM) components. Indentation and compression tests were conducted on samples produced by the FDM process, which were produced by varying the material flow during the deposition. An empirical relationship was determined between yield strength determined through compression and indentation tests. R2 = 0.92 characterized the correlation between the compression and indentation test. The results indicated that both the yield strength measured through compression tests and that measured by the indentation tests increased linearly with the density of the components. Indentation tests provided more insights concerning the tested surface's local characteristics than the compression test.
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Aluminium alloys are more and more increasing their importance in different industries, in particular, in the automotive field, where castings represent extremely interesting solutions especially for those applications in which the necessity of high mechanical properties is combined with the need of a substantial weight saving. In this work, investigations on fatigue and microstructural characteristics were done on specimens drawn directly from production components, samples dimensions were the maximum allowed by component dimensions. The influence of different casting processes are here compared.
A Load-based Micro-indentation Technique for Mechanical Property and NDE Evaluation
2009
A load-based micro-indentation technique has been developed for evaluating mechanical properties of materials. Instead of using measured indentation depth or contact area as a necessary parameter, the new technique is based on the indentation load, coupled with a multiple-partial unloading procedure for mechanical property evaluation. The proposed load-based micro-indentation method is capable of determining Young's modulus of metals, superalloys, and single crystal matrices, and stiffness of coated material systems with flat, tubular, or curved architectures. This micro-indentation technique can be viewed as a viable non-destructive evaluation (NDE) technique for determining as-manufactured and process-exposed metal, superalloy, single crystal, and TBC-coated material properties.
Frontiers in Materials
The quantification of spatially variable mechanical response in structural materials remains a challenge. Additive manufacturing methods result in increased spatial property variations—the effect of which on component performance is of key interest. To assist iterative design of additively manufactured prototypes, lower-cost benchtop test methods with high precision and accuracy will be necessary. Profilometry-based indentation plastometry (PIP) promises to improve upon the instrumented indentation test in terms of the measurement uncertainty. PIP uses an isotropic Voce hardening model and inverse numerical methods to identify plasticity parameters. The determination of the baseline uncertainty of PIP test is fundamental to its use in characterizing spatial material property variability in advanced manufacturing. To quantify the uncertainty of the PIP test, ninety-nine PIP tests are performed on prepared portions of a traditionally manufactured Al 7075 plate sample. The profilometry...
MATERIAL CHARACTERIZATION BASED ON INSTRUMENTED AND SIMULATED INDENTATION TESTS
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Aluminium alloys for the aerospace industry are often clad by roll-bonded aluminium to improve corrosion resistance. The clad layer is of the order of 100 lm in thickness and it is difficult to determine the mechanical properties of this layer by conventional mechanical testing techniques. Nanoindentation is ideally suited to determining the elastic and plastic properties of such layers and here we report on a combined approach using experimental nanoindentation and finite element analysis to extract yield stress and strain hardening exponent for an Al-clad system. The approach used was calibrated against results for an Al 2024-T351 alloy, where conventional mechanical testing data was available. For the Al 2024-T351, a forward analysis was used for extraction of load-displacement curves at different indentation depths with the help of elastic-plastic properties obtained from tensile testing. For a $100 lm clad layer of pure aluminium on Al 2024-T351, reverse analysis was used for extraction of elastic-plastic properties from a single indentation test. A yield stress of 110-120 MPa and a value of 0.075-0.1 for the work hardening exponent was obtained for the Al cladding. Nanoindentation properties including maximum load of indentation, contact depth, area of contact and pile-up obtained from the forward and reverse analyses showed excellent agreement with the experimental results.
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.
Acta Polytechnica CTU Proceedings, 2024
Laser powder bed fusion process is a versatile metal additive manufacturing process. Although significant progress has been made so far, there is still limited large-scale adoption of this technique by the industry. The main problems are repeatability and lack of proper knowledge. In this work, an innovative and non-destructive testing methodology, based on flat-top cylinder indentation, was used to define the mechanical properties of laser powder bed fused aluminium alloy to highlight any variations induced by the combination of process parameters, for global characterization, and by the building direction, for local characterization. Results show similar or improved global mechanical properties of the laser powder bed fused specimens when compared to traditional die-casted ones. Indentation tests highlight a local dependence of properties along the building direction in favor of the upper part of the samples.
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Through a proper analysis of residual strain and stress distributions obtained at the surface of high speed milled specimens of AA 6082–T6 aluminium alloy, the performance of an improved indentation method is evaluated. This method integrates a special device of indentation to a universal measuring machine. The mentioned device allows introducing elongated indents allowing to diminish the absolute error of measurement. It must be noted that the present method offers the great advantage of avoiding both the specific equipment and highly qualified personnel, and their inherent high costs. In this work, the cutting tool geometry and high speed parameters are selected to introduce reduced plastic damage. Through the variation of the depth of cut, the stability of the shapes adopted by the residual strain and stress distributions is evaluated. The results show that the strain and stress distributions remain unchanged, compressive and small. Moreover, these distributions reveal a similar ...