On the measurement of hardness at high strain rates by nanoindentation impact testing

Phani, P. Sudharshan; Hackett, B.; Walker, Christopher C.; Oliver, W. C.; Pharr, George M.

doi:10.1016/j.jmps.2022.105105

Cited by 17 publications

(4 citation statements)

References 26 publications

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“…The enhanced data acquisition rate increases the time resolution needed to measure indentation depths and loads during high-strain-rate experiments ( 8 ). With this modification, the system is capable of operating over a wide range of indentation strain rates (

, where h and

are the depth and depth rate) ranging from quasistatic tests (

~ 10 −4 -10 −2 s −1 ) up to impact tests (

> 10 4 s −1 ) ( 8 , 9 , 35 ). Quasistatic tests were conducted at constant indentation strain rate

through feedback control of the loading rate ( 36 ).…”

Section: Resultsmentioning

confidence: 99%

“…While machine-learning aided materials informatics promises to dramatically accelerate materials design and discovery ( 2 ), validating materials characterization and performance through standard high-strain-rate testing techniques, i.e., plate impact ( 3 ), split Hopkinson bar ( 4 – 6 ), and gas gun impact ( 7 ), still remains a bottleneck in the high-strain-rate materials design cycle due to the low throughput nature and high cost of these testing techniques. In this regard, high-strain-rate nanoindentation has recently emerged as a potentially useful high-throughput testing technique ( 8 ), but it remains unclear whether small-scale measurements adequately capture material deformation behavior at macroscopic scales ( 9 – 12 ).…”

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confidence: 99%

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Evolution of dislocation substructures in metals via high-strain-rate nanoindentation

Zhang,

Hackett,

Dong

et al. 2023

Proc. Natl. Acad. Sci. U.S.A.

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Deformation at high strain rates often results in high stresses on many engineering materials, potentially leading to catastrophic failure without proper design. High-strain-rate mechanical testing is thus needed to improve the design of future structural materials for a wide range of applications. Although several high-strain-rate mechanical testing techniques have been developed to provide a fundamental understanding of material responses and microstructural evolution under high-strain-rate deformation conditions, these tests are often very time consuming and costly. In this work, we utilize a high-strain-rate nanoindentation testing technique and system in combination with transmission electron microscopy to reveal the deformation mechanisms and dislocation substructures that evolve in pure metals from low (10 –2 s –1 ) to very high indentation strain rates (10 4 s –1 ), using face-centered cubic aluminum and body-centered cubic molybdenum as model materials. The results help to establish the conditions under which micro- and macro-scale tests can be compared with validity and also provide a promising pathway that could lead to accelerated high-strain-rate testing at substantially reduced costs.

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, where h and

are the depth and depth rate) ranging from quasistatic tests (

~ 10 −4 -10 −2 s −1 ) up to impact tests (

> 10 4 s −1 ) ( 8 , 9 , 35 ). Quasistatic tests were conducted at constant indentation strain rate

through feedback control of the loading rate ( 36 ).…”

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Evolution of dislocation substructures in metals via high-strain-rate nanoindentation

Zhang,

Hackett,

Dong

et al. 2023

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

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“…An impact testing approach was used for the high strain-rate indentation, as described by Phani et al ( 57 ) and Hackett et al ( 54 ). To account for the dynamic overload during impact, loads of 30 and 50 mN were used so the final load on the sample would be between 200 and 300 mN, reaching comparable indent sizes with the quasistatic testing.…”

Section: Methodsmentioning

confidence: 99%

High-throughput quantification of quasistatic, dynamic and spall strength of materials across 10 orders of strain rates

Eswarappa Prameela,

Walker,

DiMarco

et al. 2024

PNAS Nexus

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The response of metals and their microstructures under extreme dynamic conditions can be markedly different from that under quasistatic conditions. Traditionally, high strain rates and shock stresses are achieved using cumbersome and expensive methods such as the Kolsky bar or large spall experiments. These methods are low throughput and do not facilitate high-fidelity microstructure-property linkages. In this work, we combine two powerful small-scale testing methods, custom nanoindentation, and laser-driven micro-flyer shock, to measure the dynamic and spall strength of metals. The nanoindentation system is configured to test samples from quasistatic to dynamic strain rate regimes. The laser-driven micro-flyer shock system can test samples through impact loading, triggering spall failure. The model material used for testing is Magnesium alloys, which are lightweight, possess high-specific strengths, and have historically been challenging to design and strengthen due to their mechanical anisotropy. We adopt two distinct microstructures, solutionized (no precipitates) and peak-aged (with precipitates) to demonstrate interesting upticks in strain rate sensitivity and evolution of dynamic strength. At high shock loading rates, we unravel an interesting paradigm where the spall strength versus strain rate of these materials converges, but the failure mechanisms are markedly different. Peak aging, considered to be a standard method to strengthen metallic alloys, causes catastrophic failure, faring much worse than solutionized alloys. Our high throughput testing framework not only quantifies strength but also teases out unexplored failure mechanisms at extreme strain rates, providing valuable insights for the rapid design and improvement of materials for extreme environments.

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“…This opened up new possibilities in the field of indentation techniques. With the continuous advancement of technology, there is a growing demand for understanding the mechanical properties of materials, such as hardness [3][4][5][6][7], Young's modulus [8][9][10][11][12], residual stress [13][14][15][16][17], and plasticity [18][19][20][21][22]. These studies have demonstrated that the mechanical properties of materials can be extracted by comparing the load-displacement curves obtained from finite element simulations with those obtained from experimental measurements when the data are in good agreement.…”

Section: Introductionmentioning

confidence: 99%

Estimation of Mechanical Properties of Aluminum Alloy Based on Indentation Curve and Projection Area of Contact Zone

Bai,

Liu

2024

Metals

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This study proposes a method for determining aluminum alloys’ yield stress and hardening index based on indentation experiments and finite element simulations. Firstly, the dimensionless analysis of indentation variables was performed on three different aluminum alloys using the same maximum indentation depth to obtain load-displacement curves. Then, laser confocal microscopy was used to observe the residual indentation morphology. And four dimensionless parameters were derived from the load-displacement curves while another dimensionless parameter was obtained from the projection area of the contact zone. Subsequently, a genetic algorithm was employed to solve these five dimensionless parameters and estimate the yield stress and hardening index. Finally, the predicted results are compared with uniaxial tensile experiments and the results obtained are essentially the same. The yield stress and hardening index can be predicted using this method. And an example is used to verify that this method enables predictions for unidentified “mysterious material” and the expected results agree with the experiments.

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On the measurement of hardness at high strain rates by nanoindentation impact testing

Cited by 17 publications

References 26 publications

Evolution of dislocation substructures in metals via high-strain-rate nanoindentation

Evolution of dislocation substructures in metals via high-strain-rate nanoindentation

High-throughput quantification of quasistatic, dynamic and spall strength of materials across 10 orders of strain rates

Estimation of Mechanical Properties of Aluminum Alloy Based on Indentation Curve and Projection Area of Contact Zone

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