Ultrasonic fatigue of cast aluminium under cyclic compression and of superelastic Nitinol in the synchrotron

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue Pub Date : 2025-04-18 DOI:10.1016/j.ijfatigue.2025.109009

Herwig Mayer , Michael Fitzka , Harald Rennhofer , Helga C. Lichtenegger , Stefano Checchia , Florian Rödl , Jan Becker , Frederic Lauer

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Abstract

Ultrasonic fatigue testing is used for the first time to study the very high cycle fatigue (VHCF) properties of cast aluminium AlSi8Cu3–T6 under purely cyclic compression loading (load ratio R = –∞). Formation of numerous shear cracks and disruption of large material volumes caused failures under cyclic compression, whereas casting porosities were preferential sources of cracks leading to early failures at load ratios R = –1 and R = 0. The Goodman straight line approximation well predicts the mean stress sensitivity for cyclic tension, whereas the FKM guideline overestimates it for cyclic tension as well as cyclic compression.

In–situ ultrasonic fatigue tests in the synchrotron have been performed with superelastic Nitinol. Specimens were subjected to a preloading procedure which led to a multiphase austenitic − martensitic condition. Lattice deformation over an ultrasonic cycle as well as under quasi static condition confirmed similar elastic deformation at 0.1 Hz and 18.3 kHz. Progress of fatigue damage with increasing numbers of ultrasonic cycles was observed in–situ with XRD patterns from the multiphase area. Formation and growth of austenitic bands in formerly martensitic areas was found that led to a progressively increasing specimen stiffness and an increase of stresses in displacement-controlled ultrasonic fatigue tests.

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铸铝在循环压缩和超弹性镍钛诺在同步加速器中的超声疲劳

首次采用超声疲劳试验研究了纯循环压缩载荷（载荷比R = -∞）下铸铝AlSi8Cu3-T6的甚高周疲劳（VHCF）性能。在循环压缩下，大量剪切裂纹的形成和大体积材料的破坏导致了破坏，而在载荷比R = -1和R = 0时，铸造孔隙是导致早期破坏的优先裂纹来源。Goodman直线近似很好地预测了循环张力的平均应力敏感性，而FKM准则高估了循环张力和循环压缩的平均应力敏感性。采用超弹性镍钛诺对同步加速器进行了原位超声疲劳试验。试样经过预压处理，形成多相奥氏体-马氏体状态。在超声循环和准静态条件下，晶格变形证实了在0.1 Hz和18.3 kHz时类似的弹性变形。利用多相区x射线衍射（XRD）图观察了随着超声循环次数的增加，复合材料的疲劳损伤过程。在位移控制的超声疲劳试验中，发现奥氏体带在原马氏体区域的形成和生长，导致试样刚度逐渐增加，应力增加。

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来源期刊

International Journal of Fatigue 工程技术-材料科学：综合

CiteScore

10.70

自引率

21.70%

发文量

619

审稿时长

58 days

期刊介绍： Typical subjects discussed in International Journal of Fatigue address: Novel fatigue testing and characterization methods (new kinds of fatigue tests, critical evaluation of existing methods, in situ measurement of fatigue degradation, non-contact field measurements) Multiaxial fatigue and complex loading effects of materials and structures, exploring state-of-the-art concepts in degradation under cyclic loading Fatigue in the very high cycle regime, including failure mode transitions from surface to subsurface, effects of surface treatment, processing, and loading conditions Modeling (including degradation processes and related driving forces, multiscale/multi-resolution methods, computational hierarchical and concurrent methods for coupled component and material responses, novel methods for notch root analysis, fracture mechanics, damage mechanics, crack growth kinetics, life prediction and durability, and prediction of stochastic fatigue behavior reflecting microstructure and service conditions) Models for early stages of fatigue crack formation and growth that explicitly consider microstructure and relevant materials science aspects Understanding the influence or manufacturing and processing route on fatigue degradation, and embedding this understanding in more predictive schemes for mitigation and design against fatigue Prognosis and damage state awareness (including sensors, monitoring, methodology, interactive control, accelerated methods, data interpretation) Applications of technologies associated with fatigue and their implications for structural integrity and reliability. This includes issues related to design, operation and maintenance, i.e., life cycle engineering Smart materials and structures that can sense and mitigate fatigue degradation Fatigue of devices and structures at small scales, including effects of process route and surfaces/interfaces.