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| Research on deformation and damage in notched S38C axles by synergetic application of acoustic emission and digital image correlation techniques |
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Abstract UUnderstanding and precise characterization of the deformation and damage mechanisms involved in materials is essential to predict various structures’ performance, which requires big data on deformation and failure. However, the conventional mechanical tests and techniques may become inadequate to obtain the enough information reflecting deformation and damage in the structures’ interior, and fail to meet the demands of high-throughput characterization made by modern material genome engineering and data-driven industries. Herein we attempt to solve the issue by synergistic application of acoustic emission (AE) and digital image correlation (DIC) during mechanical tests. The AE technique is capable of detecting the real-time events of plastic deformation and damage interior of the specimens while the DIC helps to obtain deformation on the surfaces. As an example, deformation and damage in notched samples of S38C axles under tensile loading, widely used in express trains, has been studied. By analyzing the scaling laws between energy and duration of the acoustic emission events as well as the surface displacement field produced by DIC, we have found that plastic deformation in S38C axles is carried by dislocation glide and failure initiates through formation of surface cracks. Based on the dislocation dominated mechanism, we have further proposed the median frequency, the accumulative AE energy and AE entropy to characterize the plastic properties. Moreover, we have also proposed a model to simulate the whole deformation and failure process in the notched samples of S38C axles by phase field modeling coupled with mechanism-based crystal plasticity. The simulated force-displacement curve, distribution of strain field and damage evolution agree qualitatively with the experimental results. It is expected that the results obtained may help to understand the deformation and damage mechanisms in S38C axles. By the synergistic application of AE and DIC as well as the phase field model, efficient and precise characterization of the mechanical properties including elastic, plastic and fracture parameters can be achieved.
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Received: 03 December 2025
Published: 28 April 2026
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Corresponding Authors:
Guoliang N/ALiu
E-mail: 2021201031@tju.edu.cn
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2026, Vol. 47 
