Fracture behavior of filament in Nb3Sn strands with crack-bridging model

Yong, Huadong; Pan, Yang; Xue, Cun; Zhou, Youhe

doi:10.1016/j.fusengdes.2015.11.029

Cited by 13 publications

(2 citation statements)

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“…The mechanical properties of Nb 3 Sn materials are similar to those of ceramics; therefore, brittle fracture occurs when they are subjected to tiny deformations. As such, many experts have started to concentrate on investigating Nb 3 Sn filament fracture [41][42][43][44][45][46][47][48]. Curtin and Zhou [41,42] hypothesized that filament breakage is a random process related to axial stress, and the filament fracture length could be described using the Weibull distribution function.…”

Section: Introductionmentioning

confidence: 99%

“…Curtin and Zhou [41,42] hypothesized that filament breakage is a random process related to axial stress, and the filament fracture length could be described using the Weibull distribution function. Based on the Curtin-Zhou theory and the 'shear-lag model', Luo [43], and Wang et al [44] investigated the influence of filament fracture and damage progression on the mechanical characteristics of LMI-Nb 3 Sn strands. Yong et al [45] established a twodimensional crack bridge model to investigate the fracture behavior of filaments within the strand and calculated the stress intensity factors of modes I, II, and III crack tips, as well as the relative opening displacements between the crack surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Elastic–Plastic Mechanical Behavior Analysis of a Nb3Sn Superconducting Strand with Initial Thermal Damage

Zhang

Shi

2022

Applied Sciences

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It is well known that the parameters of Nb3Sn superconducting strands are strain sensitive, and the internal brittle Nb3Sn filament can easily break under deformations. A temperature difference from the preparation temperature of about 1000 K to the cryogenic working environment of 4.2 K damages brittle Nb3Sn fibers before working. Based on the Curtin–Zhou model, the damage theory for fiber-reinforced composites is utilized to study the influence of filament fractures caused by thermal stress. According to the typical multi-scale geometric of the EAS-Nb3Sn strand (European Advanced Superconductor, EAS), an efficient hierarchical homogenized calculation model considering filament fracture and matrix plasticity was established. In this work, we took the filament fracture caused by both thermal stresses and mechanical loads into consideration using the secant modulus and simultaneously had the impact of the plastic constitutive of the bronze matrix and the copper protective layer. Mechanical parameters, such as the homogenized secant modulus, shear modulus, and Poisson’s ratio in different directions of level scale, were predicted at various temperatures. The elastoplastic mechanical behavior of the strands subjected to axial load was analyzed, and the results were in good agreement with the experiment. The initial thermal fiber fracture has non-negligible effects on the mechanical properties of the EAS-Nb3Sn superconducting strand and play the role in accelerating the increase in fiber breakage.

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