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Short-beam shear fatigue behavior of round curved pultruded composite
Mechanics of Advanced Materials and Structures ( IF 2.8 ) Pub Date : 2021-08-03 , DOI: 10.1080/15376494.2021.1959968
Maikson L. P Tonatto 1 , José Ricardo Tarpani 2 , Sandro C. Amico 3
Affiliation  

Abstract

Short-beam shear test has been used to evaluate the fatigue strength of round curved pultruded carbon fiber – epoxy matrix composite specimens in three point bending test of a convex-beam. The specimens were cyclically loaded at peak stresses from 50 to 80% of the quasi-static short-beam strength, and load ratios of 0.1 to 0.5, and damage evolution was monitored using the apparent stiffness method. Basquins’ law was used to fit the experimental S-N data. The results showed that the fatigue strength of curved pultruded composites is lower than for conventional thin flat unidirectional laminates, and less sensitive to load-ratio effects. Residual strength of pre-fatigued specimens was determined by quasi-static short-beam tests, and it sometimes exceeded the pristine material performance due to fatigue-induced strengthening phenomenon. Stress redistribution and residual manufacturing-induced stress relief due to the previous cyclic loading were found the main responsible for mitigating damage growth under quasi-static loading. Fractographic survey indicated that stress redistribution and stress relief governed the strengthening process under high-cycle and low-cycle fatigue regime, respectively.



中文翻译:

圆形弯曲拉挤复合材料的短梁剪切疲劳行为

摘要

短梁剪切试验已被用于评估圆形弯曲拉挤碳纤维-环氧树脂基复合材料试件在凸梁三点弯曲试验中的疲劳强度。样本在准静态短梁强度的 50% 到 80% 的峰值应力下循环加载,加载比为 0.1 到 0.5,并使用表观刚度法监测损伤演变。Basquins 定律用于拟合实验 SN 数据。结果表明,弯曲拉挤复合材料的疲劳强度低于传统的薄平面单向层压板,并且对载荷比效应不太敏感。预疲劳试件的残余强度由准静态短梁试验确定,有时会因疲劳诱导强化现象而超过原始材料性能。由于先前的循环载荷,应力重新分布和残余制造引起的应力释放被发现是减轻准静态载荷下损伤增长的主要原因。断口调查表明,应力重新分布和应力释放分别控制着高周和低周疲劳状态下的强化过程。

更新日期:2021-08-03
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