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عنوان فارسی مقاله:
میکرومکانیک مبتنی بر فرسودگی وابسته به مدل ساختاری فیبر پل زدن
عنوان انگلیسی مقاله:
A micromechanics-based fatigue dependent fiber-bridging constitutive model
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Fatigue is an important factor for the deterioration of many reinforced concrete infrastructure, such as pavement [1], bridge [2], railway slippers [3], and the supporting structure of offshore windmills [4]. Under repeated loading, the intrinsic flaws and micro cracks in concrete would gradually propagate into macro cracks. This reduces not only the structural capacity and serviceability but also the durability as the aggressive acid rain or sea water would penetrate through the cracks. The coupling effect of load repetition and environmental attack greatly shorten the service life of these infrastructures. Fibers provide effective means to suppress the brittleness of cementbased materials. Under repeated loading, fiber bridging of fiber-reinforced cementitious composites (FRCC) can effectively relieve the stress concentration at the crack tip, thus decelerating the crack propagation and extending the fatigue life of the structure [5]. The extension of fatigue life with increasing fiber content has been observed in FRCC reinforced by various types of fibers, such as steel fibers [6–8], polymeric fibers [9–11], glass fibers [12], and carbon fibers [13]. The effects of fiber dimension on fatigue life, however, remain controversial. For example, Johnston and Zemp [6], on the basis of fatigue test over 100 specimens, concluded that higher fiber aspect ratio, i.e. length-to-diameter ratio, led to higher flexural fatigue strength and extended fatigue life; while Naaman and Hammound [14] noticed in their tests that fiber aspect ratio of 60 and 100 produced similar flexural fatigue strength and fatigue life. Such disagreement indicates the complicacy involved in predicting the fatigue performance of FRCC. The key to predict fatigue performance of FRCC lies in robust characterization of fatigue-induced crack propagation, the rate of which is determined by the crack-tip stress intensity factor. The crack-tip stress intensity factor is influenced by the quality of fiber bridging, which deteriorate continuously with fatigue loading [15]. Two models have been proposed to predict the fatigue-induced fiber-bridging deterioration of FRCC. In a force equilibrium-based model, Zhang et al. [16] measured the fiber-bridging law, i.e. the tensile stress vs. crack opening displacement curve, with notched cube specimens under tensile fatigue loading, so the fiber-bridging deterioration can be modelled analytically. The limitation of such method lies that micro-scale factors such as fiber geometry cannot be included and that fatigue tests must be conducted once the mix design is changed. In a fracture mechanics-based model, Li and Matsumoto [17,18] established the fiber-bridging law by summing the pullout behavior of individual fibers after fatigue deterioration. In their model, the frictional bond between fiber and matrix interface was assumed to decrease with fatigue cycles without any experimental justification. In addition, chemical adhesion between fibers and matrix was not considered. Recently, the fatigue-induced fiber and fiber-matrix interfacial deterioration has been experimentally characterized and new deterioration mechanisms have been discovered in a micro-polyvinyl alcohol (PVA) fiber reinforced cementitious composites by the authors [19,20]. To characterize fiber deterioration under fatigue, single PVA fiber was embedded in cement matrix with large embedment length to prevent full debonding of fiber from the matrix. The embedded fiber with different inclination angle underwent tensile fatigue loading at various loading level until fiber rupture. It was found that the in-situ strength of PVA fiber decreased with increasing load cycles. To investigate deterioration of fiber-matrix interface properties, single PVA fiber was embedded in cement matrix with small embedment length so that fiber underwent debonding and sliding from the surrounding cement matrix when subjected to tensile fatigue loading. It was discovered that fatigue load was able to propagate the tunnel crack along the fiber-matrix interface, which was referred as fatigue-induced fiber debonding, and an empirical relation between debonding rate and fatigue loading level similar to the Paris' law was suggested. It was observed that interface chemical bond Gd was fatigue independent while frictional bond τ0 increased with fatigue cycles N and fatigue loading levels Pmax. Such fatigue-induced interface hardening can occur during fiber debonding stage, which was referred as fatigue debonding hardening, as well as during fiber slippage stage, which was referred as fatigue slippage hardening. These phenomena led to premature fiber rupture and may cause severe fiber-bridging deterioration, which needs to be captured with proper model. In this paper, a micromechanics-based fatigue dependent fiberbridging constitutive model was proposed by taking account of fatigue dependency in material microstructure which consists of fiber, matrix, and fiber-matrix interface. Parametric study on the influence of fatigue loading level and fatigue cycle as well as fiber surface treatment on the fiber-bridging σ-δ curves was also reported and discussed.
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کلمات کلیدی:
micromechanics-based study on fatigue failure of engineered ... - RILEM www.rilem.org/gene/main.php?base=500218&id_publication=447&id_papier... Such fatigue-induced immature failure indicates cyclic loads have ... the fatigue-dependent parameters in the existing micromechanics-based model for ECC ... A Micromechanics-Based Method for Multiscale Fatigue Prediction search.proquest.com/openview/486a7020f0d126f90f4a54f6adc49dec/1?pq...cbl... by JA Moore - 2015 - Cited by 4 - Related articles A Micromechanics-Based Method for Multiscale Fatigue Prediction ... challenges is that fatigue is intrinsically a multiscale process, which is dependent on a ... A Micromechanics-Based Method for Multiscale Fatigue Prediction adsabs.harvard.edu/abs/2015PhDT........87M by JA Moore - 2015 - Cited by 4 - Related articles A Micromechanics-Based Method for Multiscale Fatigue Prediction ... challenges is that fatigue is intrinsically a multiscale process, which is dependent on a ... ICCS19 19th International Conference on Composite Structures: https://books.google.com/books?isbn=8874889771 Antonio J.M. Ferreira - 2016 - Technology & Engineering An anisotropic rate-dependent damage model is introduced to predict the ... of a micromechanics-based model in ABAQUS/Standard for fatigue life prediction of ... Life Prediction Methodology for Titanium Matrix Composites https://books.google.com/books?isbn=0803120397 W. Steven Johnson, James M. Larsen, B. N. Cox - 1996 - Technology & Engineering The analysis incorporated temperature-dependent elastic properties in the fiber ... for a micromechanics-based analytical technique to understand and predict the ... titanium matrix composites, life prediction, titanium alloys, fatigue (materials), ... [PDF]Micromechanics-based model for trends in toughness ... - Harvard SEAS www.seas.harvard.edu/hutchinson/papers/pardoen.pdf by T Pardoen - 2003 - Cited by 158 - Related articles Micromechanics-based model for trends in toughness of ... to account for both void growth and coalescence with explicit dependence on void shape and distribution effects. Based on a small ..... initial crack characteristic of a fatigue precrack.). Applications of Continuum Damage Mechanics to Fatigue and Fracture https://books.google.com/books?isbn=0803124732 David L. McDowell - 1997 - Technology & Engineering In this work, the constraint effect was found to be dependent on the ply elastic ... to be an essential contribution in micromechanics-based damage analysis, and ...
