Probabilistic micromechanical damage model for mixed mode I/II fracture investigation of composite materials

Khansari, Nabi Mehri; Fakoor, Mahdi; Berto, Filippo

doi:10.1016/j.tafmec.2018.12.003

Cited by 28 publications

(24 citation statements)

References 61 publications

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“…On their basis, it was found that microcracks develop in concrete structures during the loading process, which leads to a gradual loosening of the material. Thus, fracture toughness of brittle materials should be examined under various load states, e.g., [ 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 ].…”

Section: Purpose and Scope Of The Experimental Researchmentioning

confidence: 99%

Studies of Fracture Toughness in Concretes Containing Fly Ash and Silica Fume in the First 28 Days of Curing

Golewski

Gil

2021

Materials

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This paper presents the results of the fracture toughness of concretes containing two mineral additives. During the tests, the method of loading the specimens according to Mode I fracture was used. The research included an evaluation of mechanical parameters of concrete containing noncondensed silica fume (SF) in an amount of 10% and siliceous fly ash (FA) in the following amounts: 0%, 10% and 20%. The experiments were carried out on mature specimens, i.e., after 28 days of curing and specimens at an early age, i.e., after 3 and 7 days of curing. In the course of experiments, the effect of adding SF to the value of the critical stress intensity factor—KIcS in FA concretes in different periods of curing were evaluated. In addition, the basic strength parameters of concrete composites, i.e., compressive strength—fcm and splitting tensile strength—fctm, were measured. A novelty in the presented research is the evaluation of the fracture toughness of concretes with two mineral additives, assessed at an early age. During the tests, the structures of all composites and the nature of macroscopic crack propagation were also assessed. A modern and useful digital image correlation (DIC) technique was used to assess macroscopic cracks. Based on the conducted research, it was found the application of SF to FA concretes contributes to a significant increase in the fracture toughness of these materials at an early age. Moreover, on the basis of the obtained test results, it was found that the values of the critical stress intensity factor of analyzed concretes were convergent qualitatively with their strength parameters. It also has been demonstrated that in the first 28 days of concrete curing, the preferred solution is to replace cement with SF in the amount of 10% or to use a cement binder substitution with a combination of additives in proportions 10% SF + 10% FA. On the other hand, the composition of mineral additives in proportions 10% SF + 20% FA has a negative effect on the fracture mechanics parameters of concretes at an early age. Based on the analysis of the results of microstructural tests and the evaluation of the propagation of macroscopic cracks, it was established that along with the substitution of the cement binder with the combination of mineral additives, the composition of the cement matrix in these composites changes, which implies a different, i.e., quasi-plastic, behavior in the process of damage and destruction of the material.

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Section: Purpose and Scope Of The Experimental Researchmentioning

confidence: 99%

Studies of Fracture Toughness in Concretes Containing Fly Ash and Silica Fume in the First 28 Days of Curing

Golewski

Gil

2021

Materials

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“…concrete, wood, and some composite structures) are decisive factors in failure analysis of these materials. Unlike deformable materials, in which failure is associated with the initiation of micro-voids, in brittle and quasi-brittle materials, failure is associated with the development of micro-cracks (Khansari et al, 2019). In this case, softening is caused by the growth of the damage zone in the material, causing changes in the distribution of ensemble stresses.…”

Section: Introductionmentioning

confidence: 99%

Micro-mechanical damage diagnosis methodologies based on machine learning and deep learning models

Shamsirband¹,

Khansari

2021

J. Zhejiang Univ. Sci. A

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A loss of integrity and the effects of damage on mechanical attributes result in macro/micro-mechanical failure, especially in composite structures. As a progressive degradation of material continuity, predictions for any aspects of the initiation and propagation of damage need to be identified by a trustworthy mechanism to guarantee the safety of structures. Besides material design, structural integrity and health need to be monitored carefully. Among the most powerful methods for the detection of damage are machine learning (ML) and deep learning (DL). In this paper, we review state-of-the-art ML methods and their applications in detecting and predicting material damage, concentrating on composite materials. The more influential ML methods are identified based on their performance, and research gaps and future trends are discussed. Based on our findings, DL followed by ensemble-based techniques has the highest application and robustness in the field of damage diagnosis.

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“…Especially in the case of modified concretes with a changed composition of the cement matrix, e.g., [ 58 ]. Situations, in which complex stress states determine the destruction of materials apply to both concrete composites and other brittle materials, e.g., [ 59 , 60 , 61 , 62 , 63 , 64 ].…”

Section: Introductionmentioning

confidence: 99%

Changes in the Fracture Toughness under Mode II Loading of Low Calcium Fly Ash (LCFA) Concrete Depending on Ages

Golewski

2020

Materials

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This study investigated the influence of the curing time on the fracture toughness of concrete produced with different content of low calcium fly ash (LCFA). During the study, the amounts of 20% and 30% of pozzolanic additive were used. In order to observe the effect of the applied pozzolanic additive on the analyzed concrete properties, the obtained results were compared with the values obtained for the reference concrete. Compressive strength—fcm and fracture toughness, by using mode II loading—KIIc (shearing), were determined between the 3rd and 365th days of curing. In the course of experiments, changes in the development of cracks in individual series of concrete were also analyzed. In addition, the microstructures of all composites and the nature of macroscopic crack propagation in mature concretes were assessed. It was observed that the greatest increase in fracture toughness at shear was in the case of reference concrete during the first 28 days, whereas, in the case of concretes containing LCFA, in the period of time above 4 weeks. Furthermore, concrete without the LCFA additives were characterized by a brittle fracture. In contrast to it, concretes with LCFA additives are mainly characterized by a quasi-plastic process of failure. Moreover, most of the samples showed a typical pattern of the destruction that occurs as a result of shearing. The presented test results may be helpful in selecting the composition of concrete mixtures containing LCFA to be used in concrete and reinforced concrete structures subjected to shear loads.

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Probabilistic micromechanical damage model for mixed mode I/II fracture investigation of composite materials

Cited by 28 publications

References 61 publications

Studies of Fracture Toughness in Concretes Containing Fly Ash and Silica Fume in the First 28 Days of Curing

Studies of Fracture Toughness in Concretes Containing Fly Ash and Silica Fume in the First 28 Days of Curing

Micro-mechanical damage diagnosis methodologies based on machine learning and deep learning models

Changes in the Fracture Toughness under Mode II Loading of Low Calcium Fly Ash (LCFA) Concrete Depending on Ages

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