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Experimental investigation on mode II fracture performance of old-new concrete

Liu Shuang, Shi Zhenwu, Jiang Tao, Wang Huili

Archives of Civil Engineering

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2022

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Vol. 68, nr 3

469--480

EN

The old-new concrete interface is the weakest part in the composite structure, and there are a large number of microcracks on the interface. In order to study the mode II fracture performance of the bonding surface of old-new concrete, the effect of planting rebar and basalt fiber is investigated. Nine Z-shaped old-new concrete composite specimens with initial cracks are made. Nine shear fracture load-displacement curves are obtained, and the failure process and interface fracture are discussed. On this basis, the mode II fracture toughness and fracture energy are obtained. The regression equations for fracture toughness and fracture energy are deduced with analysis of variance (ANOVA). The results show that fracture toughness and fracture energy increase with the increase of planting rebar number and basalt fiber content. With the increase of the planting rebar number, mode II fracture toughness and fracture energy increase more significantly. Planting rebar is the major factor for mode II fracture performance.

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Ocena jakości wybranych wapieni jurajskich stosowanych w budownictwie na podstawie pomiaru ich energii pękania przy uderzeniu i mikrotwardości metodą Knoopa

Rembiś M.

Przegląd Geologiczny

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2017

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Vol. 65, nr 11/3

1461--1470

EN

The Jurassic limestones of Botticino Classico (Italy), Bilecik Beige (Turkey) and Morawica (Poland) are commonly used in the construction practice as facing and slab stones. Petrographic investigations revealed that the rocks are not homogenous in their inner development, and despite a similar age and a comparable genesis, differ also in their mechanical properties. The structural and textural rock features affect their resistance to the impact force measured as the rupture energy, according to the standard PN-EN14158:2005. The varying structure and mineral composition of these limestones result in their different microhardness values measured with the Knoop method (PN-EN 14205:2004). The variability of the lithological parameters makes possible establishing the resistance of these rocks to some damaging factors of the mechanical character on a wider scale than applying other commonly used methods of the stone quality evaluation.

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A comparative study on the damage initiation mechanism of elastomeric composites

Da Silva Botelho T., Isac N., Bayraktar E.

Archives of Computational Materials Science and Surface Engineering

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2009

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Vol. 1, nr 2

112-119

EN

Purpose: Modelling - Finite Element Analysis (FEA) of the damage initiation mechanisms in thin rubber sheet composites were carried out under static solicitation at room temperature. Natural rubber vulcanised and reinforced by carbon, NR is used in this study. Design/methodology/approach: Experimental results were compared with that of the Finite Element Analysis (FEA). Damage mechanism has been described with a threshold criterion to identify the tearing resistance, characteristic energy for tearing (T) and damage in the specimens was evaluated just at the beginning of the tearing by assuming large strain. A typical type of specimen geometry of thin sheet rubber composite materials was considered under static tensile tests conducted on the smooth and notched specimens with variable depths. In this way, the effects of the plane stress on the damage mechanism are characterized depending on the rubber materials. Findings: In this stage of this research, a finite element analysis (FEA) has been applied under the same conditions of this part in order to obtain the agreement between experimental and FEA results. The numerical modelling is a representation of a previous experimental study. The specimen is stretched more than once its initial size, so that large strains occur. A hyper elastic Mooney-Rivlin law and a Griffith criterion are chosen. The finite elements analysis was performed with ABAQUS code (V.6.4.4). The tearing energy is evaluated with contour integrals. The Griffith criterion states that a notch with an initial length will elongate of a differential length for a given strain state only if the variation of elastic energy is higher than the variation of the surface energy related to the newly created surface. Practical implications: A tearing criterion was suggested in the case of simple tension conditions by assuming large strain. In the next step of this study, a finite element analysis (FEA) will be applied under the same conditions of this part in order to obtain the agreement between experimental and FEA results. Originality/value: This study proposes a threshold criterion for the damage just at the beginning of the tearing for thin sheet rubber composites and gives a detail discussion for explaining the damage mechanisms. Comparison of FEA results with those of experimental studies gives many facilities for the sake of simplicity in industrial application.