Last. Florin Bobaru(NU: University of Nebraska–Lincoln)H-Index: 32
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Abstract null null Dynamic compact tension tests in concrete are investigated using an intermediately-homogenized peridynamic (IH-PD) model, and the results are compared with a fully-homogenized peridynamic (FH-PD) model as well as with experimental data from the literature. In the IH-PD model, concrete is considered as a two-phase material composed of aggregate and mortar, partially homogenized via a stochastic procedure. Both the FH and IH-PD models capture well the experimentally measured rea...
Abstract null null In temperature-loaded bi-material joints, highly localized stress concentrations occur at the bi-material junction at the free edge. This so-called free-edge effect may cause premature failure in form of an interface crack emanating from the free edge. In the present work, thermal crack initiation is investigated using a coupled stress and energy criterion within the framework of finite fracture mechanics by the example of a uniformly cooled epoxy–glass bi-material specimen. T...
Abstract null null Liquid nitrogen (LN2) ultra-low temperature fracturing technology has broad application prospects in the storage and transformation of geothermal wells. Therefore, it is of great significance to investigate the fracture toughness of granite samples after elevated temperature treatment and LN2 cooling. In this paper, the Cracked Straight Through Brazilian Disc (CSTBD) granite specimen was heat-treated at different temperatures to study the mode-I fracture toughness of granite a...
Abstract null null As a simple and convenient testing method, the flattened Brazilian disc (FBD) specimen has been widely used to determine the tensile strength and mode-I fracture toughness of rocks. However, the precision of the mechanical parameters calibrated by FBD testing method needs to be further evaluated. In this paper, digital image correlation (DIC) technique is used to capture the progressive failure process of FBD specimen, and some new insights are provided for further understandi...
Abstract null null S355 structural steel is a commonly used material in the fabrication of foundation structures of offshore wind turbines, which are predominantly supported using monopiles. During the manufacturing process of monopile foundations, S355 steel plates are pre-strained via a three point bending and rolling process, which subsequently changes the mechanical, fatigue and fracture properties of the material. The aim of this study is to investigate the variation in fracture toughness o...
Abstract null null The work described here has led to a simple criterion that defines the boundary of the small-scale yielding, SSY, regime to avoid invalid use of the LEFM parameter, ΔK, as the characterising parameter for fatigue crack growth rate. The approach proposed is based on the analysis of crack tip opening displacement, CTOD, and its separation into elastic and plastic components. SSY conditions are shown to dominate when the elastic component of CTOD is larger than 75% of the total C...
#5Bai-Lin Wu(CSIRO: Commonwealth Scientific and Industrial Research Organisation)
Abstract null null In this paper, the DDM numerical method is used to calculate the initiation pressure and initiation length of the circular wellbore, or the further elongated and non-elongated ‘dog-ear’ breakout wellbore under different sizes and different stress states. An analysis is made about the transfer of the fracture initiation point for the further elongated breakout wellbore and its possible impacts. The numerical results show that for small-size wellbore ((Rwσt2)/KIC2 6.4), the init...
Abstract null null The present paper presents a new multi-ΔG control approach to perform mode I fatigue crack growth tests using several constant cyclic energy release rate ranges (ΔG) on only one specimen. It was successfully applied on carbon/polyamide 6 unidirectional composite specimens. After validation checks on the approach, results show that the crack propagation behaviour exhibits three different crack propagation regimes that can be accurately described using the Hartman-Shijves equati...