B. Karihaloo - Academia.edu (original) (raw)
Papers by B. Karihaloo
Materials and Structures, 1997
Publisher Summary In this chapter the stress intensity factors (SIFs) and coefficients of higher-... more Publisher Summary In this chapter the stress intensity factors (SIFs) and coefficients of higher-order terms at the tips of several typical mixed mode cracks are directly determined by a hybrid crack element (HCE). The SIFs and coefficients of higher-order terms are compared with results available in the literature, or results obtained by the boundary collocation method, which is powerful for relatively simple geometries and loading conditions. The HCE can determine directly the SIF as well as the coefficients of higher-order terms for mixed mode cracks with high accuracy. The differences in the existing SIF solutions at mixed mode crack tips are clarified with refined analysis using the HCE.
International Journal of Solids and Structures, 1989
... Ill refer to 592 BL KARIHALW and X. HCANG tensile, in-plane shear and anti-plane shear modes)... more ... Ill refer to 592 BL KARIHALW and X. HCANG tensile, in-plane shear and anti-plane shear modes) due to a distribution of transformation strains ^,over a ... Re /'-Re 0',.,, C,,^^11-S'*, (I-cos ^) |-Reu,,,, <A2) ''(. J Im G'.,., Im /'.lm (;.,, f >'"' I''} s -C ;<(-I+;cos./>)-lt)-8cos0) -, -l-16(l ...
Construction and Building Materials, 2013
h i g h l i g h t s A procedure for constructing bilinear tension softening diagrams of concrete ... more h i g h l i g h t s A procedure for constructing bilinear tension softening diagrams of concrete mixes. The tension softening diagram corresponds to the size-independent fracture energy of the mix. Inverse identification based on hinge model.
Composites Part A: Applied Science and Manufacturing, 2013
ABSTRACT The measured mechanical and physical properties of copper–alumina (Cu–Al2O3) composites ... more ABSTRACT The measured mechanical and physical properties of copper–alumina (Cu–Al2O3) composites are influenced by the defects induced during the manufacturing of the test samples. In this paper we shall demonstrate how the fundamental knowledge of the influence of the amount and type of micro-cracks on the mechanical and thermal properties of copper–alumina composites can be used as a forensic tool in identifying the defects induced during the manufacturing process of the test samples. This process involves several steps; the preparation of ingots from commercial powders by hot iso-static pressing (HIP), followed by their machining, hot extrusion, heat treatment, and if necessary further machining to make specimens of desired shape. Each step in this manufacturing process introduces some defects, so that the mechanical and physical properties measured using these samples, such as the Young modulus, the thermal conductivity and the coefficient of thermal expansion can be very different from the expected values, despite the fact that the density of the composite measured on the same samples is very close to its theoretical value. As a result open porosity is not the likely cause and it is reasonable to suspect that closed pores (e.g. micro-cracks) in the copper matrix and at the interfaces of the alumina inclusions formed during the multi-stage manufacture of test samples are responsible for the differences in the measured and expected mechanical and thermal properties.
Computers & Structures, 1992
ABSTRACT
Magazine of Concrete Research, 2005
Part I of this three-part paper describes the various steps that led to the development of a clas... more Part I of this three-part paper describes the various steps that led to the development of a class of high performance short steel fibre-reinforced cementitious composites (HPFRCCs) which has been patented under the trade name CARDIFRC®. This class of materials generally contains no coarse aggregates and is characterised by high tensile/flexural strength and high toughness. A method is proposed for quantifying the workability of such a mix without fibres in terms of its fracture toughness.
Rationalised computational time in fracture simulation: adaptive model reduction and domain decom... more Rationalised computational time in fracture simulation: adaptive model reduction and domain decomposition
Journal of Materials in Civil Engineering, 2010
ABSTRACT This study investigates the effect of thermal cycling on the performance of concrete bea... more ABSTRACT This study investigates the effect of thermal cycling on the performance of concrete beams retrofitted with CARDIFRC, a new class of high performance fiber-reinforced cement-based material that is compatible with concrete. Twenty four beams were subjected to 24 h thermal cycles between 25 and 90°C. One third of the beams were reinforced either in flexure only or in flexure and shear with conventional steel reinforcement and used as control specimens. The remaining sixteen beams were retrofitted with CARDIFRC strips to provide external flexural and/or shear strengthening. All beams were exposed to a varied number of 24 h thermal cycles ranging from 0 to 90 and were tested in four-point bending at room temperature. The tests indicated that the retrofitted members were stronger and stifferthan control beams, and more importantly, that their failure initiated in flexure without any signs of interfacial delamination cracking. The results of these tests are presented and compared to analytical predictions. The predictions show good correlation with the experimental results.
Engineering Fracture Mechanics, 2007
... Another problem, which has also been observed with this technique, is the effect of long expo... more ... Another problem, which has also been observed with this technique, is the effect of long exposure to temperature variations [5], [6] and [7]. A new retrofitting technique using CARDIFRC, a material compatible with concrete, has recently been developed at Cardiff University. ...
International Journal of Solids and Structures
ABSTRACT
International Journal of Solids and Structures
... can be reduced to the following design requirement C -> C,,. (1.5) The optimization proble... more ... can be reduced to the following design requirement C -> C,,. (1.5) The optimization problem at ... ie the problem of minimizing the cross-sectional area Minimum-weight design of multi-purpose cylindrical bars ... It is not difficult to show that this problem has a dual, viz, the problem of ...
International Journal of Solids and Structures
Structural Optimization
ABSTRACT
Composite Structures 3, 1985
Proceedings of an international conference on Fracture Mechanics in Engineering Application, 1979
5th Symposium on Multidisciplinary Analysis and Optimization, 1994
Materials and Structures, 1997
Publisher Summary In this chapter the stress intensity factors (SIFs) and coefficients of higher-... more Publisher Summary In this chapter the stress intensity factors (SIFs) and coefficients of higher-order terms at the tips of several typical mixed mode cracks are directly determined by a hybrid crack element (HCE). The SIFs and coefficients of higher-order terms are compared with results available in the literature, or results obtained by the boundary collocation method, which is powerful for relatively simple geometries and loading conditions. The HCE can determine directly the SIF as well as the coefficients of higher-order terms for mixed mode cracks with high accuracy. The differences in the existing SIF solutions at mixed mode crack tips are clarified with refined analysis using the HCE.
International Journal of Solids and Structures, 1989
... Ill refer to 592 BL KARIHALW and X. HCANG tensile, in-plane shear and anti-plane shear modes)... more ... Ill refer to 592 BL KARIHALW and X. HCANG tensile, in-plane shear and anti-plane shear modes) due to a distribution of transformation strains ^,over a ... Re /'-Re 0',.,, C,,^^11-S'*, (I-cos ^) |-Reu,,,, <A2) ''(. J Im G'.,., Im /'.lm (;.,, f >'"' I''} s -C ;<(-I+;cos./>)-lt)-8cos0) -, -l-16(l ...
Construction and Building Materials, 2013
h i g h l i g h t s A procedure for constructing bilinear tension softening diagrams of concrete ... more h i g h l i g h t s A procedure for constructing bilinear tension softening diagrams of concrete mixes. The tension softening diagram corresponds to the size-independent fracture energy of the mix. Inverse identification based on hinge model.
Composites Part A: Applied Science and Manufacturing, 2013
ABSTRACT The measured mechanical and physical properties of copper–alumina (Cu–Al2O3) composites ... more ABSTRACT The measured mechanical and physical properties of copper–alumina (Cu–Al2O3) composites are influenced by the defects induced during the manufacturing of the test samples. In this paper we shall demonstrate how the fundamental knowledge of the influence of the amount and type of micro-cracks on the mechanical and thermal properties of copper–alumina composites can be used as a forensic tool in identifying the defects induced during the manufacturing process of the test samples. This process involves several steps; the preparation of ingots from commercial powders by hot iso-static pressing (HIP), followed by their machining, hot extrusion, heat treatment, and if necessary further machining to make specimens of desired shape. Each step in this manufacturing process introduces some defects, so that the mechanical and physical properties measured using these samples, such as the Young modulus, the thermal conductivity and the coefficient of thermal expansion can be very different from the expected values, despite the fact that the density of the composite measured on the same samples is very close to its theoretical value. As a result open porosity is not the likely cause and it is reasonable to suspect that closed pores (e.g. micro-cracks) in the copper matrix and at the interfaces of the alumina inclusions formed during the multi-stage manufacture of test samples are responsible for the differences in the measured and expected mechanical and thermal properties.
Computers & Structures, 1992
ABSTRACT
Magazine of Concrete Research, 2005
Part I of this three-part paper describes the various steps that led to the development of a clas... more Part I of this three-part paper describes the various steps that led to the development of a class of high performance short steel fibre-reinforced cementitious composites (HPFRCCs) which has been patented under the trade name CARDIFRC®. This class of materials generally contains no coarse aggregates and is characterised by high tensile/flexural strength and high toughness. A method is proposed for quantifying the workability of such a mix without fibres in terms of its fracture toughness.
Rationalised computational time in fracture simulation: adaptive model reduction and domain decom... more Rationalised computational time in fracture simulation: adaptive model reduction and domain decomposition
Journal of Materials in Civil Engineering, 2010
ABSTRACT This study investigates the effect of thermal cycling on the performance of concrete bea... more ABSTRACT This study investigates the effect of thermal cycling on the performance of concrete beams retrofitted with CARDIFRC, a new class of high performance fiber-reinforced cement-based material that is compatible with concrete. Twenty four beams were subjected to 24 h thermal cycles between 25 and 90°C. One third of the beams were reinforced either in flexure only or in flexure and shear with conventional steel reinforcement and used as control specimens. The remaining sixteen beams were retrofitted with CARDIFRC strips to provide external flexural and/or shear strengthening. All beams were exposed to a varied number of 24 h thermal cycles ranging from 0 to 90 and were tested in four-point bending at room temperature. The tests indicated that the retrofitted members were stronger and stifferthan control beams, and more importantly, that their failure initiated in flexure without any signs of interfacial delamination cracking. The results of these tests are presented and compared to analytical predictions. The predictions show good correlation with the experimental results.
Engineering Fracture Mechanics, 2007
... Another problem, which has also been observed with this technique, is the effect of long expo... more ... Another problem, which has also been observed with this technique, is the effect of long exposure to temperature variations [5], [6] and [7]. A new retrofitting technique using CARDIFRC, a material compatible with concrete, has recently been developed at Cardiff University. ...
International Journal of Solids and Structures
ABSTRACT
International Journal of Solids and Structures
... can be reduced to the following design requirement C -> C,,. (1.5) The optimization proble... more ... can be reduced to the following design requirement C -> C,,. (1.5) The optimization problem at ... ie the problem of minimizing the cross-sectional area Minimum-weight design of multi-purpose cylindrical bars ... It is not difficult to show that this problem has a dual, viz, the problem of ...
International Journal of Solids and Structures
Structural Optimization
ABSTRACT
Composite Structures 3, 1985
Proceedings of an international conference on Fracture Mechanics in Engineering Application, 1979
5th Symposium on Multidisciplinary Analysis and Optimization, 1994