M. Aliha - Academia.edu (original) (raw)

Papers by M. Aliha

Acoustic emission (AE) source location is an essential part of any quantitative AE test as it pro... more Acoustic emission (AE) source location is an essential part of any quantitative AE test as it provides information about damage mechanisms and allows spatial separation so that signals from unwanted sources can be eliminated. In this paper, an AE source location technique described as the best-matched point search method is presented. The application of the bestmatched point search method is demonstrated in two source location experiments: one on a large anisotropic carbon-fibre composite (CFC) plate and one on a thick oolitic limestone disc. In the large composite plate test, source location is achieved using the S 0 mode, which displays a complicated group velocity pattern. In the oolitic limestone experiment, three-dimensional source location is demonstrated. The best-matched point search method successfully determines the location of AE sources in both tests. Errors in source location are attributed to the extraction of delta-t times from the AE signals.

Fatigue & Fracture of Engineering Materials & Structures

Applied Sciences

Asphalt mixture is a type of textured composite material made of aggregates and mastic part. Over... more Asphalt mixture is a type of textured composite material made of aggregates and mastic part. Overall strength and failure behavior in such materials depends on the texture or heterogeneity of the mixture. In particular, the crack growth mechanism from the tip of the pre-crack is significantly affected by the texture of the asphalt composite and environmental conditions. The crack can extend through the soft mastic, tight aggregates or interface of the mastic/aggregates. In this research, by performing some fracture tests on a typical asphalt mixture with different test specimens under mode I, mixed mode I/II and mixed mode I/III, the fracture resistance and trajectory of propagating crack is studied at two low and medium temperatures (i.e., −15 and +15 °C). The load bearing capacity and the fracture resistance of the tested asphalt samples increases by decreasing the temperature. It is also shown that a significant part of fracture plane passes through the soft mastic and boundary o...

Rock Mechanics and Rock Engineering

Frattura ed Integrità Strutturale

At intermediate service temperatures hot mix asphalt (HMA) concretely are subjected to different ... more At intermediate service temperatures hot mix asphalt (HMA) concretely are subjected to different loading rates due to movement of vehicles which can significantly affect their mechanical characteristics and final service load. Hence, in this paper the effect of loading rate on intermediate temperature fracture resistance of HMA materials is investigated experimentally in different modes of cracking. Different hot mix asphalt mixtures made of various compositions were subjected to asymmetric threepoint bend loading in the form of edge cracked semi-circular bend (SCB) specimens. The effect of aggregate type and air void were studied on the fracture energy values for three mode mixities (including pure mode I, mixed mode I/II and pure mode II) and at different temperatures of 5°C, 15°C and 25°C. Trends of change in fracture energy values revealed noticeable influence of loading rate on the low and intermediate temperature cracking behavior of tested asphalt mixtures with different air void contents and aggregate types subjected to mixed mode I/II loading. Also, a change observed in fracture resistance of asphalt mixtures at nearly zero (5°C) and intermediate temperatures (25°C) that was due to change in the behavior of bitumen from elastic to viscoelastic.

Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications

The welding tool parameters play a critical role in obtaining weld strength during friction stir ... more The welding tool parameters play a critical role in obtaining weld strength during friction stir welding. In this investigation, the effect of welding tool parameters such as pin and shoulder diameter and pin height on the axial and traverse forces and also temperature of welding of AA5083 alloy was investigated. A specially designed dynamometer was used to measure the welding tool forces. Then, the mechanical properties of the welds were characterized using tensile tests. Moreover, macrostructure of welds was investigated in order to analyze weld quality. Finally, optimum values for shoulder diameter, pin height and pin diameter were determined.

Engineering Fracture Mechanics

In this contribution, low temperature crack growth resistance of Warm Mix Asphalt (WMA) mixtures ... more In this contribution, low temperature crack growth resistance of Warm Mix Asphalt (WMA) mixtures reinforced with two types of fiber, namely natural Jute fiber and synthetic Polyolefin-Aramid (FORTA) fiber is investigated experimentally. Using semi-circular bend (SCB) specimen, the influence of different fiber weight percentages (0.3%, 0.5% and 0.7%) and test temperatures (0°, -10° and -20°C) on mixed mode I+II fracture toughness values (i.e. and ) are studied. It was shown that both fibers can increase in general the fracture resistance of WMA concrete relative to the control mixture. Moreover, modes I and II fracture toughness and effective fracture toughness values are increased by decreasing the test temperature or increasing the fiber content. The FORTA fiber provided better crack growth resistance characteristics than the Jute fiber for the WMA mixtures. The effects of both natural and synthetic fibers on enhancing the performance of the tested WMA mixtures was more pronounced for dominantly pure mode I loading case.

Fatigue & Fracture of Engineering Materials & Structures

Engineering Fracture Mechanics, 2011

An edge cracked semi-circular specimen subjected to asymmetric three-point bend loading was sugge... more An edge cracked semi-circular specimen subjected to asymmetric three-point bend loading was suggested for investigating mixed mode fracture in brittle materials. Using finite element analysis, the crack parameters were obtained for various crack lengths and different locations of loading points. It was shown that by selecting appropriate positions for the loading points, full mode mixities from pure mode I to pure mode II could be achieved. Then, a series of fracture tests were conducted on PMMA using the proposed specimen. Very good agreement was found between the experimental results and those predicted from the generalized maximum tangential stress criterion.

Strength of Materials, 2015

Fatigue & Fracture of Engineering Materials & Structures, 2016

Fracture of Nano and Engineering Materials and Structures, 2006

Cracked rock masses are usually subjected to complex loading conditions. Therefore, it is among f... more Cracked rock masses are usually subjected to complex loading conditions. Therefore, it is among favorite concepts for rock fracture researchers to investigate the fracture of rocks under mixed mode I/II loading. There are numerous experimental studies on mixed mode I/II fracture of rocks using different test specimens. Semi-circular bend (SCB) specimen is one of the favorite test configurations for conducting mixed mode fracture toughness experiments in rock materials. This specimen is simple and its manufacturing is inexpensive. By changing the parameters a/R, S/R and β(see Fig. 1), the SCB specimen can provide pure mode I, pure mode II and any combination of modes I and II.

International Journal of Solids and Structures, 2009

Glasses are known to be vulnerable to tensile stresses particularly in the presence of pre-existi... more Glasses are known to be vulnerable to tensile stresses particularly in the presence of pre-existing cracks. Since cracks in glass components are very often subjected to mixed mode loading, several researchers have studied mixed mode fracture in soda lime glass using different test specimens. Among these specimens, the cracked Brazilian disc specimen has been used most frequently by investigators. However,

International Journal of Solids and Structures, 2006

... 2005. Abstract. The cracked semi-circular specimen subjected to three-point bending has been ... more ... 2005. Abstract. The cracked semi-circular specimen subjected to three-point bending has been recognized as an appropriate test specimen for conducting mode I, mode II and mixed mode I/II fracture tests in brittle materials. ...

7th RILEM International Conference on Cracking in Pavements, 2012

Acoustic emission (AE) source location is an essential part of any quantitative AE test as it pro... more Acoustic emission (AE) source location is an essential part of any quantitative AE test as it provides information about damage mechanisms and allows spatial separation so that signals from unwanted sources can be eliminated. In this paper, an AE source location technique described as the best-matched point search method is presented. The application of the bestmatched point search method is demonstrated in two source location experiments: one on a large anisotropic carbon-fibre composite (CFC) plate and one on a thick oolitic limestone disc. In the large composite plate test, source location is achieved using the S 0 mode, which displays a complicated group velocity pattern. In the oolitic limestone experiment, three-dimensional source location is demonstrated. The best-matched point search method successfully determines the location of AE sources in both tests. Errors in source location are attributed to the extraction of delta-t times from the AE signals.

Fatigue & Fracture of Engineering Materials & Structures

Applied Sciences

Asphalt mixture is a type of textured composite material made of aggregates and mastic part. Over... more Asphalt mixture is a type of textured composite material made of aggregates and mastic part. Overall strength and failure behavior in such materials depends on the texture or heterogeneity of the mixture. In particular, the crack growth mechanism from the tip of the pre-crack is significantly affected by the texture of the asphalt composite and environmental conditions. The crack can extend through the soft mastic, tight aggregates or interface of the mastic/aggregates. In this research, by performing some fracture tests on a typical asphalt mixture with different test specimens under mode I, mixed mode I/II and mixed mode I/III, the fracture resistance and trajectory of propagating crack is studied at two low and medium temperatures (i.e., −15 and +15 °C). The load bearing capacity and the fracture resistance of the tested asphalt samples increases by decreasing the temperature. It is also shown that a significant part of fracture plane passes through the soft mastic and boundary o...

Rock Mechanics and Rock Engineering

Frattura ed Integrità Strutturale

At intermediate service temperatures hot mix asphalt (HMA) concretely are subjected to different ... more At intermediate service temperatures hot mix asphalt (HMA) concretely are subjected to different loading rates due to movement of vehicles which can significantly affect their mechanical characteristics and final service load. Hence, in this paper the effect of loading rate on intermediate temperature fracture resistance of HMA materials is investigated experimentally in different modes of cracking. Different hot mix asphalt mixtures made of various compositions were subjected to asymmetric threepoint bend loading in the form of edge cracked semi-circular bend (SCB) specimens. The effect of aggregate type and air void were studied on the fracture energy values for three mode mixities (including pure mode I, mixed mode I/II and pure mode II) and at different temperatures of 5°C, 15°C and 25°C. Trends of change in fracture energy values revealed noticeable influence of loading rate on the low and intermediate temperature cracking behavior of tested asphalt mixtures with different air void contents and aggregate types subjected to mixed mode I/II loading. Also, a change observed in fracture resistance of asphalt mixtures at nearly zero (5°C) and intermediate temperatures (25°C) that was due to change in the behavior of bitumen from elastic to viscoelastic.

Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications

The welding tool parameters play a critical role in obtaining weld strength during friction stir ... more The welding tool parameters play a critical role in obtaining weld strength during friction stir welding. In this investigation, the effect of welding tool parameters such as pin and shoulder diameter and pin height on the axial and traverse forces and also temperature of welding of AA5083 alloy was investigated. A specially designed dynamometer was used to measure the welding tool forces. Then, the mechanical properties of the welds were characterized using tensile tests. Moreover, macrostructure of welds was investigated in order to analyze weld quality. Finally, optimum values for shoulder diameter, pin height and pin diameter were determined.

Engineering Fracture Mechanics

In this contribution, low temperature crack growth resistance of Warm Mix Asphalt (WMA) mixtures ... more In this contribution, low temperature crack growth resistance of Warm Mix Asphalt (WMA) mixtures reinforced with two types of fiber, namely natural Jute fiber and synthetic Polyolefin-Aramid (FORTA) fiber is investigated experimentally. Using semi-circular bend (SCB) specimen, the influence of different fiber weight percentages (0.3%, 0.5% and 0.7%) and test temperatures (0°, -10° and -20°C) on mixed mode I+II fracture toughness values (i.e. and ) are studied. It was shown that both fibers can increase in general the fracture resistance of WMA concrete relative to the control mixture. Moreover, modes I and II fracture toughness and effective fracture toughness values are increased by decreasing the test temperature or increasing the fiber content. The FORTA fiber provided better crack growth resistance characteristics than the Jute fiber for the WMA mixtures. The effects of both natural and synthetic fibers on enhancing the performance of the tested WMA mixtures was more pronounced for dominantly pure mode I loading case.

Fatigue & Fracture of Engineering Materials & Structures

Engineering Fracture Mechanics, 2011

An edge cracked semi-circular specimen subjected to asymmetric three-point bend loading was sugge... more An edge cracked semi-circular specimen subjected to asymmetric three-point bend loading was suggested for investigating mixed mode fracture in brittle materials. Using finite element analysis, the crack parameters were obtained for various crack lengths and different locations of loading points. It was shown that by selecting appropriate positions for the loading points, full mode mixities from pure mode I to pure mode II could be achieved. Then, a series of fracture tests were conducted on PMMA using the proposed specimen. Very good agreement was found between the experimental results and those predicted from the generalized maximum tangential stress criterion.

Strength of Materials, 2015

Fatigue & Fracture of Engineering Materials & Structures, 2016

Fracture of Nano and Engineering Materials and Structures, 2006

Cracked rock masses are usually subjected to complex loading conditions. Therefore, it is among f... more Cracked rock masses are usually subjected to complex loading conditions. Therefore, it is among favorite concepts for rock fracture researchers to investigate the fracture of rocks under mixed mode I/II loading. There are numerous experimental studies on mixed mode I/II fracture of rocks using different test specimens. Semi-circular bend (SCB) specimen is one of the favorite test configurations for conducting mixed mode fracture toughness experiments in rock materials. This specimen is simple and its manufacturing is inexpensive. By changing the parameters a/R, S/R and β(see Fig. 1), the SCB specimen can provide pure mode I, pure mode II and any combination of modes I and II.

International Journal of Solids and Structures, 2009

Glasses are known to be vulnerable to tensile stresses particularly in the presence of pre-existi... more Glasses are known to be vulnerable to tensile stresses particularly in the presence of pre-existing cracks. Since cracks in glass components are very often subjected to mixed mode loading, several researchers have studied mixed mode fracture in soda lime glass using different test specimens. Among these specimens, the cracked Brazilian disc specimen has been used most frequently by investigators. However,

International Journal of Solids and Structures, 2006

... 2005. Abstract. The cracked semi-circular specimen subjected to three-point bending has been ... more ... 2005. Abstract. The cracked semi-circular specimen subjected to three-point bending has been recognized as an appropriate test specimen for conducting mode I, mode II and mixed mode I/II fracture tests in brittle materials. ...

7th RILEM International Conference on Cracking in Pavements, 2012