The Experts below are selected from a list of 150 Experts worldwide ranked by ideXlab platform
J G Tom - One of the best experts on this subject based on the ideXlab platform.
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effects of ambient temperature on a quasi static axial crush configuration response of thin wall steel box components
Thin-walled Structures, 2009Co-Authors: B P Dipaolo, J G TomAbstract:Abstract An experimental investigation was performed to study the effects of ambient temperature on axial-crush response of steel, square box components. Test specimens were obtained from commercially produced, welded tube lengths of ASTM A36 and ASTM A513 Type 1 plain low-carbon steels and AISI 316 and AISI 304 austenitic stainless steels. Quasi-Static Testing was performed at different temperatures using a universal Testing machine with an environmental chamber. Removable grooved caps for end constraints and collapse initiators in the form of shallow-machined groove patterns on specimen sidewalls were used to restrict the response of the test specimens to a specific configuration (fold-formation process and the corresponding axial load–axial displacement curve shape) of the symmetric axial-crush response mode. Overall, results indicate that, for three ambient temperatures within automotive thermal operating conditions, axial crush can be restricted to a specific configuration response and a controlled and repeatable energy-absorption process can be obtained. However, depending on the material type, secondary folding-phase load and energy-absorption crush characteristics can be significantly influenced by ambient temperature.
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a study on an axial crush configuration response of thin wall steel box components the quasi static experiments
International Journal of Solids and Structures, 2006Co-Authors: B P Dipaolo, J G TomAbstract:An experimental investigation was performed to study a specific axial crush configuration response of steel, square box components under Quasi-Static Testing conditions. For a specific cross-sectional geometry/fabrication process, test specimens were obtained from commercially produced, welded tube lengths of ASTM A36 and ASTM A513 Type 1 plain low-carbon steels and AISI 316 and AISI 304 austenitic stainless steels. Removable grooved caps were used to constrain tube test specimen ends, and collapse initiators in the form of shallow machined grooves were used to control the initial transverse deformations of the test specimen sidewalls. The progressive plastic deformation for all of the test specimens was restricted to the prototype configuration response (fold formation process and the corresponding axial load-axial displacement curve shape) of the symmetric axial crush mode. Crush characteristics were evaluated and, for each material type, observed differences were less than 7% for maximum and minimum load magnitudes and less than 2% for energy absorption, displacement, and mean load quantities in both the initial phase and the secondary folding phase cycles. Overall, results of the study indicate that for a significant range of material strengths, a controlled and repeatable energy absorption process can be obtained for commercially produced steel box components undergoing symmetric axial crush response.
B P Dipaolo - One of the best experts on this subject based on the ideXlab platform.
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effects of ambient temperature on a quasi static axial crush configuration response of thin wall steel box components
Thin-walled Structures, 2009Co-Authors: B P Dipaolo, J G TomAbstract:Abstract An experimental investigation was performed to study the effects of ambient temperature on axial-crush response of steel, square box components. Test specimens were obtained from commercially produced, welded tube lengths of ASTM A36 and ASTM A513 Type 1 plain low-carbon steels and AISI 316 and AISI 304 austenitic stainless steels. Quasi-Static Testing was performed at different temperatures using a universal Testing machine with an environmental chamber. Removable grooved caps for end constraints and collapse initiators in the form of shallow-machined groove patterns on specimen sidewalls were used to restrict the response of the test specimens to a specific configuration (fold-formation process and the corresponding axial load–axial displacement curve shape) of the symmetric axial-crush response mode. Overall, results indicate that, for three ambient temperatures within automotive thermal operating conditions, axial crush can be restricted to a specific configuration response and a controlled and repeatable energy-absorption process can be obtained. However, depending on the material type, secondary folding-phase load and energy-absorption crush characteristics can be significantly influenced by ambient temperature.
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a study on an axial crush configuration response of thin wall steel box components the quasi static experiments
International Journal of Solids and Structures, 2006Co-Authors: B P Dipaolo, J G TomAbstract:An experimental investigation was performed to study a specific axial crush configuration response of steel, square box components under Quasi-Static Testing conditions. For a specific cross-sectional geometry/fabrication process, test specimens were obtained from commercially produced, welded tube lengths of ASTM A36 and ASTM A513 Type 1 plain low-carbon steels and AISI 316 and AISI 304 austenitic stainless steels. Removable grooved caps were used to constrain tube test specimen ends, and collapse initiators in the form of shallow machined grooves were used to control the initial transverse deformations of the test specimen sidewalls. The progressive plastic deformation for all of the test specimens was restricted to the prototype configuration response (fold formation process and the corresponding axial load-axial displacement curve shape) of the symmetric axial crush mode. Crush characteristics were evaluated and, for each material type, observed differences were less than 7% for maximum and minimum load magnitudes and less than 2% for energy absorption, displacement, and mean load quantities in both the initial phase and the secondary folding phase cycles. Overall, results of the study indicate that for a significant range of material strengths, a controlled and repeatable energy absorption process can be obtained for commercially produced steel box components undergoing symmetric axial crush response.
Bharat Gwalani - One of the best experts on this subject based on the ideXlab platform.
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influence of ordered l1 2 precipitation on strain rate dependent mechanical behavior in a eutectic high entropy alloy
Scientific Reports, 2019Co-Authors: Bharat Gwalani, Sindhura Gangireddy, Yufeng Zheng, V Soni, Rajiv S Mishra, Rajarshi BanerjeeAbstract:Recent studies indicate that eutectic high-entropy alloys can simultaneously possess high strength and high ductility, which have potential industrial applications. The present study focuses on Al0.7CoCrFeNi, a lamellar dual-phase (fcc + B2) precipitation-strengthenable eutectic high entropy alloy. This alloy exhibits an fcc + B2 (B2 with bcc nano-precipitates) microstructure resulting in a combination of the soft and ductile fcc phase together with hard B2 phase. Low temperature annealing leads to the precipitation of ordered L12 intermetallic precipitates within the fcc resulting in enhanced strength. The strengthening contribution due to fine scale L12 is modeled using Orowan dislocation bowing and by-pass mechanism. The alloy was tested under Quasi-Static (strain-rate = 10−3 s−1) tensile loading and dynamic (strain-rate = 103 s−1) compressive loading. Due to the fine lamellar microstructure with a large number of fcc-bcc interfaces, the alloy show relatively high flow-stresses, ~1400 MPa under Quasi-Static loading and in excess of 1800 MPa under dynamic loading. Interestingly, the coherent nano-scale L12 precipitate caused a significant rise in the yield strength, without affecting the strain rate sensitivity (SRS) significantly. These lamellar structures had higher work hardening due to their capability for easily storing higher dislocation densities. The back-stresses from the coherent L12 precipitate were insufficient to cause improvement in twin nucleation, owing to elevated twinning stress under Quasi-Static Testing. However, under dynamic Testing high density of twins were observed.
Rajarshi Banerjee - One of the best experts on this subject based on the ideXlab platform.
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influence of ordered l1 2 precipitation on strain rate dependent mechanical behavior in a eutectic high entropy alloy
Scientific Reports, 2019Co-Authors: Bharat Gwalani, Sindhura Gangireddy, Yufeng Zheng, V Soni, Rajiv S Mishra, Rajarshi BanerjeeAbstract:Recent studies indicate that eutectic high-entropy alloys can simultaneously possess high strength and high ductility, which have potential industrial applications. The present study focuses on Al0.7CoCrFeNi, a lamellar dual-phase (fcc + B2) precipitation-strengthenable eutectic high entropy alloy. This alloy exhibits an fcc + B2 (B2 with bcc nano-precipitates) microstructure resulting in a combination of the soft and ductile fcc phase together with hard B2 phase. Low temperature annealing leads to the precipitation of ordered L12 intermetallic precipitates within the fcc resulting in enhanced strength. The strengthening contribution due to fine scale L12 is modeled using Orowan dislocation bowing and by-pass mechanism. The alloy was tested under Quasi-Static (strain-rate = 10−3 s−1) tensile loading and dynamic (strain-rate = 103 s−1) compressive loading. Due to the fine lamellar microstructure with a large number of fcc-bcc interfaces, the alloy show relatively high flow-stresses, ~1400 MPa under Quasi-Static loading and in excess of 1800 MPa under dynamic loading. Interestingly, the coherent nano-scale L12 precipitate caused a significant rise in the yield strength, without affecting the strain rate sensitivity (SRS) significantly. These lamellar structures had higher work hardening due to their capability for easily storing higher dislocation densities. The back-stresses from the coherent L12 precipitate were insufficient to cause improvement in twin nucleation, owing to elevated twinning stress under Quasi-Static Testing. However, under dynamic Testing high density of twins were observed.
C R Calladine - One of the best experts on this subject based on the ideXlab platform.
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inertia and strain rate effects in a simple plate structure under impact loading
International Journal of Impact Engineering, 1991Co-Authors: L L Tam, C R CalladineAbstract:Summary Previous studies have shown that the way in which metal structures absorb energy by gross distortion under impact conditions depends on the generic type of structure. In particular they have shown that structures which respond to Quasi-Static Testing by means of an initial peak load followed by a falling load as deformation proceeds (‘type II’ response, corresponding broadly to plates loaded endwise) exhibit both inertia and strain-rate effects under impact loading from moving strikers. This paper describes a detailed study of these phenomena by means of experiment and theory. Experiments were conducted in a drop-hammer rig on a large number of specimens having the same general geometry, but made in two different sizes and of two different materials (mild steel, aluminium alloy) chosen for their different strain-rate characteristics in the plastic range. The experiments involved the overall measurement of final distortion of the specimens in relation to a wide range of Testing conditions with moderate velocity; strain gauge studies, high-speed photography and other investigations of the detailed behaviour. The main emphasis of the various assays was to discover the way in which the initial kinetic energy of the striker was dissipated within the structure. During the course of the work, Zhang and Yu proposed a simple analysis of the same phenomena by means of a model based on the ideas of classical inelastic impact theory. According to their theory, a significant fraction of the incident kinetic energy of the striker is absorbed during the initial impact event; and this fraction depends only on the ratio of the mass of the striker to the mass of the specimen and the initial crookedness, but not on the velocity of impact. Our experiments agreed with this analysis in some overall respects, but were irreconcilable with it in several others, for which we had amassed substantial data. We therefore produced a revised analysis, which was less austere than that of Zhang and Yu but which nevertheless remained essentially simple. We show in the paper that this new theory agrees satisfactorily with all aspects of the experimental observations. The analysis reveals clearly the roles of inertia and strain rate in impact conditions. It also produces two new dimensionless groups, which together provide a key to classification of the various patterns of behaviour which are possible in the impact response of ‘type II” specimens.