The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Hitoshi Soyama - One of the best experts on this subject based on the ideXlab platform.
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using cavitation peening to enhance the fatigue strength of Duralumin plate containing a hole with rounded edges
Surface & Coatings Technology, 2016Co-Authors: Osamu Takakuwa, Fumio Takeo, M Sato, Hitoshi SoyamaAbstract:Abstract The purpose of this study is to examine the effect of peening on the fatigue life of a Duralumin plate containing a hole with rounded edges. To this end, Duralumin plates containing holes with rounded edges with a radius of 0.5 mm were treated by cavitation peening (CP) and shot peening (SP). Fatigue tests under uniaxial tensile loading were carried out to obtain the lifetime versus applied stress curves, i.e., the S - N curves. Then, the fractured surfaces were examined using SEM. Also, a combination of residual stress measurements with electro-chemical polishing was carried out to evaluate the compressive residual stress profile with respect to the depth into the wall surrounding the hole. The results showed that the lifetime of the CP specimen was almost 25 times larger than that of the as-machined one. The fatigue strength, also, was increased by 18% by cavitation peening. In contrast, shot peening reduced the lifetime, since this caused the formation of a roll over layer at the rounded edges, from which cracks due to high stress can initiate. The effect on the fatigue strength of a plate with a hole can be explained on the basis of whether or not roll over occurs and on the residual stress profile with respect to the depth from the surface surrounding the hole.
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comparison between cavitation peening and shot peening for extending the fatigue life of a Duralumin plate with a hole
Journal of Materials Processing Technology, 2016Co-Authors: Hitoshi Soyama, Fumio TakeoAbstract:Abstract In order to demonstrate the advantages of cavitation peening, in which the impact due to cavitation bubbles collapsing is used to mechanically treat a surface, compared with shot peening, the fatigue lives of peened specimens comprising Duralumin plates with open holes were evaluated. In the present experiment, cavitation bubbles were generated by injecting a high speed water jet into a water filled chamber, producing what is known as a cavitating jet. The specimens, which had either a chamfered or rounded edge hole, were treated by cavitation peening and shot peening, then tested using a tensile fatigue test. The fatigue life of the shot peened specimen was equal to or less than that of the as machined specimen, whereas cavitation peening extended the fatigue life. When the cavitating jet was injected in such a way that the cavitation bubbles collapsed at the wall surrounding the hole, the fatigue life at a maximum tensile stress, σ max , of 150 MPa was extended by more than a factor of ten. It was also demonstrated that cavitation peening introduced compressive residual stress of about 300 MPa into the wall surrounding the hole.
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mechanical surface treatment of Duralumin plate by bubble induced by pulse laser
Journal of Physics: Conference Series, 2015Co-Authors: Hitoshi Soyama, Hirotoshi Sasaki, S Endo, Yuka IgaAbstract:Surface of Duralumin plate can be treated by not only laser abrasion but also bubble induced by pulse laser. The pulse laser produced two kinds of shock waves related to laser abrasion and bubble collapse. In the case of laser peening, the shock wave induced by abrasion was normally used. In the present paper, the behaviour of bubble was observed and noise was detected by the hydrophone. It was revealed that the impact induced by the bubble collapse produced by the pulse laser was stronger than that of the laser abrasion. A numerical simulation was also carried out to investigate phenomenon of bubble collapse.
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Suppression of Fatigue Crack Propagation of Duralumin by Cavitation Peening
The Journal of Engineering, 2015Co-Authors: Hitoshi Soyama, Osamu Takakuwa, Naoki Kumagai, Fumio TakeoAbstract:It was demonstrated in the present paper that cavitation peening which is one of the mechanical surface modification technique can suppress fatigue crack propagation in Duralumin. The impacts produced when cavitation bubble collapses can be utilised for the mechanical surface modification technique in the same way as laser peening and shot peening, which is called “cavitation peening”. Cavitation peening employing a cavitating jet in water was used to treat the specimen made of Duralumin Japanese Industrial Standards JIS A2017-T3. After introducing a notch, fatigue test was conducted by a load-controlled plate bending fatigue tester, which has been originally developed. The fatigue crack propagation behavior was evaluated and the relationship between the fatigue crack propagation rate versus stress intensity factor range was obtained. From the results, the fatigue crack propagation rate was drastically reduced by cavitation peening and the fatigue life of Duralumin plate was extended 4.2 times by cavitation peening. In addition, the fatigue crack propagation can be suppressed by 88% in the stable crack propagation stage by cavitation peening.
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The Use of Cavitation Peening to Increase the Fatigue Strength of Duralumin Plates Containing Fastener Holes
Materials Sciences and Applications, 2014Co-Authors: Hitoshi SoyamaAbstract:An effective method for improving the fatigue life of Duralumin plates with fastener holes, such as those used in the construction of aircraft, is to introduce a compressive residual stress around the fastener holes. Cavitation peening is a novel peening method that uses the cavitation impact produced when a high-speed water jet is injected into a water-filled chamber. In this paper, Duralumin plate specimens with holes were treated by cavitation peening under various conditions, and the fatigue strength of the specimens was determined using a plate bending fatigue test. It was revealed that a compressive residual stress was introduced not only on surfaces perpendicular to the axis of the cavitating jet but also on the walls of holes which were parallel to this. It was found that a 51% improvement in fatigue strength could be achieved by cavitation peening. Note that this is first report demonstrating an improvement in the fatigue life of Duralumin plates with fastener holes by cavitation peening.
A H W Ngan - One of the best experts on this subject based on the ideXlab platform.
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the weakest size of precipitated alloys in the micro regime the case of Duralumin
Journal of Materials Research, 2017Co-Authors: Kefu Gan, A H W NganAbstract:In the microsize regime, all crystalline metals studied to-date exhibit a “smaller-is-stronger” size effect. Here, we report an unusual weakest-size phenomenon in the precipitated alloy Duralumin 2025, i.e., below a critical size of ∼7 µm, the strength increases as the size decreases, while above this size, the strength increases toward the bulk value with increasing size. At the critical size, strain-hardening is also slowest and the room-temperature creep is fastest. Interestingly, the reduction of strength at the weakest size is more significant for the peak-aged state of Duralumin 2025 than its naturally aged state. Theoretical modeling shows that at the weakest size, both strengthening mechanisms of precipitation hardening and dislocation starvation are ineffective. The present results indicate that the conventional wisdom of precipitation hardening is not applicable in the micro-regime, and the common “smaller-is-stronger” understanding is incorrect when material microstructures impose internal length scales that can affect strength.
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size dependent creep of Duralumin micro pillars at room temperature
International Journal of Plasticity, 2014Co-Authors: A H W NganAbstract:Abstract The strength of aluminum alloy 2025 (Duralumin) micro-pillars is known to be significantly higher than that of pure Al micro-pillars of comparable sizes since the precipitates present act as obstacles to trap dislocations within the small sample volume. In this work, the creep behavior of precipitate-hardened Duralumin micro-pillars of sizes ∼1 μm to ∼6.5 μm is investigated by compression experiments at room temperature. The effects of an internal grain boundary were also investigated by comparing the creep behavior between single crystalline and bi-crystalline micro-pillars. The results reveal that peak-aged Duralumin pillars, in which the produced precipitates can efficiently block mobile dislocations, show increasingly significant creep with increasing pillar size, with a typical creep rate of ∼10−4 s−1 which is drastically larger than that of bulk at room temperature. The bi-crystalline pillars creep even faster than the single crystalline counterparts. TEM examination of the deformed microstructures reveals that the creep rate depends on the residual dislocation density, indicating that dislocations are the agents for creep. Theoretical modeling suggests that the steady-state creep rate is proportional to the lifetime of mobile dislocations, which rises with specimen size in the microns range due to the fact that the dislocations are not easily pinned in this range. As the pillar size increases in this range, the dislocations spend longer time in viscous motion across the specimen, hence the retained dislocation density is higher which leads to a higher strain rate according to the Orowan equation. It is expected that this trend of creep rate with specimen size will be reversed for larger specimens, probably in the tens of microns range, when dislocations experience a higher chance of being pinned and immobilized by the precipitates.
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size effect on deformation of Duralumin micropillars a dislocation dynamics study
Scripta Materialia, 2014Co-Authors: P P S Leung, A H W NganAbstract:Two-dimensional dislocation dynamics simulations are used to study precipitate strengthening effects in Duralumin micropillars. The results show that a refined microstructure may resist and slow down the movement of dislocations inside the confined volume, leading to hardening and a weak dependence of strength on size. This study illustrates that the deformation behavior of small crystals is controlled by the combined effect of the internal length scale and the external size of the crystal.
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size effect on the deformation behavior of Duralumin micropillars
Scripta Materialia, 2013Co-Authors: A H W NganAbstract:Pure metal microspecimens have been found to exhibit strong size dependence of strength, but alloyed counterparts with a much refined microstructural length scale due to the precipitates present are as yet unknown. Here, compression tests on Duralumin (aluminum 2025 alloy) micropillars reveal a much weaker size dependence of strength compared to pure Al, indicating the predominance of the internal length scale in determining strength. Creep is also significant in Duralumin, probably due to the viscous overcoming of obstacles during deformation.
Fumio Takeo - One of the best experts on this subject based on the ideXlab platform.
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using cavitation peening to enhance the fatigue strength of Duralumin plate containing a hole with rounded edges
Surface & Coatings Technology, 2016Co-Authors: Osamu Takakuwa, Fumio Takeo, M Sato, Hitoshi SoyamaAbstract:Abstract The purpose of this study is to examine the effect of peening on the fatigue life of a Duralumin plate containing a hole with rounded edges. To this end, Duralumin plates containing holes with rounded edges with a radius of 0.5 mm were treated by cavitation peening (CP) and shot peening (SP). Fatigue tests under uniaxial tensile loading were carried out to obtain the lifetime versus applied stress curves, i.e., the S - N curves. Then, the fractured surfaces were examined using SEM. Also, a combination of residual stress measurements with electro-chemical polishing was carried out to evaluate the compressive residual stress profile with respect to the depth into the wall surrounding the hole. The results showed that the lifetime of the CP specimen was almost 25 times larger than that of the as-machined one. The fatigue strength, also, was increased by 18% by cavitation peening. In contrast, shot peening reduced the lifetime, since this caused the formation of a roll over layer at the rounded edges, from which cracks due to high stress can initiate. The effect on the fatigue strength of a plate with a hole can be explained on the basis of whether or not roll over occurs and on the residual stress profile with respect to the depth from the surface surrounding the hole.
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comparison between cavitation peening and shot peening for extending the fatigue life of a Duralumin plate with a hole
Journal of Materials Processing Technology, 2016Co-Authors: Hitoshi Soyama, Fumio TakeoAbstract:Abstract In order to demonstrate the advantages of cavitation peening, in which the impact due to cavitation bubbles collapsing is used to mechanically treat a surface, compared with shot peening, the fatigue lives of peened specimens comprising Duralumin plates with open holes were evaluated. In the present experiment, cavitation bubbles were generated by injecting a high speed water jet into a water filled chamber, producing what is known as a cavitating jet. The specimens, which had either a chamfered or rounded edge hole, were treated by cavitation peening and shot peening, then tested using a tensile fatigue test. The fatigue life of the shot peened specimen was equal to or less than that of the as machined specimen, whereas cavitation peening extended the fatigue life. When the cavitating jet was injected in such a way that the cavitation bubbles collapsed at the wall surrounding the hole, the fatigue life at a maximum tensile stress, σ max , of 150 MPa was extended by more than a factor of ten. It was also demonstrated that cavitation peening introduced compressive residual stress of about 300 MPa into the wall surrounding the hole.
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Suppression of Fatigue Crack Propagation of Duralumin by Cavitation Peening
The Journal of Engineering, 2015Co-Authors: Hitoshi Soyama, Osamu Takakuwa, Naoki Kumagai, Fumio TakeoAbstract:It was demonstrated in the present paper that cavitation peening which is one of the mechanical surface modification technique can suppress fatigue crack propagation in Duralumin. The impacts produced when cavitation bubble collapses can be utilised for the mechanical surface modification technique in the same way as laser peening and shot peening, which is called “cavitation peening”. Cavitation peening employing a cavitating jet in water was used to treat the specimen made of Duralumin Japanese Industrial Standards JIS A2017-T3. After introducing a notch, fatigue test was conducted by a load-controlled plate bending fatigue tester, which has been originally developed. The fatigue crack propagation behavior was evaluated and the relationship between the fatigue crack propagation rate versus stress intensity factor range was obtained. From the results, the fatigue crack propagation rate was drastically reduced by cavitation peening and the fatigue life of Duralumin plate was extended 4.2 times by cavitation peening. In addition, the fatigue crack propagation can be suppressed by 88% in the stable crack propagation stage by cavitation peening.
Hideaki Tsukamoto - One of the best experts on this subject based on the ideXlab platform.
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damping properties of aluminum Duralumin multi layered graded structures fabricated by hot rolling
American Journal of Physical Chemistry, 2017Co-Authors: Hideaki TsukamotoAbstract:This study aims to fabricate aluminum (A1050)/ Duralumin (A2017) multi-layered structures with interface composition gradient by hot rolling, and investigate their nanoindentation properties, and macro-mechanical property such as damping. 2- and 6-layered aluminum/ Duralumin graded structures with asymmetric lay-ups from one side of aluminum to another side of Duralumin have been fabricated, which suffer from three different heat-treatments such as (1) as-rolled (no heat-treatment), (2) annealed at 400°C and (3) homogenized at 500°C followed by water quenching and aging (T4 heat treatment). Nanoindentation demonstrated higher hardness and elastic modulus correspond to higher Cu content in annealed and aged samples. Duralumin in annealed samples shows much lower hardness and elastic modulus than those in as-rolled and aged ones. For damping properties, 2-layered graded structures show higher values than 6-layered graded structures, which are lower than single layers of aluminum.
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impact compressive behavior of deep drawn cups consisting of aluminum Duralumin multi layered graded structures
Materials Science and Engineering B-advanced Functional Solid-state Materials, 2015Co-Authors: Hideaki TsukamotoAbstract:Abstract This study aims to investigate impact compressive behavior of deep-drawn cups consisting of aluminum (A1050)/Duralumin (A2017) multi-layered structures, which are fabricated by hot rolling. Such multi-layered structures are possibly used for a new type of crash boxes in automobiles to effectively absorb impact energy. The effect of heat treatments on micro-Vickers hardness gradients at the interfaces between layers in 2 and 6-layered aluminum/Duralumin structures have been investigated. Impact compressive behavior of deep-drawn cups consisting of such aluminum/Duralumin multi-layered graded structures has been studied in terms of energy absorption, maximum force and maximum displacement with examination based on micro-Vickers hardness results. Deep-drawn cups consisting of 6-layerd clad structures with gradient properties exhibited superior impact compressive characteristics to be effective in application to vehicle crash absorbers.
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effect of compositional gradient on mechanical properties in aluminum Duralumin multi layered clad structures
SPIE Micro+Nano Materials Devices and Applications, 2013Co-Authors: Hideaki Tsukamoto, Yoshiki Komiya, Hisashi Sato, Yoshimi WatanabeAbstract:This study aims to investigate the effect of compositional gradient on nano-, micro- and macro-mechanical properties in aluminum (A1050)/ Duralumin (A2017) multi-layered clad structures fabricated by hot rolling. Such multilayered clad structures are possibly adopted to a new type of automobile crash boxes to effectively absorb the impact forces generated when automobiles having collisions. 2- and 6-layered clad structures with asymmetric lay-ups from one side of aluminum to another side of Duralumin have been fabricated, which have been suffering three different heattreatments such as (1) as-rolled (no heat-treatment), (2) annealed at 400°C and (3) homogenized at 500°C followed by water quenching and aging (T4 heat treatment). For nano- and micro-scale mechanical properties proved by nanoindentation, higher hardness and elastic modulus correspond to higher Cu content at the interface in annealed and aged samples. For macro-scale mechanical properties, internal friction of 2-layered clad structures is higher than that of 6-layered clad structures in any heat-treatment samples. Deep drawing formability of annealed samples is considerably high compared to as-rolled and aged ones.
Avanish Kumar Dubey - One of the best experts on this subject based on the ideXlab platform.
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artificial intelligence based modeling and optimization of heat affected zone in nd yag laser cutting of Duralumin sheet
Journal of Intelligent and Fuzzy Systems, 2014Co-Authors: Gavendra Norkey, Avanish Kumar Dubey, Sanat AgrawalAbstract:Duralumin is an alloy of aluminium which has some unique properties such as high strength to weight ratio, high resistance to corrosion, light in weight, and more demanding alloy in various sectors such as space craft, marine, chemical industries, construction and automobile. These applications require very precise and complex shapes which may not be obtained with conventional machining. Pulsed Nd:YAG laser cutting may be used to fulfill these objectives by using optimum setting of process parameters. The present research paper has experimentally investigated the modeling and optimization of heat affected zone in the pulsed Nd:YAG laser cutting of Duralumin sheet with the aim to minimize heat affected zone. The quality is improved by the proper control of different process parameters such as gas pressure, pulse width, pulse frequency and scanning speed. Artificial intelligence (AI) algorithms have been used to solve the many engineering problems successfully through development of Genetic Algorithm (GA), Fuzzy Logic (FL) and Artificial Neural Network (ANN) systems. The optimization of heat affected zone has been carried out by using Hybrid Approach of Multiple Regression Analysis (MRA) and GA. In this methodology, the second order regression model has been developed by using MRA with the help of experimental data obtained by L27 orthogonal array (OA). Further this equation has been used as objective function in GA based optimization. The significant factors have been found with further discussion of their effect on the heat affected zone.
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multiple quality optimization in laser cutting of difficult to laser cut material using grey fuzzy methodology
The International Journal of Advanced Manufacturing Technology, 2013Co-Authors: Arun Kumar Pandey, Avanish Kumar DubeyAbstract:This paper investigates the laser cutting performance of 1 mm Duralumin sheet with the aim to improve quality of cut by simultaneously optimising multiple performances such as cut edge surface roughness, kerf taper and kerf width. The experimental data obtained by Taguchi methodology-based L27 orthogonal array experimentation have been used in the hybrid approach optimization of grey relational analysis and fuzzy logic theory. The predicted optimum results have been verified by conducting confirmation experiments. The verification results show an overall improvement of 19 % in multiple quality characteristics. The effects of significant factors on quality characteristics have also been discussed.
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Modeling and Optimization of Kerf Taper in Pulsed Laser Cutting of Duralumin Sheet
ASME 2012 International Manufacturing Science and Engineering Conference, 2012Co-Authors: Arun Kumar Pandey, Avanish Kumar DubeyAbstract:Duralumin sheets are strong, hard, light weight and heat treated alloy of Aluminum, widely used by different sectors such as automobile, marine, aircraft and satellites. Many a times those applications demand complex shapes and intricate profiles with stringent design requirements which are not completely achieved by conventional sheet cutting methods. Laser cutting has capability of quality cutting with above requirements in thin sheetmetals. But highly reflective and thermally conductive sheetmetals like Duralumin pose difficulty in achieving quality cuts by laser beam. The kerf taper always occurs in laser cut specimen due to inherent converging-diverging profile of laser beam. The optimization of kerf taper and other cut qualities such as surface roughness, heat affected zone and recast layer formation in difficult-to-laser-cut sheetmetals like Duralumin or Aluminium alloy has become recent research interests. The aim of present research is to optimize kerf taper in pulsed laser cutting of Duralumin sheet using hybrid approach of ‘design of experiment (DOE)’ and ‘artificial intelligence tool’ such as genetic algorithm. The empirical model for kerf taper has also been proposed with the discussion on parametric effect.© 2012 ASME
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taguchi based fuzzy logic optimization of multiple quality characteristics in laser cutting of Duralumin sheet
Optics and Lasers in Engineering, 2012Co-Authors: Arun Kumar Pandey, Avanish Kumar DubeyAbstract:Abstract Capability of laser cutting mainly depends on optical and thermal properties of work material. Highly reflective and thermally conductive Duralumin sheets are difficult-to-laser-cut. Application of Duralumin sheets in aeronautic and automotive industries due to its high strength to weight ratio demand narrow and complex cuts with high geometrical accuracy. The present paper experimentally investigates the laser cutting of Duralumin sheet with the aim to improve geometrical accuracy by simultaneously minimizing the kerf width and kerf deviations at top and bottom sides. A hybrid approach, obtained by combining robust parameter design methodology and Fuzzy logic theory has been applied to compute the fuzzy multi-response performance index. This performance index is further used for multi-objective optimization. The predicted optimum results have been verified by performing the confirmation tests. The confirmation tests show considerable reduction in kerf deviations at top and bottom sides.
