The Experts below are selected from a list of 82356 Experts worldwide ranked by ideXlab platform
Theodore L Karavasilis - One of the best experts on this subject based on the ideXlab platform.
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ultralow cycle Fatigue Tests and fracture prediction models for duplex stainless steel devices of high seismic performance braced frames
Journal of Structural Engineering-asce, 2019Co-Authors: Marco Baiguera, George Vasdravellis, Theodore L KaravasilisAbstract:AbstractThis paper presents ultralow cycle Fatigue Tests and the calibration of different fracture models for duplex stainless-steel devices of high seismic performance braced frames. Two different...
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Ultralow Cycle Fatigue Tests and Fracture Prediction Models for Duplex Stainless-Steel Devices of High Seismic Performance Braced Frames
ASCE-AMER SOC CIVIL ENGINEERS, 2019Co-Authors: Baiguera M, Vasdravellis G, Theodore L KaravasilisAbstract:This paper presents ultralow cycle Fatigue Tests and the calibration of different fracture models for duplex stainless-steel devices of high seismic performance braced frames. Two different geometries of the devices were tested in full scale under 14 cyclic loading protocols up to fracture. The imposed protocols consisted of standard, constant-amplitude, and randomly generated loading histories. The test results show that the devices have stable hysteresis, high postyield stiffness, and large energy-dissipation and fracture capacities. Following the Tests, two micromechanics-based models, i.e., the cyclic void growth model and the built-in ABAQUS ductile fracture model, were calibrated using monotonic and cyclic Tests on circumferentially notched coupons and complementary finite-element simulations. In addition, Coffin-Manson-like relationships were fitted to the results of the constant-amplitude Tests of the devices, and the Palmgren-Miner’s rule was used to predict fracture of the devices under the randomly generated loading protocols. Comparisons of the experimental and numerical results show that the calibrated models can predict ductile fracture of the devices due to ultralow cycle Fatigue with acceptable accuracy
Jyunki Funayama - One of the best experts on this subject based on the ideXlab platform.
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Developing high-performance aluminum alloy buckling-restrained braces based on series of low-cycle Fatigue Tests
Earthquake Engineering and Structural Dynamics, 2012Co-Authors: Tsutomu Usami, Chun Lin Wang, Jyunki FunayamaAbstract:In order to enhance the durability of high-performance buckling-restrained braces (BRBs) used in bridge engineering, which are expected to withstand severe earthquakes three times without being replaced, aluminum alloys were employed to manufacture BRBs. A series of low-cycle Fatigue Tests, including 18 specimens, were conducted to address the low-cycle Fatigue strength of the aluminum alloy BRB. Test results of all specimens show that stable hysteretic curves were obtained without overall buckling occurrence. Failure mode of the welded aluminum alloy BRB is obviously affected by the ribs' welding under the variable or constant strain amplitude condition. Therefore, another type of aluminum alloy BRB, the bolt-assembled BRB with or without spot-welded stoppers, is proposed and tested. Results showed that the low-cycle Fatigue performance of bolt-assembled BRBs with stoppers improved four to five times compared with welded BRBs. However, the stoppers' spot welding has an adverse effect on the failure mode because the crack, which induced the specimen's failure, initiated from the spot weld toes of the stoppers. Both bolt-assembled BRBs with and without stoppers can meet the cumulative inelastic deformation requirement proposed for high-performance BRBs under the constant strain amplitude, not larger than 2%. In addition, under the variable strain amplitude condition, only the bolt-assembled BRB without stoppers has an excellent cumulative inelastic deformation capacity and sustains two cycles of 2.5% strain amplitude. Finally, recommended Manson-Coffin equations and preliminary cumulative damage formulae for welded and bolt-assembled BRBs are given as the references of the strain-based damage evaluation. © 2011 John Wiley & Sons, Ltd.
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low cycle Fatigue Tests of a type of buckling restrained braces
Procedia Engineering, 2011Co-Authors: Tsutomu Usami, Chun Lin Wang, Jyunki FunayamaAbstract:Abstract In order to satisfy Fatigue performance requirements of High Performance Seismic Dampers (HPSDs), which are expected to withstand Level 2 earthquakes three times without being replaced, a low-cycle Fatigue experiment was carried out to address Fatigue life problems about steel Buckling-Restrained Braces (BRBs). The results of Fatigue Tests under the constant and variable amplitude loadings show that all the specimens have good Fatigue performance and the toe-finished method can effectively improve the Fatigue performance of BRBs with relatively small strain amplitudes. But the BRB's Fatigue performance is affected by the in-plane gap width between filler members and the restraining member, which is verified by the comparative Tests. Finally, Fatigue curves are compared between these full-scale BRB Tests and material Tests presented in references.
Paul C Paris - One of the best experts on this subject based on the ideXlab platform.
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study of thermal effects associated with crack propagation during very high cycle Fatigue Tests
Acta Materialia, 2008Co-Authors: N. Ranc, Daniele Wagner, Paul C ParisAbstract:This paper studies the thermal effects associated with the propagation of a Fatigue crack in a gigacycle Fatigue regime. Ultrasonic Fatigue Tests were carried out on a high-strength steel. The temperature fields measured by infrared thermography show a significant and very local increase in the temperature just before fracture. In order to better understand these thermal effects and to make a connection with the initiation and the propagation of the Fatigue crack, a thermomechanical model is developed. The Fatigue crack is modeled by a circular ring heat source whose radius increases with time. The numerical resolution of the thermal problem allows determination of the time evolution of the temperature fields in specimens and shows a good correlation with experiment. These results provide experimental proof that in a very high cycle regime, the propagation stage of the crack constitutes a small part of the lifetime of the specimen.
Marco Baiguera - One of the best experts on this subject based on the ideXlab platform.
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ultralow cycle Fatigue Tests and fracture prediction models for duplex stainless steel devices of high seismic performance braced frames
Journal of Structural Engineering-asce, 2019Co-Authors: Marco Baiguera, George Vasdravellis, Theodore L KaravasilisAbstract:AbstractThis paper presents ultralow cycle Fatigue Tests and the calibration of different fracture models for duplex stainless-steel devices of high seismic performance braced frames. Two different...
Tsutomu Usami - One of the best experts on this subject based on the ideXlab platform.
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Developing high-performance aluminum alloy buckling-restrained braces based on series of low-cycle Fatigue Tests
Earthquake Engineering and Structural Dynamics, 2012Co-Authors: Tsutomu Usami, Chun Lin Wang, Jyunki FunayamaAbstract:In order to enhance the durability of high-performance buckling-restrained braces (BRBs) used in bridge engineering, which are expected to withstand severe earthquakes three times without being replaced, aluminum alloys were employed to manufacture BRBs. A series of low-cycle Fatigue Tests, including 18 specimens, were conducted to address the low-cycle Fatigue strength of the aluminum alloy BRB. Test results of all specimens show that stable hysteretic curves were obtained without overall buckling occurrence. Failure mode of the welded aluminum alloy BRB is obviously affected by the ribs' welding under the variable or constant strain amplitude condition. Therefore, another type of aluminum alloy BRB, the bolt-assembled BRB with or without spot-welded stoppers, is proposed and tested. Results showed that the low-cycle Fatigue performance of bolt-assembled BRBs with stoppers improved four to five times compared with welded BRBs. However, the stoppers' spot welding has an adverse effect on the failure mode because the crack, which induced the specimen's failure, initiated from the spot weld toes of the stoppers. Both bolt-assembled BRBs with and without stoppers can meet the cumulative inelastic deformation requirement proposed for high-performance BRBs under the constant strain amplitude, not larger than 2%. In addition, under the variable strain amplitude condition, only the bolt-assembled BRB without stoppers has an excellent cumulative inelastic deformation capacity and sustains two cycles of 2.5% strain amplitude. Finally, recommended Manson-Coffin equations and preliminary cumulative damage formulae for welded and bolt-assembled BRBs are given as the references of the strain-based damage evaluation. © 2011 John Wiley & Sons, Ltd.
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low cycle Fatigue Tests of a type of buckling restrained braces
Procedia Engineering, 2011Co-Authors: Tsutomu Usami, Chun Lin Wang, Jyunki FunayamaAbstract:Abstract In order to satisfy Fatigue performance requirements of High Performance Seismic Dampers (HPSDs), which are expected to withstand Level 2 earthquakes three times without being replaced, a low-cycle Fatigue experiment was carried out to address Fatigue life problems about steel Buckling-Restrained Braces (BRBs). The results of Fatigue Tests under the constant and variable amplitude loadings show that all the specimens have good Fatigue performance and the toe-finished method can effectively improve the Fatigue performance of BRBs with relatively small strain amplitudes. But the BRB's Fatigue performance is affected by the in-plane gap width between filler members and the restraining member, which is verified by the comparative Tests. Finally, Fatigue curves are compared between these full-scale BRB Tests and material Tests presented in references.
