The Experts below are selected from a list of 55251 Experts worldwide ranked by ideXlab platform
D Smissaert - One of the best experts on this subject based on the ideXlab platform.
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wind turbine blade trailing edge failure assessment with sub component test on static and Fatigue Load conditions
Composite Structures, 2018Co-Authors: F Lahuerta, N Koorn, D SmissaertAbstract:Abstract Wind turbine blades present different types of failure mechanisms and modes which are associated with specific Loading conditions. Trailing edge failure mode has been documented in full-scale blade tests as one of the failure types observed in blades on service. Trailing edge failure is characterized by failure of the trailing edge adhesive joint and the buckling of the trailing edge sandwich panels. This failure is governed by the contribution of edgewise, flapwise and torsion moments, with edgewise moments being the main driver. This paper describes a blade sub-component test setup suitable for studying trailing edge failure on static and Fatigue Load conditions, which is an improvement in the experimental verification of a trailing edge blade design. The test setup and design drivers are described and studied via FE models. Static and Fatigue test results are reported for a full-scale blade section sub-component obtained from a 34 [m] wind turbine blade. Moreover, experimental results are discussed and compared with FE models to describe and study the trailing edge failure mechanism.
Michael M. Khonsari - One of the best experts on this subject based on the ideXlab platform.
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life prediction of metals undergoing Fatigue Load based on temperature evolution
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010Co-Authors: M. Amiri, Michael M. KhonsariAbstract:Abstract Fatigue failure of metals undergoing cyclic Load is evaluated based on the evolution of surface temperature. Aluminum Alloy 6061 and Stainless Steel 304 are selected as testing materials and specimens are subjected to completely reversed torsion Load. A thermographic technique is used to measure the temperature increase of the specimen due to hysteresis heating during the Fatigue testing. Experimental results indicate that the initial rate of temperature rise as a function of time can be utilized as an index for prediction of Fatigue life. An empirical correlation of the form N f = c 1 R θ c 2 with constants c1 and c2 is derived that relates the rate of temperature rise, Rθ, at the beginning of the test to the number of cycles to failure, Nf. It is shown that c1 is dependent upon the material properties and stress state whilst c2 is a constant. Experimental results are consolidated into a single curve which gives the time to failure as a function of initial slope of temperature rise, thereby enabling fast prediction of Fatigue failure.
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Rapid determination of Fatigue failure based on temperature evolution: Fully reversed bending Load
International Journal of Fatigue, 2010Co-Authors: M. Amiri, Michael M. KhonsariAbstract:An experimental and theoretical study is carried out to investigate the temperature evolution of Aluminum 6061 and Stainless Steel 304 specimens under cyclic Fatigue Load. A thermographic technique is used to measure the temperature increase of the specimen due to hysteresis heating during Fatigue testing. Results reveal that the surface temperature of a specimen under cyclic Fatigue Load can be directly related to the number of cycles to failure. In particular, it is shown that the slope of the temperature plotted as a function of time at the beginning of the test can be effectively utilized as an index for Fatigue life prediction, thereby saving testing time. The predictions of temperature changes during Fatigue are found to be in good agreement with the experimental results.
Bin Tan - One of the best experts on this subject based on the ideXlab platform.
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Smart Fatigue Load control on the large-scale wind turbine blades using different sensing signals
Renewable Energy, 2016Co-Authors: Mingming Zhang, Bin Tan, Jianzhong XuAbstract:This paper presented a numerical study on the smart Fatigue Load control of a large-scale wind turbine blade. Three typical control strategies, with sensing signals from flapwise acceleration, root moment and tip deflection of the blade, respectively, were mainly investigated on our newly developed aero-servo-elastic platform. It was observed that the smart control greatly modified in-phased flow-blade interaction into an anti-phased one at primary 1P mode, significantly enhancing the damping of the fluid-structure system and subsequently contributing to effectively attenuated Fatigue Loads on the blade, drive-chain components and tower. The aero-elastic physics behind the strategy based on the flapwise root moment, with stronger dominant Load information and higher signal-to-noise ratio, was more drastic, and thus outperformed the other two strategies, leading to the maximum reduction percentages of the Fatigue Load within a range of 12.0-22.5%, in contrast to the collective pitch control method. The finding pointed to a crucial role the sensing signal played in the smart blade control. In addition, the performances within region III were much better than those within region II, exhibiting the benefit of the smart rotor control since most of the Fatigue damage was believed to be accumulated beyond the rated wind speed.
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parameter study of sizing and placement of deformable trailing edge flap on blade Fatigue Load reduction
Renewable Energy, 2015Co-Authors: Mingming Zhang, Bin TanAbstract:This paper presents a numerical study on the parametric effect of deformable trailing edge flap (DTEF) on the Fatigue Load of a large-scale wind turbine blade. Investigations were conducted within the operation regions II and III of the turbine, respectively. Results showed that, compared with the original collective pitch method, the control effectively reduced the Fatigue Load on blade and drive-chain components, and positively affected the generator power and pitch system as well. Furthermore, the performances were gradually improved with increasing DTEF spanwise location from the rotor center, spanwise and central chordwise length, and deflection angle range, except for the worse performance with increasing spanwise location to the blade tip within region II. It was found that the smart control altered the nature of the flow-blade interactions and changed the in-phased fluid-structure synchronization into anti-phased interaction at main Load frequencies, thus significantly enhancing the damping of fluid-structure system and contributing to greatly attenuated Fatigue Load on both rotor and drive-chain components. These phenomena happened for all primary Load frequencies within region III, due to less flow detachment under the effect of the pitching function, determining its superiority over region II in terms of the control performance.
Shankar Mall - One of the best experts on this subject based on the ideXlab platform.
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Tension-tension Fatigue behavior of carbon nanotube wires
Carbon, 2013Co-Authors: Heath Edward Misak, Shankar Mall, Ramazan Asmatulu, V. Sabelkin, P.e. KladitisAbstract:The tension–tension Fatigue behavior of three types of as-received carbon nanotube (CNT) wires, comprising of 30-, 60-, and 100-yarn, was investigated. Fatigue tests were conducted at 35%, 50%, 60%, 75% and 80% of their ultimate tensile strengths which provided the Fatigue life data (S–N curves). Their electrical conductivities were measured as a function of the number of cycles. Fatigue strength of the CNT wires at a given number of cycles decreased with an increase in the number of yarns. Their electrical conductivity increased with increase of applied Fatigue Load and number of Fatigue cycles. Damage and failure mechanisms involved relative sliding of yarns in CNT wires leading to the formation of kink bands, followed by plastic deformation and then breakage of yarns. Microtomography density measurements provided the evidence that the increase in conductivity was due to the reduction of micro/nano voids between and inside the yarns, which decreased with increasing Fatigue Load and number of Fatigue cycles.
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Investigation into Wear Behavior of Cu-Al Coating on Titanium alloy under Fretting Fatigue
48th AIAA ASME ASCE AHS ASC Structures Structural Dynamics and Materials Conference, 2007Co-Authors: S.-m. Lee, Shankar MallAbstract:Fretting tests were conducted with either no Fatigue Load or with Fatigue Load to investigate the effect of contact Load and contact size. Accumulated dissipated energy versus wear volume data showed a linear relationship regardless of Fatigue Loading condition on specimen with the smaller pad size. However, two separate linear relationships were observed based on the Fatigue Loading condition with the larger pad size, such that a relatively more dissipated energy was required for a certain amount of wear with Fatigue Load on the specimen. The linear relationship between the accumulated dissipated energy and wear volume for both pad sizes extended from partial to gross slip regimes and was not affected by the applied contact Load.
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Characterization of fretting wear behavior of Cu-Al coating on Ti-6Al-4V substrate
Tribology International, 2007Co-Authors: Hyukjae Lee, Shankar Mall, J.h. Sanders, Shashi K. Sharma, Russell S. MagazinerAbstract:Abstract Fretting wear and fretting Fatigue are two commonly observed material damages when two contacting bodies with a clamping Load are under the oscillatory motion. In this study, fretting wear damage of Cu–Al coating on titanium alloy, Ti–6Al–4V substrate was investigated using the dissipated energy approach. Fretting tests were conducted with either no Fatigue Load or the maximum Fatigue Load of 300 MPa and stress ratio of 0.1 on the substrate (specimen). In order to investigate the effect of contact Load and contact size, different pad sizes and contact Loads were used in the tests. Accumulated dissipated energy versus wear volume data showed a linear relationship regardless of Fatigue Loading condition on specimen with the smaller pad size. However, two separate linear relationships were observed based on the Fatigue Loading condition with the larger pad size, such that a relatively more dissipated energy was required for a certain amount of wear with Fatigue Load on the specimen. The linear relationship between the accumulated dissipated energy and wear volume for both pad sizes extended from partial to gross slip regimes and was not affected by the applied contact Load. Further, fretting tests with and without Fatigue Load resulted in different shapes of fretting loops when the larger pad size was used.
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Investigation of high cycle and low cycle Fatigue interaction on fretting behavior
International Journal of Mechanical Sciences, 2002Co-Authors: S. Naboulsi, Shankar MallAbstract:Abstract Fretting-Fatigue behavior and damage accumulation under a variable-amplitude cycling Load is investigated in a configuration involving a cylindrical indenter in contact with finite width plate. Relative magnitudes of cyclic tangential and bulk Loads not only affect the contact conditions, but also their relative positions with respect to each other. Several stick–slip conditions on the contact surface may develop during the application of variable-amplitude Fatigue Load, and these are secondary and tertiary slips as well as shake-down. Further, residual shear traction develops during the application of cyclic Load. The appropriate characterization of fretting-Fatigue behavior or life should, therefore, include the complete history of applied cyclic tangential and bulk Loads. Furthermore, experiments from a previous study conducted under a variable-amplitude Fatigue Loading condition are analyzed to characterize the damage accrual from its individual components involving constant-amplitude Fatigue Load by incorporating the contact mechanics and a multi-axial Fatigue critical plane parameter. This analysis shows that there is nonlinear damage accumulation during variable-amplitude fretting-Fatigue Load.
Mingming Zhang - One of the best experts on this subject based on the ideXlab platform.
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Smart Fatigue Load control on the large-scale wind turbine blades using different sensing signals
Renewable Energy, 2016Co-Authors: Mingming Zhang, Bin Tan, Jianzhong XuAbstract:This paper presented a numerical study on the smart Fatigue Load control of a large-scale wind turbine blade. Three typical control strategies, with sensing signals from flapwise acceleration, root moment and tip deflection of the blade, respectively, were mainly investigated on our newly developed aero-servo-elastic platform. It was observed that the smart control greatly modified in-phased flow-blade interaction into an anti-phased one at primary 1P mode, significantly enhancing the damping of the fluid-structure system and subsequently contributing to effectively attenuated Fatigue Loads on the blade, drive-chain components and tower. The aero-elastic physics behind the strategy based on the flapwise root moment, with stronger dominant Load information and higher signal-to-noise ratio, was more drastic, and thus outperformed the other two strategies, leading to the maximum reduction percentages of the Fatigue Load within a range of 12.0-22.5%, in contrast to the collective pitch control method. The finding pointed to a crucial role the sensing signal played in the smart blade control. In addition, the performances within region III were much better than those within region II, exhibiting the benefit of the smart rotor control since most of the Fatigue damage was believed to be accumulated beyond the rated wind speed.
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parameter study of sizing and placement of deformable trailing edge flap on blade Fatigue Load reduction
Renewable Energy, 2015Co-Authors: Mingming Zhang, Bin TanAbstract:This paper presents a numerical study on the parametric effect of deformable trailing edge flap (DTEF) on the Fatigue Load of a large-scale wind turbine blade. Investigations were conducted within the operation regions II and III of the turbine, respectively. Results showed that, compared with the original collective pitch method, the control effectively reduced the Fatigue Load on blade and drive-chain components, and positively affected the generator power and pitch system as well. Furthermore, the performances were gradually improved with increasing DTEF spanwise location from the rotor center, spanwise and central chordwise length, and deflection angle range, except for the worse performance with increasing spanwise location to the blade tip within region II. It was found that the smart control altered the nature of the flow-blade interactions and changed the in-phased fluid-structure synchronization into anti-phased interaction at main Load frequencies, thus significantly enhancing the damping of fluid-structure system and contributing to greatly attenuated Fatigue Load on both rotor and drive-chain components. These phenomena happened for all primary Load frequencies within region III, due to less flow detachment under the effect of the pitching function, determining its superiority over region II in terms of the control performance.
