A method based on solution of the inverse heat conduction problem was presented for online stress monitoring and fatigue life analysis of boiler drums. The mathematical model of the drum temperature distribution is ba...A method based on solution of the inverse heat conduction problem was presented for online stress monitoring and fatigue life analysis of boiler drums. The mathematical model of the drum temperature distribution is based on the assumptions that the difference of temperature along the longitudinal axis of the boiler drum is negligible with changes only in the radial direction and the circumferential direction, and that the outer surface of drum is thermaUy insulated. Combining this model with the control-volume method provides temperatures at different points on a cross-section of the drum. With the temperature data, the stresses and the life expectancy of the boiler drum are derived according to the ASME code. Applying this method to the cold start-up process of a 300 MW boiler demonstrated the absence of errors caused by the boundary condition assumptions on the inner surface of the drum and testified that the method is an applicable technique for the online stress monitoring and fatigue life analysis of boiler drums.展开更多
Design and application of tunable phononic crystals(PnCs)are attracting increasing interest due to their promising capabilities to manipulate acoustic and elastic waves effectively.This paper investigates topology opt...Design and application of tunable phononic crystals(PnCs)are attracting increasing interest due to their promising capabilities to manipulate acoustic and elastic waves effectively.This paper investigates topology optimization of the magnetorheological(MR)materials including PnCs for opening the tunable and wide bandgaps.Therein,the bandgap tunability of the PnCs is achieved by shear modulus variation of MR materials under a continuously changing applied magnetic field.The pseudo elemental densities representing the bi-material distribution inside the PnC unit cell are taken as design variables and interpolated with an artificial MR penalization model.An aggregated bandgap index for enveloping the extreme values ofbandgap width and tunable range of the MR included smart PnCs is proposed as the objective function.In this context,the sensitivity analysis scheme is derived,and the optimization problem is solved with the gradient-based mathematical programming method.The effectiveness of the proposed optimization method is demonstrated by numerical examples,where the optimized solutions present tunable and stably wide bandgap characteristics under different magnetic fields.The tunable optimized PnCs based device that can provide a wider tunable bandgap range is also explored.展开更多
基金Funded by the National Science and Technology Support Project of China (No. 2006BAA03B02-03)
文摘A method based on solution of the inverse heat conduction problem was presented for online stress monitoring and fatigue life analysis of boiler drums. The mathematical model of the drum temperature distribution is based on the assumptions that the difference of temperature along the longitudinal axis of the boiler drum is negligible with changes only in the radial direction and the circumferential direction, and that the outer surface of drum is thermaUy insulated. Combining this model with the control-volume method provides temperatures at different points on a cross-section of the drum. With the temperature data, the stresses and the life expectancy of the boiler drum are derived according to the ASME code. Applying this method to the cold start-up process of a 300 MW boiler demonstrated the absence of errors caused by the boundary condition assumptions on the inner surface of the drum and testified that the method is an applicable technique for the online stress monitoring and fatigue life analysis of boiler drums.
基金supported by the National Natural Science Foundation of China(Grant No.12102079).
文摘Design and application of tunable phononic crystals(PnCs)are attracting increasing interest due to their promising capabilities to manipulate acoustic and elastic waves effectively.This paper investigates topology optimization of the magnetorheological(MR)materials including PnCs for opening the tunable and wide bandgaps.Therein,the bandgap tunability of the PnCs is achieved by shear modulus variation of MR materials under a continuously changing applied magnetic field.The pseudo elemental densities representing the bi-material distribution inside the PnC unit cell are taken as design variables and interpolated with an artificial MR penalization model.An aggregated bandgap index for enveloping the extreme values ofbandgap width and tunable range of the MR included smart PnCs is proposed as the objective function.In this context,the sensitivity analysis scheme is derived,and the optimization problem is solved with the gradient-based mathematical programming method.The effectiveness of the proposed optimization method is demonstrated by numerical examples,where the optimized solutions present tunable and stably wide bandgap characteristics under different magnetic fields.The tunable optimized PnCs based device that can provide a wider tunable bandgap range is also explored.
