Influencing Factors And Efficacy Analysis Of Ultrasonic Deicing Of Plate And Shell Structure

The problem of ice accumulation is widely existing in many fields such as aerospace,ship and ocean,wind power generation etc.Ice accumulation will not only increase the weight of the structure and reduce the operating efficiency of the system,but severe ice accumulation can also cause system failure and structural collapse,resulting in catastrophic consequences.As a new type of deicing method,ultrasonic deicing has the advantages of low energy consumption,simple structure and easy implementation.In this paper,researches on ultrasonic deicing of plate and shell structures were carried out.Based on ultrasonic guided wave theory and linear piezoelectricity theory,piezoelectric ultrasonic deicing systems were established.The achievability of ultrasonic de-icing and the deicing efficiency of ultrasonic deicing systems were studied by combining theoretical analysis,numerical simulation and experiment,and the low-energy ultrasonic deicing designs were carried out based on the correlation models between structural parameters,icing parameters and ultrasonic parameters.Finally,ultrasonic deicing verification was completed in an icing wind tunnel.The following research work has been carried out:Based on the elastodynamic equations,the propagation models of ultrasonic guided waves in single-layer and multi-layer plate media were established.The dispersion equations of Lamb wave and SH wave in multi-layer plate structures were given.The parameters of piezoelectric actuator were studied by using mechanics of piezoelectric materials,based on which the piezoelectric actuators were designed and the implementation schemes of the piezoelectric ultrasonic deicing system were formulated.The deicing efficiency factor(DEF)was proposed to quantitatively characterize the deicing efficiency of the plate structure for the limited boundary and incomplete debonding,then the relationship between steady-state stress and deicing efficiency was studied.The cohesive zone model(CZM)was used to simulate the mechanical behavior of interface between ice accretion and substrate,based on which ultrasonic propagation and the evolution law of delamination at interface of ice accretion and substrate during ultrasonic deicing process were revealed.Then the corresponding experiments were designed and conducted.The research results show that the deicing efficiency factor can effectively evaluate the deicing efficiency of the system,and realize the analysis and prediction of the deicing efficiency of different working conditions and deicing parameters.The ultrasonic deicing of a three-layer plate structure composed of ice-coating-substrate was studied,then interface stress concentration coefficients(ISCC)were introduced to quantitatively evaluate the deicing ability of Lamb wave and SH wave in different modes.Based on these,the effects of coating Young’s modulus,thickness,density,Poisson’s ratio and ice thickness on ultrasonic deicing were revealed.Then corresponding experiments were designed to verify above conclusions.The results show that the ultrasonic deicing efficiency of the coated plate structure is closely related to the deicing frequency and deicing mode.Under the premise of the same material properties,the ISCC value of the Lamb wave is greater than the ISCC value of the SH wave,and more attention should be paid to the Lamb wave and the frequency band below 200 k Hz.The coupling relationship between icing parameters and wing structural parameters was investigated,and the actuator parameters were designed.At same time,a numerical model of thewing structure was established,deicing efficiency factor(DEF)was used to quantitatively analyze the deicing efficiency of the system,then static experiments and icing wind tunnel tests were carried out to verify deicing efficiency,the effects of temperature,wind speed and angle of attack parameters on the deicing efficiency were given.The results show that wing structure has a higher deicing efficiency in clear ice,and the wind speed has a certain mechanical promotion effect on deicing.The uneven icing caused by the attack angle will increase the power consumption of deicing.Ultrasonic deicing can reduce power consumption above 56%compared to traditional electro-thermal deicing,which has obvious low energy consumption characteristics.