Experimental design of mechanical vibration based on energy collection of dielectric elastomers
[Objective]Carbon peaking and carbon neutrality are global trends,and developing renewable and clean energy is an important demand for many countries.Wave energy is one of the renewable energy in the ocean,whose total storage is much greater than that of solar energy and the wind energy on the earth's surface.Furthermore,wave energy has the advantages of high energy density,wide distribution,and minimal negative impact on the environment.Therefore,collecting wave energy is one of the current popular research topics in the world.Dielectric elastomer(DE),an intelligent soft material,has many potential applications in various fields,such as soft robots,phononic crystals,loudspeakers,tactile displays,resonators,and energy harvesting.In addition,it belongs to the category of rubber materials,thus,the hyperelastic constitutive model is generally utilized to describe the large deformation of DE.However,it is experimentally observed that viscoelasticity can dramatically affect the mechanical performance of DE.Although there is relatively limited research on the fractional order viscoelastic theory of DE material,this paper introduces a DE energy harvesting structure with the background of collecting wave energy into innovative experimental projects involving mechanical vibration.[Methods]A conical DE energy harvesting structure is designed,and a viscoelastic-hyperelastic constitutive model based on fractional order damping is developed to establish a dynamic model of the conical DE structure.The dynamic behaviors,such as vibration displacement,amplitude-frequency character,and output voltage,are all studied by theory and experiments.The L1 numerical difference method combined with the Runge-Kutta method is adopted for the simulation of the Caputo fractional derivative.To study more deeply,the laboratory experiments are carried out considering both the absence and the application of an electric field.First,in the absence of an electric field,the amplitude-frequency characteristic curve of the displacement response is used to compare the hyperelastic and the viscoelastic-hyperelastic constitutive models.Second,under the condition of applying an electric field,the output voltage is tested to verify the energy harvesting performance of the conical structure.[Results]The results showed that the viscoelastic-hyperelastic constitutive model fits well with the experimental results.At the same time,it is observed that viscoelasticity decreases the displacement of the transit vibration in the overall frequency regions,including low-frequency,resonance,and high-frequency regions.However,for stable vibration,the viscoelasticity reduces the amplitude in the low-frequency and resonance regions,and it enhances the amplitude in the high-frequency region.Second,under the condition of applying an electric field,although errors exist,the theoretical predicted output voltage is basically consistent with the experimental predicted output voltage to some extent.[Conclusions]This paper can provide some information for the design of a wave energy harvesting structure and the application of new intelligent DE materials on clean energy collection.DE material is introduced into the mechanical vibration experiments to test the amplitude-frequency characteristic curve and verify the influence of damping on the vibration response.The experimental process not only increases students'interest and deepens their understanding of the forced vibration response in mechanical vibration but also enhances their innovation and problem-solving abilities.At the same time,it cultivates their sense of responsibility for spontaneously developing clean energy,achieving the teaching goal of cultivating innovation ability.
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