Classical micromechanical methods for calculating the effective moduli of a heteroge- neous material are generalized to include the interface(surface)effect.By using Hashin's Composite Sphere Assemblage(CSA)model,...Classical micromechanical methods for calculating the effective moduli of a heteroge- neous material are generalized to include the interface(surface)effect.By using Hashin's Composite Sphere Assemblage(CSA)model,a new expression of the bulk modulus for a particle-reinforced com- posite is derived.It is emphasized that the present study is within the finite-deformation framework such that the effective properties are not influenced by the interface stress itself solely,but influenced by the change of the interface stress due to changes of the shape and size of the interface.Hence some inadequacies in previous papers are pointed out.展开更多
While liquid-filled porous materials widely exist in both natural and engineering fields,their overall thermo-mechanical behaviors are influenced by the combined effects of solid skeleton,pore-filling liquid,and pore ...While liquid-filled porous materials widely exist in both natural and engineering fields,their overall thermo-mechanical behaviors are influenced by the combined effects of solid skeleton,pore-filling liquid,and pore structure.When the pores are sufficiently small(e.g.,micro/nano-scale pores),surface effects also play a significant role.Accounting for surface effects and liquid compressibility,we develop a theoretical model to predict the effective thermo-mechanical properties of liquid-filled porous materials.Idealized spherical compressible liquid inclusions distributed randomly in an elastic solid matrix are con-sidered,with two scenarios separately considered.In the first scenario,the liquid inclusions are isolated so that the liquid does not flow freely.The effective coefficient of thermal expansion(CTE)and effective bulk modulus of the two-phase material are obtained via the generalized self-consistent method.In the second scenario,the liquid inclusions are connected by micro-channels.We adopt a top-down approach(the mixture theory)to establish general thermo-mechanical constitutive relations for liquid-filled porous materials with surface effects,and then use a bottom-up(micromechanics)approach to determine the coupling coefficients(effective thermo-mechanical parameters)in these constitutive relations.Results show that the presence of surface stress at the solid-liquid interface increases the effective CTE and decreases the effective bulk modulus,especially when liquid compressibility is relatively large;however,the decrease in surface stress caused by increasing temperature weakens such effect.This research not only reveals the mechanism of thermo-mechanical coupling in liquid-filled porous materials having small pores but also provides a theoretical basis for accurate prediction of their thermo-mechanical responses in complex load environments.展开更多
In summary,the interval uncertainty is introduced to the acoustic metamaterial with Helmholtz resonators.And then,new descriptions(the conservative approximation,the unsafe approximation and the approximation precisio...In summary,the interval uncertainty is introduced to the acoustic metamaterial with Helmholtz resonators.And then,new descriptions(the conservative approximation,the unsafe approximation and the approximation precision)on uncertainties of physical properties of this interval acoustic metamaterial are defined.Lastly,an optimization model for this interval acoustic metamaterial is proposed.The organization of this paper is listed as follows.The acoustic transmission line method(ATLM)for an acoustic metamaterial with Helmholtz resonators is described in Section 2.In Section3,uncertain analysis of the interval acoustic metamaterial is presented.In Section 4,optimization model of the interval acoustic metamaterial is proposed.The discussion on optimization results is shown in Section 5.In section 6,some conclusions are given.展开更多
基金The project supported by the National Natural Science Foundation of China(10032010,10372004)Shanghai Leading Academic Discipline
文摘Classical micromechanical methods for calculating the effective moduli of a heteroge- neous material are generalized to include the interface(surface)effect.By using Hashin's Composite Sphere Assemblage(CSA)model,a new expression of the bulk modulus for a particle-reinforced com- posite is derived.It is emphasized that the present study is within the finite-deformation framework such that the effective properties are not influenced by the interface stress itself solely,but influenced by the change of the interface stress due to changes of the shape and size of the interface.Hence some inadequacies in previous papers are pointed out.
基金supported by the National Natural Science Foundation of China(Grant Nos.12032010,12272179,and 52102425)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX23_0351).
文摘While liquid-filled porous materials widely exist in both natural and engineering fields,their overall thermo-mechanical behaviors are influenced by the combined effects of solid skeleton,pore-filling liquid,and pore structure.When the pores are sufficiently small(e.g.,micro/nano-scale pores),surface effects also play a significant role.Accounting for surface effects and liquid compressibility,we develop a theoretical model to predict the effective thermo-mechanical properties of liquid-filled porous materials.Idealized spherical compressible liquid inclusions distributed randomly in an elastic solid matrix are con-sidered,with two scenarios separately considered.In the first scenario,the liquid inclusions are isolated so that the liquid does not flow freely.The effective coefficient of thermal expansion(CTE)and effective bulk modulus of the two-phase material are obtained via the generalized self-consistent method.In the second scenario,the liquid inclusions are connected by micro-channels.We adopt a top-down approach(the mixture theory)to establish general thermo-mechanical constitutive relations for liquid-filled porous materials with surface effects,and then use a bottom-up(micromechanics)approach to determine the coupling coefficients(effective thermo-mechanical parameters)in these constitutive relations.Results show that the presence of surface stress at the solid-liquid interface increases the effective CTE and decreases the effective bulk modulus,especially when liquid compressibility is relatively large;however,the decrease in surface stress caused by increasing temperature weakens such effect.This research not only reveals the mechanism of thermo-mechanical coupling in liquid-filled porous materials having small pores but also provides a theoretical basis for accurate prediction of their thermo-mechanical responses in complex load environments.
基金supported by National Natural Science Foundation of China(Grant Nos.11402083&11572121)Independent Research Project of State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body in Hunan University(Grant No.51375002)Fundamental Research Funds for the Central Universities,Collaborative Innovation Center of Intelligent New Energy Vehicle,and the Hunan Collaborative Innovation Center of Green Automobile
文摘In summary,the interval uncertainty is introduced to the acoustic metamaterial with Helmholtz resonators.And then,new descriptions(the conservative approximation,the unsafe approximation and the approximation precision)on uncertainties of physical properties of this interval acoustic metamaterial are defined.Lastly,an optimization model for this interval acoustic metamaterial is proposed.The organization of this paper is listed as follows.The acoustic transmission line method(ATLM)for an acoustic metamaterial with Helmholtz resonators is described in Section 2.In Section3,uncertain analysis of the interval acoustic metamaterial is presented.In Section 4,optimization model of the interval acoustic metamaterial is proposed.The discussion on optimization results is shown in Section 5.In section 6,some conclusions are given.
