The adhesion enhancing effect induced by electro-magnetic loading and the adhesion weakening effect resulting from interfacial shear stress have been observed and widely reported in open literature.However,the adhesio...The adhesion enhancing effect induced by electro-magnetic loading and the adhesion weakening effect resulting from interfacial shear stress have been observed and widely reported in open literature.However,the adhesion behavior of multiferroic composites in the simultaneous presence of these two effects and the competitive mechanism between them are still unclear.In this paper,the non-slipping adhesive contact problem between a multiferroic half-space and a perfectly conducting rigid cylinder subject to multi-field loading is studied.The stated problem is reduced to a system of coupled singular integral equations,which are analytically solved with the analytical function theory.The closed-form solutions of the generalized stress fields including the contact stress,normal electric displacement,and magnetic induction are obtained.The stable equilibrium state of the adhesion system is determined with the Griffith energy balance criterion.The adhesion behavior subject to mechanical-electro-magnetic loading and a mismatch strain is discussed in detail.Numerical results indicate that exerting electro-magnetic loading can enhance the adhesion effect for both two types of multiferroic composites,namely,κ-class(non-oscillatory singularity)andε-class,which is different from the case of piezoelectric materials.It is found that the contact size finally decreases in the simultaneous presence of the electro-magnetic enhancing and shear-stress weakening effects.The results derived from this work not only are helpful to understand the contact behavior of multiferroic composites at micro/nano scale,but also have potential application value in achieving switchable adhesion.展开更多
This paper investigates the adhesive nanocontact behavior of an elastic halfplane indented by a rigid cylindrical indenter,incorporating the simultaneous effects of surface elasticity,couple stresses,and adhesion.The ...This paper investigates the adhesive nanocontact behavior of an elastic halfplane indented by a rigid cylindrical indenter,incorporating the simultaneous effects of surface elasticity,couple stresses,and adhesion.The free surface of the half-plane is modeled by the Steigmann-Ogden surface elasticity theory,while the bulk material behavior is described by the classical couple-stress elasticity theory.The adhesion at the contact interface is characterized by the Maugis-Dugdale(MD)adhesive contact model.Building on the fundamental nonclassical Flamant solution,the governing equations and boundary conditions of the nanocontact problem are reformulated into a system of triple integral equations.These equations are solved numerically by the Gauss-Chebyshev quadratures in combination with an iterative algorithm.The validation against the existing literature confirms the accuracy and robustness of the proposed solution methodology.Comprehensive parametric studies are performed to elucidate the critical roles of surface elasticity and couple stresses in adhesive nanocontact.The numerical results provide insights into the complex interactions among surface,couple-stress,and adhesive effects.Specifically,the interplay between the surface and adhesive effects is predominantly competitive,while the interaction between the couple stresses and adhesion exhibits an intricate nature.The findings highlight the necessity of simultaneously considering surface elasticity,couple stresses,and adhesion in nanoindentation analyses to achieve accurate predictions of material responses.展开更多
This paper studies the bandgap characteristics of a locally resonant metamaterial beam with time delays.The dispersion relations are addressed based on transfer matrix method.The governing equations of motion of the b...This paper studies the bandgap characteristics of a locally resonant metamaterial beam with time delays.The dispersion relations are addressed based on transfer matrix method.The governing equations of motion of the beam in the frequency domain are given according to spectral element method.The amplitude-frequency responses of the forced beam are determined by solving linear algebraic equations.The obtained results show that the time-delayed feedback control has great relationships with the location,width and number of the bandgaps.It is interesting that the time delay can change the direction of the movement of the bandgap and give rise to the generation of multiple bandgaps.The influences of different combinations of control parameters on the bandgap properties are shown,such as broadening effects.展开更多
In this paper,an incremental contact model is developed for the elastic self-affine fractal rough surfaces under plane strain condition.The contact between a rough surface and a rigid plane is simplified by the accumu...In this paper,an incremental contact model is developed for the elastic self-affine fractal rough surfaces under plane strain condition.The contact between a rough surface and a rigid plane is simplified by the accumulation of identical line contacts with half-width given by the truncated area divided by the contact patch number at varying heights.Based on the contact stiffness of two-dimensional flat punch,the total stiffness of rough surface is estimated,and then the normal load is calculated by an incremental method.For various rough surfaces,the approximately linear load-area relationships predicted by the proposed model agree well with the results of finite element simulations.It is found that the real average contact pressure depends significantly on profile properties.展开更多
橡胶材料因具有良好的抗震、吸能作用,在实际工程中应用广泛.然而橡胶超弹性材料的碰撞属于强非线性问题,分析橡胶材料的接触碰撞和大变形问题对于提高装置的缓冲性能具有重要意义.光滑有限元法(smoothed finite element method,S-FEM)...橡胶材料因具有良好的抗震、吸能作用,在实际工程中应用广泛.然而橡胶超弹性材料的碰撞属于强非线性问题,分析橡胶材料的接触碰撞和大变形问题对于提高装置的缓冲性能具有重要意义.光滑有限元法(smoothed finite element method,S-FEM)是一种弱形式的数值计算方法,相比于传统的有限元方法,光滑有限元法对网格的质量要求不高,允许单元在计算过程中发生较大的变形,且光滑域的构造比较灵活,在不增加自由度的前提下,可以达到较高的精度.在光滑有限元法的基础上,采用双势方法进行接触计算,以充分利用光滑有限元法计算大变形问题的优点和双势方法求解接触力的优势.通过与有限元软件MSC.Marc的数值结果对比,验证了该算法的准确性和能量守恒性,并且分析了摩擦因数对碰撞体的影响.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.12272269,11972257,and 11472193)the Shanghai Pilot Program for Basic Researchthe Shanghai Gaofeng Project for University Academic Program Development。
文摘The adhesion enhancing effect induced by electro-magnetic loading and the adhesion weakening effect resulting from interfacial shear stress have been observed and widely reported in open literature.However,the adhesion behavior of multiferroic composites in the simultaneous presence of these two effects and the competitive mechanism between them are still unclear.In this paper,the non-slipping adhesive contact problem between a multiferroic half-space and a perfectly conducting rigid cylinder subject to multi-field loading is studied.The stated problem is reduced to a system of coupled singular integral equations,which are analytically solved with the analytical function theory.The closed-form solutions of the generalized stress fields including the contact stress,normal electric displacement,and magnetic induction are obtained.The stable equilibrium state of the adhesion system is determined with the Griffith energy balance criterion.The adhesion behavior subject to mechanical-electro-magnetic loading and a mismatch strain is discussed in detail.Numerical results indicate that exerting electro-magnetic loading can enhance the adhesion effect for both two types of multiferroic composites,namely,κ-class(non-oscillatory singularity)andε-class,which is different from the case of piezoelectric materials.It is found that the contact size finally decreases in the simultaneous presence of the electro-magnetic enhancing and shear-stress weakening effects.The results derived from this work not only are helpful to understand the contact behavior of multiferroic composites at micro/nano scale,but also have potential application value in achieving switchable adhesion.
基金Project supported by the National Natural Science Foundation of China(No.12072072)。
文摘This paper investigates the adhesive nanocontact behavior of an elastic halfplane indented by a rigid cylindrical indenter,incorporating the simultaneous effects of surface elasticity,couple stresses,and adhesion.The free surface of the half-plane is modeled by the Steigmann-Ogden surface elasticity theory,while the bulk material behavior is described by the classical couple-stress elasticity theory.The adhesion at the contact interface is characterized by the Maugis-Dugdale(MD)adhesive contact model.Building on the fundamental nonclassical Flamant solution,the governing equations and boundary conditions of the nanocontact problem are reformulated into a system of triple integral equations.These equations are solved numerically by the Gauss-Chebyshev quadratures in combination with an iterative algorithm.The validation against the existing literature confirms the accuracy and robustness of the proposed solution methodology.Comprehensive parametric studies are performed to elucidate the critical roles of surface elasticity and couple stresses in adhesive nanocontact.The numerical results provide insights into the complex interactions among surface,couple-stress,and adhesive effects.Specifically,the interplay between the surface and adhesive effects is predominantly competitive,while the interaction between the couple stresses and adhesion exhibits an intricate nature.The findings highlight the necessity of simultaneously considering surface elasticity,couple stresses,and adhesion in nanoindentation analyses to achieve accurate predictions of material responses.
文摘This paper studies the bandgap characteristics of a locally resonant metamaterial beam with time delays.The dispersion relations are addressed based on transfer matrix method.The governing equations of motion of the beam in the frequency domain are given according to spectral element method.The amplitude-frequency responses of the forced beam are determined by solving linear algebraic equations.The obtained results show that the time-delayed feedback control has great relationships with the location,width and number of the bandgaps.It is interesting that the time delay can change the direction of the movement of the bandgap and give rise to the generation of multiple bandgaps.The influences of different combinations of control parameters on the bandgap properties are shown,such as broadening effects.
基金supported by the National Natural Science Foundation of China(Grant Nos.12372100,12302126,and 12302141)the China Postdoctoral Science Foundation(Grant No.2023M732799)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.xzy012024020)Sihe Wang also thanks the support from the China Scholarship Council(CSC).
文摘In this paper,an incremental contact model is developed for the elastic self-affine fractal rough surfaces under plane strain condition.The contact between a rough surface and a rigid plane is simplified by the accumulation of identical line contacts with half-width given by the truncated area divided by the contact patch number at varying heights.Based on the contact stiffness of two-dimensional flat punch,the total stiffness of rough surface is estimated,and then the normal load is calculated by an incremental method.For various rough surfaces,the approximately linear load-area relationships predicted by the proposed model agree well with the results of finite element simulations.It is found that the real average contact pressure depends significantly on profile properties.
文摘橡胶材料因具有良好的抗震、吸能作用,在实际工程中应用广泛.然而橡胶超弹性材料的碰撞属于强非线性问题,分析橡胶材料的接触碰撞和大变形问题对于提高装置的缓冲性能具有重要意义.光滑有限元法(smoothed finite element method,S-FEM)是一种弱形式的数值计算方法,相比于传统的有限元方法,光滑有限元法对网格的质量要求不高,允许单元在计算过程中发生较大的变形,且光滑域的构造比较灵活,在不增加自由度的前提下,可以达到较高的精度.在光滑有限元法的基础上,采用双势方法进行接触计算,以充分利用光滑有限元法计算大变形问题的优点和双势方法求解接触力的优势.通过与有限元软件MSC.Marc的数值结果对比,验证了该算法的准确性和能量守恒性,并且分析了摩擦因数对碰撞体的影响.
