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PurposeAn inter-story isolation structure (IIS) for AP1000 nuclear power plants (NPPs) is provided to resolve the conflict of seismic safety and the optimal location of air intakes.Design/methodology/approachThe effect of passive cooling system (PCS) is better with lower altitude of air intakes than that in the original design of AP1000 NPPs. Seismic performances of IIS NPPs, including the seismic responses, damping frequency bandwidth and seismic reduction robustness, are improved by combining the position of air intakes lower and the optimal design method.FindingsTheoretical analysis and numerical simulation are illustrated that the seismic reduction failure of IIS NPPs is the lowest probability of occurrence when PCS has highest working efficiency.Originality/valueThe IIS NPPs can transfer the contradiction between PCS work efficiency and seismic safety of NPPs to the mutual promotion of them.

The purpose of this paper is to evaluate the stress concentration at the tip of a permeable interfacial crack near an eccentric elliptical hole in piezoelectric bi-materials under anti-plane shearing. Fracture analysis is performed by Green’s function method and the conformal mapping method, which are used to solve the boundary conditions problem. The mechanical model of the interfacial crack is constructed by interface-conjunction and crack-deviation techniques so that the crack problem is simplified as solving a series of the first kind of Fredholm’s integral equations, from which the dynamic stress intensity factors (DSIFs) at the inner and the outer crack-tips can be derived. The validity of the present method is verified by comparing with a crack emerging from the edge of a circular hole as a reference. Numerical cases reveal parametric dependence of DSIFs on the geometry of eccentric elliptical holes and interfacial cracks, the characteristics of the incident wave, the equivalent piezoelectric elastic modulus and piezoelectric parameters. The results illustrate that the eccentric distance has a great effect on the stress concentration at the crack tip, which may be harmful to the normal service of piezoelectric devices and materials. In addition, the method proposed in this paper can also deal with non-eccentric problems and has wider applicability.

Purpose Seismic isolation, as an effective risk mitigation strategy of building/bridge structures, is incorporated into AP1000 nuclear power plants (NPPs) to alleviate the seismic damage that may occur to traditional structures of NPPs during their service. This is to promote the passive safety concept in the structural design of AP1000 NPPs against earthquakes. Design/methodology/approach In conjunction with seismic isolation, tuned-mass-damping (TMD) is integrated into the seismic resistance system of AP1000 NPPs to satisfy the multi-functional purposes. The proposed base-isolation-tuned-mass-damper (BIS-TMD) is studied by comparing the seismic performance of NPPs with four different design configurations (i.e. without BIS, BIS, BIS-TMD and TMD) with the design parameters of the TMD subsystem optimized. Findings Such a new seismic protection system (BIS-TMD) is proved to be promising because the advantages of BIS and TMD can be fully used. The benefits of the new structure include effective energy dissipation (i.e. wide vibration absorption band and a stable damping effect), which results in the high performance of NPPs subject to earthquakes with various intensity levels and spectra features. Originality/value Parametric studies are performed to demonstrate the seismic robustness (e.g. consistent performance against the changing mass of the water in the gravity liquid tank and mechanical properties) which further ensures that seismic safety requirements of NPPs can be satisfied through the use of BIS-TMD.

Piezoelectric materials have been widely used in modern science and technology due to their electro-mechanical coupling response. Sometimes, because of the stiff and brittle nature of some piezoelectric materials, the piezoelectric devices with defects may face fracture or failure during their service procedures. Therefore, it has become important to investigate the failure behaviors caused by defects, such as cracks and holes. Based on the study of the dynamic anti-plane characteristics for radial crack emanating from a circular cavity in piezoelectric bi-materials, this paper aims to analyzes the dynamic incident anti-plane shearing (SH-wave) in piezoelectric bi-materials, which contains two interfacial cracks, near an eccentric elliptical hole. Green’s function method, the conformal mapping method, the interface conjunction techniques and the crack-deviation techniques are utilized to obtain a series of first kind Fredholm’s equations, based on which the dynamic stress intensity factor (DSIF) at the outer and the inner cracks’ tips are theoretically expressed. Numerical examples were graphically presented to illustrate the effects of the piezoelectric parameter, the effective piezoelectric elastic modulus, the dimensionless incident wave number and geometric parameters on the DSIF at both of the tips. Previous studies are not comprehensive, especially when the center of the hole deviates from the interface. Therefore, the impact of eccentric distance on DSIF is considered in this paper. The solution of this problem provides a more accurate and efficient method for the investigation of dynamic fracture properties of piezoelectric materials and has an important theoretical significance in engineering design.

Green's function method, complex function method and multi-polar coordinate method are used to study the dynamic anti-plane debonding of a cylindrical inclusion near the interface of a quarter-infinite piezoelectric medium. Green's function and the mechanical model of the local "debonding" of inclusion are constructed by using the mirror method, and a series of Fredholm integral equations of the first kind for the problems are established, and then the analytical expression of the crack (debonding) dynamic stress intensity factors (DSIFs) was obtained. Finally, the influence of incident wave frequency, physical and structural geometric parameters of piezoelectric material on the dynamic stress intensity factor at the crack tip of debonded structure is illustrated by numerical examples. The results show that the dynamic characteristics of the debonded structure are more obvious in the case of low frequency and large piezoelectric characteristic parameters, and the period of the dynamic stress intensity factor at the crack tip becomes shorter as the wave number of the incident wave increases.

Dynamic incident anti-plane shearing (SH-wave) analysis is considered to calculate the dynamic stress intensity factors (DSIFs) in transversely isotropic piezoelectric bi-materials, which contain symmetrically radial cracks, near the edges of a non-circular cavity. Green’s functions are established based on complex variable and conformal mapping methods. Conjunction and crack-deviation techniques are used to evaluate DSIFs at the cracks’ tips. Boundary conditions are solved by applying the orthogonal function expansion technique. Models with elliptic cavities are studied numerically based on FORTRAN language program. A comparison is accomplished to adjust program validity. Results clarified the influences on DSIFs under proper conditions.

In transversely isotropic piezoelectric bi-materials, a theoretical analysis is followed to calculate the dynamic stress intensity factors (DSIFs) due to existence of a permeable interfacial crack, near the edge of a circular cavity. The model is subjected to dynamic incident anti-plane shearing (SH-wave) and Green's function method is the base of formulation. Conjunction and crack-simulation techniques are applied to obtain DSIFs at the crack’s inner tip. Calculations are prepared based on FORTRAN language program. For calibration of program, a comparison is accomplished between the present model and another with a crack emerging from the cavity edge. Calculating results clarified the influences of the physical parameters, the structural geometry and the wave frequencies on the dimensionless DSIFs and how those affected the efficiency of piezoelectric devices and materials.

A theoretical analysis is followed to calculate the dynamic stress intensity factors (DSIFs) in transversely isotropic piezoelectric bi-materials, due to existence of a permeable interfacial crack, near the edge of a circular cavity. The model is subjected to dynamic incident anti-plane shearing (SH-wave) and the formulation based on Green's function method. Conjunction and crack-simulation techniques are applied to obtain DSIFs at the crack’s outer tip. Calculations are prepared based on FORTRAN language program. A comparison is accomplished between the present model and another model with a crack emerging from the cavity edge to calibrate the program. Calculating results showed the influences of the physical parameters, the structural geometry and the wave frequencies on the dimensionless DSIFs and how those affected the efficiency of piezoelectric devices and materials.

The present paper is exposed theoretically to the influence on the dynamic stress intensity factor (DSIF) in the piezoelectric bi-materials model with two symmetrically permeable interfacial cracks near the edges of a circular cavity, subjected to the dynamic incident anti-plane shearing wave (SH-wave). An available theoretical method to dynamic analysis in the related research field is provided. The formulations are based on Green’s function method. The DSIFs at the inner and outer tips of the left crack are obtained by solving the boundary value problems with the conjunction and crack-simulation technique. The numerical results are obtained by the FORTRAN language program and plotted to show the influence of the variations of the physical parameters, the structural geometry, and the wave frequencies of incident wave on the dimensionless DSIFs. Comparisons with previous work and between the inner and outer tips are concluded.

Inverse dynamics problem of large-displacement motion simulator is solved by Roberson-Wittenburg method. Simulation graphs plotted by matlab prove the validity of solution. This paper can be used in control studies of motion simulator.

The kinematics and dynamic analysis of the large-displacement motion simulator is analyzed and derived in detail. By using MATLAB program, the simulation curves of the derived kinematics and dynamic formula match to the practical situation. Our result will provide the theoretical direction for the further study of the large-displacement motion simulator.

Use the mirror method to transform the quarter space to the whole space under the complex coordinate system, and with the help of the boundary conditions around the cylindrical lining to solve the unknown coefficient. To do some numerical calculations of the dynamic stress concentration factor and the electric field intensity concentration factor around the cylindrical lining by using the program. In the numerical calculations stage, by changing the medium’s parameters, the structure’s geometry influence and the frequencies of incident wave to obtain more results on dynamic stress concentration factor (DSCF) and electric field intensity concentration factor (EFICF).The calculating results indicate that, under the action of SH wave the DSCF and EFICF around the cylindrical lining are similar to each other, and regularly distributed along the edge of the cylindrical lining. While the magnitude of DSCF and EFICF are larger than any other situations when the frequency of the incident wave was low. And the results are similar to results of the whole space condition too.

The residual fatigue life of a submarine pressure structure is investigated, based on the combination between the methods of conventional Monte Carlo and classical probabilistic fracture mechanics. Firstly, Monte Carlo method is employed to obtain the reliability of given initial fatigue life. Secondly, the two induced factors MA1 and MA2 in the paper are estimated according to the initial fatigue life and the reliability. Thirdly, based on the two factors, the residual fatigue life based on other reliability is obtained by using classical probabilistic fracture mechanics method. Numerical examples show that the proposed method is more efficient without accuracy loss for residual fatigue life compared with Monte Carlo method. This method can also be employed to predict the residual fatigue life on other analogue structures.

A new method is presented in the paper. The fatigue life reliability of submarine cone-cylinder shell is investigated, based on the combination between the methods of conventional Monte Carlo and classical probabilistic fracture mechanics. Firstly, Monte Carlo method is employed to obtain the reliability of given initial fatigue life. Secondly, the two induced factors M1 and M2 in the paper are estimated according to the initial fatigue life and the reliability. Thirdly, based on the two factors, the other fatigue life reliability is obtained by using classical probabilistic fracture mechanics method. Finally, numerical cases show that the proposed method is more efficient without accuracy loss for fatigue life reliability compared with Monte Carlo method. This method can also be applied to predict the fatigue life reliability of analogue structures.

The seismic reliability analysis of complex structure is carried out based on the response surface method and finite element method. Firstly, the appropriate design points are selected based on the mean values and standard deviations of the basic random variables. Secondly, the finite element method is employed to obtain the values of the limit state function of the complex structure. Thirdly, with selected design points and the obtained values of the limit state function of the complex structure, a polynomial function is constructed to approximate the original implicit limit state function. Then, with the established explicit polynomial limit state function and available methods of structural reliability analysis, the seismic reliability of the complex structure is estimated. Numerical analyses show that the established method is simple to use for the evaluation of the reliability analysis of complex structure.

In this paper, a new method is given about using Hamilton principle to establish multi-degree-of-freedom electro-hydraulic mix-drive motion simulator model. And dynamic analysis is performed based on kinetics and kinematics. The simulation is done on multi-degree-of-freedom electro-hydraulic mix-drive motion simulator and Hamilton principle. As cases, some calculating results on dynamic simulation are plotted with the help of Matlab Lagrange. The work in the paper could be seen as a theoretical basis to research motion simulator in depth.

Dynamic antiplane behaviors are investigated theoretically in this paper for a quarter infinite piezoelectric medium with a subsurface circular inclusion. Based on complex variable and mirror image method, the expressions are obtained on dynamic stress concentration factor (DSCF) and electric field intensity concentration factor (EFICF) at the inclusion’s edge caused by the interaction between the inclusion and the right angle edge under time-harmonic anti-plane shearing. While some calculating cases are plotted, so as to show how the frequencies of incident wave, the piezoelectric material’s parameters and the structure’s geometry influence on DSCF and EFICF. The calculating results indicate that dynamic analyses are important to a quarter-infinite piezoelectric medium with defects at the surface vicinity.

The problem of dynamic stress intensity factor is investigated theoretically in present paper for a radial crack on a circular cavity in an infinite piezoelectric medium, which is subjected to time-harmonic incident anti-plane shearing. First, a pair of electromechanically coupled Green’s functions are constructed which indicate the basic solutions for a semi-infinite piezoelectric medium with a semi-circular cavity. Second, based on the crack-division technique and conjunction technique, integral equations for the unknown stresses’ solution on the conjunction surface is established, which are related to the dynamic stress intensity factor at the crack tip. Third, the analytical expression on dynamic stress intensity factor at the crack tip is obtained. At last, some calculating cases are plotted to show how the frequencies of incident wave, the piezoelectric characteristic parameters of the material and the geometry of the crack and the circular cavity influence upon the dynamic stress intensity factors. While some of the calculating results are compared with the same situation about a straight crack and with static solutions.

Dynamic anti-plane characteristic is investigated theoretically on two dissimilar piezoelectric media with an interfacial crack subjected to time-harmonic incident anti-plane shearing in this paper. The formulations are based on the method of complex variable and Green’s function. Dynamic stress intensity factors at the crack’s tip are obtained by solving boundary value problems with the methods of conjunction and crack-division technique. The calculating results are plotted to show how the frequencies of incident wave, all kinds physical parameters of two dissimilar piezoelectric materials, applied electric loads and the dimension of the interfacial crack influence upon the dynamic stress intensity factor (DSIF). And some of the calculating results are compared with other published documents.

Wave propagation in an infinite elastic piezoelectric medium with a circular cavity and an impermeable crack subjected to steady-state anti-plane shearing was studied based on Green’s function and the crack-division technique. Theoretical solutions were derived for the whole elastic displacement and electric potential field in the interaction between the circular cavity and the impermeable crack. Expressions were obtained on the dynamic stress concentration factor (DSCF) at the cavity’s edge, the dynamic stress intensity factor (DSIF) and the dynamic electric displacement intensity factor (DEDIF) at the crack tip. Numerical solutions were performed and plotted with different incident wave numbers, parameters of piezoelectric materials and geometries of the structure. Finally, some of the calculation results were compared with the case of dynamic anti-plane interaction of a permeable crack and a circular cavity in an infinite piezoelectric medium. This paper can provide a valuable reference for the design of piezoelectric actuators and sensors widely used in marine structures.

Dynamic interaction is investigated theoretically between a circular cavity and a crack near the surface in a semi-infinite piezoelectric medium subjected to time-harmonic incident anti-plane shearing in this paper. The formulations are based on the method of complex variable and Green’s function. Dynamic stress concentration factors at the edge of the circular cavity and dynamic stress intensity factors at the crack tip are obtained by solving boundary value problems with the method of orthogonal function expansion. The calculating results are plotted to show how the frequencies and the orientation of incident wave, piezoelectric characteristic parameters of the material and the structural geometries influence upon the dynamic stress concentration factor (DSCF) and dynamic stress intensity factor (DSIF).

In this paper, the dynamic interaction is investigated theoretically between a crack and a circular cavity in an infinite piezoelectric medium under time-harmonic incident anti-plane shearing. The formulations are based on the method of complex variable and Green’s function. The resulting dynamic stress intensity factors at the crack’s tip and dynamic stress concentration factors at the cavity’s edge are obtained with crack-division technique. Numerical results are plotted to show how the frequencies of incident wave, the piezoelectric characteristic parameters of the material and the geometry of the crack and the circular cavity influence upon the dynamic stress intensity factors and dynamic stress concentration factors.

Scattering and dynamic stress concentrations of time harmonic SH-wave in an infinite elastic piezoelectric medium with a movable rigid cylindrical inclusion are studied in this paper with the help of complex variable and wave function expansion method. The relations that a movable rigid cylindrical inclusion depends on intensity of incident wave and electric field are revealed. The expressions of dynamic stress at the edge of the inclusion are obtained. Numerical calculations are made with different wave numbers and different piezoelectric characteristic parameters. The calculating results show that dynamic stress concentrations at the edge of the inclusion have linear dependence on the incident electric field. And dynamic analyses are very important for an infinite piezoelectric medium with a movable rigid cylindrical inclusion at larger piezoelectric characteristic parameters.

In this article, dynamic interaction is investigated theoretically between several circular cavities in an infinite piezoelectric medium under time-harmonic incident anti-plane shear wave load. The theoretical formulations are based upon the use of complex variable and multi-coordinates. Dynamic stress concentration factors at the edges of the circular cavities are obtained by solving boundary value problems with the method of orthogonal function expansion. As examples, some calculating results of two interacting circular cavities in an infinite piezoelectric medium are plotted to show how the frequencies of incident wave, the piezoelectric characteristic parameters of the material and the structural geometries influence on the dynamic stress concentration factors.Copyright © 2008 by ASME