A model suitable for describing the mechanical response of thin elastic objects is proposed to simulate the deformation of guide wires in minimally invasive interventions. The main objective of this simulation is to p...A model suitable for describing the mechanical response of thin elastic objects is proposed to simulate the deformation of guide wires in minimally invasive interventions. The main objective of this simulation is to provide doctors an opportunity to rehearse the surgery and select an optimal operation plan before the real surgery. In this model the guide wire is discretized with the multi-body representation and its elastic energy derivate from elastic theory is a polynomial function of the nodal displacements. The vascular structure is represented by a tetrahedron mesh extended from the triangular mesh of the artery, which can be extracted from the patient＇s CT image data. The model applies the energy decline process of the conjugate gradient method to the deformation simulation of the guide wire. Experimental results show that the polynomial relationship between elastic energy and nodal displacements tremendously simplifies the evaluation of the conjugate gradient method and significantly improves the model＇s efficiency. Compared with models depending on an explicit scheme for evaluation, the new model is not only non-conditionally stable but also more efficient. The model can be applied to the real-time simulation of guide wire in a vascular structure.展开更多
In order to study the influence of longitudinal slope on the mechanical response of steel deck pavement,a method of slope-modulus transformation was proposed for the mechanical analysis of the steel deck pavement base...In order to study the influence of longitudinal slope on the mechanical response of steel deck pavement,a method of slope-modulus transformation was proposed for the mechanical analysis of the steel deck pavement based on the time-temperature equivalence principle.Considering the mechanical action on a slope,a finite element model of the deck pavement was established to determine the critical load position of tensileand shear stress of the steel deck pavement.Additionally,the influence of longitudinal slope on the mechanical response of the deck pavement under the conditions of uniform speed and emergency braking was analyzed.The results indicate that the maximum transverse tensile stress at the pavement surface and the maximum transverse shear stress at the pavement bottom are always greater than their longitudinal counterparts under uniform speed.Under emergency braking,however,the critical slope gradient of t e maximum transverse and longitudinal tensile stress at t e pavement surface is 6%.The maximum longitudinal shear stess at t e pavement bottom is always greater ta n t e maximum tansverse shear stess.This stidy is helpful in t e strctural design of large longitudinal slope steel deck pavements.展开更多
Beipanjiang Bridge is a long-span concrete arch bridges with stiffened skeleton(CABSS)in China.It has a fixed end arch with the span of 445 m and the rise of 100 m.To evaluate the rationality of the construction seque...Beipanjiang Bridge is a long-span concrete arch bridges with stiffened skeleton(CABSS)in China.It has a fixed end arch with the span of 445 m and the rise of 100 m.To evaluate the rationality of the construction sequence and the time-dependent behavior of CABSS,an experimental study of a model bridge was explored.But the measured displacement and stress ratios of arch rib between prototype and model bridge did not subject to linear similarity relation when the time-dependent behavior was considered.So,the three-dimensional finite element models were established,and verified by the measured data.Then,the displacements and stresses of the prototype and model were compared with each other,when the elastic analysis or coupling of temperature and shrinkage,creep effect was considered.Furthermore,a parametric study was studied.The results showed that when the temperature,shrinkage and creep effect of concrete are considered,the finite element analysis results of prototype and model agree well with the measured results.The displacement and stress ratios of prototype and model bridge in construction and bridge completed stage do not present the geometric similarity ratio 7.5 and 1.0,respectively.They are also much influenced by concrete predicting model and variation of temperature.展开更多
Integral method is employed in this paper to alleviate the error accumulation of differential equation discretization about time variant t in Time Domain Finite Element Method (TDFEM) for electromagnetic simulation. T...Integral method is employed in this paper to alleviate the error accumulation of differential equation discretization about time variant t in Time Domain Finite Element Method (TDFEM) for electromagnetic simulation. The error growth and the stability condition of the presented method and classical central difference scheme are analyzed. The electromagnetic responses of 2D lossless cavities are investigated with TDFEM; high accuracy is validated with numerical results presented.展开更多
文摘A model suitable for describing the mechanical response of thin elastic objects is proposed to simulate the deformation of guide wires in minimally invasive interventions. The main objective of this simulation is to provide doctors an opportunity to rehearse the surgery and select an optimal operation plan before the real surgery. In this model the guide wire is discretized with the multi-body representation and its elastic energy derivate from elastic theory is a polynomial function of the nodal displacements. The vascular structure is represented by a tetrahedron mesh extended from the triangular mesh of the artery, which can be extracted from the patient＇s CT image data. The model applies the energy decline process of the conjugate gradient method to the deformation simulation of the guide wire. Experimental results show that the polynomial relationship between elastic energy and nodal displacements tremendously simplifies the evaluation of the conjugate gradient method and significantly improves the model＇s efficiency. Compared with models depending on an explicit scheme for evaluation, the new model is not only non-conditionally stable but also more efficient. The model can be applied to the real-time simulation of guide wire in a vascular structure.
基金The National Science Foundation of China(No.51778142)
文摘In order to study the influence of longitudinal slope on the mechanical response of steel deck pavement,a method of slope-modulus transformation was proposed for the mechanical analysis of the steel deck pavement based on the time-temperature equivalence principle.Considering the mechanical action on a slope,a finite element model of the deck pavement was established to determine the critical load position of tensileand shear stress of the steel deck pavement.Additionally,the influence of longitudinal slope on the mechanical response of the deck pavement under the conditions of uniform speed and emergency braking was analyzed.The results indicate that the maximum transverse tensile stress at the pavement surface and the maximum transverse shear stress at the pavement bottom are always greater than their longitudinal counterparts under uniform speed.Under emergency braking,however,the critical slope gradient of t e maximum transverse and longitudinal tensile stress at t e pavement surface is 6%.The maximum longitudinal shear stess at t e pavement bottom is always greater ta n t e maximum tansverse shear stess.This stidy is helpful in t e strctural design of large longitudinal slope steel deck pavements.
基金Projects(20-JKKJ-17,18-JKKJ-05)supported by the Shanxi Communications Holding Group Co.,Ltd.,ChinaProject(41907239)supported by the National Natural Science Foundation of China+1 种基金Project(2020M670698)supported by the China Postdoctoral Science FoundationProject(2019L0295)supported by the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi,China。
文摘Beipanjiang Bridge is a long-span concrete arch bridges with stiffened skeleton(CABSS)in China.It has a fixed end arch with the span of 445 m and the rise of 100 m.To evaluate the rationality of the construction sequence and the time-dependent behavior of CABSS,an experimental study of a model bridge was explored.But the measured displacement and stress ratios of arch rib between prototype and model bridge did not subject to linear similarity relation when the time-dependent behavior was considered.So,the three-dimensional finite element models were established,and verified by the measured data.Then,the displacements and stresses of the prototype and model were compared with each other,when the elastic analysis or coupling of temperature and shrinkage,creep effect was considered.Furthermore,a parametric study was studied.The results showed that when the temperature,shrinkage and creep effect of concrete are considered,the finite element analysis results of prototype and model agree well with the measured results.The displacement and stress ratios of prototype and model bridge in construction and bridge completed stage do not present the geometric similarity ratio 7.5 and 1.0,respectively.They are also much influenced by concrete predicting model and variation of temperature.
基金the National Natural Science Foundation of China (No.60601024).
文摘Integral method is employed in this paper to alleviate the error accumulation of differential equation discretization about time variant t in Time Domain Finite Element Method (TDFEM) for electromagnetic simulation. The error growth and the stability condition of the presented method and classical central difference scheme are analyzed. The electromagnetic responses of 2D lossless cavities are investigated with TDFEM; high accuracy is validated with numerical results presented.
