A dynamic finite element method for the estimation of cable tension

Yonghui Huang,Quan Gan,Shiping Huang,Ronghui Wang 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.4

Cable supported structures have been widely used in civil engineering. Cable tension estimation has great importance in cable supported structures’ analysis, ranging from design to construction and from inspection to maintenance. Even though the Bernoulli-Euler beam element is commonly used in the traditional finite element method for calculation of frequency and cable tension estimation, many elements must be meshed to achieve accurate results, leading to expensive computation. To improve the accuracy and efficiency, a dynamic finite element method for estimation of cable tension is proposed. In this method, following the dynamic stiffness matrix method, frequency-dependent shape functions are adopted to derive the stiffness and mass matrices of an exact beam element that can be used for natural frequency calculation and cable tension estimation. An iterative algorithm is used for the exact beam element to determine both the exact natural frequencies and the cable tension. Illustrative examples show that, compared with the cable tension estimation method using the conventional beam element, the proposed method has a distinct advantage regarding the accuracy and the computational time.

A dynamic finite element method for the estimation of cable tension

Huang, Yonghui,Gan, Quan,Huang, Shiping,Wang, Ronghui 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.4

Cable supported structures have been widely used in civil engineering. Cable tension estimation has great importance in cable supported structures' analysis, ranging from design to construction and from inspection to maintenance. Even though the Bernoulli-Euler beam element is commonly used in the traditional finite element method for calculation of frequency and cable tension estimation, many elements must be meshed to achieve accurate results, leading to expensive computation. To improve the accuracy and efficiency, a dynamic finite element method for estimation of cable tension is proposed. In this method, following the dynamic stiffness matrix method, frequency-dependent shape functions are adopted to derive the stiffness and mass matrices of an exact beam element that can be used for natural frequency calculation and cable tension estimation. An iterative algorithm is used for the exact beam element to determine both the exact natural frequencies and the cable tension. Illustrative examples show that, compared with the cable tension estimation method using the conventional beam element, the proposed method has a distinct advantage regarding the accuracy and the computational time.

Experimental and numerical investigations on remaining strengths of damaged parabolic steel tubular arches

Yonghui Huang,Airong Liu,Yong-Lin Pi,Mark A. Bradford,Jiyang Fu 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.1

This paper presents experimental and numerical studies on effects of local damages on the in-plane elastic-plastic buckling and strength of a fixed parabolic steel tubular arch under a vertical load distributed uniformly over its span, which have not been reported in the literature hitherto. The in-plane structural behaviour and strength of ten specimens with different local damages are investigated experimentally. A finite element (FE) model for damaged steel tubular arches is established and is validated by the test results. The FE model is then used to conduct parametric studies on effects of the damage location, depth and length on the strength of steel arches. The experimental results and FE parametric studies show that effects of damages at the arch end on the strength of the arch are more significant than those of damages at other locations of the arch, and that effects of the damage depth on the strength of arches are most significant among those of the damage length. It is also found that the failure modes of a damaged steel tubular arch are much related to its initial geometric imperfections. The experimental results and extensive FE results show that when the effective cross-section considering local damages is used in calculating the modified slenderness of arches, the column bucking curve b in GB50017 or Eurocode3 can be used for assessing the remaining in-plane strength of locally damaged parabolic steel tubular arches under uniform compression. Furthermore, a useful interaction equation for assessing the remaining in-plane strength of damaged steel tubular arches that are subjected to the combined bending and axial compression is also proposed based on the validated FE models. It is shown that the proposed interaction equation can provide lower bound assessments for the remaining strength of damaged arches under in-plane general loading.

Fundamental impedance‑based digital synchronous rectification scheme for bidirectional CLLC resonant converters

Guopeng Zhang,Xindi Sun,Hao Wang,Yonghui Liu,Haijun Tao,Lulu Huang 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.1

Synchronous rectification (SR) is an effective way to improve the efficiency of CLLC resonant converters. The soft switching of SR is affected by the parasitic capacitance and the zero-crossing point of the current of the secondary inductance. Therefore, based on uncontrolled rectification on the secondary of the converter, the effective range of soft switching for SR under different operating modes is analyzed. A fundamental impedance model is established to obtain the discharge time of the parasitic capacitance and the zero-crossing point of the current of the secondary in the upper resonant frequency mode. The relationship between the SR signals and primary driving signals in different operating modes is summarized, which can improve the operating range of the SR while ensuring soft-switching. This in turn, ensures the operating efficiency of the converter. The calculation method of the turn-ON and turn-OFF times of the SR in different modes is improved. In addition, the proposed SR method can be used in bidirectional CLLC resonant converters that do not have SR functionality. To accomplish this, only the control program needs to be updated. Experimental results on a 200 V 500 W prototype are given to verify the effectiveness of the SR method.

Stress field interference of hydraulic fractures in layered formation

Zhu, Haiyan,Zhang, Xudong,Guo, Jianchun,Xu, Yaqin,Chen, Li,Yuan, Shuhang,Wang, Yonghui,Huang, Jingya Techno-Press 2015 Geomechanics & engineering Vol.9 No.5

Single treatment and staged treatments in vertical wells are widely applied in sandstone and mudstone thin interbedded (SMTI) reservoir to stimulate the reservoir. The keys and difficulties of stimulating this category of formations are to avoid hydraulic fracture propagating through the interface between shale and sand as well as control the fracture height. In this paper, the cohesive zone method was utilized to build the 3-dimensional fracture dynamic propagation model in shale and sand interbedded formation based on the cohesive damage element. Staged treatments and single treatment were simulated by single fracture propagation model and double fractures propagation model respectively. Study on the changes of fracture vicinity stress field during propagation is to compare and analyze the parameters which influence the interfacial induced stresses between two different fracturing methods. As a result, we can prejudge how difficult it is that the fracture propagates along its height direction. The induced stress increases as the pumping rate increasing and it changes as a parabolic function of the fluid viscosity. The optimized pump rate is $4.8m^3/min$ and fluid viscosity is $0.1Pa{\cdot}s$ to avoid the over extending of hydraulic fracture in height direction. The simulation outcomes were applied in the field to optimize the treatment parameters and the staged treatments was suggested to get a better production than single treatment.