Papers by Keyword: Numerical Analysis

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Authors: Tao Lu, Yu Lin Lu, Jing Yan Huo
Abstract: The Equivalent Linear Method is a common way used in earthquake engineering to analyze nonlinear site seismic response, but the response under strong motion is underestimated by the way. For analyzing nonlinear response more veritably, in the study, a time-domain nonlinear analysis method was proposed and used in a case for 1D seismic response analysis of soil layers under strong motion. The results obviously showed that, comparing with true nonlinear method, the Equivalent Linear Method underestimated in the case in natural period range of common civil engineering structures. The true nonlinear method adopted in the study is more fitful for nonlinear response of soil layers under strong motion.
Authors: Pei Yao Sheng, Shi Zhao Wang, Zhong Ji
Abstract: Polymer-mineral composite material is prepared by using modified epoxy resin as binder and mineral particles as aggregates. Its excellent damping characteristic and low thermal expansion make it ideal in manufacturing machine tool beds. However, the properties of this material depend on its formula and structure, so it is very important to develop an efficient method to numerically model the materials and then to optimize their properties. In this paper, 2D meso-scale finite element modeling is presented for numerical analysis of the mechanical properties of polymer-mineral composite material. The material was treated as a 2-phase composite composed of aggregates and binder which was epoxy resin mixed with fillers. Based on grading curve, the weights of aggregates were converted into the corresponding area, the aggregate particles were randomly generated and assembled with binder to produce the model. And then 2D numerical simulations were conducted under different gradations. The results show that: (1) the 2D FE model is very close to the real polymer-mineral composite material in the aspect of density and aggregate shapes and sizes, which validate the fidelity of the generated finite element model and numerical analysis method; (2) by comparing the materials’ properties under four different gradations, it can be found that the materials with SAC gradation have the best mechanical property.
Authors: Shu Ren Wang, Jing Min Yu, Hai Qing Zhang
Abstract: For difficulties and deficiencies for complex geologic body and structural engineering with FLAC3D, the three-dimensional complicated model was built by using MIDAS/GTS-FLAC3D coupling technique, which was based on the Kangjiagou-bridge-Miaoliang-tunnel project crossing the mined-out regions in Liulin section of Qingdao-Yinchuan highway. The interactions between the mined-out regions and surface structures such as the tunnel lining and bridge were analyzed as the following sequence of operations: the mining process step-by-step was performed corresponding to the years, and then the grouting treatment was carried out after mining coal in Kangjiagou, next, Miaoliang tunnel was excavated and Kangjiagou bridge was constructed. The surface deformations under different working conditions were revealed, and the ground subsidence basin characteristics were analyzed. Also, the deformations and forces of key bearing parts of the tunnel lining and bridge structure were predicted in order to guide the engineering design and construction. The above-mentioned results have important theoretical meaning for guiding the similar engineering practice.
Authors: Wei Shen Zhu, Jian Hua Liu, Shu Cai Li
Abstract: A brief description is given to the visco-plastic constitutive model of 3-D FLAC software and some treating methods for the numerical analysis. The excavation steps and the exerting time of excavation loads are determined in the light of the real construction process. The rockmass mechanical parameters are determined according to back analysis of in-situ measured displacement data. The analysis results of displacement and stability of the opening complex surrounding rocks in the construction process and in a long period of time after excavation completion are given.
Authors: Wen Tsung Liu, Xu Yan Lu
Abstract: This study is analyzed by numerical analysis using finite element method program of Plaxis-3D Tunnel at Kaohsiung Science Park in Taiwan. It probes the risk of tunneling procedure adopting pipe jacking construction (PJC) with man–made excavation. The main parameters of numerical calculation in this research include advancement size, soil improvement ratio and void contraction ratio, etc. Those parameters are calculated to displacement and stress distribution and we get ground movement, settlement at crown and heave at invert of tunnel excavation to assess the security. This study finds that it is safe by excavation using PJC with man-made while the gap has to be less than 38mm. Actually, the gap is 100 ~ 150mm under PJC with man-made, and it will result in high risk. Therefore, the PJC with shield has more security than other methods through monitoring ground settlement.
Authors: Feng Jun Liu, Lei Xie, He Hua Zhu, Ning Yu
Abstract: The rotational angle of joint is the key factor for segment lining design. Using the nonlinear finite element program of MARC (MSC2003), the 3D numerical analysis on segment joint of prestressed concrete lining has been carried out. During the analysis, Coulomb and Stick-slip friction models were used as the friction type between the concrete and the prestressing steel strands. The selection of friction model used in the numerical analysis is very important. The study showed that the Stick-slip friction model is more suitable than Coulomb friction model for analysis of the P&PCSL joint. The value of friction coefficient should be thought over carefully.
Authors: Qing Fen Li, Li Zhu, Guo Jin, Xiu Fang Cui
Abstract: The computational analysis of a three-dimensional (3D) finite element model of all fracture modes (AFM) specimen on mixed-mode I-II fracture was presented in this paper. The separated energy release rates (SERRs) along the crack front of the AFM-model were calculated by the modified virtual crack closure integral (MVCCI)-method and commercially available software ANSYS. The influence of finite geometry and loading angles on mixed mode I-II fracture was investigated.
Authors: Jia Qing Du, Shou Ji Du, Zhi Wang
Abstract: With the oil and gas exploitation develop to the deep sea; offshore platform under extreme environment load needs more stable anchorage foundation. Based on the slender suction anchor of SPAR, three-dimensional numerical analysis method was presented to study the ultimate pull-out capacity. Based on the geological conditions from South China Sea, clay and sand was selected as soil conditions to make a comparison analysis. The effects of soil type, load positions, load angles and aspect ratio on the ultimate bearing pull-out resistance of the suction foundation were studied. The comparison analysis results indicated that the ultimate pull-out resistance of suction anchors in sand has a greater rise rate and achieve ultimate pull-out capacity need smaller displacement than in clay; load point and load angles have a great impact on the resistance and there is a critical aspect ratio under inclined loading in sand.
Authors: Zi Zhen Cao, Ji Feng Zhang, Yun Wan, Yong Gang Xie
Abstract: A three-dimensional progressive damage model is proposed to predict the open-hole tensile strength of Glare laminates. For the glass fiber reinforced epoxy the user subroutine UMAT is employed for description of the failure modes, such as matrix cracking and fiber failure. Behavior of the delamination between plies of the laminate is described using cohesive elements. Laminates with a rhombic hole, a square hole and a circular hole are taken into consideration separately. The results obtained by the present solution approach are validated with those available in the literatures.
Authors: José A.S. Cardoso, Virgínia Infante, Bruno A.S. Serrano
Abstract: The stop-drilling technique is a simple and economic way to delay crack propagationby drilling a hole on the crack tip and reducing stress concentration. This paper presents thepropagation of cracks and investigates how the increasing of the stop-drill diameter improvescrack initiation life in specimens of 2024-T3 aluminium alloy of C-130 aircraft skin. A numericalmethod was applied to simulate an automatic crack propagation by interacting ANSYSr andMATLABr, and several experimental fatigue tests were done to support the computationalresults. A Morrow equation was used to predict the fatigue life of the stop-drill. Good agreementof stress intensity factor along crack length was obtained between numerical and experimentalresults. All results show that fatigue life increases when the stop-drill diameter is larger. Whencompared to the 2mm diameter stop-drill, the experimental results show an improvement of189% and 464% to 4mm and 6mm diameter stop-drill fatigue life, and the numerical results of333% and 952%, respectively.
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