This work builds on an earlier work done which used global coordinates where a large number of elements were needed to form a convergence of results for shop built spherical pressure vessels. In this work area coordin...This work builds on an earlier work done which used global coordinates where a large number of elements were needed to form a convergence of results for shop built spherical pressure vessels. In this work area coordinates were used. Any action that leads to an inability on the part of a structure to function as intended is known as failure. This research, therefore, investigates stresses developed in a shop built carbon steel spherical storage vessels using finite element approach as the analytical tool. 3-D finite element modeling using 3-node shallow triangular element with five degrees of freedom at each node is employed. These five degrees of freedom are the essential nodal degrees of freedom without the sixth in-plane rotation. The resulting equations from finite element analysis are coded using FORTRAN 90 computer programme. Spherical storage vessels are subjected to various internal loading pressures while nodal displacements, strains and the corresponding maximum Von-mises stresses are determined. The calculated maximum Vonmises stresses are compared with the yield strength of the shell plate material. Using specified safety factor, safety internal pressures with the corresponding shell thicknesses for shop built spherical pressure vessels are determined. The finite element modeling carried out in this research can be used to predict in-service stresses, strains, and deformations of shop built spherical pressure vessels using Von-mises yield stress as the failure criteria. The results obtained were validated by analytical method and it showed there was no significant difference (P > 0.05) with values obtained through analytical method.展开更多
针对当前年检方式对汽车尾气排放情况进行检测存在的问题,设计了一种基于JN5121无线传感器网络技术的汽车尾气在线检测系统;该系统采用英国Jennic公司的JN5121无线模块及相应Zigbee软件开发包设计无线传感器网络终端设备节点和协调器节...针对当前年检方式对汽车尾气排放情况进行检测存在的问题,设计了一种基于JN5121无线传感器网络技术的汽车尾气在线检测系统;该系统采用英国Jennic公司的JN5121无线模块及相应Zigbee软件开发包设计无线传感器网络终端设备节点和协调器节点的软硬件,采用Visual Studio C#开发上路汽车尾气数据显示的监测计算机软件,提高了汽车尾气检测的灵活方便性,实现对汽车尾气的全面实时监测;实验结果表明,该检测系统运行稳定可靠,有利于加强对汽车尾气污染的防治和构筑可持续发展的生态环境,具有一定的推广价值。展开更多
Isopaxametric quadrilateral elements are widely used in the finite element method. However, they have a disadvantage of accuracy loss when elements are distorted. Spline functions have properties of simpleness and con...Isopaxametric quadrilateral elements are widely used in the finite element method. However, they have a disadvantage of accuracy loss when elements are distorted. Spline functions have properties of simpleness and conformality. A 17onode quadrilateral element has been developed using the bivaxiate quaxtic spline interpolation basis and the triangular area coordinates, which can exactly model the quartic displacement fields. Some appropriate examples are employed to illustrate that the element possesses high precision and is insensitive to mesh distortions.展开更多
文摘This work builds on an earlier work done which used global coordinates where a large number of elements were needed to form a convergence of results for shop built spherical pressure vessels. In this work area coordinates were used. Any action that leads to an inability on the part of a structure to function as intended is known as failure. This research, therefore, investigates stresses developed in a shop built carbon steel spherical storage vessels using finite element approach as the analytical tool. 3-D finite element modeling using 3-node shallow triangular element with five degrees of freedom at each node is employed. These five degrees of freedom are the essential nodal degrees of freedom without the sixth in-plane rotation. The resulting equations from finite element analysis are coded using FORTRAN 90 computer programme. Spherical storage vessels are subjected to various internal loading pressures while nodal displacements, strains and the corresponding maximum Von-mises stresses are determined. The calculated maximum Vonmises stresses are compared with the yield strength of the shell plate material. Using specified safety factor, safety internal pressures with the corresponding shell thicknesses for shop built spherical pressure vessels are determined. The finite element modeling carried out in this research can be used to predict in-service stresses, strains, and deformations of shop built spherical pressure vessels using Von-mises yield stress as the failure criteria. The results obtained were validated by analytical method and it showed there was no significant difference (P > 0.05) with values obtained through analytical method.
文摘针对当前年检方式对汽车尾气排放情况进行检测存在的问题,设计了一种基于JN5121无线传感器网络技术的汽车尾气在线检测系统;该系统采用英国Jennic公司的JN5121无线模块及相应Zigbee软件开发包设计无线传感器网络终端设备节点和协调器节点的软硬件,采用Visual Studio C#开发上路汽车尾气数据显示的监测计算机软件,提高了汽车尾气检测的灵活方便性,实现对汽车尾气的全面实时监测;实验结果表明,该检测系统运行稳定可靠,有利于加强对汽车尾气污染的防治和构筑可持续发展的生态环境,具有一定的推广价值。
基金supported by the Natural Science Foundation of China China (Nos. 60533060, 10672032, and 10726067)the Science Foundation of Dalian University of Technology (No. SFDUT07001)
文摘Isopaxametric quadrilateral elements are widely used in the finite element method. However, they have a disadvantage of accuracy loss when elements are distorted. Spline functions have properties of simpleness and conformality. A 17onode quadrilateral element has been developed using the bivaxiate quaxtic spline interpolation basis and the triangular area coordinates, which can exactly model the quartic displacement fields. Some appropriate examples are employed to illustrate that the element possesses high precision and is insensitive to mesh distortions.
