粘性土的弹粘塑性本构方程及其应用

从常规试验成果出发，用弹粘塑性应力－应变－时间本构方程来描述粘性土的剪胀特性和时间效应。并采用Ｐｅｒｚｙｎａ的粘塑性方程，结合关联和不相关联流动法则，建立应力－应变－时间关系，对粘性土的有效应力路径特别是塑性区的剪胀特性和应力－应变关系的时间依存性进行了数值模拟计算，得出了与试验相近的结果。通过计算结果和试验结果的对比分析，探讨了该计算模型的合理性和可行性。     

Research progress of cross-laminated timber and bamboo (CLBT)

正交胶合木(CLT)结构因其具有施工便捷、结构性能优良和易于维护保养等优点在欧洲和北美等地获得了广泛关注，并越来越普遍地应用于多层甚至高层建筑之中。我国有丰富的竹资源，同时竹材具有良好的力学性能、可加工性和耐久性。在可工业化生产的结构用胶合竹(Glubam)基础上，作者借鉴CLT的概念进一步提出了正交或交错胶合竹木(简称CLBT或CLTB)。在综述国内外学者在正交胶合木结构的力学性能、连接方式和抗震性能等方面的研究成果基础上，介绍正交胶合竹木的力学与物理性能试验结果，包括正交胶合竹木板梁的弯曲试验、柱的轴心受压试验以及墙体的热学和声学性能试验等，提出基于高阶剪切变形理论的解析模型用以估算CLBT梁、柱在相应荷载作用下的变形量，并通过试验验证该模型的准确性。相关初步研究结果表明：正交胶合竹木CLBT有良好的力学性能和与正交胶合木相当的保温隔热及隔声性能；采用国产速生杨木与Glubam胶合竹组坯制备的正交胶合竹木梁板的力学性能不逊于采用进口木材的同类竹木梁板。因此，正交胶合竹木的研发与应用将有助于进一步合理利用我国的速生林资源和丰富的竹资源；竹木等生物质材料在建筑中的应用对于实现碳中和具有重要的促进意义。     

基于有限元分析方法对接地装置冲击特性研究

由于冲击电流的作用,接地体周围的土壤将会产生火花效应,使得土壤的电阻率会发生变化,进而对冲击电流的散流过程造成影响.因此本文采用有限元分析方法,利用COMSOL Multiphysics软件,构建了考虑火花效应的接地装置冲击散流模型,主要研究了垂直、水平接地体的冲击散流过程,通过模型的计算发现,接地装置在冲击散流的过程中电流主要从接地装置的末端散流到土壤中,这一情况也与实际情况相符合.     

Mechanical behaviors of four‐step 1 × 1 braided carbon/epoxy three‐dimensional composite tubes under axial compression loading

This article focuses on the quasistatic axial compression behavior and the consequent energy absorption of three different types of carbon/epoxy braided composite tubes. The focus is to evaluate the effect of sample length and braiding angle on the energy absorption and failure mechanism of the braided composite tubes. All tubes were manufactured with carbon fiber through four‐step 1 × 1 braiding process and epoxy resin. Quasistatic axial compression tests were carried out to comprehend the failure mechanism and the corresponding compressive load–displacement characteristics of each braided composite tube. The quasistatic compression test parameters such as the compression peak load and the energy absorption of all these composite tubes were compared. It was found that as the length of the sample increased, the peak load reduced and the energy absorption of the braided tubes at 45° braiding angle was considerably higher than that of other braiding angles of 25° and 35°. The failure modes included matrix crack along the braiding angle, fiber breakage, bulging and debonding between yarns. POLYM. COMPOS., 37:3210–3218, 2016. © 2015 Society of Plastics Engineers     

基于商务设施分布的CBD选址研究——以长沙市为例

该文从CBD最本质的反映——商务设施入手,分析了其空间分布特征及时空演变与CBD选址的关系,并以长沙市为例进行实证研究。     

丘陵城市滨水景观规划初探——以邵阳市邵水西岸为例

文章从一般城市滨水区设计理念认识出发,分析丘陵城市滨水空间景观特征和规划设计理念,并以邵阳市为例,探讨了丘陵城市滨水区的规划设计方法。     

基于Unity3D的交互式虚拟油库培训系统研发

油库储存了大量易燃易爆品,设备操作过程较为复杂,易发生事故,所以员工须经过培训后才能上岗。传统培训系统偏重理论层面,培训效果差。以Unity3D作为开发平台,研发出一套交互式虚拟油库培训系统。系统采用C#作为交互脚本的开发语言,SQL Server进行数据管理,以第一人称视角漫游的形式实现设备属性查询、设备交互操作、重要工艺流程仿真等功能。系统具备非常真实的三维效果及交互功能,加强了对油库工作人员的培训效果。     

Compressive behavior of biaxial spacer weft knitted fabric reinforced composite at various strain rates

The in‐plane and out‐of‐plane compressive properties of biaxial weft knitted E‐glass fabric reinforced vinyl ester composite at quasi‐static strain rate of 0.001/s and high strain rates from 700/s to 2200/s were tested to investigate the strain rate effect on the compressive behavior. The compressive tests were conducted on split Hopkinson pressure bar at high strain rate and on MTS 810.23 system at quasi‐static state. The experimental results indicated the strain rate sensitivity of compressive stiffness, failure stress, and strain of the composite in both out‐of‐plane and in‐plane compressive direction. The compressive stiffness and failure stress linearly increased with the increase of strain rate. The failure strain linearly decreased with the increase of strain rate. As the strain rate increased, the main failure mode at out‐of‐plane compression is the interlaminar shear failure and at in‐plane direction is the delamination. At the high strain rate of 2200/s, the composite coupon was compressed into debris with the shear or delamination failure. POLYM. COMPOS., 28:224–232, 2007. © 2007 Society of Plastics Engineers     

三维编织复合材料弹道侵彻准细观层次有限元计算

三维编织复合材料相比于层合复合材料有较高的层间剪切强度和断裂韧性,因而具有更高的冲击损伤容限。用钢芯弹对三维编织复合材料作弹道贯穿测试,得到弹体的入射速度和剩余速度,并考察侵彻破坏模式。目前对三维编织复合材料弹道侵彻性能计算主要建立在连续介质假设上,从真实细观结构计算三维编织复合材料弹道冲击性能尚有一定难度,用三维结构复合材料的纤维倾斜模型在准细观结构层次上分解三维编织复合材料,就其中的一块倾斜单向板作弹道侵彻有限元计算,由弹体动能损失得到贯穿整个复合材料靶体后弹体的剩余速度。有限元计算及与弹道测试结果的比较证明在准细观层次上计算三维编织复合材料弹道冲击性能的有效性。      

Transverse impact damage and energy absorption of 3-D multi-structured knitted composite

Knitted composites have higher failure deformation and energy absorption capacity under impact than other textile structural composites because of the yarn loop structures in knitted performs. Here we report the transverse impact behavior of a new kind of 3-D multi-structured knitted composite both in experimental and finite element simulation. The knitted composite is composed of two knitted fabrics: biaxial warp knitted fabric and interlock knitted fabric. The transverse impact behaviors of the 3-D knitted composite were tested with a modified split Hopkinson pressure bar (SHPB) apparatus. The load–displacement curves and damage morphologies were obtained to analyze the energy absorptions and impact damage mechanisms of the composite under different impact velocities. A unit-cell model based on the microstructure of the 3-D knitted composite was established to determine the composite deformation and damage when the composite impacted by a hemisphere-ended steel rod. Incorporated with the unit-cell model, a elasto-plastic constitute equation of the 3-D knitted composite and the critical damage area (CDA) failure theory of composites have been implemented as a vectorized user defined material law (VUMAT) for ABAQUS/Explicit. The load–displacement curves, impact deformations and damages obtained from FEM are compared with those in experimental. The good agreements of the comparisons prove the validity of the unit-cell model and user-defined subroutine VUMAT. This manifests the applicability of the VUMAT to characterization and design of the 3-D multi-structured knitted composite structures under other impulsive loading conditions.