非柔性连接石化储罐配管温差应力分析与对策

储罐配管在温差作用下产生热位移会导致管壁产生热应力,未采用柔性连接的配管由于热应力集中作用可能发生破漏。针对与石油化工储罐非柔性连接的配管的安全问题,应用ANSYS有限元分析软件模拟计算石化企业典型配管的热应力分布;根据不同类型配管的分析结果,提出了工程技术与管理方面的针对性安全措施。研究结果表明:温差效应对石化储罐配管热应力影响显著,随内外温差的增加,配管应力集中的区域增大,最大热应力值增大;补偿措施能够改善配管的柔性,降低配管应力;约束载荷限制配管热膨胀从而增大配管应力;三通管是多根配管接合的区域,这种复杂管道交汇处会形成明显应力集中。研究结果对于提高石油化工非柔性连接配管安全性有一定的指导意义。     

西南山区某气井井场地基稳定性模拟分析

中国西南山区蕴藏着丰富的天然气资源,但随着开发规模的日益扩大,天然气井逐步转向山区这类地质环境恶劣的地区。本文以西南山区某气井为原型,在详细阐明井场区地质环境背景特征的基础上,首先对井场出现的典型地质问题——地下采空区进行定性判断和分析;之后选用F lac-2D有限差分软件,对井场加载前/后地下采空区可能造成的井场地基应力和变形特征,采用双洞和采空区这2种计算模型,进行数值模拟分析。模拟结果表明,井场加载前/后地基最大位移量为2 mm,地基局部地段出现拉应力区,但总体上地基稳定。研究结论将为后期建设中井场建筑物的优化布局及基础的选型提供依据。     

烟囱与吸收塔合一结构分析

通过手工计算和ANSYS有限元软件计算两种方法对安徽新源热电有限公司烟囱与吸收塔合一结构进行结构计算。分析了结构在风载荷、地震载荷作用下的应力和变形,比较了手工计算和有限元电算结果,可为类似工程的计算提供理论参考。     

单块集尘板振打加速度的有限元分析

采用有限元分析软件ABAQUS,对单块集尘板振打加速度进行了分析计算。并将计算结果与解析法和实测法结果进行对比。对比结果表明,有限元计算值更接近于实测值。用有限元法对某厂实际运行的电除尘器加速度进行求解,计算结果与实际基本吻合。由于有限元法能非常方便地处理各种复杂板型、不同的悬挂方式、振打锤的大小以及振打方式,因此,有限元法对于现有极板的分析与新型极板的研究均具有重要的实际意义。     

首钢孟家冲尾矿坝渗流稳定分析

针对孟家冲尾矿库坝面出现的渗水现象,对坝体的渗流以及稳定进行计算分析。计算结果表明,由于堆积坝的不断升高,导致坝体浸润线抬高,安全稳定系数降低,从而将造成坝体失稳,出现溃坝事故。为消除隐患,提出采用辐射井排渗的设计方案,并对该方案的可行性进行计算分析。     

某军机整体壁板裂纹损伤强度评估研究

用全机有限元模型模拟损伤部位的局部位移和力边界条件,对机翼整体壁板高应力区的裂纹型损伤分析,研究了不同损伤尺寸对整体壁板强度的影响,给出损伤尺寸与残余过载、残余强度系数的关系,结论对外场评定战伤飞机损伤程度提供依据.     

爆炸荷载作用下钢筋混凝土防爆墙动力响应研究

为了研究钢筋混凝土防爆墙的抗爆能力,采用有限元分析方法对不同纵向配筋率、不同高跨比、不同厚度的墙体在爆炸动态荷载作用下的动力响应进行研究,对各种不同设置的钢筋混凝土防爆墙的抗爆性能进行评估。结果表明:减小高跨比对提高钢筋混凝土防爆墙的抗爆能力最为重要,提高纵向配筋率,增加厚度都能增加防爆墙的抗爆能力。     

重型自卸汽车车架横梁异常断裂原因分析

针对无副车架的重型自卸汽车在使用过程中出现的车架横梁异常断裂问题,建立了以板壳单元为基本单元的自卸汽车车架有限元分析模型,采用NASTRAN有限元分析软件对车架强度进行分析.有限元分析结果表明,车架横梁异常断裂现象是横梁连接部位应力值大于材料的屈服强度引起的,这与实车车架断裂结果吻合.根据实际工艺要求,改造车架结构,将连接第2根横梁和纵梁的L板厚度变大,并将平衡悬架推力杆支座由整体式支撑改为分体式支撑,从而使两处的最大应力值分别比原结构下降20.4%和51.7%.改进后车架断裂区的强度明显提高,这表明改造方法有效.     

MODEL FOR PREDICTING TRANSPORT OF PESTICIDES AND THEIR METABOLITES IN THE UNSATURATED ZONE1

ABSTRACT: A finite element model based on Galerkin's upstream weighted residual technique was developed to predict the simultaneous convective-dispersion transport and transformations of pesticides and their metabolites in the unsaturated zone. Transformations of the parent compound and its metabolites were assumed to be first-order reactions for oxidation and hydrolysis, while adsorption of the pesticide species (parent compound and metabolites) to the soil components was assumed to be represented by a linear equilibrium (Freundlich type) isotherm. Volatilization and plant root uptake of pesticides in the solution phase were neglected in the analysis. The proposed model was used to simulate the transport and transformation of aldicarb and its metabolites, aldicarb sulfoxide and aldicarb sulfone, in the soil profile. Several examples are used to demonstrate the accuracy, validity, and applicability of the proposed model. Simulated results indicate that the proposed model can potentially be used to estimate the mass flux of water, and pesticide and pesticide metabolite concentrations in the subsurface environment. However, further verification of the model against actual field data is needed to fully demonstrate the model's potential.     

NUMERICAL MODELING OF SALTWATER INTRUSION IN THE NORTHERN GUAM LENS1

ABSTRACT This paper deals with the application of a two-dimensional, saltwater intrusion model to the aquifer in Northern Guam. The model used finite element theory and the Galerkin, weighted-residual technique as its basis. The Northern Guam lens was discretized into 299 linear, triangular elements and 189 nodes. The model was calibrated using 1978 hydrologic data. The output of the model was compared with measured water levels in six observation wells. The calibrated values of permeability and porosity were then used to verify the model using 1979 data. A calibrated and verified model can be used to make an infinite variety of management and planning studies. In this study, three applications are provided that would be considered typical management runs. Steady state runs were made to compare the four conditions of no pumping, 1978 pumping levels, twice 1978 pumping levels, and five times 1978 pumping levels. The water levels due to these conditions are shown in plan and in cross sections of the aquifer. The effect of zero recharge to the aquifer is next demonstrated for the pumping levels existing during 1978. The final run shows how long the aquifer takes to reach steady state when the pumping rate is increased from the 1978 pumping level to twice that value. The program can be used for numerous other studies for management and planning purposes.