厚板薄板通用的协调矩形单元

在板的有限元分析中 ,构造协调和无剪切闭锁现象的中厚板单元一直是人们所关注的问题和难题。文献[2 ,3 ] 提出了一种假设剪切应变场的方法 ,基于广义协调理论成功地构造出厚板薄板通用的三角形和四边形单元 ,但这类单元并不具有完备性和真正的C1阶连接性。为此 ,文献[1] 构造出了具有完备和真正C1阶协调的薄板矩形单元 ,为构造这类单元的构造提供了一个有效的新途径。本文首先从Mindin厚板理论出发 ,导出单元各边的剪应变和节点剪应变公式 ,进行合理插值导出单元的剪应变场 ,当板的厚度变小时 ,厚板理论理论自动退化为薄板理论 ,各边剪应变以及单元剪应变插值函数自动退化为零 ,厚板单元自动退化为薄板单元 ,彻底消除了剪切闭锁现象。然后根据转角场、挠度场和剪应变场的关系 ,通过反复试算构造出一个具有 12个自由度的厚板薄板通用协调矩形单元 ,通过理论证明该厚板薄板通用单元具有完备性、C1阶连续性和无剪切闭锁现象 ,从而较好地解决了厚板薄板能单元的C1阶连续性和无剪切闭锁现象的难题。为了验证该协调单元的正确性 ,对不同厚距比 (h/l)的四边简支和固定方形板在均布载荷作用下的中心挠度和弯矩进行分析。数值算例表明 :该单元精度高 ,原理简明 ,列式简单 ,自由度少 ,收敛速度快 ;

长效锚挂/粘双连接陶瓷薄板饰面保温装饰板结构一体化外墙保温系统研究——绿色建材低碳产品与技术案例

外墙保温产品的高质量发展是实现建筑高质量发展的重要保障。外墙保温系统的力学安全性、防火安全性、保温隔热性、防水阻水性、装饰防护性及长效耐久性,是建筑外墙保温系统长寿命高质量发展的基本要求。以陶瓷棉、玄武岩棉为保温材料的陶瓷薄板饰面保温装饰板,以其特有的机械锚固、机械拖挂+无空腔粘结双系统固定方式,形成锚挂/粘双连接保温装饰结构一体化系统,可解决目前外墙保温系统防火性能差、易脱落、装饰层耐久性差等质量通病。加大推动锚挂/粘双连接陶瓷薄板饰面保温装饰板结构一体化外墙保温系统的应用,对构筑安全耐久、保温隔热、防火防水等性能优异的建筑外墙围护系统具有重要的现实意义。

薄板点焊试件的应力强度因子计算

采用简化模型和边界配置方法,对薄板点焊试件进行了断裂分析,计算了焊接周围裂纹Ⅰ、Ⅱ、Ⅲ型的应力强度因子。本方法具有计算量小,精度高的优点,适用于不同几何尺寸薄板点焊试样的断裂计算。

《CABR/T陶瓷薄板饰面保温装饰一体板建筑构造》图集介绍

保温一体板是将保温与装饰两大产品体系复合成一体化的成品板,CABR/T陶瓷薄板饰面保温装饰一体板是一种采用陶瓷薄板作为饰面层的保温装饰一体板。为了促进广大设计人员和工程技术人员更好地了解该一体板的设计应用,本文对《CABR/T陶瓷薄板饰面保温装饰一体板建筑构造》图集中CABR/T陶瓷薄板饰面保温装饰一体板的细部节点进行解释和分析。

四边简支矩形板的稳定

用变分法讨论了四边简支矩形板的稳定问题,给出了薄板的临界载荷。

八钢1420冷轧板形缺陷分析及控制方法

介绍了1420冷轧板形缺陷的种类,及其产生原因,通过八钢1420冷连轧机组试生产,结合机组的特点,并介绍了控制方法。

Unified Solution Method of Rectangular Plate Elastic Bending

The bending of rectangular plate is divided into the generalized statically determinate bending and the generalized statically indeterminate bending based on the analysis of the completeness of calculating condition at the corner point. The former can be solved directly by the equilibrium differential equation and the boundary conditions of four edges of the plate. The latter can be solved by using the superposition principle. Making use of the recommended method, the bending of the plate with all kinds of...

Deflection and stress of hollow CRCP slab under concentrated vehicle load

Based on the equivalence principle of deflection and stress, the concentrated vehicle load which acts on the center of continuously reinforced concrete pavement （CRCP） is translated into the equivalent half-wave sine load by the Fourier transform. On the basis of this transform and the small deflection theory of elastic thin plates, the deflection and stress formulae of CRCP under the concentrated vehicle load with a hollow foundation are put forward. The sensitivity of parameters is analyzed. The results show that maximum deflection is directly proportional to the concentrated vehicle load and the slab width, and inversely proportional to the lateral bending stiffness and slab thickness. The effects of slab width and thickness are significant with regard to maximum deflection. Maximum stress is directly proportional to the concentrated vehicle load and the slab width as well as inversely proportional to slab thickness. The effect of slab thickness is significant with regard to maximum stress. According to the calculation results, the most effective measure to reduce maximum deflection and stress is to increase slab thickness.

Bearing mechanism and thickness optimization of ore roof in bauxite stope

Based on the elastic thin plate theory,the main law of the ore roof failure was analyzed and the formula of the ore roof thickness was deduced.The results show that the tensile stress in the roof center accounts for the roof failure.According to the limit failure conditions of the point,the formula of the ore roof thickness was derived.Taking No.10 stope of a bauxite mine as an engineering case,the optimal thickness of the ore roof was 0.36 m.The safety factor was taken as 1.3,therefore the design thickness was 0.5 m.In the whole industrial test process,the dynamic alarm devices did not start the alarm and the ore roof was not damaged.Compared with other stopes under similar conditions,its thickness was reduced by 0.1-0.3 m.The recovery rate of the ore roof was increased by 16.7%-37.5%.

Influence of variables in deep drawing of AA 6061 sheet

Deep drawing is one of the most important processes for forming sheet metal parts.It is widely used for mass production of cup shapes in automobile,aerospace and packaging industries.Cup drawing,besides its importance as forming process,also serves as a basic test for the sheet metal formability.The effect of equipment and tooling parameters results in complex deformation mechanism.Existence of thickness variation in the formed part may cause stress concentration and may lead to acceleration of damage.Using TAGUCHI's signal-to-noise ratio,it is determined that the die shoulder radius has major influence followed by blank holder force and punch nose radius on the thickness distribution of the deep drawn cup of AA 6061 sheet.The optimum levels of the above three factors,for the most even wall thickness distribution,are found to be punch nose radius of 3 mm,die shoulder radius of 8 mm and blank holder force of 4 kN.

Double Symplectic Eigenfunction Expansion Method of Free Vibration of Rectangular Thin Plates

The free vibration problem of rectangular thin plates is rewritten as a new upper triangular matrix differential system. For the associated operator matrix, we find that the two diagonal block operators are Hamiltonian. Moreover, the existence and completeness of normed symplectic orthogonal eigenfunction systems of these two block operators are demonstrated. Based on the completeness, the general solution of the free vibration of rectangular thin plates is given by double symplectie eigenfunction expansion method.

Analytical Approaches of Composite Rectangular Thin Plates

The purpose of the present study was to explore and subsequently establish a technique for determination of analytical solutions for the differential equation for composite thin plates. The considered reasons for the solutions were to exactly satisfy the boundary conditions and to verify as close as possible the differential equation of the plate. There are studied two solutions for orthotropic plate with clamped edges, and made comparisons with the solutions presented by Reddy [1] and with the exact solution by Timoshenko and Woinowsky. The models are based on the CLPT （classical laminated plate theory）. The Ritz method, in conjunction with the weighted residue method for the coefficients calculation, is used to analytically determine the bending solutions of orthotropic laminated plates subjected to uniform pressure on the bottom laminate. The purposed solutions were critically analysed considering a FEM （finite element method） solution for comparison. Finally, it is presented the experimental device and the experimental test results, as well. Fabrics have been incorporated into two composite plates were required scalps on one direction, thus ensuring different elasticity modules on both directions. Thorough comparison between analytical solutions, numerical results and experimental data is performed and a good agreement is obtained.

HMPT-BOF-RH-CSP process for SPHE substrate of cold rolled deep drawing steel

Based on hot metal pretreatment （HMPT）-basic oxygen furnace （BOF）-Rheinstahl Heraeus （RH）-compact strip production （CSP） process, parameters controlling on cold rolling deep drawing substrate SPHE were investigated during smelting and rolling process by composition design and technology control. The influence of parameters on chemical compositions, mechanical properties and microstructure was revealed by scanning electron microscope （SEM）. The results show that, 1） main chemical components in SPHE are w（C）_〈40×10^-6, w（Si）_〈 0.01%, w（S）_〈0.009%, w（N）〈20×10^-6, w（O）〈_ 25×10^-6; 2） main mechanical properties of the SPHE are Crs=274 MPa, 00=334 MPa, A=48.9%; 3） main performances of deep drawing quality （DDQ） grade steel produced by SPHE are as follows, transversely crs=167 MPa, 00=298 MPa, n=0.219, r=2.46; vertically σs=166 MPa, 00=298 MPa, n=0.226, r=2.39; in 45° direction σ=171 MPa, 00=308 MPa, n=0.214, t=2.26; 4） microstrueture of DDQ is ferrite, average grain size is Grade 7.5, and inclusion size is 3-10μm.

大型油罐基础设计与选型

目前，容积为5000－10000m^3的大型油罐在国内已经相当普遍，这类可挠性很大的薄板结构在土木工程中也是不多见的。本文在归纳介绍大型油罐基础选型的同时，介绍了几种常用储罐基础类型（其中包括护坡式、环墙式、外环墙式以及山区罐和特种罐的基础）的技术性能，并对储罐基础的失效及其在设计中的预防试验进行了总结。

CVC技术的研究

CVC(Continually Variable Crown——连续可变凸度)技术,把轧辊加工成“S”形,两根对应轧辊的辊形曲线完全一样,但彼此相差180°放置。通过轧辊的横向移动,使轧辊的辊缝凸度连续变化,以适应不同的轧制条件,从而使轧制的薄板板形良好。CVC技术既可用于冷轧,也可用于热轧,既可用于二辊、四辊轧机,也可用于六辊轧机。CVC技术原理见图1。

Eucalypt Wood Anatomical and Physical Properties and Their Effects on Plywood Veneer Quality

In order to better understand the reasons why eucalypt veneer checks easily and severely, wood samples of three eucalypt species were selected, and their anatomical and physical properties were examined according to conventional methods and the national standards. The effects of variances in cell wall thickness of wood fibre and vessel, and diameter of the cell lumen as well as the tissue ratio on the quality of plywood veneer were analysed. The results show that： 1） There is a great difference in fibre cell wall thickness and diameter of the cell lumen between early wood and late wood of Eucalyptus delegatensis. 2） E. obliqua has a high wood fibre tissue ratio and the thickest fibre cell wall, but the difference inthe fibre cell wall thickness between early wood and late wood is the smallest. 3） The wood fibre tissue ratio of E. regnans is smaller than that of E. obliqua, and its wood fibre cell wall isthe thinnest and there is only a very small difference in fibre cell wall thickness between early wood and late wood. The difference inthe diameter of wood fibre cell lumen among early wood, transition area and late wood is also small： 4） E. delegatensis has the highest tangential shrinkage rate and radial-tangential shrinkage rate, andE. obliqua has the lowest. It is the variability of wood anatomical properties of these species that cause the difference in the veneer shrinkagei and then affects plywood veneer quality.

发电机爪极与风扇点焊的探索

论述了电视风扇与爪极焊接，探讨了1 mm低碳钢板与20mm以上低碳钢（铸造钢）板点焊的机理．提出了薄板与厚板点焊时，电场与温度场只决定于薄板上使用的电极工作型面．指出了物体的热情性对焊接的影响。