GRC轻质隔墙条板墙体裂缝控制技术研究

GRC轻质隔墙条板是高层钢筋混凝土结构建筑中重要的隔墙材料产品,但因其墙体开裂现象普遍,制约了产品的发展,深入剖析GRC板墙体裂缝问题,从产品质量、施工材料、施工技术等全方位研究入手,探索出了行之有效的裂缝控制技术。     

Three-point-support method based on position determination of supports and wafers to eliminate gravity-induced deflection of wafers

The flatness measurement of large and thin wafers is affected greatly by gravity. Inverting method is often used to cancel the effect. However, it is required that the positions of the supports and wafers are perfectly symmetric about the inversion axis. In this study a three-point-support method based on position determination of supports and wafers was proposed. The supporting balls and the wafer were placed in arbitrary positions and their positions were obtained by measurement and fed into the FEM model which was developed to calculate the gravity-induced deflection (GID). The methods to acquire the positions of the supports and the wafer were proposed. The position measurement accuracy of the supports was improved greatly by circle fitting to the profile of the supporting ball. Wafer edge point was obtained accurately as the intersection point between the wafer surface line and the edge profile. The method to measure the wafer thickness using only one displacement sensor on the same equipment was presented. The simulation results were verified by experimental results. The centering device for the wafer and the positioning accuracy requirements of the supports are not needed any more. The effect of the positions of the supports and the wafer was reduced to be less than 1 μm for a 300 mm diameter and 397 μm thickness wafer with GID over 140 μm. This method could also be used for accurate flatness measurement of other large and thin panels.     

Non-linear curling of wide single-flange steel panels

An original analytical model to study the non-linear flange curling in wide single-flange panels is presented in this paper. Flange curling phenomenon is the tendency of the wide thin flanges (in compression or tension) to move towards the neutral axis, when thin-walled members are subjected to bending. Despite the simplicity of the formula developed in earlier works of Winter to account for the flange curling effects, which is used in current steel codes, recent work has showed that this expression is rather restrictive and does not apply for all cases. The analytical expressions reported here are rather general since they (i) consider the restraining effect provided by the web, (ii) account for the shift of the neutral axis due to curling, (iii) incorporate the decrement of the second moment of area due to curling, and (iv) are fully analytical, thus avoiding iterative techniques. The analytical model is applied to study the curling behaviour of profiled steel decks and cassette-wall panels and is validated by means of comparisons with experimental results available in the literature. Since the EC3 rules state that the tensioned wide flange in liner trays should be reduced if the curling displacement is higher than 5% of the web height, approximate expressions to evaluate the reduced width of the wide thin flange under curling are proposed.     

Experimental analysis of behavior and damage of sandwich composite materials in three-point bending. Part 2. Fatigue test results and damage mechanisms

The analysis of stiffness degradation and the identification of damage mechanisms during and after fatigue tests of sandwich panels with PVC foam cores have been performed. The sandwich panels with cross-ply laminates skins made of glass fiber and epoxy resin were manufactured by vacuum moulding and subjected to three-point bending tests. Two PVC cores of similar type but with differing densities were investigated. The effect of core density and thickness on the damage behavior was highlighted. Using the cyclic life criterion, fatigue curves were plotted according to two models and compared with those of the literature. It has been demonstrated that the sandwich SD 2, with the higher core density, withstands a higher load and possesses greater rigidity in static tests, combined with an enhanced fatigue resistance, when compared to sandwich SD 1 which has a lower core density. Translated from Problemy Prochnosti, No. 3, pp. 32–44, May–June, 2009.     

Nonlinear mechanical,thermal and thermo-mechanical postbuckling of imperfect eccentrically stiffened thin FGM cylindrical panels on elastic foundations

This paper presents an analytical approach to investigate the nonlinear stability analysis of eccentrically stiffened thin FGM cylindrical panels on elastic foundations subjected to mechanical loads, thermal loads and the combination of these loads. The material properties are assumed to be temperature-dependent and graded in the thickness direction according to a simple power law distribution. Governing equations are derived basing on the classical shell theory incorporating von Karman–Donnell type nonlinearity, initial geometrical imperfection, the Lekhnitsky smeared stiffeners technique and Pasternak type elastic foundations. Explicit relations of load–deflection curves for FGM cylindrical panels are determined by applying stress function and Galerkin method. The effects of material and geometrical properties, imperfection, elastic foundations and stiffeners on the buckling and postbuckling of the FGM panels are discussed in detail. The obtained results are validated by comparing with those in the literature..     

Surface‐discharge electrode design methods for ACPDPs

Abstract— In order to lower development costs and to shorten development time, small panels, under 10‐in on the diagonal, are used for the experiments to improve the luminous efficiency of plasma‐display panels. However, it is difficult to show the same results as those of large panels, over 40 in. on the diagonal. In this paper, first, we show that the luminous efficiency and the voltage margin of mini‐panels are not obtained with large panels by using an actual 46‐in. PDP. The reason is that the resistance in the large panels is larger than that in the mini panels and the voltage drop in the large panels are larger than in mini‐panels. Therefore, we conclude that the bus electrode width and the transparent electrode width are important factors in the design of large PDPs. Next, we show the technique of designing large panels by using a database obtained from mini‐panels. The estimated cell‐design results show good agreement with an actual 46‐in. PDP in luminous efficiency and minimum sustain voltage. We show that a desired large PDP can be obtained by using the cell design proposed in the present paper.     

A study on the chromaticity shifts of blue phosphor for color plasma displays

The dependency of the chromaticity shifts on the concentration of Eu²⁺ doped in BaMgAl₁₀O₁₇ (BAM) was investigated under heat‐treatment and vacuum ultraviolet (VUV) irradiation. The Eu²⁺ ions in BAM show an asymmetrical broad emission band with a maximum at ～452 nm under excitation of VUV light at room temperature, showing that multiple crystalline cationic sites exist in the host. It was found that the chromaticity shifts greatly decrease with increasing heat‐treatment temperature. Regardless of the Eu²⁺ concentration, the chromaticity shifts caused by heat‐treatment are greater than that caused by VUV irradiation. Compared with conventional BAM, a solid solution of BAM with barium aluminate as a powder and film was also studied, and very few chromacity shifts were observed. It is suggested that the distribution of Eu²⁺ ions in different sites in a BAM lattice results in different chromaticity coordinates. By increasing the Eu²⁺ concentration in BAM, or under heat‐treatment and VUV irradiation, the emission band shifts towards longer wavelengths.     

Multiple-dial check reading: Pointer symmetry compared with uniform alignment.

24 Ss participated in two experiments in which they were required to pick out, from printed panels containing 16 dials, the dial with a deviating pointer. Two versions of a uniformly-aligned configuration and one version of a symmetrically-aligned configuration were studied. S was required to identify both the "different" dial and the direction of the deviating pointer. It was found that (1) both configurations were equally effective for check reading after extended practice, (2) early in practice symmetrical alignment configurations appear to be more difficult, (3) transfer effects from pointer symmetry to uniform alignment are greater than transfer effects in the other direction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

改动分隔屏对喷燃锅炉屏式过热器后速度偏差沿高度方向分布特性的影响

试验研究了在改动前分隔屏的工况下 ,四角喷燃锅炉屏式过热器后 ,左右速度偏差沿水平烟道高度方向的分布特性 ,改动分隔屏的各工况分别为 :向左侧偏转 30°、45°、6 0°;全部偏置在右侧以及各个前屏向左侧偏转不同角度的组合式偏屏。研究表明 ,屏式过热器后左右速度的偏差主要集中在水平烟道的下半部区域。在改动屏的各工况中 ,均能使这一区域的速度偏差系数有不同程度的下降 ,与标准运行工况相比 ,下降幅度为 2 0 %～ 5 0 %。     

Numerical investigation of the response of sandwich-type panels using thin-walled tubes subject to blast loads

The response of a novel lightweight panel design under blast loading is numerically investigated. The sandwich-type panel uses thin-walled square tubes as the core material with mild steel outer plates. A parametric study is carried out with ABAQUS/Explicit to examine the effects and interaction between design variables in three different tube layouts. Tube position, thickness and aspect ratio as well as top plate thickness are varied. Buckling stability and absorption performance are shown to be highly sensitive to tube placement due to interaction effects between the top plate and tubes. For each panel an optimal tube positioning is obtained corresponding to nearly perfect axial progressive symmetric tube buckling. Tube thickness is shown to influence the onset of buckling and hence affects the stability of the core, while energy absorption performance is also highly configurable. Tube aspect ratio shows only a small effect on core buckling stability and energy absorption. Top plate thickness influences absorber performance significantly while having a small effect on buckling stability. A simple theoretical analysis is presented and shows reasonable agreement with the numerical simulations.