Experimental and numerical study regarding H-steel all-bolted connection steel frame with composite wall boards

H-steel all-bolted connection steel frame structures with heat preservation and decoration composite wall boards were investigated and the seismic performances of three scaled specimens were studied.The failure modes,hysteresis curves,bearing capacity,ductility,energy dissipation capacity,stiffness degradation and strain distribution were discussed.The calculation method of structural theoretical internal force was presented.The results showed that the overall structural seismic performance was better,and the structural ductility met the demands of elastic-plastic inter-story drift angle for seismic design.The H-steel weak-axis connection structure obtained better energy dissipation capacity,and its bearing capacity and stiffness were slightly different from the strong-axis connection.The heat preservation and decoration performance of composite wallboard and the all-bolted connection of the steel frame realized prefabrication during the whole construction period.The plastic hinge of the steel beam can be moved outwards because of the L-angles,which effectively avoids stress concentration in joint areas and expands the plastic hinge range.The errors between the theoretical structural capacity calculated by the plastic analysis method and the test results were within 2.44%.In addition,structural failure mechanisms and bearing capacities were verified by the finite element(FE)analysis,and the effects of the main parameters on the structures were investigated.The FE verification results were the same as in the test.The research results provide theoretical support and technical guidance for the application of thermal insulation and decorative composite wall panels in H-shaped steel all-bolted steel frames.

Effect of Low pH on Forming Process of Desulfurization Gypsum Composite Boards Strengthened by Melamine-formaldehyde Resin

Through exploring the effects of low pH on the composite system of desulfurization gypsum(DG)enhanced by melamine-formaldehyde resin(MF),it is found that the inducing of sulfate-ion,in contrast to chloride and oxalate ions,favors the longitudinal growth of the crystalline form of the hydration product,which was relatively simple and had the highest length to width(L/D)ratio.At the same time,MF can also improve L/D ratio of gypsum hydration products,which favors the formation of hydrated whiskers.Finally,in a composite system composed of hemihydrate gypsum,MF,and glass fibers,when dilute sulfuric acid was used to regulate pH=3-4,the tight binding formed among the components of the composite system compared to pH=5-6.The hydration product of gypsum adheres tightly to glass fiber surface and produces a good cross-linking and binding effect with MF.The flexural strength,compressive strength,elastic modulus,and water absorption of the desulphurized gypsum composite board is 22.7 MPa,39.8 MPa,5608 MPa,and 1.8%,respectively.

Optimum preparation technology for Chinese fir wood/Ca-montmorillonite (Ca-MMT) composite board

For this study, an intercalation compounding method was used to prepare Chinese fir wood/Ca-montmorillonite （Ca-MMT） composite board to improve its properties such as surface mechanical properties, flame retardance and dimensional stability. By virtue of water-soluble phenolic resin （PF）, Chinese fir wood and Ca-MMT were mixed by pressure and vacuum impregnation. The optimum impregnation technology of Chinese fir wood/Ca-MMT composite board was obtained by using an orthogonal design and a single factor design of pressure and vacuum impregnation, using weight percent gain （WPG） as the basic index. The results are as follows： 1） On the basis of the orthogonal design and an actual experiment, the optimum preparation technology of Chinese fir wood/Ca-MMT composite board is 20% PF resin dispersion concentration （wt%）, 1.0 CEC amount of organic intercalation agent, 0.098 MPa vacuum degree, 5% concentration of Ca-MMT and 1.0 MPa pressure. 2） The WPG of the composite board samples of 450 mm length was much larger than that of the samples of 600, 750 and 900 mm length. Warm water extraction contributed little to WPG

Stress Analysis of Printed Circuit Board with Different Thickness and Composite Materials Under Shock Loading

In this study,the deformation and stress distribution of printed circuit board(PCB)with different thickness and composite materials under a shock loading were analyzed by the finite element analysis.The standard 8-layer PCB subjected to a shock loading 1500 g was evaluated first.Moreover,the finite element models of the PCB with different thickness by stacking various number of layers were discussed.In addition to changing thickness,the core material of PCB was replaced from woven E-glass/epoxy to woven carbon fiber/epoxy for structural enhancement.The non-linear material property of copper foil was considered in the analysis.The results indicated that a thicker PCB has lower stress in the copper foil in PCBs under the shock loading.The stress difference between the thicker PCB(2.6 mm)and thinner PCB(0.6 mm)is around 5%.Using woven carbon fiber/epoxy as core material could lower the stress of copper foil around 6.6%under the shock loading 1500 g for the PCB with 0.6 mm thickness.On the other hand,the stress level is under the failure strength of PCBs with carbon fiber/epoxy core layers and thickness 2.6 mm when the peak acceleration changes from 1500 g to 5000 g.This study could provide a reference for the design and proper applications of the PCB with different thickness and composite materials.

Study on the Adhesive for the Production of High Strength Four Layer Composite Corrugated Board

In order to study of adhesive which is applicable to the production of high strength four layer composite corrugated board,the composite corrugated medium was respectively coated with cassava starch adhesive,environmental-friendly modified water glass binder,CP-88 starch adhesive,polyvinyl alcohol adhesive and polyvinyl acetate adhesive,then the edgewise crush resistance and flat crush resistance contrast experiment on produced corrugated board samples was tested.The experiment results demonstrated that the produced corrugated board with environmental-friendly modified water glass binder had high edgewise crush resistance,general flat crush resistance and more economic,so the environmental-friendly modified water glass binder can be used for the production of high strength four layer composite corrugated board.

Experimental study on axial compressive behaviors of prefabricated composite thermal insulation walls after single-side fire exposure

The axial bearing capacity of prefabricated composite walls composed of inner and outer concrete wythes,expandable polystyrene(EPS)boards and steel sleeve connectors is investigated.An experimental study on the axial bearing capacity of four prefabricated composite walls after fire treatment is carried out.Two of the prefabricated composite walls are normal-temperature specimens,and the others are treated with fire.The damage modes and crack development are observed,and the axial bearing capacity,lateral deformation of the specimens,and the concrete and reinforcing bar strain are tested.The results show that the ultimate bearing capacity of specimens after a fire is less than that of normal-temperature specimens;when the insulation board thicknesses are 40 mm and 60 mm,the decrease amplitudes are 20.8%and 16.8%,respectively.The maximum lateral deformation of specimens after a fire is greater than that of normal-temperature specimens,and under the same level of load,the lateral deformation increases as the insulation board thickness increases.Moreover,the strain values of the concrete and reinforcing bars of specimens after a fire are greater than those of normal-temperature specimens,and the strain values increase as the thickness of insulation board increases.

基于改性PP成型的工控机电路板支撑架注射模设计

针对工控机电路板支撑架大型塑件的成型,选用了一种玻纤改性增强聚丙烯(PP)复合材料用于塑件的注射成型。模具结构为三板模结构,分3次开模打开。为保证塑件模腔充填均衡性、饱满性而设计了两个点浇口用于模腔的浇注。针对塑件二级子特征较多,特别是异型螺柱深筋位较多的特点,设计了多个局部镶件用于这些局部特征的成型,在提高局部成型镶件强度的同时,降低了这些成型件的加工难度。针对模腔局部位置排气难点,设置了多个透气镶件以增强排气。设置了锁扣机构、定距拉杆机构用于模具的开模闭模控制;设计了弹料机构用于流道废料的可靠脱模、定位机构以确保塑件的成型精度和模具工作寿命;3个滑块机构用于塑件侧壁直壁及直壁上侧孔的成型与脱模。模具结构形式合理,成型件便于加工且实用可靠,能为同类模具设计提供有益借鉴。

复合保温板与加气混凝土砌块墙体一体化施工力学性能研究

针对复合保温板与砌块填充墙连接的安全性,采用HC-MD60高精度铆钉拉拔仪,进行锚栓抗拉承载力和复合保温板拉伸黏结强度现场原位检测试验。测试结果表明:锚栓抗拉承载力平均值为2.345 kN,复合保温板表面抗裂加强层与保温芯材之间的黏结强度平均值为0.17 MPa,复合保温板内侧黏接层与砌块墙体黏结强度为0.1 MPa,黏锚结合的力学性能满足DB/T 29-281—2020《天津市外模板现浇混凝土复合保温系统应用技术规范》要求。

内夹单层镀锌板复合望板系统耐火性能研究

为了研究新型木-钢结构望板系统相对于传统木结构望板系统及冷摊瓦屋顶系统耐火极限性能,该文采用Abaqus模拟软件建立了有限元分析模型。在标准升温曲线下,对三种屋顶系统进行温度场模拟分析。结果得出,随着时间及温度的增加,传统木结构望板系统及冷摊瓦屋顶系统中,木板先于木梁炭化完全;新型木-钢结构望板系统中,木板后于木梁炭化完全且上下两板炭化速度有明显改变。之后对三种屋顶系统在同等荷载作用下,进行结构场分析,结果表明:新型木-钢结构望板系统耐火极限相对于传统木结构望板系统提高73%,相对于冷摊瓦系统提高52%。得出新型木-钢结构望板系统具有更好的耐火性能,可为村镇木结构建筑和改造提供参考。

建筑外墙用新型复合保温板力学性能试验研究

为研究新型复合保温板的受力性能,设计进行不同保温芯材复合保温模板的力学性能试验。结果表明:挤塑聚苯复合保温板在压缩过程中试件四周出现褶皱,但无明显裂纹;岩棉条复合保温板在受压过程中,岩棉纤维发生弯曲或折断,成条状相互分离;插丝岩棉复合保温板随压力作用,纤维之间挤压密实,表现出较强的抗压能力;石墨聚苯复合保温板受压过程中四周出现褶皱;在一定范围内随保温芯材厚度增加,复合保温板的弹性模量和压缩强度增加,挤塑聚苯板保温芯材的弹性模量和压缩强度较石墨聚苯板保温芯材高。

某气田复合板压力容器腐蚀原因分析

为了确定复合板(Q345R+316L)压力容器的腐蚀原因并制定应对措施,对复合板腐蚀部位进行了宏观形貌分析和理化检验,并采用循环极化法和恒电位法对复合板复层不锈钢在氯离子环境下的耐点蚀性能和钝化能力进行验证。结果表明:复合板在氯化物环境下存在明显的点蚀倾向,且无法进行再钝化,不满足当前环境下的服役工况,需要对压力容器采取一定应对措施来控制氯离子腐蚀的发生。

沸石胶凝增强复合包装板材的制备及性能

目的 为了拓展固废资源化的应用,本研究以生物质废料(秸秆粉、废木屑)为基体,以预处理后的污水污泥焚烧灰作为填料,采用热压成型制备了一种沸石胶凝增强复合包装板材。方法 通过XRD、SEM等方法表征预处理前后填料的元素组成、晶体结构、微观形貌等,并研究预处理填料对制备复合包装板材性能的影响趋势以及增强机制。结果 添加质量分数为22.5%的预处理后的填料制备的复合板材,其弯曲强度为27.73MPa,压缩强度为44.38MPa,在力学性能、隔热性能和吸水厚度膨胀率等方面均明显优于未经过预处理的对照组,满足GB/T7284—2016《框架木箱》、GB/T23898—2009《木托盘用人造板》等国家标准的要求。复合板材性能的增强主要归因于预处理引起填料相组成及结构的变化。由于方沸石晶相的生成,填料对自身和基体的吸附性、易分散性得到极大改善。结论 经过预处理的填料制备的沸石胶凝增强复合包装板材性能优异,在木包装领域及建筑领域具有广阔的应用前景。该研究可为大宗固体废弃物资源化利用提供高附加值的解决方案,还可以为缓解林产资源短缺的现状提供新的思路。

Experimental Study on Corrosion of Stainless Steel in Low Temperature Multi effect Seawater Desalination

Starting from the corrosion mechanism,this paper analyzes the characteristics of various types of stainless steel and selects the best performance composite plate composite plate stainless steel.Analyze and select the most suitable corrosion detection method based on specific practical multi working conditions,discuss the interference factors that affect metal corrosion during experimental simulation,and the advantages of newly developed sheet metal.The new development of composite board panels,with the substrate and composite materials applying their respective capabilities for MED,will bring breakthrough progress to the scientific research and engineering applica-tion of composite boards.

装配式GRC-PC复合墙板收缩性能的试验研究

文中开展了不同工艺条件下装配式GRC-PC复合墙板收缩性能的研究,并与单一材料墙板进行了对比。结果表明,GRC墙板与C30混凝土墙板的收缩应变随着时间的延长,呈现先快速降低后平稳的趋势;C30混凝土墙板的收缩应变稳定在-80×10^(-6)μm,较GRC墙板的收缩应变降低93.2%。与GRC墙板收缩应变相比,GRC-PC墙板的表面收缩应变及内部收缩应变的降低幅度分别为89.2%、94.9%;与C30墙板收缩应变相比,复合墙板内部的收缩应变降幅达到33.3%。加入钢丝网后,GRC-PC复合墙板+钢丝网的表面收缩应变开始下降,具有更好的抗裂性能。

PET泡沫板在建筑领域的应用研究

PET泡沫板是一类性能优异的可回收利用的高强度发泡塑料制品,该材料在建筑领域有着广阔的应用前景,有助于建筑材料的循环利用,减少环境污染,节约社会资源。但目前其在建筑领域的应用较少。本文结合PET泡沫板的物理力学性能及相关试验分析了其在建筑领域的应用形式,总结了各应用形式的标准化现状,并对其在建筑领域的应用前景进行了展望。

建筑高性能复合保温板中聚氨酯胶粘剂粘接性能研究

研究建筑高性能复合保温板聚氨酯胶粘剂粘接性能。制备预聚体,将其与多种环保材料结合,采用聚合法制备聚氨酯胶粘剂;利用制备完成的聚氨酯胶粘剂,粘接2块建筑高性能复合保温板,测试该胶粘剂在不同热压机热压时长作用下,预聚体不同用量以及催化剂掺量变化下粘接复合保温板的性能。结果表明,延长热压机的热压时长至10.5 min,增加预聚体用量为15%,选择0.05%用量的二月桂酸二丁基锡(DT)催化剂,能够获得粘接性能较好的建筑高性能复合保温板聚氨酯胶粘剂。

碳纤维复合板叠层铆接参数优化与性能测试及工艺对比

为了提升建筑工程用纤维复合材料的拉伸性能,设计了不同叠层顺序、铺层层数的碳纤维复合板,并对比了传统工艺和新型工艺下碳纤维复合板的拉伸性能和断口形貌。结果表明,碳-铝复合板的最大拉伸载荷(2.22 kN)明显高于铝-碳复合板(0.67 kN),且相较于铝-碳复合板,断裂后碳-铝复合板的位移相对更大;随着铺层层数增加,碳-铝复合板的拉剪面积逐渐增加,拉伸强度呈现先增加后减小的趋势,在铺层层数为16时取得拉伸强度最大值。传统工艺下碳纤维复合板的最大拉伸载荷为1.53 k N,而新型工艺下碳纤维复合板的拉伸载荷为2.22 kN,约为传统工艺下碳纤维复合板最大载荷的1.45倍。

SiO_(2)气凝胶改性复合防火聚苯板的制备及性能

构建了聚苯乙烯泡沫颗粒与玻化微珠二级级配模型,得出聚苯乙烯泡沫颗粒与玻化微珠的最佳粒径比约为5∶2,体积比约为100∶7.根据级配模型配制骨料,采用模压成型工艺制备复合防火聚苯板,显微结构显示其骨料堆积紧密、有序.分析了硅酸盐胶凝材料、SiO_(2)气凝胶及憎水剂对复合防火聚苯板性能的影响.结果表明:复合防火聚苯板的阻燃性能及拉拔强度随着硅酸盐胶凝材料掺量的增加而增大;导热系数和拉拔强度随着SiO_(2)气凝胶掺量的增加而降低,软化系数随着SiO_(2)气凝胶掺量的增加而升高;吸水率随着憎水剂掺量的增加而降低.