碳纤维复合材加固T形梁的三维设计软件开发

利用大型通用有限元软件提供的二次开发功能,编制了碳纤维复合材加固钢筋混凝土T形梁的三维设计专用软件。突破了现有的单一截面设计,能以崭新的彩色三维方式展示结构整体的承载能力。该软件除了计算可靠之外,还可提供海量数据,满足实际工程的需要。

碳纤维复合材加固钢筋混凝土结构的研究进展

综合评述了目前国内外常用的抗震加固技术,分析了各加固技术的优缺点.概述了碳纤维复合材(CFRP,Carbon Fiber Reinforced Plastics)加固的特点,并分别从柱的受压加固、梁的受弯受剪加固、耐久性和粘结性能等方面介绍了CFRP加固钢筋混凝土结构的国内外研究进展,总结了影响CFRP加固效果的因素.

碳纤维复合材加固钢筋混凝土受弯构件平面假设研究

利用大型通用有限元软件ANSYS,对碳纤维片复合材加固钢筋混凝土T形梁的平面假设进行了研究,分析了各级荷载下横截面上的水平位移。分析结果表明,平面假设在所有情况下均是有效的。

碳纤维复合材在某增层改造加固工程中的应用

重点介绍了碳纤维复合材在南京某酒店工程增层改造加固中的实际施工应用,通过工程实例较为详细地阐述了碳纤维复合材的特点,加固的适用范围及具体方式,加固的原则及材料、技术要求和构造规定,施工工艺流程,粘贴不良处的修补,施工质量保证措施等,对日后粘贴碳纤维复合材加固工程结构施工有很好的借鉴意义。

混凝土梁碳纤维复合材加固的探讨

以机房加固工程中钢筋混凝土梁的加固设计为背景,介绍碳纤维复合材加固的原理并探讨承载力验算方法及碳纤维复合材加固的施工工艺。

碳纤维增强复合材料筋材应力松弛性能的试验研究

为合理确定湖北十淅高速丹江口水库特大桥地锚桥台预应力碳纤维增强复合材料(Carbon Fiber Reinforced Polymer, CFRP)筋材的松弛损失,对不同应力比下所用CFRP筋材的应力松弛效应进行了试验研究。基于黏结式锚具和机械压接式锚具锚固的CFRP筋材试件的轴向拉伸试验结果,明确了不同锚固形式对CFRP筋材破坏形态的影响及CFRP筋材的材料性能;基于CFRP筋材试件1 000 h的应力松弛试验,获得了不同应力水平下CFRP筋材应力松弛的发展规律。结果表明:黏结式锚具锚固的轴拉试件发生了理想的筋材拉断爆裂破坏,但应力松弛试件在试验过程中应变变化较大;机械压接式锚具锚固的轴拉试件提前发生了CFRP筋材的层裂剥离破坏,但应力松弛试件在试验过程中应变变化较小,满足GB/T 21839—2019中应力松弛试验的相关要求。随着初始应力比的提高,CFRP筋材的应力松弛越大,初始应力比分别为0.53、0.63和0.82的试件1 000 h的松弛率分别为1.06%、1.65%和2.31%;CFRP筋材应力松弛的发展收敛较快且随初始应力的增加而更快趋于稳定,初始应力比为0.53、0.63和0.82的试件24 h的应力松弛量分别为1 000 h的45.3%、58.8%和59.7%,200 h的应力松弛量分别为1 000 h的78.3%、81.2%和82.7%;基于试验结果,建立了CFRP筋材应力松弛的预测模型,且具有较高预测精度,并预测了丹江口水库特大桥地锚桥台所用预应力CFRP筋材10年,30年、50年和100年的松弛率分别为1.91%、2.18%、2.32%和2.52%。

碳纤维布加固钢筋混凝土梁试验研究

共进行了6根碳纤维布加固钢筋混凝土梁和1根未加固梁的正截面承载力对比试验,研究了碳纤维布加固钢筋混凝土梁的破坏机理、应变分布情况、承载力、刚度和延性,分析了碳纤维布的粘贴层数、粘贴锚固方式、二次受力对加固效果的影响,并进行了试验梁的正截面承载力理论计算,与试验结果比较一致,验证了现行规范所提供的计算理论和构造措施的合理性。

碳纤维加固混凝土结构应用实例

目前一些工程使用中发现混凝土构件存在质量隐患,包括构件受力裂缝,板底或板肋蜂窝、麻面及露筋,混凝土强度不足等,影响结构安全。结合实际应用阐述了碳纤维的高抗拉性、高弹性、轻质及耐腐蚀性等优良性能,分析了碳纤维加固的适用范围,并以某办公楼加固工程中钢筋混凝土梁的加固设计为背景,介绍碳纤维复合材加固的原理并探讨承载力验算方法及碳纤维加固混凝土结构的工艺流程、施工方法及质量控制要点。

基于分层损伤分析的碳纤维增强树脂复合材料-金属传动轴扭转性能

为提高油动四旋翼无人机载重能力,对碳纤维增强树脂复合材料(CFRP)-金属传动轴进行研究。CFRP-金属传动轴扭转强度影响因素为CFRP管制孔质量问题和传动过程中销钉对连接孔的挤压作用。研究导致CFRP管孔入出口分层损伤的力学行为,揭示了CFRP管制孔质量的影响机制并优化了制孔工艺。利用扭转试验对销接式CFRP-金属传动轴和附有内外衬套的混合式CFRP-金属传动轴进行对比分析。结果表明:在CFRP管内外附有铝合金衬套可有效减少制孔时的分层损伤,使孔入口质量提高了4.4%,孔出口质量高了8.3%,同时抑制销钉对连接孔的挤压作用。优化后的传动轴承受扭矩从499 N·m提高到952 N·m。

Numerical study of directional heat transfer in composite materials via controllable carbon fiber distribution

Carbon fiber reinforced polyamide 12(CF/PA12),a new material renowned for its excellent mechanical and thermal properties,has drawn significant industry attention.Using the steady-state research to heat transfer,a series of simulations to investigate the heat transfer properties of CF/PA12 were conducted in this study.Firstly,by building two-and three-dimensional models,the effects of the porosity,carbon fiber content,and arrangement on the heat transfer of CF/PA12 were examined.A validation of the simulation model was carried out and the findings were consistent with those of the experiment.Then,the simulation results using the above models showed that within the volume fraction from 0% to 28%,the thermal conductivity of CF/PA12 increased greatly from 0.0242 W/(m·K)to 10.8848 W/(m·K).The increasing porosity had little influence on heat transfer characteristic of CF/PA12.The direction of the carbon fiber arrangement affects the heat transfer impact,and optimal outcomes were achieved when the heat flow direction was parallel to the carbon fiber.This research contributes to improving the production methods and broadening the application scenarios of composite materials.

框架剪力墙工程加固的设计与施工

河北某工程因主体验收时,部分柱混凝土强度等级达不到设计要求,进行了加固设计,论述施工方法步骤。

Effect of specific pressure on fabrication of 2D-C_f/Al composite by vacuum and pressure infiltration

Carbon fiber reinforced aluminum matrix （Cf/Al） composite has many excellent properties, and it has received more and more attention. Two-dimensional （2D） Cf/Al composites were fabricated by vacuum and pressure infiltration, which was an integrated technique and could provide high vacuum and high infiltration pressure. The effect of specific pressure on the infiltration quality of the obtained composites was comparatively evaluated through microstructure observation. The experimental results show that satisfied Cf/Al composites could be fabricated at the specific pressure of 75 MPa. In this case, the preform was infiltrated much more completely by aluminum alloy liquid, and the residual porosity was seldom found. It is found that the ultimate tensile strength of the obtained Cf/Al composite reached maximum at the specific pressure of 75 MPa, which was improved by 138.9% compared with that of matrix alloy.

Threshold pressure and infiltration behavior of liquid metal into fibrous preform

A dynamic measuring apparatus was developed to investigate the infiltration process of liquid metal into the fibrous preform. 10% （volume fraction） chopped carbon fiber preforms were infiltrated with magnesium alloy under different infiltration pressures. The threshold pressure and flow behavior of liquid metal infiltrating into the preforms were calculated and measured. The microstructure of obtained Ct4Mg composites was observed. The results indicate that the measured threshold pressure for infiltration was 0.048 MPa, which was larger than the calculated value. The infiltration rate increased with the increase of infiltration pressure, but the increase amplitude decreased gradually. The tiny pores in the composites could be eliminated by increasing the infiltration pressure. When the infiltration pressure rose to 0.6 MPa, high quality C1/Mg composite was obtained.

Impact Responses of the Carbon Fiber Fabric Reinforced Composites

To study the response characteristics of the carbon fiber fabric reinforced composites under impact loading, one dimensional strain impact test, multi gauge technique and Lagrange analysis method are used. The decaying rule of the stress σ , strain ε , strain rate ε · and density ρ with time and space is obtained. By the theory of dynamics, the impact response characteristics of the material is analyzed and discussed.

Study on mechanical properties of composite materials by in-situ tensile test

The mechanical properties of the SiC fiber-reinforced Mg-Al metal matrix composite materials have been studied on internal microstructure by (scanning electron microscopy) SEM in-situ tensile test. The emergence and propagation of the crack, and the fracture behavior in materials have been observed and studied. It is found that in the case of the tensile test, the crack emerged in SiC fiber initially. In the case of the strong cohesion of the fiber-metal interface, the crack propagated in the fiber, meanwhile the fibers in the neighborhood of the cracked fiber began to crack and the Mg-Al metal deformed plastically, and at last the material fractured. Otherwise the toughness of the materials grows in the case of the lower cohesion of the fiber-metal matrix interface.

极品

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中国产C919大飞机订单507架 巴黎航展开幕C919大型客机计划年内下线

日前,在法国巴黎举行的世界第一大航空航天展览上,空客携全球首款电力飞机亮相,中国产C919大飞机订单数达到了507架。据中国商用飞机有限责任公司透露,在第五十一届巴黎国际航空航天博览会开幕当日,平安国际融资租赁有限公司与中国商飞签署50架C919大型客机购机意向协议,平安租赁成为C919大型客机第19家客户。此外。

Mechanism of improving ductility of high strength concrete T-section beam confined by CFRP sheet subjected to flexural loading

For the purpose of inventing a new seismic retrofitting method for the reinforced high strength concrete （HSC） T-section beam using carbon fiber reinforced polymer （CFRP） sheet, three series, a total of twelve T-section beams with nine specimens confined by CFRP sheet in the plastic zone and three control beams were conducted up to failure under four-point bending test. The effectiveness of confining CFRP sheet on improving the flexural ductility of tmstrengthened T-section beams was studied. The parameters such as the width and the thickness of CFRP sheet and the type of T-section were analyzed. The experimental results show that ductility and rotation capacity of plastic hinge can be improved by the confinement of CFRP sheet, and the ductility indices increase with the increment of width and thickness of CFRP sheet. A plastic rotation model considering the width of CFRP sheet and the effect of flange of T-section beam is proposed on the basis of the model of BAKER, and the test results show a good agreement with the perdicted results. The relevant construction suggestions for seismic retrofitting design of beam-slabs system in cast-in-place framework structure are presented.

Improved wettability and mechanical properties of metal coated carbon fiber-reinforced aluminum matrix composites by squeeze melt infiltration technique

In order to improve the wettability and bonding performance of the interface between carbon fiber and aluminum matrix,nickel-and copper-coated carbon fiber-reinforced aluminum matrix composites were fabricated by the squeeze melt infiltration technique.The interface wettability,microstructure and mechanical properties of the composites were compared and investigated.Compared with the uncoated fiber-reinforced aluminum matrix composite,the microstructure analysis indicated that the coatings significantly improved the wettability and effectively inhibited the interface reaction between carbon fiber and aluminum matrix during the process.Under the same processing condition,aluminum melt was easy to infiltrate into the copper-coated fiber bundles.Furthermore,the inhibited interface reaction was more conducive to maintain the original strength of fiber and improve the fiber−matrix interface bonding performance.The mechanical properties were evaluated by uniaxial tensile test.The yield strength,ultimate tensile strength and elastic modulus of the copper-coated carbon fiber-reinforced aluminum matrix composite were about 124 MPa,140 MPa and 82 GPa,respectively.In the case of nickel-coated carbon fiber-reinforced aluminum matrix composite,the yield strength,ultimate tensile strength and elastic modulus were about 60 MPa,70 MPa and 79 GPa,respectively.The excellent mechanical properties for copper-coated fiber-reinforced composites are attributed to better compactness of the matrix and better fiber−matrix interface bonding,which favor the load transfer ability from aluminam matrix to carbon fiber under the loading state,giving full play to the bearing role of carbon fiber.

Experimental study and analysis on fatigue stiffness of RC beams strengthened with CFRP and steel plate

The objective of this work is to investigate the fatigue behavior of reinforced concrete(RC) beams strengthened with externally bonded carbon fiber reinforced polymer(CFRP) and steel plate. An experimental investigation and theoretical analysis were made on the law of deflection development and stiffness degradation, as well as the influence of fatigue load ranges. Test results indicate that the law of three-stage change under fatigue loading is followed by both midspan deflection and permanent deflection, which also have positive correlation with fatigue load amplitude. Fatigue stiffness of composite strengthened beams degrades gradually with the increasing of number of cycles. Based on the experimental results, a theoretical model by effective moment of inertia method is developed for calculating the sectional stiffness of such composite strengthened beams under fatigue loading, and the calculated results are in good agreement with the experimental results.