模拟海洋环境条件下碳纤维复合材料力学性能试验研究

本文主要进行了CFRP材料浸渍于碱溶液、浸渍于盐溶液及经人工老化后的力学性能试验。试验证实,上述几种长期环境条件作用对CFRP的极限强度影响不大,但能显著降低CFRP的极限延伸率,碱溶液浸渍、盐溶液浸渍显著降低了CFRP的弹性模量,而人工老化则几乎没什么影响。试验结果分析证明,应用于加固结构分析的CFRP的应力-应变关系,可应用线弹性关系。     

淡水环境中水工钢闸门与碳纤维布黏结性能研究

水工钢闸门长期频繁处在干湿交替状态,易发生金属腐蚀并降低结构的稳定性和承载性,碳纤维复合增强材料(CFRP)具有良好的抗腐蚀能力和抗拉能力,用作加固材料能延长闸门使用寿命,施工时保证CFRP与闸门之间的有效黏结是重难点。设计了9组CFRP与钢板黏结剪切试验,基于CFRP与钢板的黏结剪切破坏分析CFRP的黏结长度、钢板腐蚀程度以及黏结宽度等对有效黏结长度的影响。数据表明,CFRP与钢板的有效黏结长度是80 mm,且长度随钢板腐蚀程度加深而递减,与CFRP的粘贴宽度无关;CFRP与钢板的极限黏结力之间是线性增大关系,且当有效黏结长度低于实际粘贴长度时,极限黏结力不再动态变化。另外,试件所展现出黏结破坏的延性得到了一定的改善。     

CFRP修复含裂纹加筋板极限强度仿真研究

[目的]为研究碳纤维增强复合材料(CFRP)粘贴修复含裂纹加筋板的极限强度,[方法]采用非线性有限元法对在轴向压缩载荷作用下的CFRP修复含裂纹加筋板的极限强度进行分析,基于CFRP修复含裂纹加筋板模型,对仿真结果与文献的试验结果进行比较,验证所提方法的准确性。以CFRP双面修复含裂纹加筋板为例,研究CFRP加筋板的极限强度,并对胶层剥离机理和胶层应力进行分析。[结果]结果表明,使用CFRP修复含裂纹加筋板后其极限强度得到了明显提高,且接近于含几何初始缺陷加筋板的极限强度;CFRP修复含裂纹加筋板的脱胶行为发生在极限强度之后。[结论]使用CFRP修复含裂纹损伤的加筋板可有效提高其极限承载能力,研究结果可为船舶与海洋工程结构修复提供参考。     

CFRP加固损伤钢板的拉伸及疲劳性能研究

文章基于Dugdale模型理论提出CFRP加固含裂纹钢板加固量的计算方法。通过虚拟裂纹闭合法建立模型来模拟塑性钢板的破坏过程,并完成相关试验,验证了CFRP加固含裂纹钢板有效粘贴长度、有效粘贴宽度取值的有效性。同时利用Paris公式预估疲劳寿命,并结合相关试验数据,探究了CFRP加固对含裂纹钢板疲劳寿命的提高作用。研究表明,有效粘贴长度、有效粘贴宽度的理论取值有效;通过CFRP双侧加固竖裂纹、斜裂纹钢板构件可分别使其疲劳寿命得到显著提高。     

CFRP加固钢筋混凝土T梁抗弯性能试验研究

文中通过五根试验T梁研究了CFRP加固梁在不同锚固方式下的的承载力、挠度、裂缝宽度、破坏形态等特性,比较了原梁与各个加固梁之间的试验参数,分析了参数差异的原因.建立缠绕锚固CFRP加固梁的非线性有限元模型,提出了CFRP加固梁缠绕锚固的承载力建议计算公式.研究表明采用碳纤维缠绕端箍板的锚固方式加固效果良好,对实际工程加固具有很好的现实意义.     

CFRP加固钢结构技术在船舶结构中的应用前景

从建筑结构加固技术出发,系统阐述了CFRP加固技术在建筑结构及钢结构中的应用,并基于对船舶结构特点的分析,对CFRP加固钢结构技术应用在船舶结构中的可行性及前景进行了深入的探讨.     

混凝土构件直接粘贴CFRP加固的腐蚀界限研究

为弥补现有规范不足、解决不同腐蚀等级构件碳纤维加固效果参差不齐的问题,在氯化钠溶液中通电模拟海洋腐蚀环境,加速腐蚀出不同腐蚀程度的RC梁,粘贴CFRP加固后进行加载试验,通过分析不同腐蚀程度构件承载力损失和直接粘贴、凿除粘贴两种CFRP处理方式的加固效果,研究腐蚀等级对海工RC梁CFRP抗弯加固的影响,并探讨直接粘贴CFRP加固的腐蚀界限。结果表明,在低腐蚀等级条件下,直接粘贴CFRP加固能有效减小腐蚀梁在荷载作用下的主裂缝宽度,减缓梁开裂的时间,提高抗弯承载力和整体刚度,但随腐蚀等级的增加,这些作用越来越弱,当梁腐蚀裂缝宽度超过1 mm、主筋锈蚀率达15%时,直接粘贴CFRP加固已不再适合。     

CFRP修复的FPSO点蚀船体梁极限强度分析

采用非线性有限元法对中拱和中垂工况条件下碳纤维增强聚合物(Carbon Fiber Reinforced Polymer, CFRP)修复的浮式生产储卸油装置(Floating Production Storage and Offloading, FPSO)点蚀船体梁极限强度进行仿真分析。对比FPSO的完整船体梁、点蚀船体梁和CFRP修复的点蚀船体梁的中拱极限弯矩和中垂极限弯矩，分析CFRP对FPSO点蚀船体梁的修复效果，并分析胶层失效规律。结果表明，CFRP可为船舶的高效修复提供一种新的方式。     

疲劳强度极高的新材料

日本科学技术厅航空空间研究所最近研制成功一种疲劳强度极高的热可塑复合材料。这种材料系将碳纤维浸透PEEC树脂,然后经过烧结制成。与目前用作飞机尾翼的CFRP(碳·环氧复合材料)相较,新材料的疲劳寿命约为CFRP材料的1000倍,而重量约为CFRP材料的60％,是制造航天飞机等的理想材料。     

基于非线性波调制CFRP板冲击损伤的检测研究

文中用非线性波调制法检测CFRP板中由钢珠冲击产生的损伤;通过压电晶片CFRP板中激励低频振动和高频载波,研究冲击损伤、振动、波之间的相互作用;采用损伤指数评价板内不同程度的冲击损伤,分析非线性波调制强度的影响因素.结果表明在冲击作用下CFRP板内非线性波调制强度逐步增强,损伤指数与冲击次数成指数衰减规律;检测时应尽可能提高低频振动激励电压以提高非线性波调制法对微损伤的检出能力.     

复合材料螺旋桨弯扭耦合刚度特性分析

[目的]复合材料螺旋桨的弯扭耦合变形程度反映了桨叶的刚度特性,而桨叶刚度特性又与其水动力性能存在一定的相关性,将从刚度的角度对复合材料螺旋桨的纤维铺层进行优化设计.[方法]首先,以DTMB 4383复合材料螺旋桨为研究对象,基于复合材料螺旋桨流固耦合自迭代算法,构建桨叶弯扭刚度数值计算方法;然后,分别在桨叶铺设单向碳纤...     

橡胶-碳纤维复合水润滑轴承材料的研究

为探究橡胶-碳纤维复合橡胶水润滑轴承材料的摩擦学性能,在SSB-100型船舶艉轴承试验机上,对复合橡胶轴承材料和普通橡胶轴承材料进行台架上的摩擦、磨损试验结果表明：复合橡胶轴承材料的力学性能、摩擦、磨损性能均优于普通橡胶,即碳纤维的加入可以改善普通水润滑橡胶轴承的综合性能。     

Fatigue behaviour and life prediction of filament wound CFRP pipes based on coupon tests

This paper investigates the fatigue behaviour of filament wound Toray T700/Epotech X4201 composite pipes with different lay-ups. The present work compares the fatigue behaviour of coupon specimens manufactured with two different fiber orientations under tension-tension and tension-compression cyclic actions. The test results show that the lay-up and stress ratio have significant effect on the failure mechanism and fatigue life of carbon fiber reinforced polymer (CFRP) composite coupons. This paper develops an empirical model, which integrates the effect of stress ratio in a fatigue damage parameter, to evaluate the fatigue life of the CFRP filament wound coupons. Combined with the numerically calculated stresses at the critical locations corresponding to the fatigue damage locations, the proposed empirical model developed from the coupon test database predicts successfully the fatigue life of full diameter CFRP pipes, using stresses computed at critical locations in the CFRP pipe.     

Analysis of impact damage characteristics of marine carbon fiber composite laminates embedded with PEI film北大核心CSCD

[目的]在传统船用碳纤维复合材料层合板层间添加热塑性相材料能有效提升船用复合材料的抗冲击性能,为探究其冲击损伤特性,开展实验研究。[方法]使用光学显微镜观察层合板的热塑性/热固性界面,分析两相材料的结合方式;对不同结构的复合材料层合板进行低、中、高3种不同能量的低速冲击;通过超声C扫描与电子显微镜,对各试件的损伤形貌进行观测,以研究各试件的冲击响应及损伤机理。[结果]结果显示,相较于碳纤维层合板,含热塑性相的船用复合材料层合板具有更好的损伤阻抗;内部嵌膜层合板试件在冲击能量为8和12 J的冲击下,内部分层损伤分别减少了19%和39%,且受到12 J冲击后,内部结构损伤较小,完整性较好。[结论]将PEI热塑性膜嵌于内部能提升层合板的韧性,显著减少内部分层损伤,明显提升内部嵌膜层合板的抗冲击性能。     

Hydrothermally degraded carbon fiber / epoxy plates subjected to underwater explosive loading in a fully submerged environment

An experimental and computational investigation was conducted to evaluate the underwater blast response of fully submerged carbon fiber composite plates after prolonged exposure to saline water. The material was a biaxial carbon fiber/epoxy composite with a [±45°] fiber orientation layup. The plates were placed in a saline water bath with a temperature of 65 °C for 35 and 70 days, which simulates approximately 10 and 20 years of operating conditions in accordance to Fick's law of diffusion coupled with Arrhenius's Equation and a reference ocean temperature of 17 °C. Underwater blast experiments were performed in a 2.1 m diameter pressure vessel. The composite plates were placed in the center of the vessel while fully submerged in water, and an RP-85 explosive was detonated at a standoff distance of 102 mm from the center of the plate. Two cases of fluid hydrostatic gage pressures were investigated: 0 MPa, and 3.45 MPa. Two high speed cameras were utilized for three-dimensional Digital Image Correlation, which provided full-field displacements and velocities of the composite plates during underwater blast loading. A third high speed camera captured the behavior of the explosive gas bubble. Moreover, the pressure fields generated by the explosive detonation and resulting gas bubble were recorded with tourmaline pressure transducers. A water diffusion study was completed which showed that the diffusion of water into the composites reached a point of complete saturation after 35 days of exposure. Quasi-static material characterization tests were performed before and after prolonged exposure to saline water. The properties obtained from quasi-static testing also served as material inputs for the numerical models. The quasi-static test results showed that the tensile modulus E_1,2 does not change with exposure to saline water, whereas the in-plane shear modulus G₁₂ decreases with saline water exposure. During blast loading, for the case of 0 MPa hydrostatic gage pressure, the gas bubble interacts with the composite plate substantially. In such an event, the out of plane displacement increased for saline water exposed plates when compared to virgin structures. For the case of 3.45 MPa hydrostatic gage pressure, the gas bubble does not visibly interact with the composite plate. In this case, the out of plane displacement for specimens exposed to saline water was similar to the virgin specimen. A fully coupled Eulerian–Lagrangian fluid structure interaction simulation was performed by using the DYSMAS code. The numerical simulations showed that the displacement of fully submerged composite plates is driven by the displacement of fluid, as well as the size of the gas bubble formed by the explosive rather than the peak pressure generated by the explosive. The numerical simulations were in agreement with the experimental findings in terms of pressure history and plate deformation.     

损伤钢筋混凝土框架加固后地震损伤分析

通过对3榀相同的钢筋混凝土框架进行模拟地震作用的水平低周反复荷载试验,选取基于滞回特性和能量耗散的累积损伤模型,对复合加固、碳纤维加固框架的累积损伤程度加以计算,从而评价模型的适用性。结果表明,加固对于降低框架的累积损伤程度是有效的,累积损伤模型能够综合地反映结构的累积损伤特征,从而为结构的修复加固提供参考依据。     

不同碳材料对挥发性有机气体的吸附性能研究

本文以苯、正庚烷、1,2-二氯乙烷、氟利昂22(F22)作为VOCs代表物质,考察了不同碳材料对VOCs的吸附能力。试验结果表明:不同碳材料对苯、正庚烷、1,2-二氯乙烷的吸附呈现出相似规律。在相同的吸附条件下,吸附能力是球形活性炭>常规活性碳>改性活性碳纤维>活性炭纤维,同一种碳材料对三种代表物质的吸附能力为:正庚烷>苯>1,2-二氯乙烷。几种碳材料对F22的吸附能力很差。     

Stress and failure analyses of thermoplastic composite pipes subjected to torsion and thermomechanical loading

The interest of using thermoplastic composite pipes has increased in offshore deepwater oil fields. Thermoplastic composite pipes consist of several carbon/glass fiber reinforced laminate layers to confer stiffness and strength located between inner and outer homogeneous thermoplastic layers for fluid containment and protection. This paper presents a theoretical analysis for thermoplastic composite pipes under combined pure torsion and thermomechanical loading from operational thermal gradients, considering the inner and outer isotropic homogeneous layers and intermediate transversely isotropic laminate ply layers. Perfect bond between adjacent layers and interfaces continuities are assumed. Based on the obtained stresses in the principal material directions, through-thickness failure indexes related to the von Mises and Maximum Stress or Tsai-Hill criteria are respectively evaluated for homogeneous and laminate layers. For each thermal gradient, the limit torque (i.e. when the failure index is equal to 1) is calculated. From the case study, it is observed that without thermal loading or for small operational temperature, failure occurs in the laminate, otherwise it is observed in the inner homogeneous layer. The thickness of the homogeneous layer significantly affects the limit torque and the absolute values of the limit clockwise and anticlockwise torque slightly differ when the operational temperature is included.     

连续玄武岩纤维增强复合材料船体水下爆炸响应的数值仿真

运用有限元程序MSC.Dytran数值计算水下爆炸载荷作用下连续玄武岩纤维复合材料船体舱段结构的响应,采用层合板模型模拟纤维复合材料,选取一般耦合算法计算流体与结构的耦合效应,并将计算结果与E玻璃纤维复合材料船体仿真结果进行比较,分析2种材料船体结构压力时历曲线、破坏起始位置及破坏形式,得出结论:玄武岩纤维复合材料和E玻璃纤维复合材料船体底板在爆炸载荷的作用下起始破坏形式不同,玄武岩纤维的压缩强度和拉伸强度之比较高,在实际设计制造中更有优势。在船舶建造中可以使用连续玄武岩纤维复合材料替代玻璃纤维复合材料。     

一种新型纤维增强酚醛树脂密封材料的制备及表征

酚醛树脂具有力学性能好,耐热性好,耐磨损以及阻燃等优点,被广泛的应用于各种工业领域.但是其延展性差,韧性差,反应残余物对人体危害大限制了其在现代工业的应用.本文中,我们在酚醛树脂中引入芳纶长纤维,木质素短纤维及无机纳米铜添加剂,制备了一种新型密封材料.通过力学性能测试,红外谱图分析,摩擦系数测定以及扫描电镜观察对复合材...