夹芯复合材料/钢板胶接接头力学特性

对4种夹芯复合材料/钢板连接接头进行四点弯曲试验和数值研究。试验获得了接头的失效载荷、载荷-位移曲线以及失效模式,通过对比发现接头的承载能力与接头形式有很大关系。采用有限元方法获取了接头载荷-位移曲线以及应力分布,并研究了接头各设计参数对接头弯曲刚度的影响。     

复合材料层合板螺栓连接接头极限强度分析

对基于不同渐进失效准则计算复合材料层合板螺栓连接接头极限承载力的高精度预报方法展开研究。基于Abaqus有限元软件,采用USDFLD子程序对接头进行渐进失效分析。分别采用最大应力准则、蔡-希尔失效判据、霍夫曼失效准则、蔡-吴失效准则、哈辛失效准则等5种失效准则进行数值计算。建立不同的场变量描述纤维、基体、界面的损伤状态,研究复合材料层合板螺栓连接接头在拉伸载荷作用下的损伤发展过程。研究表明,基于这5种失效准则计算的有限元仿真结果均与试验值较为接近,其中采用纤维失效和基体失效分开考虑的哈辛失效准则计算的复合材料层合板螺栓连接接头的极限强度与试验结果的准确度吻合最好,较适用于复合材料螺栓连接结构的有限元仿真。     

LNG船用聚氨酯绝缘箱胶接工艺及关键技术

对新型液化天然气(Liquefied Natural Gas,LNG)船用聚氨酯绝缘箱在常温作业条件下的大面积胶接界面的胶接工艺进行研究,阐述涂胶量与胶接接头的性能和失效形式的关系。研究发现:当涂胶量为200~550 g/m^(2)时,随着涂胶量的增加,胶层厚度增加,接头的垂直拉伸性能先增强后减弱;当涂胶量小于300 g/m^(2)时,胶接接头的失效形式为界面混合破坏;当涂胶量大于350 g/m^(2)时,胶接接头的失效形式为聚氨酯泡沫板内聚破坏;适用于实际生产中的涂胶量的工艺窗口和精度控制范围为400 g/m^(2)±20 g/m^(2)。阐述大面积胶接界面的质量控制方法,明确胶条的排布形式和压合过程中压合台面与箱体平面平行度对箱体各位置的胶接性能的影响规律;在固化压力、胶条形状和胶条中心间距均相同的情况下,采用平行式胶条排布形式和压合台面与箱体平面的平行度小于0.1 mm,可使绝缘箱的整体胶接性能的一致性得到充分保证。     

船用电缆接头胶接用导电胶

广州电器科学研究所、广州造船厂的工人、技术人员和干部一起,经过8个月的共同努力,初步试制出电缆接头胶接用常温固化导电胶。用这种导电胶胶接的电缆接头,电气性能和机械强度均满足实际使用要求。船用电缆接头原用锡焊或冷压工艺连接。锡焊劳动条件差且不安全,操作技术要求高。冷压需要专门的压接工具,劳动强度较大,船上空间紧凑,安装施工不便。采用导电胶胶接,工     

外接平板型金属夹层结构连接构件极限强度分析

激光焊接钢质夹层结构在国外已用于实船,其连接形式是亟待解决的关键问题之一。基于有限元分析软件ANSYS,研究了面内载荷作用下,I型金属夹层结构外接平板型连接构件的失效模式和极限承载能力,以及5种典型初始缺陷的尺寸和连接构件的设计参数对极限载荷的影响规律。结果显示,连接构件较短时,结构失效的主导因素是焊接接头形成了塑性铰;连接构件较长时,主导因素是连接构件失稳。对于各种类型的初始缺陷,随初始缺陷尺寸的增大,极限载荷均降低;连接构件、以及靠近连接构件的夹层面板和夹层腹板的初始缺陷对极限载荷的影响较大。在控制重量的条件下,欲增大极限承载能力,最有效的途径是增大连接构件厚度,并选取合适的连接构件长度。     

大潜深平台多耐压体连接结构接头连接设计

多耐压体大潜深平台在深海静水压力作用下各耐压体纵向变形存在明显差异,导致连接结构发生弯曲变形,会对结构安全和相连设备造成不利影响。对比分析连接结构焊接和接头连接的优缺点,提出一种固定接头与活动接头结合的连接结构接头连接方案,使得连接结构最大主应力相比焊接时降低41.1%。为使连接结构接头连接方案能够更好地承载纵向冲击载荷,设计了一种位移补偿接头,既能在下潜过程中实现耐压体纵向自由移动,又能在下潜到工作深度后和固定接头一起承受纵向冲击载荷。本文可为多耐压体大潜深平台连接结构设计提供有益参考。     

材料与结构形式变化对玻璃钢船用粘接T型接头性能的影响

本文概述有关单板加筋式玻璃钢舰船用T型接头的设计问题。首先，对问题作了简要的回顾，对这类接头设计用的现行方法作了介绍。对起重要作用的各因素，特别是对接头特性具有重大影响的诸因素加以说明。这些因素在接头的试验和数值计算模型化中系统地予以考虑。给出了机械性能试验得到的载荷／挠度曲线，并说明了这种接头在载荷作用下的力学特性。然后使用数值有限元模型以深入了解内部载荷分配和破坏的机理。并采用模拟方法着重说明材料及结构形式变化对T型接头性能的重要影响。     

基于多重静态子结构的浮桥接头受力分析

本文以基于某型浮桥基本构型,对主尺度作适当变化的概念浮桥为研究对象,基于有限元静力缩聚理论,采用多重子结构分析方法分析模块化拼组的浮桥结构,利用弹性地基板单元模拟浮力,根据模块间拼组接头的连接特点,将接头连接效应考虑成节点自由度耦合,采用超单元拼组方法建立了河中舟和临界长浮桥有限元模型,对浮桥进行了最不利加载,经过求解,提取、分析了浮桥结构纵向拼组接头以及最不利河中舟横向拼组接头的接头力,相关分析方法可以为浮桥接头设计优化提供技术支撑。     

铝/钢复合过渡接头焊接温度场及性能试验研究

本文通过试验方法对比研究了焊接热循环对三种应用于舰船铝合金、钢质结构连接的铝合金-钢复合过渡接头温度场及界面结合性能的影响。在前期研究的基础上,试样依次采用铝合金TIG焊、MIG焊实现过渡接头与铝合金板材之间的焊接。过渡接头复合界面的温度场及焊接前后界面结合性能测试结果表明：焊接热循环对过渡接头复合界面剪切强度及厚度方向的抗拉强度具有显著的影响。同一焊接条件下,焊接热循环在新型四层复合过渡接头界面上产生的温度峰值明显低于目前广泛应用的两种三层复合过渡接头,四层复合过渡接头焊接前后的性能也大大高于后者,即使采用小宽度焊接试样,其焊后性能仍能满足舰船设计指标要求。因此,是能满足“更高施焊温度、更大应力承载、结合界面更强和更高结构韧性”要求的新型铝合金、钢结构焊接连接用过渡接头。     

船舶轻量化T型连接结构设计及强度试验

文章从船舶轻量化的角度出发,提出了一种由复合材料夹芯板和增强泡沫胶接而成的新型T型连接结构,解决了船舶复合材料上层建筑内部壁板之间的连接问题。基于复合材料结构的设计原理和力学特性,设计了T型连接结构的拉伸试验和压缩试验,研究其在不同载况下的极限承载和损伤模式,证明T型连接损伤模式复杂,抗拉能力弱,尤其面板与腹板连接区的胶层是承载薄弱环节;依据试验结果验证数值计算方法,并规划3条技术路径以研究T型连接的抗拉特性,应用数值方法提取对应技术路径的应力和位移特征量,分析T型连接面板与腹板连接区的胶层几何参数对抗拉强度和重量的响应规律,获得连接区胶层几何夹角的建议取值为45°~60°,为复合材料船舶轻量化胶接结构的优化设计和实际应用提供了有益参考。     

Effects of adhesive type on the mechanical properties of adhesive joints between polyurethane top coats and polyurethane-based adhesives after accelerated atmospheric ageing

The performance of a sealed stainless steel bracket system, adhesively bonded with two polyurethane-based adhesives (flexible adhesive, stiff adhesive) onto a marine polyurethane top coat, is investigated. The investigated joint connections on the coatings exhibited a high mechanical stability even after accelerated ageing (salt spray exposure, cyclic temperature variations, high relative humidity). The aged joints retained up to 81% of their tensile strength and up to 92% of their lap-shear strength. The torsional rigidity of the adhesive joint exceeded the required clamping torque of the designed bolt. A cyclical lifetime of >9·10⁶ load cycles was estimated. Effects of cyclic ageing on the creep performance of the adhesive joint were found to be insignificant. Under tensile loads, the joints with stiff adhesive material exhibited a linear-elastic performance without the capability to deform prior to failure. The joints with the flexible adhesive material, in contrast, exhibited a behavior typically for ductile materials featuring a pronounced yield plateau prior to failure. Failure loads were higher, and displacement was notably lower, for the joints with stiff adhesive material. All joint connections met the requirements for a safety factor for the design for marine applications (11.6 for the flexible adhesive; 14.3 for the stiff adhesive). When the flexible adhesive is applied, the cohesive strength of the adhesive material is the limiting design factor. When the stiff adhesive is utilized, the load carrying capacity is higher, and the interface between priming coat and steel substrate is the limiting design area of the joints. The strength utilization of the adhesive materials depended on the particular structure of the entire joint configuration, particularly on the interface between steel substrate and the coating material. A number of assessment factors, namely stress limit factor, coating adhesion factor and safety factor, are introduced and discussed for tensile and shear loads.     

Optimisation of laser-welded sandwich panels with multiple design constraints

This paper investigates the possibilities for structural optimisation of laser-welded sandwich panels with an adhesively bonded core and uni-directional vertical webs. Closed form expressions for the equivalent stiffness and elastic buckling strength of laser-welded sandwich panels are discussed and numerically evaluated to demonstrate the effect of parameter variations on stress and deflection. Due to the number of design variables and constraints a structural optimisation method based on the method of moving asymptotes (MMA) is implemented and used to minimise the structural weight per square meter of panel for a typical accommodation deck configuration. It is concluded that, within the span of production parameters and rule requirements, substantial improvements can be made with or without an adhesively bonded core. Without core material and without any changes to the surrounding structure the structural weight for standard production panels can be reduced considerably, by reducing the face plate thickness and by using thinner and fewer webs. Additional weight can be saved by removing all but a few webs and injecting low-cost polyurethane foam into the cavities, giving added thermal–acoustic insulation, or by incorporating a more structural core with greater thickness and higher density, by which the free span of the sandwich panel can be increased.     

Mechanical behaviour of vinylester adhesive joints used in laminated material for steel structures

One of the most important applications of adhesives in shipbuilding is the manufacturing of structural laminated materials. The application of these types of hybrid materials in a marine environment for extended periods of time and under adverse environmental conditions results in the accelerated degradation of the adhesive. Therefore, a specific experimental procedure is required to ensure the adequate performance of this adhesive bonded joint during its service life. In this study, an experimental method to analyse a vinylester adhesive in steel–adhesive–steel test specimens was applied (“mixed cantilever beam” specimens were used and mixed mode tests were carried out to obtain the fracture envelope). It was concluded that the energy release rate increased with the stress mode under dry conditions. In addition, the cohesive laws of vinylester showed that both the tangential stress and the strain are higher than the normal stress and strain. Finally, it was observed that adding distilled water to the adhesive joint for short periods of time improved its fracture strength.     

Creep investigations on adhesively bonded fasteners developed for offshore steel structures

Fastening or reinforcement onto an existing steel structure may create constraints such as the use of hot works (i.e. welding) or loss of weathertightness (i.e. drilling holes and bolting). In order to limit these constraints, there may be a strong interest in using adhesively bonded fasteners. Such a solution requires however strong justification especially regarding long-term properties. This paper presents the results of experimental and numerical investigations realized on the creep behaviour of such bonded fasteners developed for offshore steel structures. Experimental investigations were conducted at room temperature following a precise and repeatable implementation protocol. The results of the various investigations revealed a non-linear evolution of creep displacements according to a Burger law. Numerical modelling has therefore been developed on the basis of Burger's law. A preliminary static study aimed at validating the geometric model and analyzing the initial stress state in the adhesive. The creep study was then carried out to compare numerical results to experimental ones. Although additional investigations are needed, numerically determined creep displacements demonstrated a good consistency with the experimental investigations.     

不同强度匹配10CrNi3MoV船体钢焊接结构的安全评定

为了研究不同强度匹配对焊接接头安全性能的影响,基于"欧洲工业结构完整性评定程序(SINTAP)"提供的失效评定图FAD方法,针对不同强度匹配的10CrNi3MoV船体钢焊接接头,建立了对应的失效评定曲线。根据母材与焊缝的拉伸试验及CTOD(裂纹尖端张开位移)试验结果,对比分析了3种匹配条件下的接头安全评定结果。研究表明,对于选定的评定级别,不同强度匹配系数对FAD图形状的影响很小;焊缝强度较高时,接头对塑性失稳的抵抗能力取决于母材性能;接头韧度水平相似时,低匹配接头对塑性失稳及脆性断裂的抵抗能力均稍差,弱于等匹配与高匹配;焊缝强度稍高于母材的"等强匹配"安全裕度最大,安全性最佳。     

船用膜片联轴器的膜片组件简化建模方法及模态试验

针对船用膜片联轴器的膜片组件螺栓连接的复杂性问题,基于薄层单元法对膜片组件的有限元模型进行简化,提出一种新型简化建模方法——结构分割法。对模型静刚度进行计算,确定结构分割法中结合面单元的弹性模量和泊松比。该方法相较于传统的薄层单元法计算效率更高。将结构分割法模型的模态仿真结果与试验结果进行对比,结果表明,结构分割法模态分析得到的振型与试验测得的前三阶振型吻合较好,固有频率误差均在10%之内,验证简化模型仿真的正确性,可为船用膜片组件结合部动力学快速有效建模提供思路。     

船用玻璃纤维增强复合材料与钢连接结构的力学特性（英文）

The use of a glass-fiber reinforced composite in marine structures is becoming more common, particularly due to the potential weight savings. The mechanical response of the joint between a glass-fiber reinforced polymer(GRP) superstructure and a steel hull formed is examined and subsequently modified to improve performance through a combined program of modeling and testing. A finite-element model is developed to predict the response of the joint. The model takes into account the contact at the interface between different materials, progressive damage, large deformation theory, and a non-linear stress-strain relationship. To predict the progressive failure, the analysis combines Hashin failure criteria and maximum stress failure criteria. The results show stress response has a great influence on the strength and bearing of the joint. The Balsawood-steel interface is proved to be critical to the mechanical behavior of the joint. Good agreement between experimental results and numerical predictions is observed.     

结构系统疲劳可靠性分析的一阶和二阶混合方法

本文提出了复杂结构系统疲劳可靠性分析的一阶和二阶混合方法。引进Ｈｏｈｅｎｂｉｃｈｌｅｒ等提出的并联系统可靠性分析的二阶渐近式计算失效途径的疲劳失效概率;利用并联系统等效线性安全余量的概念,形成由失效途径的等效失效单元组成的串联系统;并最终计算整个系统的疲劳失效概率。计算结果表明,这一方法能有效地提高结构系统疲劳失效概率的计算精度。