共查询到16条相似文献,搜索用时 203 毫秒
1.
拉剪胶接接头的峰值应力常发生在搭接区端头,而中间区的应力非常小,为降低应力集中,提高接头强度和连接效率,系统研究胶层变刚度的混元胶接技术,将高弹性模量的脆性胶置于中间区,而低模量的韧性胶置于搭接区边缘.以胶接理论为基础,考虑被粘物剪切应变,建立单搭拉剪混元胶接接头的线弹性应力和刚度解析模型.理论模型中的正应力和剪应力与有限元模型吻合得较好,证实理论模型的正确性.有限元和解析解均表明,混元胶接接头在搭接区端头的峰值剪应力分别较单一刚性胶和柔性胶胶接时下降了52.1%和24.4%,参数研究中确定了影响混元胶接接头应力和刚度分布特征的关键耦合参数. 相似文献
2.
3.
胶接接头中总存在胶瘤,由于建模复杂,胶接接头有限元分析中胶瘤常被忽略.但胶瘤能减少峰值应力,提高结构强度和刚度.为此,提出一种简化的胶接有限元模型,即用壳单元代表胶瘤,体单元代表被粘体和胶层,并用弹性理论建立壳单元等效厚度公式.以体单元精细模型结果作为对比的真实解,考察五种载荷工况下,单搭接头简化有限元模型的胶层应力和刚度.分析表明,壳单元等效厚度公式正确,胶接简化有限元模型精度高,可用于诸如汽车等大型结构中;用壳单元简单模型可定量分析胶瘤大小和形状对接头应力和总体刚度性能的影响. 相似文献
4.
搭接长度对胶接接头工作应力分布影响的数值分析 总被引:12,自引:2,他引:12
运用弹塑性有限元法对单搭接金属胶接接头承载后的应力分布特征进行分析,重点研究搭接长度对分别采用酚醛树脂和丙烯酸酯制备的接头应力分布和接头强度的影响。结果表明,胶粘剂的性能对应力分布有较大影响,酚醛树脂胶粘剂制备的接头中胶瘤承担了相当多的载荷,且随搭接长度的增加,von Mises等效应力峰值和剪切应力峰值均趋于向胶层内转移,胶层中各部位的应力亦均有下降;当采用丙烯酸酯胶制备的接头时,胶瘤承载作用并不明显,其应力峰值出现在胶层中被粘物拐角处。 相似文献
5.
镁合金激光胶接焊接头微观及力学性能 总被引:5,自引:0,他引:5
采用激光胶接焊焊接镁舍金,利用现代测试手段分析接头的微观组织特征,并分别研究激光焊、胶接和激光胶接焊3种接头在相同工艺参数下的剪切力和抗剥离力,在较好的工艺参数下,激光胶接焊焊缝成形良好。在激光热源的作用下,焊缝区内胶层受热分解并以气体形式逸出焊缝,并未影响焊缝的组织熔舍;焊缝边缘附近胶层炭化裂解,存在胶层失效区,虽减小胶层的承载面积,但该区域很窄,对接头的实际承载能力影响不大。激光胶接焊接头剪切力最大,胶接接头次之,激光焊接接头剪切力最小;激光胶接焊接头的抗剥离力远大于胶接接头的抗剥离力。激光胶接焊有效提高接头的实际承载能力,因此具有很大的发展潜力。 相似文献
6.
L形碳纤维增强复合材料/铝合金胶接复合构件剥离应力建模与分析 总被引:1,自引:0,他引:1
针对承受剥离载荷的L形碳纤维增强复合材料(Carbon fiber reinforced plastic/polymer,CFRP)/铝合金胶接复合构件,以微元受力平衡方程为基础,建立胶层平均剥离应力的二维分布方程。在方程中引入基材的弯曲刚度系数,描述背材与基材均为刚性材料的情况下胶层剥离应力的分布规律。其应力分布曲线为拉压应力交替作用的阻尼调和函数,周期与峰值由胶接件构型尺寸与材料性能参数决定。通过CFRP/铝合金剥离试验及三维有限元模拟对理论模型进行对比验证,结果的总体趋势与数值吻合程度较好,并分析不同方法获得的剥离应力分布状态之间的差异及其产生的原因。基于胶接复合构件的理论模型与三维有限元模型,研究基材厚度改变对剥离应力分布的影响,发现伴随着CFRP板厚度的增加,剥离应力的峰值明显下降,在剥离前沿的应力集中现象得到改善。 相似文献
7.
8.
本文主要研究了胶层脱粘对金属平板复合材料补片胶接修理后拉伸剩余强度的影响。首先根据补片下方剪应力分布解析公式,将胶接修理区域划分为脱粘安全区和脱粘影响区,然后进行了金属平板结构胶接修理的剩余强度试验以研究胶层脱粘的影响,并验证理论分析结果。结果表明:在脱粘安全区内,胶层自身不参与承载,胶层脱粘对金属平板结构的拉伸剩余强度没有影响;而在脱粘影响区内,出现的胶层脱粘会对金属平板结构的拉伸剩余强度产生影响。 相似文献
9.
10.
利用弹塑性有限元法,研究四种不同弹性模量的胶粘剂 (丙烯酸酯胶、聚氨基甲酸乙酯胶、环氧树脂胶和酚醛树脂胶粘剂等) 形成的胶瘤对铝合金单搭接接头应力分布的影响.结果表明,当胶瘤采用不同于胶层的胶粘剂时,随着胶瘤弹性模量的减小,在胶层与胶瘤的连接处胶层中应力峰值显著提高,且均高于由单一胶所形成接头的应力峰值.对被粘物中紧邻界面层中的应力分布而言,峰值应力出现在胶瘤与胶层的连接处及靠近搭接区两端部处.随着胶瘤弹性模量的增加,靠近被粘物承载端的区域的应力越大,而自由端的应力越小,且靠近承载端的区域的应力峰值由胶瘤与胶层的连接处向承载端一侧转移,因而采用弹性模量低的胶粘剂形成胶瘤对接头的承载不利. 相似文献
11.
Wilma Polini Andrea Corrado 《The International Journal of Advanced Manufacturing Technology》2020,106(3):817-828
Adhesively bonded joints are widely used in the design of structures due to the high strength-to-weight ratio. The entire literature generally investigates on how to improve the strength of adhesive joints because the use of adhesive joints is increasing in many industries. However, the strength of adhesive joints depends on the geometric errors of parts to be joined, the bonding process and the equipment used to join the parts. This work aims to numerically investigate how a possible error due to the bonding process influences the strength of the adhesive joint. The single-lap joint was used as a type of joint due to its simple geometry, and the adherends misalignment was considered as error due to the bonding process. Considering the single-lap joint as an assembly made of two adherends and an adhesive, it is possible to reason in terms of tolerance analysis where, varying the geometry of the adherends, it is possible to evaluate how it influences the strength of the adhesive joint. In order to perform this analysis, a numerical tool, based on FEA and MATLAB® software packages, was used to manage the geometrical deviations of the adherends. The effect of the adherends misalignment on the reduction of the strength of the adhesive joint was testified by experimental tests. 相似文献
12.
A simple but effective design to improve the strength of thick adhesive composite strap joints is validated with experiment and finite element method. The strap joint under investigation, with a particular application to naval ship structures, consists of two thick woven E-glass/vinyl ester laminates joined together with two steel doublers. Longitudinal tensile loads are applied to the joints, resulting in large concentrated shear and peel stresses near the free edges of bondlines. The new design intends to reduce the adhesive peel stress by application of through-the-thickness compressive pre-stress along the bondline and thus leads to an increase of joint strength. Experiment results show that all the joint failures are delamination of the top layer of the laminated adherends. The test further confirms that joint strength increases significantly by applying the transverse pre-stress. Finite element analysis reveals that the pre-stress can effectively reduce the magnitude even reverse the sign of the peel stress in the adhesive layer and the adherends. Recessing the adhesive leading edge could magnify the pre-stress effect and reduce the adhesive peel stress, but would increase the shear stress. For those composite joints with low transverse interlaminar strength and susceptible to delamination, this simple design/technique can considerably improve their joint strength. 相似文献
13.
Daxin Ren Liming Liu Yongfei Li 《The International Journal of Advanced Manufacturing Technology》2012,61(1-4):195-204
This paper presents the research on weldability of magnesium alloy AZ61 sheets by overlap laser welding, adhesive bonding, and laser seam weld bonding processes. Microstructures and mechanical properties of the joints are investigated. In overlap laser welding, the joint fractures at the interface between the sheets and maximum shear strength can reach 85% of that of the base metal. Off-center moment during tensile shear test can lead to the strength loss, while the weld edge can also influence the strength as a cracking source. Adhesive bonded joint can offer high tensile shear failure force but low peel strength. Laser weld bonded joint offers higher tensile shear failure force than either laser welded joint or adhesive bonded joint does, and the improved failure load is due to combined contribution of the weld seam and the adhesive. The weld seam can block the adhesive crack propagation, and the adhesive improves the stress distribution, so they can offer a synergistic effect. 相似文献
14.
15.
16.
Mohammad Ali Saeimi Sadigh 《Journal of Mechanical Science and Technology》2016,30(4):1555-1561
Creep behavior of double lap adhesively bonded joints was investigated using experimental tests and numerical analysis. Firstly, uniaxial creep tests were carried out to obtain the creep characteristics and constitutive parameters of the adhesive at different stress and temperature levels. Generalized time hardening model was used to predict the creep behavior of the adhesive. This model was modified to simulate the creep behavior at different stress and temperature levels. Secondly, the developed model was used to simulate the creep behavior of bonded joints using finite element based numerical analysis. Creep deformations of the joints were measured experimentally and good agreement was observed in comparison with the results obtained using numerical simulation. Afterward, stress redistribution due to the creep along the adhesively bonded joint was obtained numerically. It was observed that temperature level had a significant effect on the stress redistribution along the adhesive thickness. 相似文献