共查询到18条相似文献,搜索用时 109 毫秒
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基于理论解的三种胶接接头简化有限元单元 总被引:1,自引:0,他引:1
建立了非对称胶接接头位移理论,它能严格满足包括胶层端头剪应力为零在内的所有边界条件。由于上被粘物、下被粘物具有不同材料和厚度,研究非对称胶接接头更具一般性。以位移理论解为基础,通过一组特定位移约束条件确立了被粘物纵向和横向位移函数,获得了非对称T形、L形和单搭接接头简化有限元单元的单元刚度矩阵。这些胶接接头简化单元能大幅降低整体有限元模型的自由度数量,避免以往胶层单元胶层厚度估计过大的不足,并考虑了被粘物间连续传力的特性,更适于大型有限元模型中对胶接接头的简化建模。精细有限元模型的数值验证表明,三种胶接接头简化有限元单元精度很好,使其应用到诸如汽车白车身、飞机等大型有限元模型中成为可能。 相似文献
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运用实验方法研究了胶接接头的静强度及其疲劳性能。对胶接接头进行静力学实验,并在此基础上选用6种不同载荷水平对胶接接头进行疲劳实验,获得了接头的载荷-寿命(F-N)曲线。试验结果表明:胶接接头静强度为同尺寸铝合金板静强度的77.5%,说明胶接接头有较高的静强度。当疲劳载荷水平大于最大静载荷平均值的50%时,接头F-N曲线呈线性趋势变化;随着疲劳载荷水平的不断提高,接头失效形式更多地表现为混合破坏。通过分析疲劳失效接头刚度变化可知:在各疲劳载荷水平下,接头刚度的线性趋势变化在整个疲劳周期内占很大比例,疲劳载荷水平越低,接头刚度降低越慢;接头刚度的变化表明在接头内产生了裂纹并逐步扩展。 相似文献
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以α-氰基丙烯酸酯类瞬干胶为胶粘剂,采用剪切试验、接触角试验和扫描电镜观察系统研究了丙酮简单清洗、喷砂处理、阳极氧化处理以及偶联剂处理对5083铝合金板胶接接头剪切强度的影响。结果表明:经简单清洗后,所得胶接接头的剪切强度最低;在附着力和机械啮合的共同作用下,喷砂处理和阳极氧化处理胶接接头的强度得到了提高,其中阳极氧化处理的效果最为明显,与简单清洗胶接接头相比,剪切强度提高了223.1%;胶接前适当使用偶联剂可以使简单清洗和喷砂处理胶接接头的剪切强度提高,在该试验条件下,KH-550偶联剂体积分数为5%时,胶接接头的剪切强度均达到了最大值;但偶联剂使阳极氧化处理形成的纳米小孔不能发挥机械啮合作用,所得胶接接头的剪切强度相比未使用偶联剂的反而降低。 相似文献
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本文对两种钢板单搭胶接接头在不同的拉伸速率下(准静态、10m/s、20m/s)实验研究了不同拉伸速率对两种钢板接头力学性能的影响。结果表明钢板胶接接头在高速拉伸(10m/s、20m/s)时的强度相对于准静态(13mm/min)有明显提高,并且随着拉伸速率的增加而增大。这是由于在高速拉伸时接头及胶层高速形变,应变率大大增大,胶层粘性因素所产生的应力大大增加,使得接头强度提升。失效模式也随着发生改变,呈现出脆性断裂模式。被粘物材料性能的不同也会对接头强度产生影响,且这种影响随着拉伸速率的增加逐渐减小。 相似文献
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In this paper, the effects of bolt torque tightening on the fatigue strength of double‐lap simple bolted and hybrid (bolted/bonded) joints have been studied experimentally. To do so, two types of joints, that is, double‐lap simple and hybrid (bolted/bonded) joints, were studied. For each type of joints, three sets of specimens were prepared and subjected to the tightening torque of 1, 2.5 and 5 Nm, and then, fatigue tests were carried out at different cyclic longitudinal load levels. Experimental tests results showed that the hybrid joints have better fatigue performance in comparison with the simple bolted joints. In addition, the investigation revealed the positive role of tightening torque on the fatigue life of both simple and hybrid joints. 相似文献
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Abstract: We present the results of investigations into the strain distributions in the adhesive layers of epoxy‐bonded aluminium–aluminium and aluminium–carbon fibre reinforced polymer (Al/CFRP) double‐lap shear joints. The area of the adhesive at the end of the overlap region, where high stresses are predicted and failure generally initiates, has been studied at high magnification. 2‐D maps of the longitudinal and engineering shear strains in this region have been obtained experimentally by using high magnification moiré interferometry (HMMI). These results have been compared with the strain maps predicted by 3D elastic and elasto‐plastic finite element (FE) modelling. Excellent agreement is seen between the experimentally measured and FE‐predicted strain distributions, thus validating both methods. In some cases, quantitative comparison of the strains along certain profiles is compromised by noise in the measurements, especially for the Al/CFRP joints, which experienced lower overall strains. The source of such errors is discussed in the paper. 相似文献
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混凝土后锚钢筋又称植筋。在工程实际中,后锚钢筋能有效地解决新老混凝土连接、钢筋漏埋、错埋等钢筋生根问题,被广泛应用于结构加固改造中。结合单锚钢筋、群锚钢筋的粘结锚固性能试验和极限承载能力分析,研究了后锚钢筋与混凝土的粘结机理、粘结破坏形态与静力承载能力计算方法,并讨论了胶层厚度,植筋深度与直径等对静力承载能力的影响;结合植筋钢筋混凝土受弯构件和压弯构件在低周反复周期荷载作用下的滞回特性,分析研究了植筋混凝土构件的延性和抗震性能,并与常规整体浇注构件的特性进行了对比分析,验证了在植筋锚固长度大于20D的情况下,植筋构件的极限承载能力、极限变形能力和延性等主要力学指标都与整浇构件相当,植筋构件的抗震性能是可靠的。 相似文献
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1.IntroductionRecently,progress of vapour phasegrowth of diamond fihn under non-equilib-rium reaction condition has shown theprospect of its commercial production in re-spect of effectiveness and economy.Theprocess proceeds in the thermodynamical 相似文献
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Peter Schmidt Ulf Edlund 《International journal for numerical methods in engineering》2006,66(8):1271-1308
This paper deals with the derivation of a finite element (FE) method for an adhesively bonded joint which consists of two relatively thin bodies, joined by an even thinner adhesive layer. It is based on a model of the compound joint where the three bodies involved are described as material surfaces. A geometrically two‐dimensional model, where the middle surfaces of the upper and lower body are represented as geometrically coinciding surfaces, is obtained. An elastic–plastic material model with damage is used for the adhesive layer, and an important implication is that the (quasi‐static) propagation of the local failure zone in the adhesive layer in a structure can be simulated. Consequently, the failure load is obtained as a computational result and no failure criterion is needed. The problem is discretized, and a surface model, where only a single surface needs to be FE‐meshed, is obtained. A single‐lap joint is analysed and good agreement is obtained when compared to an analysis using a fine mesh with brick element. Furthermore, the failure load is computed and compared with experiments. The derived FE method opens up the possibility to efficiently model and analyse the mechanical behaviour of large bonded structures. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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Francis M.G. Ramírez Marcelo F.S.F. de Moura Raul D.F. Moreira Filipe G.A. Silva 《Fatigue & Fracture of Engineering Materials & Structures》2020,43(7):1307-1326
The structural applications of adhesively bonded joints on transportation industries have been increasing, and it is expected that this rising trend persists in the future. The appropriate design of these joints should address two main issues: fatigue behaviour and environmental effects. Environmental effects consist of the degradation of the bonded joints by means of harmful influence of temperature, moisture or both simultaneously. These effects can have an impact on the fatigue behaviour of bonded joints because they influence the quality of the bonding. The combination of environmental effects and fatigue lead to synergetic consequences resulting in premature and unpredictable rupture, which transforms these issues into relevant and actual research topics. The present paper describes the most recent works addressing the referred subjects. Experimental works and analytical/numerical approaches are also described aiming to give a picture of the real state‐of‐the‐art. Actual limitations and perspectives of future evolution are also discussed. 相似文献
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Efstathios E. Theotokoglou 《International Journal of Fracture》1999,98(3-4):361-367
The solution of the plane elasticity problem of two bonded isotropic linearly elastic half-planes of different elastic properties
having a crack L along the interface as well as a crack S in one of the half planes which intersects the interface crack,
is given by using the Muskhelishvili's complex variable method with sectionally holomorphic functions. The initial problem
is reduced to a Hilbert problem, the solution of which in the case of a dislocation existing in either half-planes constitutes
the Green's functions of the problem. Finally, a singular integral equation is derived for the problem only along the crack
S. The singular integral equation is solved numerically and results are presented for the stress intensity factors.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献