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1.
《天津大学学报(英文版)》2020,(4)
The eff ect of Zn interlayer on the microstructural evolution and mechanical behavior of dissimilar ultrasonic-spot-welded Al/Cu joints was investigated. The tensile lap shear strength in relation to welding energy was analyzed. The experimental results show that two intermetallic compounds, Cu_5Zn_8 and Al_2Cu, were generated at the interface of the ultrasonic-spotwelded Al/Cu joint with a Zn interlayer. The primary joining mechanisms of the joint included the intermetallic compound bonding and metallic bonding caused by solid shear plastic deformation. Meanwhile, with increasing welding energy, the plastic deformation of the material became more substantial. With increasing welding energy, the tensile lap shear strength of the joints fi rst increased and then decreased for the ultrasonic-spot-welded Al/Cu joints with and without Zn interlayers. Under the energy input of 700 J, the bearing load capacity of the ultrasonic-spot-welded Al/Cu joints with a Zn interlayer improved signifi cantly due to the observed intermetallic compound(Cu_5Zn_8). 相似文献
2.
By using semisolid joining technique,the bonding of stainless steel and semisolid aluminum alloy is successfully realized.The relationships between interracial shear strength and solid fraction of aluminum alloy,bonding pressure and time of keeping pressure were studied by the method of orthogonal experiment.The interfacial structure and the fracture structure of the bonding plate are studied by means of optical microscope (OM) and scanning electron microscope (SEM).The results show that there is the best solid fraction between the solid phase line and the liquid phase line of the semisolid aluminum alloy,with the increase of bonding pressure and pressure time,the interfacial shear strength increases rapidly,and then with further increase of bonding pressure and pressure time,the shear strength rises little.Along the interface,solid phase and liquid phase bond with stainless steel by turns because of the different diffusion ability.So,a new type of non-equilibrium diffusion interfacial structure is constructed at the interface of stainless steel and aluminum alloy,compound mechanism of plastic and brittle fracture interface was formed at the shear fracture interface. 相似文献
3.
Zhi-jiang Jin Cheng-hang Jiang Xian-ping Wan Po Chen Xiao-fang Wang 《浙江大学学报(A卷英文版)》2010,11(6):440-448
With von Mises yield criterion, the loading range of Net Section Collapse （NSC） Criteria is extended from combined tension and bending loadings to combined bending, torsion and internal pressure loadings. A new theoretical analyzing method of plastic limit load for pressure pipe with incomplete welding defects based on the extended NSC Criteria is presented and the correlative formulas are deduced, the influences of pipe curvature, circumferential length and depth of incomplete welding defects on the plastic limit load of pressure pipe are considered as well in this method. Meanwhile, according to the orthogonal experimental design method, the plastic limit loads are calculated by the finite element method and compared with the theoretical values. The results show that the expressions of plastic limit load of pressure pipe with incomplete welding defects under bending, torsion and internal pressure based on extended NSC criteria are reliable. The study provides an important theoretical basis for the establishment of safety assessment measure towards pressure pipe with incomplete welding defects. 相似文献
4.
房丽敏 《广东教育学院学报》2010,(5):62-66
采用在密度泛函理论框架下的第一性原理方法,系统地分析了4种可能Au/SrTiO3（001）界面模型的界面能、原子间距、电子结构及其化学键特征.研究表明：Au/SrTiO3（001）界面的稳定性与其界面原子构型密切相关;Au与排列在以TiO2原子层截止SrTiO3（001）表面的氧原子上的界面构型最为稳定. 相似文献
5.
This work applied the ultrasonic bonding to package flip chip GaN-based light emitting diodes (flip chip LEDs) on Si substrates.
The effects of ultrasonic bonding parameters on the reliability of flip chip GaN-based LED were investigated. In the sequent
aging tests, samples were driven with a constant current of 80 mA for hundreds hours at the room temperature. It was found
that the electroluminescence (EL) intensity variation had a large correlation to the ultrasonic power, and then to the bonding
temperature and force. A high bonding temperature and ultrasonic power and a proper bonding force improved the EL intensity
significantly. It was contributed to a strong atom inter-diffusion forming a stable joint at the bonding interface. The temperature
fluctuation in the aging test was the main factor to generate a high inner stress forming delamination at the interface between
the chip and Au bump. As a result, delamination had retarded the photons to emit out of the LED packaging and decay its EL
intensity. 相似文献
6.
16MnⅥ(HIC)锻钢为低合金高强度结构抗氢钢,焊接性能良好。针对冷高分罐在制造过程中易出现的突出问题,分析了其基体材料16MnⅥ(HIC)的焊接性,阐述了克服该材料在焊接过程中出现缺陷的工艺措施。试验结果表明,通过采取合理的焊接工艺,可保证该类材料的焊接性,并为窄间隙埋弧焊焊接高压重容提供依据。 相似文献
7.
吴晓红 《武汉职业技术学院学报》2014,(3):82-84
采用波长为1.06μm的Nd:YAG激光器对胃镜活检钳进行焊接,通过调节激光的电流、脉冲宽度、离焦量等工艺参数对其进行精密焊接试验。研究结果表明,影响焊接效果的因素中,脉冲宽度决定了焊缝的凸起程度。通过采用较小激光能量条件下重复焊接两次或者三次这一独特工艺方法来克服激光能量稳定性、工件公差等缺陷,达到很好的焊接效果。 相似文献
8.
郑占彬 《河北能源职业技术学院学报》2011,11(2):57-58
主要阐述了装船机皮带系统结构特点,在实际应用中,皮带接口采用硫化冷粘接工艺存在的缺陷,为了适应实际的工作环境,选用硫化热粘接工艺,用以改变在生产中遇到的问题,重点介绍了硫化热粘接的工艺技术,为现场实施做以参考。 相似文献
9.
To study the mechanical properties of the film/substrate structure, the finite element code ABAQUS v6.9-1 is adopted to simulate the tensile mechanical behavior of the nanoscale thin film bonded to a substrate. The bifurcation phenomenon of the structure under uniaxial tension is found: the single-neck deformation, the multiple-neck deformation and the uniform deformation. The substrate and the film are regarded as power-hardening materials obeying the J 2 deformation theory. Firstly, the influence of material hardening match on tensile bifurcation mode is analyzed under perfectly well-bonded interface condition. Then, the effects of interfacial stiffness and other superficial defects surrounding the imperfection on bifurcation mode are investigated. It is concluded that under the well-bonded interface condition, if the stress of the substrate is larger than the film, the film will uniformly deform with the substrate; if the stress of the substrate is smaller than the film, the film will form a single neck, except the case that a weakly-hardening film is bonded to a steeply-hardening substrate when multiple necks can be formed. With the decrease of interfacial stiffness, the uniform deformation mode can transform into the multiple-neck deformation mode, and further transform into the single-neck deformation mode. And other defects surrounding the imperfection can influence the wavelength of deformation and neck number. 相似文献
10.
Stress-induced phase transformation has been investi-gatedfor several decades and much work was devotedtothephase transformationinincompressible materials[1—3].Oneimportant result wasthatthe material losingstrongellipticityat some deformationgradientis a… 相似文献
11.
12.
曾其科 《河北能源职业技术学院学报》2021,21(1)
金属垫片被广泛地用于高温、高压、强腐蚀介质的法兰联接中,是压力容器和管道中常见的密封形式。本文建立了螺栓-法兰-垫片联接系统模型,分析了预紧状态和工作状态平面金属垫片的应力应变。结果显示,垫片高应力区域出现在外圆周部分,圆周外沿首先发生塑性变形;介质压力作用加剧了垫片塑形变形,对垫片轴向变形量影响较大。 相似文献
13.
谢磊 《河北职业技术学院学报》2014,(2):44-46
根据HIPS材料在注射成型过程中的特性,综合考虑注塑机、42寸平板彩电前壳结构、热流道气辅注塑模具结构以及气针进气式气辅注射成型的特点,经过实践摸索,选用了合理的注塑工艺参数,解决了生产过程中42寸前壳易产生的收缩痕、注不满、熔接痕、烧焦痕、变形、气胀、串气等缺陷的问题,提高了塑件的合格率。 相似文献
14.
基于仿真模拟软件SYSWELD,建立了P91钢材料属性数据库,设计开发了考虑马氏体相变的“热-冶金-力学”耦合计算方法,采用热循环曲线法对P91钢平板对接接头残余应力场进行数值模拟仿真分析。参照原始焊接工艺方案进行上下0.5mm/s焊接速度的调整,并进行残余应力仿真计算。结果表明,马氏体相变能抵消焊缝热收缩时产生的拉应力。后道焊缝焊接过程中施加的热载荷对前道焊缝应力变化和平板角变形有着显著的影响。考虑后道焊缝焊接过程中施加的热载荷对前道焊缝组织变化的影响时,焊接接头整体的拉应力大幅度下降,热影响区的拉应力上升,角变形起缓和作用。焊接速度越大,Von Mises残余应力和横向残余应力越大,纵向残余压应力越小。 相似文献
15.
为了更好地保护古建筑,采用试验方法研究了CFRP加固古建筑榫卯节点后的抗震性能.基于某古建筑实际尺寸,制作了1:8缩尺比例的木结构空间框架模型,并考虑梁柱连接为燕尾榫形式.进行了低周反复加载试验,包括3组未加固构架试验和2组CFRP加固试验.基于试验相关数据,获得了节点的弯矩-转角滞回曲线和骨架曲线,并对比分析了节点加... 相似文献
16.
张建 《温州职业技术学院学报》2014,(1):61-64
低温环境金属的焊接易导致焊接接头产生冷裂纹.为减少焊接冷裂纹的产生,需采用预热措施.采用焊条电弧焊在环境温度为-15℃下进行T形接头焊接仿真,运用Simufact-Welding软件分析焊件预热到80℃和120℃时焊缝处的残余变形和残余应力.结果表明,预热到120℃时,焊缝处的残余变形小;预热到120℃时,除焊缝起始点和终止点外,其余焊缝处的残余应力小.因此,合理控制预热温度,可减小晶粒脆化;适当增大t./5时间,有利于缓解接头的冷却速度,减小淬硬倾向. 相似文献
17.
The main thrust of this research was to determine the effectiveness of polyvinyl alcohol (PVA) powder in enhancing the durability of short GFRC materials. Accelerated aging of the materials was achieved through low-pressure steam curing in a moist chamber. The strength and ductility of GFRC were measured by the direct tension test, which showed that incorporation of PVA powder into GFRC could improve its mechanical behaviour and turn it from brittle to ductile. To investigate the mechanism of the tensile strength enhancement, the fiber-matrix interface was examined by polarizing optical microscopy and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDAX). It was found that PVA powder tended to migrate to the fiber-matrix interfacial zone and thus prevented the accumulation of calcium hydroxide in this area. PVA film around the fiber resulted in a more ductile interfacial microstructure and better bonding between fiber and matrix, which should be responsible for enhancing the tensile property and preventing the aging of GFRC. Furthermore, PVA powder reduced the microhardness and brittleness at the interface. 相似文献
18.
Thehigh temperature pressuresensorhaswidespreadapplicationsinthefieldsofpetroleumlog ging,automonitor ,aerospace ,andsoon ,foritsfeaturesofhighworkingtemperature,smallbulkandhighsensi tivity ,whereaspackagingtechnologyisamainfactorwhichhaslimiteditsdevelopmentandapplicationforalongtime.Sensorpackagegenerallyadoptsnon isolatedpackageatpresent ,itisonlyapplicabletothatpressuremeasurementinwhichthegasorliquidiselectricalinsu latorandhasnocorrosiontothesensorchipandmetalelectrode ,andtherangeisalso… 相似文献
19.
成磊 《晋城职业技术学院学报》2011,4(2):39-43
采用ANSYS有限元分析软件建立Au-Al引线键合模型考察键合区在热循环加载下的应力应变情况;并采用Coffin-Manson方程计算了在热循环加载下焊点的疲劳寿命。结果表明：随着热加载循环次数的增加,模型的应力应变将增大;施加约束后,模型的应力将减小,引线键合的寿命延长。此方法可以比较各种不同情形下Au-Al引线键合热可靠性。 相似文献
20.
研究了Ｓ２５Ｃ与ＳＵＳ４０５钢的真空扩散焊接的变形率、抗拉强度及硬度．金相及显微分析可见，在焊接接头的结合界面上，Ｓ２５Ｃ钢一侧存在脱碳层，ＳＵＳ４０５钢一侧存在增碳层，这是造成接头组织分布及硬度分布不均匀的主要原因．还采用电子探针进行了微区分析，研究了碳、铬元素的分布． 相似文献