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为研究编织复合材料在静载及疲劳载荷下的分层特性及损伤演化模式,对斜纹编织CF3052/3238A碳纤维/环氧树脂复合材料II型静开裂及疲劳开裂性能进行了测试。结果表明:斜纹编织CF3052/3238A碳纤维/环氧树脂复合材料裂纹扩展行为受纬向纤维影响存在周期性局部受阻现象,分层破坏模式除层间开裂外还存在纬向纤维脱粘;斜纹编织CF3052/3238A碳纤维/环氧树脂复合材料裂纹扩展速率符合Paris公式,不同加载控制模式下编织复合材料疲劳驱动力增长规律存在本质区别:恒幅疲劳载荷下斜纹编织复合材料疲劳驱动力呈抛物线型单调增长;而恒幅疲劳位移下复合材料疲劳驱动力随分层长度呈波峰型分布;采用基于载荷控制模式和位移控制模式下的疲劳驱动力模型,可对斜纹编织CF3052/3238A碳纤维/环氧树脂复合材料进行损伤演化表征,其表征效果良好,具有工程参考价值。 相似文献
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提出一种基于虚拟裂纹闭合技术的界面元模型,用以模拟复合材料的分层破坏和预测结构的承载能力。界面元被嵌入在模型分层扩展路径上,计算结构的能量释放率,结合幂指数破坏准则,模拟复合材料的分层扩展。对由于裂尖单元长度不同所带来的分析误差进行了适当的修正,以降低网格粗细变化所带来的不利影响。为了检验该界面元的可靠性,分别将其应用于对双悬臂梁(DCB) 模型、端边切口(ENF) 模型和混合模式弯曲(MMB) 模型的分层扩展分析中。计算结果与解析解基本吻合,从而验证了采用该界面元模拟复合材料分层破坏的可行性。用该方法对3个含有不同初始损伤复合材料T型接头的界面拉脱分层破坏进行数值模拟,计算结果与试验数据吻合良好。 相似文献
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为了给碳纤维增强聚合物(CFRP)复合材料粘接结构的安全设计及应用提供参考,针对CFRP复合材料-铝合金对接接头,研究了拉-拉交变载荷作用下的疲劳寿命特性及剩余强度变化规律。设计专用夹具,完成接头的制作及固化,并测试其拉伸、剪切准静态失效强度,在此基础上进行不同载荷水平下的疲劳寿命测试。选取特定载荷水平,测试不同循环次数后的接头剩余强度,并对失效形式进行观察分析。结果表明:CFRP复合材料-铝合金对接接头强度-寿命(S-N)曲线在单对数坐标上符合线性函数规律;随着交变载荷循环周期的增加,接头剩余强度呈先慢后快的下降趋势,而且在较大的载荷水平下,下降幅度更为明显;经历交变载荷循环前、后接头失效形式发生改变,由局部CFRP复合材料表层撕裂转变为局部界面破坏。结合试验测试所获得的初始失效准则,并引入疲劳退化因子,建立内聚力模型对交变载荷作用下的粘接接头强度衰减进行数值模拟,结果表明所建立模型能够有效预测交变载荷作用下的接头剩余强度。 相似文献
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针对传统内聚力损伤模型(CZM)无法考虑层内裂纹对界面分层影响的缺点,提出了一种改进的适用于复合材料层合板低速冲击损伤模拟的CZM。通过对界面单元内聚力本构模型中的损伤起始准则进行修正,考虑了界面层相邻铺层内基体、纤维的损伤状态及应力分布对层间强度和分层扩展的影响。基于ABAQUS用户子程序VUMAT,结合本文模型及层合板失效判据,建立了模拟复合材料层合板在低速冲击作用下的渐进损伤过程的有限元模型,计算了不同铺层角度和材料属性的层合板在低速冲击作用下的损伤状态。通过数值模拟与试验结果的对比,验证了本文方法的精度及合理性。 相似文献
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基于各向异性双材料界面断裂力学理论,再根据D-B模型假设的有限裂纹尖端奇异性将消失,推导出复合材料分层裂纹尖端粘聚区长度的计算模型。结果显示复合材料分层裂纹尖端粘聚区具有振荡性(当振荡因子0时),并且粘聚区长度与裂纹长度、应力值及振荡因子有关。将新模型应用于界面单元法中,模拟了双悬臂梁(DCB)和混合型弯曲梁(MBB)分层扩展过程中的载荷-位移关系,并比较了不同的粘聚区长度对收敛性和计算精度的影响,结果表明该模型可较精确地计算复合材料的粘聚区长度,以此为基础划分网格能同时保证收敛性和计算精度要求,并可有效地节省运算时间。 相似文献
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燃气轮机叶片在实际工作过程中,易受到非对称循环载荷作用而发生疲劳失效。为便于准确地预测非对称循环加载下叶片材料的裂纹萌生及扩展寿命,首先考虑平均应力效应和高应力区的塑性变形影响,对Chaboche模型进行改进,然后将改进的Chaboche模型和Walker裂纹扩展公式相结合,建立了一种非对称循环载荷作用下裂纹萌生及扩展综合寿命模型,并用试验数据进行验证分析。结果表明,该模型预测得到的裂纹萌生寿命、裂纹扩展寿命与试验数据基本吻合,验证了新模型的适用性和准确性,为燃气轮机叶片损伤分析和寿命预测奠定理论基础。 相似文献
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Li Longbiao 《Applied Composite Materials》2017,24(4):965-981
In this paper, the synergistic effects of temperature, oxidation and multicracking modes on damage evolution and life prediction in 2D woven ceramic-matrix composites (CMCs) have been investigated. The damage parameter of fatigue hysteresis dissipated energy and the interface shear stress were used to monitor the damage evolution inside of CMCs. Under cyclic fatigue loading, the fibers broken fraction was determined by combining the interface/fiber oxidation model, interface wear model and fibers statistical failure model at elevated temperature, based on the assumption that the fiber strength is subjected to two-parameter Weibull distribution and the load carried by broken and intact fibers satisfy the Global Load Sharing (GLS) criterion. When the broken fibers fraction approaches to the critical value, the composite fatigue fractures. The evolution of fatigue hysteresis dissipated energy, the interface shear stress and broken fibers fraction versus cycle number, and the fatigue life S–N curves of SiC/SiC at 1000, 1200 and 1300 °C in air and steam condition have been predicted. The synergistic effects of temperature, oxidation, fatigue peak stress, and multicracking modes on the evolution of interface shear stress and fatigue hysteresis dissipated energy versus cycle numbers curves have been analyzed. 相似文献
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Hossein Hosseini-Toudeshky Ali Jasemzadeh Bijan Mohammadi 《Applied Composite Materials》2011,18(6):571-584
Repaired panels with composite patches subjected to fatigue loading may fail due to the progressive debonding between the
composite patch and aluminium panel. The objective of this paper is to study the initiation and propagation of a possible
fatigue debonding in the adhesive layer while the crack also growths in the panel for single-side repaired aluminium panels.
For this purpose three dimensional finite elements method with a thin layer solid like interface element is employed. Fracture
mechanics approach is used for the analysis of crack growth in aluminium panel and the interface elements with fatigue constitutive
law for mixed mode debonding growth in the adhesive layer. A user element routine and a damage model material routine were
developed to include the interface element and to simulate the initiation and propagation of damage in adhesive layer under
cyclic loading. It is shown that, the debonding propagation and crack growth rate of the repaired panels depend on the composite
patch material and interface bonding properties significantly. It is also shown that using of patch material with higher elastic
module leads to the faster damage or debonding growth in the adhesive layer during the fatigue loading. 相似文献
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S. I. Rokhlin Y. C. Chu W. Huang 《Mechanics of materials : an international journal》1995,21(4):251-263
This paper describes an experimental nondestructive technique for fatigue damage assessment in metal matrix composites by measuring ultrasonic phase velocity and attenuation. A [0/90] SiC/Ti---15V---3Cr---3Al---3Sn metal matrix composite is considered as a model system. Cyclic loading at 50 and 70% of the ultimate sample strength were used until failure. The ultrasonic phase velocities and attenuations were measured periodically and found to be very sensitive to fatigue damage. The fatigue-induced changes in the composite elastic constants were calculated from the measured ultrasonic velocity data. For samples heat treated prior to fatigue (815°C) above the matrix β transus (about 760°C), the dominant damage mechanism is debonding of the fiber/matrix interface. We found that when samples were fatigued for less than 50% of the lifetime, the reduction of the composite moduli was linearly dependent on the number of fatigue cycles, which is explained by extension of interfacial partial debonds. This was supported by micromechanical analysis based on a partial disbond model. The rate of decrease in the composite moduli in the second half of the fatigue life was found to be lower, which may serve as a basis for estimation of the remaining fatigue life of the composite from ultrasonic velocity and attenuation measurements. The attenuation data was obtained in directions perpendicular to the fiber. A single-fiber scattering model has been used to explain the effect of the fiber/matrix interface on attenuation. Good correlation between attenuation and moduli measurements was observed. 相似文献
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依据广义自洽方法,建立了包含芳纶纤维、界面相、橡胶基体和等效介质的代表性体积单元(RVE)模型。采用自定义材料子程序对内聚力疲劳累积损伤模型进行编译,分别在基体/界面相的界面和纤维/界面相的界面设置内聚力单元,研究界面相性能参数对纤维增强橡胶密封复合材料(SFRC)界面疲劳损伤行为的影响。探讨了界面相厚度和模量的确定方法,获得了不同界面相厚度和模量下SFRC界面脱粘起始位置以及脱粘起始疲劳次数。结果表明,较低的界面相模量能够抑制界面脱粘的产生;随着界面相厚度的增加,界面脱粘的起始疲劳次数增加,SFRC抗疲劳损伤能力得到提高。 相似文献
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Zhenhui TIAN Huifeng TAN Xingwen DU Center for Composite Materials Harbin Institute of Technology Harbin China 《材料科学技术学报》2006,22(5):647-650
The fatigue damage accumulation of [±20°] laminated steel cord reinforced rubber composite under T-T loading was studied. Results indicate that the increase in the cyclic maximum strain exhibits three-stage tendency in the process of fatigue. The macroscopic fatigue damage initiates from the ends of steel cords in the form of cylindrical crack. Damage propagates along with the increase in crack numbers, the cord/matrix interface debonding and the growth of interply cracks. By using the dynamic creep as parameter, a linear fatigue damage accumulation model was established. This model can be used under dual loading conditions to estimate the residual fatigue life of the specimen. 相似文献
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Fretting fatigue is a complex mechanical failure phenomenon, in which two contact surfaces undergo a small relative oscillatory motion due to cyclic loading. This study proposes a methodology to analyze the fretting fatigue failure mechanism of automotive shock absorber valve by means of experimental and numerical approaches. A servo hydraulic test set-up is used to simulate fretting fatigue under real working conditions. Moreover, a 3-D finite element model is developed to analyze the contact status and stress distribution at contact interface between connected components, i.e. washer-disc contact. The experimental test results depict that fretting damage appears at contact interface between washer and disc, which causes the initial crack nucleation and advancing the crack up to the final fracture of valve disc. Stress field, obtained by numerical simulation, is used to monitor some fretting fatigue features such as the distribution of relative slip amplitude, contact pressure and different stress fields at contact interfaces. Eventually, the crack initiation site is estimated by monitoring variation of equivalent multiaxial damage stress at contact interface. 相似文献
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本研究用真空热压法制备了两种铺层的C/AI正交层板(0/90/0)s及(90/0/90)s.在MTS NEW810上进行了一系列疲劳损伤及破坏试验.疲劳损伤的行为研究工作包括:以刚度下降为损伤参数对C/AI正交层板进行了降级应力分析,并由此来预计在△Sh以下,正交层板不会发生疲劳损伤累积.研究了C/Al正交层板在同一应力水平而不同应力范围作用下的疲劳响应,发现试样在疲劳损伤时其刚度下降值相近似,即疲劳破坏的门槛值依赖于所施加的应力水平.依据MMC对各种循环载荷的不同响应,基体的疲劳损伤状态在S-N平面上可分为三种不同的区域:无损伤区,损伤累积区和断裂区.利用扫描电镜及金相显微镜分别对其疲劳断口形貌、基体裂纹进行观察,对该正交层板的疲劳破坏行为进行分析及讨论.结果表明:C/Al正交层板的疲劳断口呈脆断型,其中主承力层(0°铺层)断口平齐,偏轴层(90°铺层)断口平齐最差,层间损伤形式有局部分层、界面连续开裂及复合丝之间基体开裂等三种形式;其疲劳破坏主导因素是层间局部严重损伤及主承力层中复合丝大量断裂由于其疲劳裂纹沿垂直于载荷方向迅速扩展,寻找适中的界面结合强度对改善C/Al层板的疲劳性能有很大影响. 相似文献
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Paul Robinson Ugo Galvanetto Davide Tumino Giordano Bellucci David Violeau 《International journal for numerical methods in engineering》2005,63(13):1824-1848
This paper presents a computational technique for the prediction of fatigue‐driven delamination growth in composite materials. The interface element, which has been extensively applied to predict delamination growth due to static loading, has been modified to incorporate the effects of cyclic loading. Using a damage mechanics formulation, the constitutive law for the interface element has been extended by incorporating a modified version of a continuum fatigue damage model. The paper presents details of the fatigue degradation strategy and examples of the predicted fatigue delamination growth in mode I, mode II and mixed mode I/II are presented to demonstrate that the numerical model mimics the Paris law behaviour usually observed in experimental testing. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献