共查询到20条相似文献,搜索用时 15 毫秒
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M. S. Found S. B. Kanyanga 《Fatigue & Fracture of Engineering Materials & Structures》1996,19(1):65-74
Abstract— A review of variable fatigue loading of carbon fibre/epoxy laminates indicates that for two-stage loading, low-to-high loading is generally more damaging than high-to-low loading. Damage accumulation under two-stage loading appears to produce linear damage in some CFRP materials and non-linear behaviour in others. The behaviour of those materials exhibiting linear damage may be predicted by the Palmgren-Miner rule. A model is presented for determining the longitudinal split growth in notched unidirectional carbon fibre/epoxy test coupons. The model is able to predict the non-linear split growth for low-to-high loading whilst the linear damage accumulation for high-to-low loading may best be determined by use of the Palmgren-Miner rule. 相似文献
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60Coγ射线辐照对碳纤维表面及其复合材料层间剪切强度的影响 总被引:3,自引:0,他引:3
对60Coγ射线辐照处理的PAN 基碳纤维的力学性能、表面形貌及表面结构的变化和其与环氧树脂复合后层间剪切强度进行了初步的研究。60Coγ射线在1×102~ 1×103Gy 辐照剂量时, 使PAN 基中强碳纤维本身的力学性能显著提高; 使碳纤维表面的含氧官能团浓度和石墨化程度得以提高; 由此制备的碳纤维环氧复合材料的层间剪切强度SIL SS提高了31% 左右。而在辐照剂量≥1×104Gy 时, 由于辐照损伤及热效应, 使碳纤维的力学性能下降, 增加了表面的炭化及其撕裂程度,从而减小了碳纤维环氧复合材料的层间剪切强度SIL SS。 相似文献
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尝试用电化学阻抗图谱和循环伏安曲线的方法研究电化学表征参数与复合材料腐蚀程度之间的相关性, 用电化学方法研究了环境因素对碳纤维增强环氧树脂基复合材料内部结构的破坏机理。测试结果显示, 碳纤维本身不会发生电化学反应, 主要破坏机理为溶液离子逐渐渗入复合材料内部, 导致复合材料内部结构受到破坏。用电化学方法可以在线获得复合材料内部溶液离子浓度及溶液离子在复合材料内部的渗透过程, 据此可判断复合材料内部在环境因素作用下的变化。 相似文献
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Y. J. Guo X. R. Wu Z. L. Zhang 《Fatigue & Fracture of Engineering Materials & Structures》1997,20(12):1699-1708
Abstract— The objective of this work is to study the delamination growth behaviour of hybrid composite-aluminium bonded laminates. A modified Double Crack Lap Shear (DCLS) specimen was chosen for this study. An expression relating the delamination size and the compliance of a DCLS specimen was derived, and a test method for the delamination growth rate in DCLS specimens developed. The delamination sizes and the delamination growth rates of DCLS specimens were determined by monitoring the compliances of specimens during fatigue. Delamination growth rates at different stress ratios ( R = 0.1, 0.3,0.5) were measured. A Walker-type equation for the delamination growth rate was obtained by a multiple linear regression analysis.
It was shown that the compliance method for determining the delamination growth rate of DCLS specimens is not only convenient and practical, but also accurate. The delamination size in DCLS specimens increases linearly with cycles during fatigue, i.e. delamination growth rate is constant, independent of delamination size. The energy release rate was adopted to characterize delamination growth behaviour. Good agreement between the Walker equation and test results of the delamination growth rate was found. 相似文献
It was shown that the compliance method for determining the delamination growth rate of DCLS specimens is not only convenient and practical, but also accurate. The delamination size in DCLS specimens increases linearly with cycles during fatigue, i.e. delamination growth rate is constant, independent of delamination size. The energy release rate was adopted to characterize delamination growth behaviour. Good agreement between the Walker equation and test results of the delamination growth rate was found. 相似文献
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层间弱粘贴复合材料层板的热弹性脱层 总被引:1,自引:1,他引:0
本文建立了一个层间弱粘贴复合材料层板热弹性脱层模型.该模型建立在两个描述层间弱粘贴的基本假设基础上.层间位移不连续由层间粘贴的物理关系来描述,表现为层间位移跳跃值与层间残余横向应力的关系;层间温度不连续由层间传热薄层来描述,并据此给出一个计算层间温度跳跃值的计算公式,表现为温度跳跃值与层间横向张开量之间的关系.在此假设基础上,根据平衡方程和静态传热方程导出了正交柱面弯曲层板热弹性脱层解.算例显示了层间弱粘贴对层板热弹性响应的影响. 相似文献
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首先用实验直接测定或从文献中引用单向纤维增强层板的强度的Weibull分布参数α和β.用经典层板理论分析层板中的面内应力;邻层的裂纹引起的应力集中用剪滞法计算;层间应力用简化的平衡方程来确定,层板中单层的当地强度由于邻层的约束作用而提高,假定单层的承载能力直到其裂纹密度饱和时才耗尽;用增强软X光照相技术来监测裂纹密度的发展并测定相应的约束系数,建立最普遍的统计强度准则,结合作用应力的计算和统计强度预报,确定不同层板中各单层的破坏顺序和最终损伤状态.根据最终损伤状态来确定层板的统计强度,并用试验验证. 相似文献
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SUMMARY A study of delamination crack growth due to bending in cross-ply laminates is presented. For the understanding of interlaminar fracture behaviour of laminated composites the modelling of delamination crack growth induced by bending and shear cracks in three point bending specimens is carried out. A plane strain two-dimensional (2-D) finite element analysis is used to determine the strain energy release rates during delamination of the laminated beam. Contact elements were used to prevent the material interpenetration on the crack surfaces. The solution of the contact problem taking into account friction along crack surfaces is obtained. Energy release rates GI and GII for Mode I and Mode II fracture are calculated by virtual crack closure integral (VCCI) methods. Comparison of total energy release rates, obtained by local energy methods, with an analytical solution based on the beam theory and a global energy method have been carried out. Good agreement of the results obtained by various methods have been observed. Comparison of the results obtained by the solution of the contact problem and without contact elements have been performed. Significant differences between the values of energy release rates obtained with and without using contact elements have been observed. The influence of the coefficient of friction on the energy release rates is insignificant. 相似文献
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碳纳米管/环氧树脂复合物的固化行为 总被引:6,自引:0,他引:6
用差示扫描量热仪(DSC)研究了4,4’-二氨基二苯甲烷环氧树脂(TGDDM)/4,4'-二氨基二苯基砜(DDS)环氧树脂体系及其多壁碳纳米管复合物的固化行为。碳纳米管加入TGDDM/DDS体系后,起始固化反应速率增大,达到最大反应速率的时间减小,说明碳纳米管对环氧树脂的固化反应有催化作用。和纯树脂相比,在固化反应初期碳纳米管复合物的活化能降低。在玻璃化现象出现以前,Kamal的固化动力学模型得到的结果与实验数据相当吻合。 相似文献
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