共查询到19条相似文献,搜索用时 46 毫秒
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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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为研究复合材料层合板吸湿后的分层现象,首先建立了吸湿后复合材料层合板快速加热导致分层损伤的有限元模型,并对ABAQUS有限元软件进行二次开发,通过UAMP子程序模拟吸湿后复合材料快速加热时水分汽化引起的局部高压载荷作用下层合板分层扩展与载荷施加过程;然后,采用该模型预测了饱和吸湿T650-35/HFPE-II-52碳纤维聚酰亚胺复合材料层合板快速加热至310 ℃时产生的分层现象,并将数值模拟与文献实验结果对比;最后,运用该模型分析了树脂吸湿量和富脂区树脂聚集体积对层合板分层损伤面积的影响。结果表明:建立的有限元模型有效;快速加热后,层合板的分层损伤面积随树脂吸湿量的增加而增加;当富脂区树脂聚集体积较小时,其对层合板快速加热后分层损伤面积影响较小,但当富脂区树脂聚集体积增加到一定值后,层合板分层损伤面积随富脂区树脂聚集体积的增加而显著增加。所得结论表明,使用ABAQUS的UAMP子程序建立的有限元模型可以有效分析吸湿后复合材料层合板快速加热导致的分层现象。 相似文献
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纤维增强复合材料层合板由于层间力学性能弱,容易出现分层损伤。分层的扩展往往伴随着纤维桥联效应,纤维桥联能显著增大层合板尤其是多向层合板分层扩展的阻力。考虑纤维桥联效应的三线性内聚力模型能表征分层扩展实验中断裂韧性的“R曲线”特征,比传统的双线性模型能更为准确地描述复合材料的分层扩展行为。本论文基于三线性内聚力模型,对含圆形分层复合材料层合板的轴向压缩进行数值模拟,探讨纤维桥联效应对分层扩展及后屈曲行为的影响规律。研究结果发现,纤维桥联对层合板的屈曲载荷影响较小;混合屈曲模式下,三线性模型预测的上下子板相对法向位移明显低于双线性模型;相同分层深度下,三线性模型预测的层合板后屈曲更早转变为整体屈曲模式。随着分层深度的增加,层合板的屈曲模式由局部屈曲逐步过渡为混合屈曲和整体屈曲;当分层深度较浅时,Ⅰ型分层扩展占主导;随着分层深度的增加,Ⅰ型分层逐渐减弱,而Ⅱ型和Ⅲ型分层扩展则显著增强;当分层接近板中面时,Ⅰ型分层停止扩展,以Ⅱ型及Ⅲ型分层为主。 相似文献
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采用有限元方法研究了含穿透分层损伤复合材料加筋层合板的动力响应和承载能力。根据复合材料层合板一阶剪切理论, 推导了复合材料层合板单元的刚度阵和质量阵列式;同时采用Adams 应变能法与Rayleigh阻尼模型相结合的方法, 构造了相应的阻尼阵列式;为了防止在低阶模态中分层处出现的上、下子板不合理的嵌入现象, 建立了含分层损伤复合材料加筋层合板动力分析中分层分析模型和虚拟界面联接模型。并采用Tsai提出的刚度退化准则和动力响应分析的精细积分法, 对在动荷载作用下含分层损伤复合材料加筋层合板结构进行了破坏和承载能力分析。通过典型算例分析, 分别讨论了外载频率、分层深度、筋的位置以及破坏过程中刚度退化对含损伤复合材料加筋层合板动力响应特征和承载能力的影响, 得到了一些具有理论和工程价值的结论。 相似文献
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为了优化设计PE/PE层合板复合材料和准确评价其性能,必须深入地研究该类材料的损伤破坏机理,进而揭示其损伤扩展规律,预测因损伤的存在对材料刚度、强度等宏观性能的影响。基于拟三维模型的概念,提出了适合于数值模拟PE/PE层合板复合材料力学行为的修正模型。应用此有限元数值模型,对3种准各向同性UHMWPE/HDPE层合板在拉伸载荷条件下的损伤及损伤扩展进行了模拟,对这些材料的破坏机理进行了探讨,并预测了它们的强度。通过试验,可知应用上述模型进行数值模拟所获得的结果与试验数据是吻合的。证明了修正后的有限元数值模型的有效性。 相似文献
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In this paper, the extended finite element method (XFEM) is extended to simulate delamination problems in composite laminates. A crack-leading model is proposed and implemented in the ABAQUS® to discriminate different delamination morphologies, i.e., the 0°/0° interface in unidirectional laminates and the 0°/90° interface in multidirectional laminates, which accounts for both interlaminar and intralaminar crack propagation. Three typical delamination problems were simulated and verified. The results of single delamination in unidirectional laminates under pure mode I, mode II, and mixed mode I/II correspond well with the analytical solutions. The results of multiple delaminations in unidirectional laminates are in good agreement with experimental data. Finally, using a recently proposed test that characterizes the interaction of delamination and matrix cracks in cross-ply laminates, the present numerical results of the delamination migration caused by the coupled failure mechanisms are consistent with experimental observations. 相似文献
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Review of delamination predictive methods for low speed impact of composite laminates 总被引:3,自引:0,他引:3
David J. Elder Rodney S. Thomson Minh Q. Nguyen Murray L. Scott 《Composite Structures》2004,66(1-4):677-683
Predicting the damage tolerance of laminated composite aircraft components subjected to low velocity impact events, such as runway debris or hail, is providing a significant challenge to the current methods. This paper reviews the current damage mechanics and fracture methods for predicting delamination under impact available in the literature. Many damage mechanics models are available, some providing good delamination predictions. The linear elastic fracture mechanics method has been used extensively where the shape of the delamination front can be predicted and a suitably shaped mesh can be provided. However, as impact events produce irregular shaped delamination fronts, this method requires an adaptive mesh approach that is not yet available in any of the major analysis codes. The cohesive fracture model solves some of the limitation of the linear elastic fracture mechanics method, however a definitive study of its abilities has yet to be found in the literature. The delamination threshold load method is an extremely simple method and provides surprisingly good results. The review concludes that additional development of current techniques is required before a definitive predictive delamination method will be available. 相似文献
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Unidirectional fiber-reinforced composite laminates are widely used in aerospace industry for a great variety of structural parts. In order to enhance the exploitation of material reserves, there is a need for the integration of progressive damage scenarios in the design phase. Due to their hazardous effects on the load-carrying capacity of composite structures, this work focusses on the simulation of delaminations. A finite element based on a cohesive zone approach is developed. Two constitutive laws are proposed. One is characterized by linear degradation after delamination onset, the other is governed by exponential softening response. The damage process is history-dependent leading to an irreversible stiffness degradation in damaged zones. The practicability of the proposed model and the assets and drawbacks of the two material laws are shown by some numerical examples. 相似文献
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《Composites Part B》2001,32(4):287-298
This paper describes an application of Strip Element Method (SEM) and adaptive Multilayer Perceptron Networks (MLP) for inverse identification of interfacial delaminations in carbon/epoxy laminated composite beams. Displacement responses calculated using SEM for laminated beams containing predetermined delamination parameters (i.e. delamination location, depth and length) are used as training data for the MLP. Once the MLP is trained, the MLP networks are then employed for inverse determination of delamination using experimental displacement responses measured with a scanning laser vibrometer. The outputs of the initially trained MLP, which are the reconstructed delamination parameters, are then compared with the experiments data. The MLP will be re-trained and re-used for parameter reconstruction until satisfactory results are obtained. Examples show that the procedure performs well for the determination of a wide range of values for the location, depth and length of delamination. 相似文献
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Some aspects of numerical simulation of Lamb wave propagation in composite laminates using the finite element models with explicit dynamic analysis are addressed in this study. To correctly and efficiently describe the guided-wave excited/received by piezoelectric actuators/sensors, effective models of surface-bounded flat PZT disks based on effective force, moment and displacement are developed. Different finite element models for Lamb wave excitation, collection and propagation in isotropic plate and quasi-isotropic laminated composite are evaluated using continuum elements (3-D solid element) and structural elements (3-D shell element), to elaborate the validity and versatility of the proposed actuator/sensor models. 相似文献
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建立了缝合复合材料层板在低速冲击载荷下的渐进损伤分析模型。模型中采用空间杆单元模拟缝线的作用;采用三维实体单元模拟缝合层板,通过基于应变描述的Hashin准则,结合相应的材料性能退化方案模拟层板的损伤和演化;采用界面单元模拟层间界面,结合传统的应力失效判据和断裂力学中的应变能释放率准则判断分层的起始和扩展规律。通过对碳800环氧树脂复合材料(T800/5228)层板的数值仿真结果和试验结果相比较,验证了模型的正确性,同时讨论了不同冲击能量下缝合层板的损伤规律。研究结果表明:缝线能够有效地抑制层板的分层损伤扩展;相同冲击能量下缝合与未缝合层板的基体损伤和纤维损伤在厚度分布上相似,缝合层板的损伤都要小于未缝合层板。 相似文献
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The transition of delamination growth between different ply interfaces in composite tape laminates, known as migration, was investigated experimentally. The test method used promotes delamination growth initially along a 0/θ ply interface, which eventually migrates to a neighbouring θ/0 ply interface. Specimens with θ = 60° and 75° were tested. Migration occurs in two main stages: (1) the initial 0/θ interface delamination turns, transforming into intraply cracks that grow through the θ plies; this process occurs at multiple locations across the width of a specimen, (2) one or more of these cracks growing through the θ plies reaches and turns into the θ/0 ply interface, where it continues to grow as a delamination. A correlation was established between these experimental observations and the shear stress sign at the delamination front, obtained by finite element analyses.Overall, the experiments provide insight into the key mechanisms that govern delamination growth and migration. 相似文献
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《Composites Part A》2007,38(9):2024-2033
In the current investigation, effects of through-the-thickness stitching with two different types of aramid threads, Kevlar® and Twaron® threads, on the buckling loads of delaminated glass/epoxy composite laminates are studied. Buckling loads are predicted based on the Southwell, Vertical displacement and Membrane strain plot methods by using the experimental data. From the Southwell, Vertical displacement and Membrane strain plot methods it is observed that stitching either by Kevlar® or Twaron® threads is effective in improving the buckling strength of glass/epoxy composite laminates when the delamination length is greater than 0.5L, L being the length of the laminate. For long delaminations, Kevlar® stitched glass/epoxy composite laminate is best in retaining its buckling strength when re-loading is done. Southwell plot method tends to overestimate the buckling loads as the data obtained from this method are influenced by the breakages in the glass/epoxy composite laminate buckling test specimens. 相似文献