共查询到15条相似文献,搜索用时 31 毫秒
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混杂纤维复合材料受拉构件的最优混杂比研究 总被引:9,自引:1,他引:8
基于复合材料力学中的复合定律和断裂应变破坏准则,讨论了混杂纤维复合材料的断裂特性,得到了以纤维层拉伸强度和拉伸模量表示的两种纤维混杂复合材料受拉构件的临界混杂比和拉伸强度;并讨论了最优混杂比的选取方法。算例表明,文中给出的最优混杂比的确定,就是一种满应力的优化设计,它可用于固体火箭发动机混杂纤维缠绕壳体的初步设计。 相似文献
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三维机织复合材料纤维体积含量计算方法 总被引:5,自引:0,他引:5
三维机织复合材料的纤维体积含量是一个表征其性能的重要指标,目前尚无确切的检测标准可依。文中阐述了适用于三维机织复合材料纤维体积含量测定的3种新方法:称量法、理论模型法、数字图像分析法。分析了每一种方法的适用范围,并指出数字图像分析法是今后的发展方向。 相似文献
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混杂纤维缠绕壳体设计 总被引:10,自引:0,他引:10
应用网格理论,得到了固体火箭发动机混杂纤维缠绕壳体在内压作用下的平衡方程。给出了混杂纤维缠绕圆筒壁厚的计算公式。讨论了用模拟实验压力容器确定纤维发挥强度的问题。算例表明,文中给出的设计计算方法,可用于混杂纤维缠绕壳体的初步设计。 相似文献
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研究了树脂、纤维及其纤维增强复合材料的阻尼性质,利用体积混合率法则对混杂纤维增强复合材料的阻尼性质进行了分析。结果表明,混合率法则在复合材料的阻尼研究过程中是一个有效的方法,为相关领域的研究工作指明了方向。 相似文献
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采用三维机织工艺结合树脂传递模塑(RTM)技术制备了两种碳-芳纶混杂正交三向复合材料,即z向纱均采用芳纶纤维,经纬纱分别为炭纤维和经纬纱间隔排列炭纤维和芳纶纤维的混杂正交三向复合材料,以恒定应力幅值、应力比和频率,开展了复合材料经向拉伸疲劳性能试验,通过与炭纤维复合材料的对比,分析了碳-芳纶混杂方式对复合材料拉伸疲劳性能(疲劳寿命、疲劳破坏特征和疲劳后强度/刚度)的影响。当z向纱选用芳纶纤维,面内经纬纱为炭纤维的混杂复合材料经向拉伸疲劳寿命表现出正混杂效应;当进一步混入芳纶纤维,面内经纬纱为炭纤维和芳纶纤维间隔排列正交三向复合材料疲劳寿命表现为负混杂效应,对疲劳刚度损失有一定的抑制作用。可见,炭纤维正交三向复合材料中引入芳纶纤维,对其复合材料拉伸疲劳性能有重要影响,通过设计纤维混杂方式和混杂比例可进一步提高复合材料疲劳性能。 相似文献
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《固体火箭技术》2017,(1)
设计制备了Z向纱为芳纶纤维、经纬纱为炭纤维和经纬纱间隔排列芳纶纤维与炭纤维的混杂织造的2种炭/芳纶混杂正交三向织物增强环氧树脂复合材料,采用基于全场位移的数字图像相关(DIC)方法,进行了其材料级拉伸性能试验,通过与炭纤维、芳纶纤维2种非混杂的正交三向复合材料对比,分析了炭/芳纶混杂方式对复合材料拉伸性能的影响。实验结果表明,经纬纱采用炭纤维,Z向纱为芳纶纤维的混杂正交三向复合材料面内拉伸模量和断裂强度最大,断裂伸长率和泊松比较高;接下来的复合材料拉伸模量和强度从高到低依次是非混杂的炭纤维复合材料、经纬纱采用炭纤维和芳纶间隔排列的混杂复合材料和非混杂的芳纶纤维复合材料。因此,按比例合理布置炭纤维和芳纶纤维的混杂正交三向复合材料,可实现强度和韧性的折衷设计。 相似文献
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马立 《运载火箭与返回技术》1998,19(4):46-51
本文主要研究了碳纤维织物增强复合材料的纤维体积含量Vf对开孔层压板的抗拉强度σ断裂伸工率ε的影响。采用T300碳纤维平纹织物为增强材料,经树脂传递模塑法(RTM工艺)复合而成T300/环氧TDE-85层压板,用岛津强力测试机进行拉伸性能测试。 相似文献
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减少含硼推进剂残渣中氮化硼含量的研究 总被引:3,自引:1,他引:3
针对含硼推进剂燃烧残渣中存在较多氮化硼(BN)问题,采用氧弹法进行硼点火的模拟实验,并用热分析、X射线转靶衍射和元素分析等方法研究了BN的来源及其生成量与空气压强、包覆剂的关系。结果发现BN中氮元素主要来源于空气中氮气,其生成量随空气压强的上升而增加,并与包覆剂的含氧量有关。提出了抑制BN生成的有效途径。 相似文献
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A. S. Kovtyukh 《Cosmic Research》2006,44(5):393-397
The energy dependence of a fraction of ring current protons of ionospheric origin is calculated using the AMPTE/CCE data for a typical strong magnetic storm (max|D st | ≈ 120 nT). It is shown that this fraction monotonically decreases from ~ 83 to 25–30% with an increase in proton energy from 5 to 315 keV at L = 6–7 (L is the McIlwain parameter) and is 30–40% at energy 40–50 keV corresponding to the maximum of proton energy density at L = 6–7. It is demonstrated that the core of the ring current (L = 3.7–4.7) was enriched by solar protons with E ≈ 10–200 keV during the active phase of the storm (the maximum effect is reached at E ≈ 20–50 keV). 相似文献
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At high cabin pressure [e.g. 1013 hPa (14.7 psi) 21% O2] there are serious issues relative to specification of suit pressure and the need for prebreathing. A high pressure suit will be costly but use of the existing, flexible suit requires up to 6 h of prebreathing. Or one could use a cabin pressure of 700 hPa (10.2 psi) prior to extravehicular activity (EVA) in order to use the existing suit with only 1 h of prebreathing. If these normal cabin pressures and O2 levels are utilized, existing physiological and medical databases apply, providing a known basis for evaluating effects of long duration space missions. If a 345 hPa (5 psi), 70-100% O2 atmosphere is adopted the existing suit can be used with no prebreathing required. However, there is no reference database on physiological effects under the conditions of lower pressure and higher O2 concentration. This paper considers the major issues involved in defining habitat pressure, O2 fraction, and EVA suit design for operations in space. A preliminary model for evaluating habitat/suit pressure and O2% strategies is presented. 相似文献
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Hydrogen is one of the most promising fuels for the airbreathing hypersonic propulsion system, and it attracts an increasing attention of the researchers worldwide. In this study, a typical hydrogen-fueled supersonic combustor was investigated numerically, and the predicted results were compared with the available experimental data in the open literature. Two different chemical reaction mechanisms were employed to evaluate their effects on the combustion of H2–O2, namely the two-step and the seven-step mechanisms, and the vitiation effect was analyzed by varying the H2O mass fraction. The obtained results show that the predicted mole fraction profiles for different components show very good agreement with the available experimental data under the supersonic mixing and combustion conditions, and the chemical reaction mechanism has only a slight impact on the overall performance of the turbulent diffusion combustion. The simple mechanism of H2–O2 can be employed to evaluate the performance of the combustor in order to reduce the computational cost. The H2O flow vitiation makes a great difference to the combustion of H2–O2, and there is an optimal H2O mass fraction existing to enhance the intensity of the turbulent combustion. In the range considered in this paper, its optimal value is 0.15. The initiated location of the reaction appears far away from the bottom wall with the increase of the H2O mass fraction, and the H2O flow vitiation quickens the transition from subsonic to supersonic mode at the exit of the combustor. 相似文献