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针对压力容器承载性能,基于经典层合板刚度等效理论,提出了一种可以考虑复合材料缠绕层单层厚度的压力容器承载性能分析方法;与实际铺层有限元模型进行对比,验证了分析方法的有效性;对不同单层厚度的复合材料进行了单向拉伸试验,获得材料强度与单层厚度的关系;分析了超薄单层复合材料缠绕压力容器的应力分布、失效系数分布及失效压力。结果表明,超薄单层复合材料缠绕压力容器的应力和损伤分布更为均匀,失效内压较常规单层厚度复合材料可提高54.5%。该研究成果可为超薄单层复合材料缠绕压力容器的结构设计提供可靠的理论参考。 相似文献
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基于超声导波的压力容器健康监测研究的第三部分,主要考察所研究的健康监测技术在纤维缠绕压力容器损伤定位中的应用。开展纤维缠绕压力容器的疲劳和打压爆破试验,设计远程在线监测系统以实时获取不同工况中纤维缠绕压力容器损伤定位结果。在打压和疲劳试验过程中,采集压力容器在不同状态中的导波信号,并分别测量金属内胆和复合材料层的应变变化,建立导波幅值与压力容器疲劳状态和受压状态之间的关联。开展纤维缠绕压力容器在打压爆破过程中的损伤定位,研究疲劳对损伤定位精度的影响规律。结果表明,在疲劳试验中,应变片能够连续记录并反映压力容器的应变状态,但疲劳周期随残余应变的变化趋势不明显,而导波幅值随疲劳周次的增加而线性下降;对经过5 700周疲劳和未经过疲劳的纤维缠绕压力容器,导波幅值随着其内部压力的增加而线性下降,而应变值随着压力的增加线性增加,二者的对应关系可用于判定纤维缠绕压力容器的受压状态;利用所研发的在线监测系统可以远程获取纤维缠绕压力容器损伤位置信息,5700周的疲劳在很大程度上影响定位精度,而未经疲劳试验的压力容器的损伤定位误差较小。 相似文献
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天然气汽车复合材料气瓶的优化设计 总被引:3,自引:0,他引:3
以网格理论为基础 ,讨论了纤维缠绕车用气瓶在内压作用下的优化设计 ,对于等强度复合材料气瓶 ,以层厚为设计变量 ,最小体积质量比为目标函数 ,对不同缠绕角的情况利用序列二次规划算法进行优化设计 相似文献
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创造性地将"通用双公式"模型嵌入到纤维缠绕层网格理论中,解决了因传统网格理论无法准确模拟纤维纱片在高纬度球壳处的重叠现象而带来的纤维层结构设计安全裕度大、结构效率低的问题。基于新方法理论,以球形复合材料气瓶为例,分别从外形尺寸、纤维层重量和强度三个方面验证了新设计方法的准确性和先进性,并采用C#语言开发了一套球形复合材料压力容器(COPV)纤维缠绕层结构设计软件,以提高设计效率,普及新设计方法。 相似文献
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超高压水射流作用下岩石损伤破碎机理 总被引:12,自引:0,他引:12
由于水射流的高紊动与岩石材料的复杂性,水射流作用下岩石破坏机理的研究一直都是难点问题。运用全解耦流固耦合理论,建立超高压水射流冲击岩石介质的数值分析模型,射流采用标准k-ε模型和控制体积法,岩石采用线弹性和有限元法,计算分析淹没条件下岩石介质在水射流冲击作用下内部的应力分布规律。其次,根据岩石介质内部应力分布特征,基于岩石微元强度遵循Weibull分布的概率理论,将Mohr-Coulomb破坏准则作为随机分布变量,建立岩石损伤变量演化方程和连续损伤统计本构模型及用量纲一破坏系数来表征岩石破坏的准则。再次,按建立的流固耦合分析模型、岩石损伤模型和破坏准则,运用分阶段法对水射流的破岩过程进行了数值分析。最后,运用扫描电镜对水射流切割岩石断口形貌进行观测试验,分析岩石在超高压射流作用下微观破坏机制,主要有穿晶断裂和剪切错动两种形式,进一步验证数值模拟分析的结果,建立起水射流破岩过程中岩石微观破坏机制和宏观断裂分析的桥梁。 相似文献
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M. L. Alves P. Santana N. Fernandes P. A. F. Martins 《The International Journal of Advanced Manufacturing Technology》2013,67(9-12):2671-2680
This paper presents a new manufacturing process for producing metallic liners for composite overwrapped pressure vessels (COPV’s) that are commonly utilized in spacecraft. The process combines an innovative tube-forming operation, which is capable of shaping commercial tubes into seamless metallic liners in a single stroke of a press, with a sequence of post-forming operations comprising machining, joining by crimping and welding, and gas tightness testing by means of non-destructive examination. The presentation focuses on the manufacturing process as a whole, but tube-forming in particular, and was written with the objective of providing details of the deformation mechanics, formability limits and tooling system of the tube-forming operation. Different types of COPV’s liners with 120 mm diameter are included in the presentation to illustrate the effectiveness and flexibility of the tube-forming operation in meeting the specific requirements of aerospace applications concerning storage capacity and available shapes. The process running under steady-state production conditions is expected to reduce the overall production costs of COPV’s by roughly one third. 相似文献
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I. V. Sergeichev F. K. Antonov A. A. Safonov A. E. Ushakov 《Journal of Machinery Manufacture and Reliability》2013,42(1):29-35
A methodology of computing the damageability of composite materials at low-speed impact is suggested. The methodology is based on applying a fracture criterion of the monolayer and following computation of material damageability taking the interaction of different damage evolution mechanisms into account. This approach allows us to obtain the distribution of damageability parameters in the surface of the monolayer and the width of material at an arbitrary moment of time until complete destruction of the construction component, computing the degradation of elastic properties, and the position and sizes of delamination regions after the impact. Applying this methodology for estimating residual strength permits the avoidance of excessive conservatism of the projected strength of construction components from composite materials which have incurred impact damage. 相似文献
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预测承受随机载荷结构件的疲劳寿命是一个复杂的问题,应用Miner线性损伤准则经常会得出偏于冒险的寿命预测。非线性累积损伤理论考虑了加载顺序对疲劳寿命的影响,精度更高,但计算繁琐,且未能用于频域寿命计算。文中给出了一种基于非线性累积损伤的随机振动疲劳寿命分析方法,该方法将频域疲劳寿命的预估结果平分为若干段,考虑顺序效应对每一段结果进行修正并叠加,得到修正的振动疲劳寿命结果,通过简单试验件试验验证了该方法的准确性,对于某加筋板结构在动力学准确建模、多轴应力等效的基础上进行寿命估算,结果证明了方法的有效性和工程可用性。 相似文献
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Chang-Min Suh Sung-Ho Kim Sang-Yeob Oh 《Journal of Mechanical Science and Technology》2005,19(7):1424-1431
In this study, head injury by impact force was evaluated by numerical analysis with 3-dimensional finite element (FE) model.
Brain deformation by frontal head impact was analyzed to evaluate traumatic brain injury (TBI). The variations of head acceleration
and intra-cranial pressure (ICP) during the impact were analyzed. Relative displacement between the skull and the brain due
to head impact was investigated from this simulation. In addition, pathological severity was evaluated according to head injury
criterion (HIC) from simulation with FE model. The analytic result of brain damage was accorded with that of the cadaver test
performed by Nahum et al. (1977) and many medical reports. The main emphasis of this study is that our FE model was valid
to simulate the traumatic brain injury by head impact and the variation of the HIC value was evaluated according to various
impact conditions using the FE model. 相似文献
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Bin Jiang Tiantian He Yunpeng Gu Qilong Wang Guanglei Cao 《The International Journal of Advanced Manufacturing Technology》2017,92(1-4):139-150
Under the influence of a high-speed, interrupted-cutting impact load, a great difference is existed among the internal load propagation of a milling cutter. Furthermore, the cutter damage caused by partial particle severe vibration has restricted the improvement of a high-speed milling energy efficiency; thus, the essence of wave dynamics damage in milling cutter remains has yet to be revealed. In this paper, through the relation between the systematic whole vibration and the particle motion, the dynamic response of milling cutter’s particle to cutting force load can be solved by the particle motion differential equation which is constructed with a one-dimensional string dynamic system. A combination of Newton’s second law and the constitutive equation of milling cutter material establishes the wave dynamics equation of milling cutter components. An approach for solving the wave front position and wave velocity of milling cutter’s stress wave is proposed, and the propagation path of transient cutting force to the milling cutter is communicated. The attenuation model of stress wave reflection is established to provide a method for revealing the stress wave transmission and distribution in milling cutter. The constitutive relation of milling cutter components under the impact load is obtained by split Hopkinson pressure bar experiment. A force connection method is adopted to make the trans-scale correlation analysis between continuum medium mechanics and molecular dynamics, thereby revealing the wave dynamics damage characteristics of a high-speed milling cutter. The results show that the potential damage position and types of milling cutter can be distinguished by the above method. 相似文献
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块煤破碎是获得小粒度煤的主要途径,而冲击破碎是目前广泛使用的块煤破碎方法。用裂纹扩展理论对冲击载荷作用下块煤的断裂破碎行为进行分析,得到块煤内部由应力波导致的裂纹扩展速度和瞬时裂纹长度的函数表示,给出块煤在冲击载荷作用下的断裂破碎准则。选择不同粒度的块煤进行冲击实验,实验结果表明断裂破碎准则可有效判别冲击载荷作用下块煤的断裂破碎情况,可作为冲击破碎机械初步选型的依据。 相似文献
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This paper investigates the relationship between the stability contour determined from the nonlinear simulation and that from the linear theory. The nonlinear bearing forces are directly obtained from the bearing pressure distribution which is solved from the Reynolds equation at each journal position. It is found that the critical speeds in the case of nonlinear bearing forces are the same as those predicted by the linear theory, although the whirl loci under large dynamic excitations are significantly different from those arising from the linear bearing forces. Typical whirling trajectories under impact excitation, position perturbation and synchronous unbalance excitations are simulated and presented to explain the stable, critical and unstable phenomena. The whirl displacement signals are also transformed to the frequency domain, and their whirling frequencies are analyzed according to their frequency characteristics. 相似文献
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The dynamic response and damage of laminated composite cylindrical shell subjected to impact load is numerically investigated using the finite element method. A nine-node isoparametric quadrilateral element based on Sander's shell theory is developed, in which the transverse shear deformation is considered. A semi-empirical contact law that accounts for the permanent indentation is incorporated into the finite element program to evaluate the contact force. The Newmark time ingegration algorithm is used for solving the time dependent equations of the shell and the impactor. The Tsai-Wu failure criterion is used to estimate the failure of the laminated shell. Numerical results, including the contact force history, interlaminate damage zone, and failure indices in the shell are presented. Effects of curvature, impact velocity and mass of impactor on the composite shell behaviors are discussed. 相似文献