考虑自紧工艺的复合材料压力容器金属内衬断裂分析

发布时间：2018-04-27 20:24

本文选题：复合材料 + 压力容器　；参考：《大连理工大学》2012年硕士论文

【摘要】：纤维缠绕压力容器以其高比强度、高比模量、重量轻以及可设计性等优点迅速替代纯金属气瓶在航天系统中取得广泛应用,其失效破坏也成为航天工程界十分关注的问题。和力学性能较好的纤维相比,通常在工作压力下处于塑性状态的金属内衬是失效研究的重点,而破坏前先泄露又是其常见的失效模式。纤维缠绕压力容器在服役过程中需要多次充放压力,使内衬经历塑性循环,从而导致无损检测漏掉的裂纹发生疲劳扩展,最终造成裂纹穿透、气体泄漏。这就使得纤维缠绕压力容器金属内衬中裂纹的研究变的非常重要。利用有限元软件的子模型技术,本文在ANSYS上建立了包含裂纹的圆柱形气瓶的有限元模型,在考虑内衬塑性的基础上使用区域积分法计算了裂纹前缘的J积分值。内衬材料为铝合金,采用双线性硬化曲线模拟,考虑Bauschinger效应的影响。通过J积分值的比较,首先讨论了是否施加自紧工艺及不同大小的自紧压力对裂纹尖端场强度的影响,结果发现气瓶经过自紧之后内衬中裂纹前缘的J积分值比没有自紧处理的要大,并且随着自紧压力的提高J积分呈增大趋势。由此可见,自紧工艺增加了内衬裂纹开裂的可能性。其次,通过直筒段中间位置与过渡段位置圆裂纹的裂纹尖端场强度的比较,发现中间位置的裂纹比较危险。最后,研究了复合材料层和内衬不同厚度、不同缠绕方式对裂纹尖端场强度的约束效应,结果显示纤维层和内衬厚度越厚,对内衬的约束越大,内衬裂纹的J积分值越小,且随着裂纹尺寸的增大约束效应越显著。缠绕方式对比的结果表明,交错缠绕对内衬的约束要大一点。本文的研究成果将对包含裂纹的复合材料压力容器的安全度评估具有参考价值。
[Abstract]:The filament wound pressure vessel, with its advantages of high specific strength, high specific modulus, light weight, and design, can quickly replace the pure metal cylinder in the space system, and its failure damage has become a concern in the space engineering field. Compared with the fiber with better mechanical properties, it is usually in the plastic state under the working pressure. Metal lining is the focus of failure research, and the leakage before the failure is a common failure mode. In the course of service, the filament wound pressure vessel needs to be filled with pressure many times to make the lining undergo plastic circulation, which leads to the fatigue crack growth of the cracks which are missing from the nondestructive testing, and the final cause of the crack penetration and gas leakage. The study of cracks in metal lining of pressure vessels becomes very important.
Using the submodel technique of the finite element software, the finite element model of a cylindrical cylinder containing cracks is built on ANSYS. The J integral value of the front edge of the crack is calculated by using the region integral method on the basis of the plastic lining of the lining. The lining material is aluminum alloy, and the bilinear hardened curve is used to simulate the effect of the Bauschinger effect. After the comparison of J integral values, it is first discussed whether the effect of self tightening process and the self tightening pressure of different sizes on the field strength of the crack tip is discussed. It is found that the J integral value of the crack front in the inner lining of the cylinder is larger than that without self tightening after the self tightening of the cylinder, and the J integral is increasing with the increase of the self tightening force. The tight process increases the possibility of crack cracking of the inner lining. Secondly, through the comparison of the crack tip field strength between the middle position of the cylinder and the circular crack at the transition section, it is found that the cracks in the middle position are more dangerous. Finally, the binding effect of the different thickness of the composite layer and the inner lining and the different wrapping methods on the field strength of the crack tip is studied. It shows that the thicker the fiber layer and lining, the greater the constraint to the inner lining, the smaller the J integral value of the inner lining cracks, and the more significant the constraint effect is with the increase of the crack size. The result of the intertwining way shows that the interlace winding is more constrained by the inner lining.
The research results in this paper will be of reference value for the safety assessment of composite pressure vessels containing cracks.

【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH49

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