【作者】 程涵；

【导师】 史治宇；

【作者基本信息】 南京航空航天大学 ， 工程力学， 2013， 博士

【摘要】 随着材料科学的迅猛发展，柔性充气展开织物的力学性能大大提高，并凭借其折叠后体积小、重量轻、工作效率高的特点在航空、航天、兵器等领域中得到了广泛的应用。织物展开过程在表象上原理简单，但实质上却是一个典型的流固耦合强非线性过程，往往是整个织物工作过程中最薄弱和最危险的环节，展开失效所带来的后果往往很严重。本文主要对柔性织物折叠建模方法进行研究，并对折叠织物充气展开过程开展了流固耦合方法的数值模拟研究，研究结果和一些试验结果进行了对比。折叠建模是研究充气展开必须首要解决的关键问题，现有方法很难建立复杂折叠模型，本文提出了逆向折叠建模方法及实现逆向折叠建模的两种方法：基于动力学计算的逆向折叠建模和基于约束变形的逆向折叠建模。本文分别以这两种方法对外形复杂，折叠方式特殊的某气囊进行了折叠建模，通过充气展开模拟验证了本文提出的新型建模方法的可行性和准确性。折叠建模往往会产生误差，基于几何原理的传统技术对误差的修正效果有限，本文提出了基于有限元技术的初始矩阵修正方法。通过这种修正方法，本文首次实现了经纬向的降落伞折叠，同样该修正方法还被用于其他折叠模型的修正上。通过对比计算验证了该修正方法的可行性和准确性。在完成柔性织物折叠建模和修正研究的基础上，本文建立了基于非线性有限元理论的任意拉格朗日欧拉（ALE）流固耦合模型。开展了如下工作：（1）在无限质量情况下，对降落伞进行了充气过程的三维流固耦合研究，获得了丰富的伞衣结构、流场结果信息。通过对数值结果分析和试验对比，总结了无限质量情况下开伞规律，并提出了在特定情况下，充气过程中会出现“瓶颈”现象；（2）在有限质量情况下，对美国C9伞进行了充气过程的流固耦合研究，不仅得到了伞衣结构和流场结果信息，还获得了该型伞的气动减速特性，计算结果和塔架投放试验和空投试验进行了比较，总结了有限质量情况下降落伞从充气到稳降过程的变化规律；（3）针对不同的透气性织物材料，开展了充气过程的流固耦合模拟，研究了织物透气性对减速特性的影响。最后本文开展了绕透气伞衣的CFD流场计算，本文提出了采用多孔介质域代替传统固壁面伞衣边界的处理方法，可以大大提高计算准确性。本文的研究结果对了解柔性充气展开织物，尤其是降落伞的工作机理，提高分析水平有重要意义。更多还原

【Abstract】 With the rapid development of materials science, the mechanical property of flexible inflatablefabric is greatly improved. And the flexible inflatable fabric has been widely used in aviation,aerospace, weapons and other fields with advantages like small folded volume, light weight and highefficiency. The fabric deployment process seems to be simple in principle, but actually it is a typicalFluid-Structure Interaction and nonlinear process. The deployment is the weakest and most dangerouspart in the entire work process of fabric, and the consequence of deployment failure is often severe.This paper mainly focuses on the flexible fabric folded modeling method, and the Fluid-StructureInteraction numerical simulation of folded fabric deployment process is conducted. The numericalresults are compared with tests results.Folding modeling is the first problem of inflatable fabric research. Complex folding model isdifficult to be created through current methods. Therefore two methods of reverse folding modelingmethods and realization of this modeling are proposed as: reverse folding modeling based ondynamics calculation and reverse folding modeling based on constraint deformation. These twomethods are utilized for folding modeling an airbag folded in a special way with complex shape, andthe inflation simulation is conducted to verify the feasibility and accuracy of this new modelingmethod. Folding modeling often cause errors, and the effect of traditional error correction technologybased on geometric principles is limited. An initial metric correction method based on finite elementtechnology is proposed. In this paper this correction method is utilized to achieve parachute folding inlatitude and longitude directions, and this method is also suitable for the correction of other foldingmodels. The feasibility and accuracy of this correction method is verified by comparison calculation.Based on the flexible fabric folding modeling and correction research, the arbitrary LagrangianEulerian (ALE) fluid-structure interaction model based on nonlinear finite element theory isestablished. The following work is conducted.(1) Under condition of infinite mass thethree-dimensional FSI research of parachute inflation process is conducted and abundant canopystructure and flow field information is obtained. By comparing the numerical results and test results,the parachute open laws under infinite mass condition are summed, and in particular case the"bottleneck" phenomenon emerges in inflation process.(2) Under condition of finite mass the canopystructure, flow field information and deceleration characteristics of U.S. C9parachute are obtainedthough FSI research in inflation process. By comparing the calculation results, tower test and airdrop test results, the parachute change laws of inflation to terminate descent process under finite masscondition are summed.(3) FSI simulations of inflation process are conducted for fabric with differentporosities, and the influence of fabric permeability in deceleration characteristics is studied.At last the CFD calculation of flow field around a porous canopy is conducted, the method ofreplacing traditional canopy wall boundary with porous domain greatly improve the calculationaccuracy.The study results are important to improve analysis level of understanding flexible inflatablefabric, especially parachute working mechanism.更多还原