【作者】 李翠玉；

【导师】 张义同；

【作者基本信息】 天津大学 ， 固体力学， 2005， 博士

【摘要】 织物变形和屈曲的模拟技术在服装CAD、虚拟服装店、虚拟现实、人物动画、电子游戏等众多领域有着广泛的应用。从20世纪80年代开始,国内外学者对编织物的悬垂和屈曲的数值模拟进行研究,这些研究把编织物看作是正交异性的连续体,用有限元方法进行模拟,取得了一定的进展。同时也发现,模拟的精度与实验相比存在较大的误差,某些屈曲现象很难模拟出来。国内学者张义同等在国家自然科学基金的资助下,建立了编织物的细观本构模型,并基于此模型,对编织物在受到单向拉伸时的屈曲、以及在受简单剪切时的屈曲现象成功地进行了解析分析。与编织物不同,对针织物相关理论的研究很少见到。本文建立了针织物的细观力学本构模型,对针织物的悬垂和屈曲进行了解析分析和数值模拟。同时,也对编织物的悬垂和屈曲用有限元方法进行了数值模拟。具体内容如下:1.建立了针织物的细观力学本构模型。这个本构模型更好地描述了针织物的力学性质,特别是针织物由于其特有的细观针织结构所具有的某些性质。2.基于本文建立的针织物细观本构模型和有限弹性变形的增量理论,分析了针织物片在受到沿纹路方向单向拉伸时的屈曲现象。分析结果表明,针织物片在受到沿纹路方向的单向拉伸时只存在弯曲模态屈曲,这与在实验中观察到的针织物片的屈曲现象是一致的。3.基于本文建立的针织物细观本构模型和有限弹性变形的增量理论,分析了针织物片在受到沿织层方向单向拉伸时的屈曲现象。分析结果表明,针织物片在受到沿织层方向的单向拉伸时不会屈曲,这与实验结果也是相符的。4.进行了针织物的拉伸实验,并得到了相应的弹性模量值。5.基于本文建立的针织物细观本构模型,采用大变形曲壳单元,用有限元方法对针织物的悬垂屈曲进行了数值模拟。有限元模拟结果和实验结果达到了数值上的基本吻合。6.基于已有的编织物细观本构模型,采用大变形曲壳单元,用有限元方法对编织物的悬垂屈曲进行了数值模拟。分析了编织物面内的压缩模量在其屈曲分析中的重要作用。有限元模拟结果和实验结果达到了数值上的基本吻合。更多还原

【Abstract】 The simulating techniques of deformation and buckling of fabric have extensive applications in many fields, such as CAD for garments, virtual clothing stores, virtual reality, computer cartoons, and computer games. Since the eighties of the twentieth century, many researchers have devoted their works on the numerical simulations of the draping and buckling of woven fabric. The woven fabric was modeled as the orthotropic continuum. Based on the models the draping and buckling of woven fabric were numerically simulated. It was found that the simulations did not well agree with the experiment observations, and some buckling deformations can’t even been predicted. Supported by the National Nature Science Foundation of China, the micro-mechanical model for woven fabric was proposed and, based on the model, some buckling phenomena of woven fabric sheet under tension and simple shear were analytically predicted successfully.In contrast with the research on woven fabric, there are little works reported in literature. In this thesis the micro-mechanical constitutive model for knitted fabric is proposed, the analytical and numerical studies of draping and buckling of knitted fabric are carried out, and finally, the buckling of woven fabric is simulated numerically. The works in this thesis are briefly listed below.1. The micro-mechanical constitutive model for knitted fabric is proposed that describes the special mechanical properties due to the micro-knitting structure.2. Based on the micro-constitutive model of knitted fabric and the well-established theory of small deformation superimposed on large deformation, the buckling of knitted fabric sheets under uniaxial tension along wale direction is investigated. It is shown that only the flexural buckling mode is possible, that is in good agreement with the experiment observation.3. Based on the micro-constitutive model of knitted fabric the buckling of knitted fabric sheets under uniaxial tension along course direction is analyzed. It is proved that the knitted fabric sheets don’t buckle, that is also in good agreement with the experiment observation.4. The experiments of knitted fabric subjected tension are carried out, and the elastic moduli is measured.5. Based on the micro-constitutive model of knitted fabric the draping and buckling of knitted fabric sheets are simulated numerically by using the curved shell element for large deformation. The simulated result agrees well with the image of buckled knitted fabric sheets.6. Based on the micro-constitutive model of woven fabric the draping and buckling of woven fabric sheets are simulated numerically by using the curved shell element for large deformation and the finite element method. The important effect of compress moduli on the buckling analysis is analyzed. The simulated result agrees well with the image of buckled woven fabric sheets.更多还原