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3D服装CAD技术包括3D人体测量和3D人体数据处理、3D人体计算机建模、3D服装设计与制板、3D裁剪缝合及3D服装虚拟展示等方面的技术。3D服装CAD生成系统不仅涉及数学建模、电脑3D编程、光学、色彩学等,还涉及织物纹理、图案、纤维特性等性能的真实反映,需建立几何模型及相应的物理模型,开发3D服装CAD技术并使之产业化是服装工业步入新一代的高科技产业的必经之路。 相似文献
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关于微分方程建模方法的研究 总被引:1,自引:0,他引:1
骆桦 《纺织高校基础科学学报》1998,11(3):253-256
用微分方程建立模型参加全国大学生数学建模竞赛取得了较好的成绩,研究了微分方程建模方法,提出并解决了建模中的实际问题,指出了模型的求解方法。 相似文献
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针对生物发酵过程模型难以建立的问题,提出了一种非线性系统的建模方法.基于非线性自回归滑动平均(NARMAX)模型,设计了用径向基神经网络取代NARMAX模型中的映射的NN-NARMAX模型,用遗传算法确定NARMAX模型中的延时参数以及神经网络输出滤波的参数.应用该算法建立了啤酒发酵罐温度控制模型,和Elman神经网络对比实验表明,该模型的控制精度较高,能够较好地解决生物发酵过程控制温度建模的问题. 相似文献
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为了探究双轴肩搅拌摩擦焊接工艺参数对焊接过程中产热的影响,实现工艺优化,在实际焊接过程中,课题组将焊接工艺中的焊接速度和搅拌针旋转速度引入模型,并综合考虑上、下轴肩和搅拌针在焊接稳定阶段与工件不同的接触模型,分析搅拌针的受力状况,建立了搅拌针受力模型;基于受力模型建立了轴肩和搅拌针的产热模型,对该模型进行数值模拟;通过数值模拟的数据与实测数据对比分析,修改工艺参数中的搅拌针旋转速度,分析工艺参数与产热的关系。结果表明:建立的双轴肩搅拌摩擦焊产热模型可以准确预测实际焊接过程中产生的温度;此外,在一定范围内增加搅拌针旋转速度,焊接产生的温度也随之增加并且在焊缝中心温度呈哑铃状分布。 相似文献
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文章通过对盘式干燥器主要承压部件──加热盘的受力分析,建立了加热盘上、下板的力学模型,并推出了板的挠曲线方程式和应力计算公式,由此得到了板厚度的计算方法。 相似文献
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通过WeldCalc2.1应用碳当量法分析在相同线能量下不同板厚的预热温度,以及对各个参数间的选择关系进行研究,表明相同板厚条件下焊接线能量越高则预热温度要求越低,不同焊接线能量下不同板厚的预热温度趋势基本一致,随着厚度的增加则预热温度要求相应的增加。焊接工作点位于T8/5的临界线与最低预热温度与最高层间温度之间能保证焊接质量,并通过试验以及与以往研究结果进行对比分析,验证了研究结果的正确性。 相似文献
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徐宏 《食品与生物技术学报》1985,4(3)
本文根据求解平面梁结构作横向振动的有限元公式,推得了传递矩阵的表达式,此表达式与常用的根据材料力学弯曲变形所得公式相同。从而证明了两种方法在求解链式结构动力问题中是等效的并据此对传递矩阵法进行了修正,使该方法不仅可以考虑剪切变形和弹性支承的影响,而且可以考虑分布质量、分布回转效应及动力修正的影响。 相似文献
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我们编制了用于肋壳结构分析的有限元程序。本文对梁单元的刚度矩阵和载荷向量进行了变换,以实现各个梁单元的节点位移同与其连接的壳单元的节点位移的协调。采用波前法解方程组,因此可用微机分析中等规模的结构。应用该程序对无锡少年宫天文台的肋壳结构进行了计算。 相似文献
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以邵尔A硬度70度的惯性往复振动机械橡胶支承弹簧为研究对象,采用2参数Mooney-Rivlin橡胶弹性理论模型,根据橡胶硬度与材料常数C1、C2的关系确定C1、C2之和,利用ANSYS软件的plane182平面单元建立橡胶弹簧的轴对称有限元模型,分别取C2/C1=0、0.02和0.2,对模型进行不同轴向静载荷的非线性有限元静力分析,得到弹簧轴向变形与载荷的非线性关系,通过与橡胶弹簧实验测试结果的对比,确定了C2/C1的合理取值,并验证了上述有限元分析方法的可行性和正确性。为复杂结构橡胶弹簧的设计、刚度特性分析提供了一种有效的方法。 相似文献
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目的:提高码垛机器人的动态性能并降低能耗。方法:通过静、动力学分析确定以质量最小、最大位移最小、第一阶固有频率最大、最大应力最小为优化目标,以结构参数为设计变量,利用Box-Behnken和RSM方法建立目标函数的近似模型;提出一种基于有限元分析结果的层次分析法(AHP-FEA)用于权重系数的分配,并以综合目标函数作为评价指标,利用NSGA-Ⅱ算法求解;基于AHP-FEA方法获得腰部转台的优化模型,并与初始模型进行对比。结果:在保证结构强度、刚度和振动稳定性的情况下,质量减轻了9.6%。结论:与常见的平均分配法和经验赋权法相比,采用AHP-FEA权重系数下的优化综合目标函数值最小,其综合优化效果更优。 相似文献
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建立了MD-1200YJ型码垛机器人大臂的有限元模型,通过模态试验验证有限元模型的准确性;通过考虑动力学因素的静力学分析、约束模态分析、振动响应试验、频率响应分析,确定以质量最小、第一和二阶固有频率最大、最大位移最小、最大应力最小为优化目标,以结构参数为设计变量,以设计变量的边界条件为约束条件,利用Box-Behnken和RSM方法建立目标函数的近似模型,并利用NSGA-Ⅱ算法求得最优解。结果表明,前两阶固有频率提高,结构刚度和振动稳定性提高,降低振动对零部件疲劳损害影响以及最大应力和位移均在允许范围内的情况下,质量减轻了11.3%,验证了该轻量化设计方法的有效性。 相似文献
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本文介绍了有限单元法的基本原理,分析了影响有限元计算精度的单元划分质量指标,并提出有关总刚方程解法及提高有限元计算精度的建议。 相似文献
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Bart M. Nicolaï Jose A. EgeaNico Scheerlinck Julio R. BangaAshim K. Datta 《Journal of food engineering》2011,103(1):38-46
In this article we have used four different global optimisation algorithms for interval finite element analysis of (non)linear heat conduction problems: (i) sequential quadratic programming (SQP), (ii) a scatter search method (SSm), (iii) the vertex algorithm, and (iv) the response surface method (RSM). Their performance was compared based on a thermal sterilisation problem and a food freezing problem. The vertex method proved to be by far the fastest method but is only effective if the solution is a monotonic function of the uncertain parameters. The RSM was also fast albeit much less than the vertex method. Both SQP and SSm were considerably slower than the former methods; SQP did not converge to the real solution in the food freezing test problem. The interval finite element method was used as a building block for a fuzzy finite element analysis based on the α-cuts method. The RSM fuzzy finite element method was identified as the fastest algorithm among all the tested methods. It was shown that uncertain parameters may cause large uncertainties in the process variables. The algorithms can be used to obtain more realistic modelling of food processes that often have significant uncertainty in the model parameters. 相似文献
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Min Hu Anders Olsson Marie Johansson Jan Oscarsson 《Holz als Roh- und Werkstoff》2018,76(6):1605-1621
Strength of structural timber depends to a high degree on the occurrence of knots and on the local fibre deviation around such defects. Knowledge of local fibre orientation, obtained by laser scanning, has been utilized in a previously developed machine strength grading method, but rather crude assumptions regarding the fibre orientation in the interior of boards and a mechanical model that does not capture the full compliance of knotty sections were adopted. The purpose of the present study was to suggest and verify a model with which local bending stiffness can be predicted with high accuracy. This study included development of a model of fibre orientation in the interior of boards, and application of a three-dimensional finite element model that is able to capture the compliance of the board. Verification included bending of boards in the laboratory and application of digital image correlation to obtain strain fields comparable to those obtained by finite element simulation. Results presented comprise strain fields of boards subjected to bending and calculated bending stiffness profiles along boards. Comparisons of results indicated that the model suggested here was sufficient to capture the variation of local bending stiffness along boards with very high accuracy. 相似文献
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This paper reports the compressive behaviors of biaxial warp-knitted (BWK) composite material under compression with various strain rates. The compression stress–strain curves and the failure modes along three orthogonal directions were obtained from split Hopkinson pressure bar (SHPB) apparatus. A finite element analysis (FEA) model based on a simplified model of BWK composite was also carried out to verify the experimental results. In the simplified model, an equivalence resin (ER) combined tricot yarns with resin, and the stiffness matrix was derived from the mechanical parameters of the tricot yarns and the resin. A good agreement between experimental and FEA demonstrates that the simplified method is applicable of modeling the high strain-rate behaviors. By comparing the experimental damage morphologies with the damage development and morphologies observed from the model, it was found that the FEA model offers a better understanding to the compression damage mechanisms. The model can also be extended to design the impact performance of the BWK composite with high efficiency. 相似文献