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成形极限图也称成形极限曲线,常用FLD或FLC表示.成形极限图是判断和评定金属薄板成形性的最为简便和直观的方法,是对板材成形性能的一种定量描述,是解决板材冲压问题的一个非常有效的工具,同时也是对冲压工艺成败性的一种判断曲线.相对于通常使用的基本成形性能指标(σs、σb、δ10)及杯突值而言,成形极限图可以较好地反映材料的极限变形能力,定量衡量钢板冲压成形性能的好坏.对具体冲压零件成形后的应变进行测试和分析,得到零件表面应变分布情况,将应变分布点放在该材料的成形极限图中,有助于科学评估板材对零件的实际成形效果,通过分析零件变形大小与成形极限的关系,可以确定零件冲压成形的危险部位、材料使用是否合理. 相似文献
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平面应变用于评定薄钢板成形性能的研究 总被引:2,自引:0,他引:2
对大量汽车零件进行冲压成形分析,表明平面应变在零件的危险区域中是个重要因素。用两种方法测定了薄钢板的平面应变值,其结果接近,但拉伸试验法较成形极限试验简单。此外还探讨了平面应变在评定薄钢板成形性能方面的实际应用。 相似文献
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冲压成形是金属板材加工异形件的最基本方式。金属材质不同,冲压成形异形件的难易程度不同,主要影响因素是冲压成形性能和冲压成形极限。文章结合铍板材的冲压成形性能和冲压成形极限,对铍板材冲压成形异形件的难易性作了探讨。 相似文献
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面向离散时间非线性动态系统,提出一种基于事件的迭代神经控制框架。主要目标是将迭代自适应评判方法与事件驱动机制结合起来,以解决离散时间非线性系统的近似最优调节问题。首先,构造两个迭代序列并建立一种事件触发的值学习策略。其次,详细给出迭代算法的收敛性分析和新型框架的神经网络实现。这里是在基于事件的迭代环境下实施启发式动态规划技术。此外,通过设计适当的阈值以确定事件驱动方法的触发条件。最后,借助两个仿真实例验证本文控制方案的优越性能,尤其是在通信资源的利用方面。本文的工作有助于构建一类事件驱动机制下的智能控制系统. 相似文献
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煤气混合过程是一个将两种或两种以上的煤气按照一定比例进行混合利用的过程,是一个复杂的工业过程,具有多变量耦合、非线性、难以建立数学模型等特点,应用传统的PID控制方法难以满足工业现场生产的需要。目前,人工智能控制方法为解决这一多变量、强耦合的复杂工业过程提供了强有力的工具。以酒钢400万t选矿厂第五煤气混合加压站作为研究对象,针对其煤气混合过程提出了前馈+PID的混合煤气压力控制、基于模糊控制技术的混合煤气热值控制,并进行了工业应用,通过实际应用效果的分析,证明了所提出的提高智能控制方法的可行性。 相似文献
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针对板形控制系统及智能控制系统的特点,将人工智能控制理论引入KZR轧机板形控制系统中.仿真结果表明该系统具有良好的控制性能,提高了板形控制质量,为板形控制系统的设计提供了一种全新的方法. 相似文献
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Determining the deformation response of geosynthetics under load is important in developing an in-depth understanding of the engineering behavior of these materials. Current strain determination methods employed as part of tensile tests mostly assume that the strain is uniform throughout the specimen and, hence, are incapable of determining local strains. Geosynthetics have occasionally been instrumented with strain gauges and extensometers; however, these direct contact methods have limitations in fully defining strain distributions in a test specimen. Recent technological advancements in image analysis offer great potential for a more accurate and noncontact method of determining strains. An image-based particle tracking method was used to define the strain distribution in various geosynthetics during wide-width tensile testing. The method used a block-based matching algorithm functioning under LABVIEW. The measured gross strain values were compared to those determined from strain gauges and extensometers. The strain values determined by these methods were comparable to the image-based ones, and the absolute value of the difference was less than 10% for the geosynthetics tested. Furthermore, the image-based analysis was effective in also determining the local strains. 相似文献
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Carsten Müller‐Bollenhagen Martina Zimmermann Hans‐Jürgen Christ Xuelan Schröder Bernd Engel André Große‐Wöhrmann Franz‐Theo Suttmeier 《国际钢铁研究》2008,79(10):745-752
Metastable austenitic steels undergo deformation‐induced martensitic transformation which can lead to a distinct increase of fatigue strength at an optimal volume fraction of martensite. This effect was used in the present study to define the local strength behaviour of a structural component part for the very high cycle fatigue (VHCF) regime. The investigation was on a discontinuous two‐stage forming process that consists of U‐O‐forming and rotary draw bending and results in a cross tube of a trailer coupling as exemplary dynamically loaded component. The volume fraction of martensite can be adjusted by means of plastomechanical simulation of the forming process and its parameters as part of the online process control. The formation of martensite shows a strong dependence on forming parameters (e.g. temperature and strain‐rate) and batch variations. These disturbance variables can only be taken into account by a closed‐loop control. Non‐isothermal material models were analysed according to their simulation accuracy of the martensite evolution. For the online control various hierarchical mathematical models were studied with regard to time effort and model error. 相似文献
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