共查询到20条相似文献,搜索用时 46 毫秒
1.
2.
3.
4.
5.
6.
在分析新型多位气缸运动过程的基础上,应用热力学和空气动力学的基本理论,对新型多位气缸的每一个行程都建立了动态特性数学模型,采用四阶龙格一库塔法对各腔压力变化、活塞位移和运动速度进行了数字仿真。这对了解该新型多位气缸的性能和实际应用提供了重要依据。 相似文献
7.
多级液压缸换级时的级间缓冲性能会对液压系统工作的平稳性及安全性产生影响。以某三级液压缸为例,采用基于动网格及UDF(用户自定义函数)的三维非稳态计算流体力学方法,并计入活塞与缸筒的摩擦力,对收回阶段的液压油流动及活塞运动特性进行计算,分析液压缸的缓冲和换级性能。结果表明:采用圆柱形缝隙节流效果明显,但单个活塞收回时间较长,存在两级活塞同时运动的情况;换级时会产生较大的压力及加速度突变,导致系统产生液压冲击和振动。模拟结果能够为多级液压缸缓冲结构的优化设计提供参考。 相似文献
8.
9.
为了进一步提高水力喷砂射孔技术的射流压力,摆脱传统的地面增压方式因压力传输困难、能耗高等原因对深层地层岩石压裂难的困境,基于实际射孔工艺要求,设计了井下水力增压器。根据井下水力增压器的结构和工作原理,考虑活塞与活塞筒之间的泄漏层对增压效果的影响,建立了增压缸流体域模型,利用动网格技术对增压缸的增压特性进行数值模拟研究。研究结果表明:增压过程中,增压腔压力和流体出射速度均随时间先增大后逐渐呈现出高频周期性波动的规律;增压腔压力和流体出射速度随输入压力和低压腔与增压腔流体的有效作用面积比的增大而增大,且增压腔压力近似等于输入压力和有效作用面积比的乘积;泄漏层厚度对增压腔压力和流体出射速度的波动性影响很大。该研究结果为后期增压器结构设计和参数优选提供了参考。 相似文献
10.
针对轴流式止回阀的止回性能,通过动网格数值试验的方法,采用正交试验设计和极差分析,研究缓冲结构的活塞直径、活塞行程、阻尼孔直径3个结构参数对阀瓣止回性能的影响。分析3个结构参数对止回性能的〖JP2〗权重影响;以阀瓣的完全闭合时间及止回过程中的最大液动力为目标进行多目标优化设计,在保证瞬态液动力尽可能小的情况下减少阀瓣的闭合时间,实现“快关缓闭”,提升阀门的稳定性。结果表明:笛形缓冲结构在0.035 2 s时,由于通孔面积变化导致缓冲阻尼发生突变,使得阀瓣闭合过程中发生震颤,而改进后的缓冲结构具有恒定的阻尼,提升了阀瓣运动的稳定性;通过对3个结构参数的正交试验结果进行极差分析可知,3个结构参数对于阀瓣闭合时间的影响程度排序为:活塞直径(0.021 8)>缓冲行程(0.017 8)>阻尼孔直径(0.013 5),对于最大液动力的影响程度排序为:缓冲行程(204 107)>活塞直径(140 362)>阻尼孔直径(140 086);缩短阀门的止回时间与减小阀芯振动是两个相悖的目标,不存在唯一的最优结构参数,应根据实际工况选取适当的优化结果。 相似文献
11.
12.
生产调度问题在实际应用中更多地表现为动态调度,在分析调度问题的三个动态因素:加工机床集、加工任务集和时间的基础上,并结合车间实际生产情况,对时间的动态变化这个影响动态调度最基本的因素进行了研究。提出了动态工作日制的动态实现策略和实现的关键的算法,为动态日制的离散实现提供了一个具体应用的方案,最后演示了一个对动态工作日制的管理及其实现的示例,证明了该方案实际应用的可行性。 相似文献
13.
14.
Ya. S. Shvartsbart 《Metal Science and Heat Treatment》1971,13(3):244-245
15.
A multiple view binocular stereoscopic X-ray imaging technique developed as a part of a feasibility study for a security screening application is presented. The experimental system utilises a single X-ray source and a multiple view line-scan camera incorporating an X-ray image intensifier. This set up is used to simulate coplanar configurations of discrete linear X-ray detector arrays. A number of perspective images (typically 6–16) are produced during a single linear translation of the object under inspection. A sequential display of the images produces linear motion parallax in the display. Further work enabled motion parallax to be combined with binocular parallax [NDT&E Int 29 (1996) 27] to produce dynamic binocular stereoscopic images. The perspective images may also be used for the extraction of three-dimensional coordinate information. The results produced by an experimental system are presented together with a theoretical discussion. 相似文献
16.
Piezoelectric dynamometer are generally used for force measuring. Delivered signals are distorted due to their self dynamic behaviour. Their dynamic characteristics are identified under normal machining operation. The proposed method is based on the interrupted cutting of a specially designed workpiece that provides a strong broadband excitation. The three components of the exciting force and the acceleration of the gravity centre of the dynamometer cover plate are measured simultaneously. Although the input acceleration components are correlated in the frequency bandwidth of interest, a method is presented to determine the nine terms of the dynamometer transfer matrix from only one cutting experiment. Series of different pulse excitations are carried out to validate the proposed method. Then, the determined transfer matrix is used for dynamic cutting force compensation under some milling operations. 相似文献
17.
The dependence of the stability of a spiral domain in an ac magnetic field on the allowable deformations of the domain shape has been investigated within the phenomenological model. The allowable deformations of the domain are characterized by some set of free parameters from the total number of parameters determining the domain shape. It has been shown that, in this model, the possible scenarios of the existence and disappearance of the spiral domain, some of which are implemented in experiments, can be established. Factors that determine the life span of the spiral domain have also been established within this model. 相似文献
18.
19.