重庆时时彩骗局|重庆时时彩的规律

折弯板材英文文献和中文翻译

时间:2017-09-19 20:48来源:毕业论文
Air-bending of sheet metal is one of the widely used industrial processes. This single-step air-bending processing is suitable for simple structure pares. However, large parts with complex surfaces could not be bent by the single-step air-be
Air-bending of sheet metal is one of the widely used industrial processes. This single-step
air-bending processing is suitable for simple structure pares. However, large parts with
complex surfaces could not be bent by the single-step air-bending. To solve this problem,
a multi-step incremental air-bending forming could be utilised. Sheet incremental
air-bending forming system with significant flexibility uses the principles of stepped
manufacturing. It transforms the complicated geometry information into a series of
parameters of single-step, and then the plastic deformation is carried out step by step
through the computer numerical controlled movements of the punch and sheet feed to get
the desired part. Just like the traditional stamping, springback is unavoidable in the
incremental air-bending forming. Due to the existence of springback, the precision of
products and subsequent assembly operations were severely affected. How to effectively
control springback has been the key issue to precision forming.13521
  In the past, sheet metal multi-step air-bending processes are dependent on the
designer’s experience and involve trails and errors to obtain the desired result. Trail and
error can involve adjustments made to the machine tools and process control to
compensate for springback by experiment iteration. This practice would consume high
cost, much time as well as labour cost. We note that numerous fundamental studies have
been conducted over the years in an attempt to predict and control springback on
single-step air-bending processes of sheet metal (Kurtaran, 2008; Narayanasamy and
Padmanabhan, 2009; Gardiner, 1957). With the advent of computation technology, sheet
metal bending processes can be analysed prior to experiments using the finite element
method (Heller and Kleiner, 2006; Streppel et al., 2001; Singh et al., 2004). However,
most of these researches are only limited to single-step air-bending forming, relatively 本文来源:http://www.mamitama.com/a/www.ijie.com/

重庆时时彩的规律 www.mamitama.com,脑血管造影可以明确诊断动脉瘤或血管畸形,但是当脑血管造影阴性,特别是在脑内血肿较大时,应考虑破裂的动脉瘤或血管畸形被暂时压迫阻塞而不显影;微小的血管畸形,血管造影也可为假阴性。喉癌(carcinomaoflarynx)是一种比较常见的恶性肿瘤,发病率约占全身肿瘤...喉癌(carcinomaoflarynx)是一种比较常见的恶性肿瘤,发病率约占全身肿瘤的1~5%,在耳鼻喉科领域中仅次于鼻咽癌和鼻腔,鼻窦癌,居第三位。

源自六`维`论^文-网.加7位QQ3249^114 重庆时时彩的规律 www.mamitama.com


little has been devoted to the detailed analysis on the numerical simulation of the
multi-step incremental air-bending forming. Therefore, in order to reduce the number of
practical forming experiments, the authors think that it is of great worth to study
multi-step incremental air-bending forming with finite element simulation method to
obtain the optimised process parameters of large workpiece forming.
     It should be noted that the yield criterion is the key factor influencing the result of the
finite element simulation. As literature (Ming and Li, 1999) mentioned, the Hill’48
anisotropic yield criterion was better able to describe steel sheet material yield behaviour
(Hill, 1984), while Barlat’s 89 anisotropic yield criterion could provide favourable
agreement with the experimental value of aluminum alloy sheet forming (Barlat and
Lian, 1989). Therefore, this study intends to simulate multi-step incremental air-bending
forming process of anisotropic steel sheet with Hill’s quadratic yield criterion.
     In the present paper, the FE simulation is performed by ABAQUS/Explicit and
Standard modules. Plane strain element CPE8R (namely the eight-node biquadratic plane
strain quadrilateral, reduced integration elements), exponent hardening material, Hill’48
anisotropic yield function are applied to the simulation. Then, shape curves and plastic
strain distributions along geometry neutral layer of the simulated workpieces formed with
three different tool parameters are compared with practical CAD data. Finally, a large
workpiece is manufactured with the optimised simulation results. As will be shown
through subsequent manufacturing example of workpiece, finite-element simulation
method offers several advantages, including excellent convergence rate, ease of 折弯板材英文文献和中文翻译:/a/fanyi/20170919/13768.html
------分隔线----------------------------
推荐内容
小说 小说 小说 小说 小说 小说
小说 小说 小说 小说 小说 小说
小说 小说 小说 小说 小说 小说
青海快三连线走势图 北京赛车pk10公式 亚洲博彩 河南十一选五走势图表 双色球56开奖结果
快乐10分走势图云南 吉林时时彩开奖号吗 pk10冠军杀号 江西多乐彩玩法 时时彩走势图看法秘诀