共查询到20条相似文献,搜索用时 156 毫秒
1.
2.
用网格自动应变测试分析系统ASAME测试了11炉批冷轧薄板的成形极限,对实际测量的成形极限与模拟计算的成形极限进行了比较。对冲压的摩托车油箱进行应变分析,根据成形极限图(FLD)确定冲压零件的安全裕度,评价材料的适用性。 相似文献
3.
板材成形性能的评价一般基于成形极限图(FLD).然而,无论是经由理论计算还是实验方法来获得成形极限图依然很困难而且很耗时.提出了一种预测深拉延部分成形极限图的新方法.假设对所有钢板来说其成形极限图的形状几乎都是一样的,而深拉延变形区域内其失效厚度应变也几乎一样,据此可利用体积不变原理推导出主应变和次应变之间的关系.结果表明,根据此方法计算的左半侧(拉深应变区)成形极限图与实验获得的FLD基本一致. 相似文献
4.
5.
成形极限图的测试、应用和可信度分析 总被引:2,自引:0,他引:2
成形极限图通常是通过钢模胀形试验测得,实际测量的成形极限图与ASAME自动应变测试分析系统模拟计算的成形极限曲线吻合较好;应用成形极限图分析冲压零件成形的安全裕度和进行选材预测时,对以平面应变和胀形为主的成形零件具有较高的可信度,而对以深拉延变形为主的成形零件可信度不高。 相似文献
6.
7.
为建立磁脉冲辅助冲压成形(EMAS)工艺的有效性,采用准静态平面应变预拉伸和动态磁脉冲成形相结合的方法对5052-O铝合金板材的准静态/动态平面应变状态复合成形极限进行了试验研究.结果表明:准静态/动态复合加载过程能显著改善该铝合金板材的室温成形性;准静态/动态平面应变复合成形极限比准静态平面应变成形极限有显著提高,相似或者略高于完全磁脉冲平面应变成形性,且随着准静态预应变水平的增加,准静态/动态复合变形成形极限变化不大.预变形的存在不会削弱复合成形过程的极限变形能力. 相似文献
8.
9.
10.
AZ31B镁合金管材热态内压成形性能的研究 总被引:1,自引:0,他引:1
为了研究变形镁合金AZ31B管材的热态内压成形性能,通过单向拉伸测试了不同温度和应变速率下其力学性能的变化,通过胀形实验研究了温度对内高压成形性能的影响,以及相应变形条件下微观组织的变化.实验结果表明:在20~300℃时,AZ31B的屈服强度和抗拉强度随着温度的升高而降低,总伸长率随着温度的升高而提高,均匀伸长率随着温度的升高先增大后减小;当应变速率在0.001~0.1s-1时,屈服强度和抗拉强度随应变速率的增大而升高,总伸长率随着应变速率的增大而减小,均匀伸长率随着应变速率的增大先增加后减小;当温度在20~250℃时,镁合金管材的极限胀形率随温度的升高先增大后减小,在175℃时达到最大值.微观组织观察表明,175℃下不完全动态再结晶和孪晶两种微观组织的出现是使镁合金管材极限胀形率提高的主要原因. 相似文献
11.
对ME20M镁合金板料进行了热拉深成形性能实验与数值模拟.研究表明,ME20M镁板热拉深成形极限高度随实验参数的不同而不同,其塑性成形性能随温度的升高明显改善;数值模拟可以很好地预测不同实验参数下镁合金板料热拉深成形极限的高度.对热拉深成形件传力区部位进行金相实验得知,合理控制热拉深实验参数能保证镁合金塑性成形件微观组织,进而保证成形件质量. 相似文献
12.
《材料与设计》2015
The potential process for mass production of magnesium alloy components in vehicles—warm stamping process was investigated systematically in the present study. For analyzing the forming process, an accurate numerical model describing the unique characteristics of magnesium alloy sheets under warm forming is very essential. Aiming at this, hardening/softening model for 1.5 mm thickness AZ31B magnesium alloy sheet were firstly constructed based on uniaxial tensile tests. Secondly, semispherical drawing was carried out under the selected temperature to generate experimental forming limit curve (FLC) for AZ31B sheet. Then, friction coefficient was identified using a high-temperature tribo-tester. Finally, numerical simulation was implemented and formability of AZ31B sheet warm forming was verified with experiment. The result shows that the formability, thickness distribution and equivalent strain distribution in simulation agreed well with the actual specimens, which thus provided a good data base for describing the unique characteristics of magnesium alloy sheets under warm forming. 相似文献
13.
The forming limit diagram (FLD) is a useful concept for characterizing the formability of sheet metal. In this work, the formability, fracture mode and strain distribution during forming of Ti6Al4V titanium alloy and Al6061-T6 aluminum alloy sheets has been investigated experimentally using a special process of hydroforming deep drawing assisted by floating disc. The selected sheet material has been photo-girded for strain measurements. The effects of process parameters on FLD have been evaluated and simulated using ABAQUS/Standard. Hill-swift and NADDRG theoretical forming limit diagram models are used to specify fracture initiation in the finite element model (FEM) and it is shown that the Hill-swift model gives a better prediction. The simulated results are in good agreement with the experiment. 相似文献
14.
15.
Ndèye Awa Sène Pascale Balland Robert Arrieux Pierre Vacher 《International Journal of Material Forming》2013,6(1):41-48
As a result of an increasing industrial demand for very small parts, this paper proposes an extension of the concept of forming limit diagrams for very thin sheets (thicknesses of 0.1 mm) called micro-forming limit diagrams (MFLD). A specific drawing tool of small size was designed and subsequently achieved in the laboratory. The formability of a rolled and annealed 1050A aluminum sheet (99.5%) was characterized and analyzed. Seeing the size of the specimen and the tool, the spacer is replaced by a central electro-discharged smaller thickness. The micro-forming press was coupled with a system for strain measurements based on image analysis with a correlation method. After experimental tests with 7 different geometries, the strains were determined at the beginning of the necking from the various images. Based on this, three methods of determination of the MFLD were proposed (white pixel emergence, polynomial method and strain profile analysis) and compared. Finally, an experimental deep drawing cylindrical cup test rendered it possible to validate the most accurate method for determining the micro-forming limit diagram. 相似文献
16.
K ANKAMMA D V V SATYANARAYANA G CHANDRAMOHAN REDDY M KOMARAIAH N ESWARA PRASAD 《Sadhana》2011,36(2):223-249
An effort has been made to comprehensively evaluate and rationalize the in-plane anisotropy in tensile properties and the
effect of aging on the nature of deformation (strain hardening behaviour) and formability characteristics, especially the
limit drawing ratio and forming limit diagram. Despite weak crystallographic texture and excellent ductility and high work
hardening exponents, the alloy sheets of C-263 exhibit significant extent of in-plane anisotropy in its tensile properties
and yield loci. The absolute magnitudes of yield stress and the exact nature of anisotropy that can be predicted from the
tensile part of the yield locus need to be employed with caution. This is because when the magnitudes of the yield stresses,
obtained from yield locus are more than 5 times higher as compared to the yield and ultimate tensile strength values and the
nature and degree of in-plane anisotropy under tensile loading matches with that of only the compressive yield stresses of
yield locus. The alloy sheet, due to weak crystallographic texture and relatively high strengths, is found to be far more
suitable for structural applications, rather than for deep drawing applications, which was reflected in low limit drawing
ratio values (1.34 for CR+ST and 1.23 for peak aged conditions). Further, the study conducted reveals that the safer forming
limits in strain space is higher for CR+ST condition; while, the safer forming limits in stress space are higher for peak
aged (CR+ST+1073 K/8 h) condition. Finally, detailed studies are outlined to arrive at suitable microstructural and textural
characteristics that provide significantly enhanced drawability in the Nimonic C-263 alloy sheets. 相似文献
17.
18.
The tensile properties and press formabilities of laminates experimentally produced from mild steel and various aluminium alloy sheets are examined. The tensile properties of the laminates are approximately predictable by the mixture rule of the properties of the individual sheets. The forming limits in deep drawing, as well as stretch forming due to various types of fractures of the laminated composite sheets, cannot be predicted without considering the stress and strain histories of the individual sheets during forming. Furthermore, it is found that the drawability, as well as the stretch formability, is improved by setting the mild steel sheet on the punch side for the case of aluminium alloy sheet with comparatively high ductility, and by sandwiching the aluminium alloy sheet with the mild steel sheets for the case of low ductility. 相似文献
19.
W. Bleck A. Frehn J. Ohlert H.‐M. Sonne G. Steinbeck 《Materialwissenschaft und Werkstofftechnik》2004,35(8):495-504
Influence of temperature and prestraining on the plastic material behaviour of modern sheet steels for autobody applications Within the scope of a common research project of the automotive and steel industry, characteristic values describing the plastical behaviour of 20 sheet steels have been determined. In detail, quasistatic tensile tests at the testing temperatures ‐40 °C, 23 °C and 100 °C were carried out to obtain flow curves for the as delivered materials as well as for steels after a defined prestraining or heat treatment. Additionally, sheet metal testing led to forming limit diagrams and limiting drawing ratios including the working ranges for deep drawing. The results of the tensile tests showed significant differences between steel groups with regard to their strain hardening behaviour, which can be described by the ratio of yield and tensile strength Rp0,2/Rm or the ΘIV‐value, and their temperature sensitivity. Within one steel group, consisting of steels with similar strain hardening behaviour, it might be possible to determine flow curves of one steel in a defined condition in order to calculate the flow curves of other steels with different strength. An advantage would be a lesser number of experimental tests which have to be performed in order to supply reliable input data for numerical material and component modelling. 相似文献
20.
Formability of sheet steel in stamping operation primarily depends on strain hardening exponent (n), average plastic strain ratio (
) and the maximum strain the material can undergo before the onset of localized necking. The formability parameters (n and
) and the forming limit diagrams have been evaluated for a variety of sheet steel products, extensively used for press forming
of components of diverse shapes e.g. extra deep drawing quality auto-body sheets, high strength cold rolled sheets, LPG steel
for gas cylinders, austenitic and ferritic stainless steels, etc. The effect of sulphide shape control on formability of hot
rolled HSLA steel has also been studied. Additionally, the press performance of auto-body sheets and austenitic stainless
steels have been monitored and evaluated at customer’s end for complete information on the formability. 相似文献