Effect of process parameters on springback behaviour during air bending of electrogalvanised steel sheet

This work aims to study the springback behaviour of electrogalvanised (EG) steel sheets during the air bending process. Experiments have been conducted to analyse the influence of various parameters such as coating thickness, orientation of the sheet, punch radius, die radius, die opening, punch velocity, and punch travel on springback behaviour. It is established that the springback increases with increasing coating thickness, punch radius, punch travel, die radius, die opening, and punch velocity. The 90° orientation exhibits higher springback than 0° orientation.     

带凸缘圆筒件成形数值模拟

拉深成形中凸、凹模圆角半径一直都是成形的关键,严重影响成形的质量。以板料成形理论和abaqus软件为基础,探讨带凸缘圆筒件拉深成形过程中凸、凹模圆角半径的影响。结果表明：拉深成形过程中,板料最大应力主要集中在凸、凹模圆角半径处;在一定范围内拉深时采用较大的圆角半径,整形以后侧壁的厚度也较大;但凸、凹模圆角半径处的壁厚变化则刚好相反,随着首次拉深圆角半径的增大,壁厚逐渐变薄,甚至出现破裂和折叠;运用有限元数值模拟能很好地预测其成形缺陷,并可对计算参数进行优化。     

弹性模具上板料大变形冲压的力学建模

A semi-analytical method was proposed to solve the mechanics problem of stamping a sheet on elastic die.The sheet was divided into four parts according to its deformation and contact with the punch and elastic die.Analytical solutions were derived individually for each part by using elastic large deflection and plastic large deformation.Solutions were found out with MATLAB by developing a numerical algorithm.Interface forces were obtained by iteration under the compatibility conditions between the neighboring parts of the sheet.Computation shows the method is efficient.     

碳纤维薄板粘贴长度对混凝土应力场的影响

对碳纤维薄板增强混凝土三点弯曲缺口梁为研究对象，采用有限元方法分析了不同粘贴长度的碳纤维薄板对混凝土的切口尖端应力场及界面处的应力场的影响。结果表明，合适的粘贴长度将使切口尖端的应力集中降低，试件的极限承载力得到提高，过长的贴板对应力控制作用不明显，在混凝土底部出现新的宏观裂缝导致试件破坏。     

激光毛化板和喷丸板的摩擦行为研究

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｔｈｅｓｕｒｆａｃｅｔｅｘｔｕｒｅｓｔｅｅｌｓｈｅｅｔｓｈａｖｅｂｅｅｎｅｘｔｅｎｓｉｖｅｌｙｕｓｅｄｉｎａｕｔｏｍｏｂｉｌｅｉｎｄｕｓｔｒｙｆｏｒｔｈｅｉｒｇｏｏｄｆｏｒｍａｂｉｌｉｔｙａｎｄｐａｉｎｔｉｎｇｐｅｒｆｏｒｍａｎｃｅ.Ａｓｋｎｏｗｎ,ｔｈｅｒｅｅｘｉｓｔｅｓｆｒｉｃｔｉｏｎｂｅｔｗｅｅｎｔｈｅｓｈｅｅｔａｎｄｍｏｄｅｌｄｕｒｉｎｇｓｔａｍｐｉｎｇ.Ｗｈｅｎｔｈｅｓｈｅｅｔｉｓｄｅｆｏｒｍｅｄｉｎｔｏａｗｏｒｋｐｉｅｃｅ,ｔｈｅｐｒｏｃｅｓｓｏｆｓｈｅｅｔ…     

Data Mining方法在提高薄板冲压成型回弹预测准确性中的应用

A new method was worked out to improve the precision of springback prediction in sheet metal forming by combining the finite element method (FEM) with the data mining (DM) technique. First the genetic algorithm (GA) was adopted for recognizing the material parameters. Then according to the even design idea, the suitable calculation scheme was confirmed, and FEM was used for calculating the springback. The computation results were compared with experiment data, the difference between them was taken as source data, and a new pattern recognition method of DM called hierarchical optimal map recognition method (HOMR) is applied for summarizing the calculation regulation in FEM. At the end, the mathematics model of the springback simulation was established.Based on the model, the calculation errors of springback can be controlled within 10 % compared with the experimental results.     

Weld Characteristics and NC Bending Formability of QSTE340 Welded Tube

The mechanical characteristics of the weld joint were investigated by tensile test, microstructure test, and microhardness test. The welded tube NC bending tests were carried out to evaluate the weld on the formability of the QSTE340 welded tube. The results show that the wall thinning degree, cross-sectional deformation and springback angle increase significantly as the weld line is located on the outside of the bend compared with that located on the middle and inside, and the welded tubes produce nearly identical performance as the weld line is located on the middle and inside. The wall thickening degree decreases much as the weld line is located on the inside of the bend. So the welded tube can acquire good bending formability as the weld line is located in the region away from the outside of the bend.     

圆筒弯扭组合变形中弯曲切应变的测量误差分析

在实际测量过程中，电阻应变片的贴片位置、栅长大小以及横向效应均会对测量的精确度产生影响。该文从以上3个方面对《材料力学》课程的电测综合性实验——圆筒的弯扭组合实验中，利用全桥接法测量弯曲切应变的误差原因进行了全面分析，指出测量误差主要是由于电阻应变花的敏感栅中心偏离中性轴所致。     

76例片状增生性瘢痕切除并刃厚皮片移植或瘢痕上皮回植术对比研究

目的:探讨片状增生性瘢痕外科手术治疗的方法及疗效。方法:对76例片状增生性瘢痕采用随机分组进行增生性瘢痕切除并刃厚皮片移植术;增生性瘢痕切除、瘢痕上皮回植术两种手术方法比较性研究。结果:两种方法在疗效上无显著差异(P>0.05),但手术野数目和住院时间存在显著差异(P<0.05)。结论:片状增生性瘢痕可以采用瘢痕切除、刃厚皮片移植或瘢痕上皮回植术治疗,瘢痕上皮回植术优于刃厚皮片移植术。     

Analysis and Simulation of Superplastic Sheet-Metal Bulging by Finite Element Method

ＡｎａｌｙｓｉｓａｎｄＳｉｍｕｌａｔｉｏｎｏｆＳｕｐｅｒｐｌａｓｔｉｃＳｈｅｅｔＭｅｔａｌＢｕｌｇｉｎｇｂｙＦｉｎｉｔｅＥｌｅｍｅｎｔＭｅｔｈｏｄＬｉＪｉｎｇｙｉ（李靖谊）ＺｈａｎｇＺｈｏｎｇｙｕａｎ（张中元）ＹｕｎＱｉｊｉ（运启冀）ＷａｎｇＷｅｉ...     

Analytical model for straight hemming based on minimum energy method

An analytical model for straight hemming was developed based on minimum energy method to study the effect of flanging die corner radius on hemming qualities. In order to calculate plastic strain and strain energy more exactly, the neutral layer of specimen corner after hemming is assumed to be a half ellipse with its major semi-axis unknown. Isotropic hardening rule is adopted to describe bending and reverse bending processes neglecting Bauschinger effect. The model takes into account the material property parameters in order to satisfy a wide application range of different materials. Specimen profile, creepage/growing (roll-in/roll-out) and maximum equivalent strain are predicted, which are greatly influenced by the flanging die corner radius. Experimental facilities were designed and hemming experiments were undertaken. The predicted results of the present analytical model were compared to experimental data as well as finite element (FE) simulation results. It was confirmed that they are in good agreement, and the model can be used to evaluate whether the material used as an outer panel for hemming is appropriate and to optimize process parameters when the material used for hemming is changed.     

Study on the Stress of DLC/MCT Interface by Finite Element Method

l IntroductionDLC film is one of coating materials that has highhardness and good wear-resisbot PrOPerlies. When thefilm is deposited on low haulness substrates with thedifferent YOung's model and expansion coefficient, ahigh stress occurs in the film, which resulted in thedecrement of the adherence of the film and the filmspliting or carking['~4]. In order to improve theadherence of DLC film on the soft subside, the mostcommon method is tO colltrol the iIYIPurities, such as H,St, N and…     

冷轧薄板冲压性能的影响因素

概述了冷轧薄板的冲压性能的评价指标,详细介绍了冷轧薄板的化学成分、织构和晶粒尺寸、表面质量、厚度尺寸公差、冷轧工艺条件、拉伸试验值对冷轧薄板冲压性能的影响,并应用ANS YS/LS-DYNA软件对板材弯曲成形过程进行了模拟.     

精冲过程的数值模拟及工艺参数优化

精冲过程是典型的局部塑形大变形过程，基于其成形特点建立有限元数值仿真模型，对精冲工艺进行弹塑形大变形有限元仿真．模型采用网格重划分方法解决网格畸变情况严重时造成计算终止以及计算结果不收敛的问题，同时引入McClintock韧性断裂准则来预测裂纹出现和扩展的时间及位置．在此基础上，给出了剪切区内应力、应变的分布以及发展趋势，同时针对精冲过程中的工艺参数，如凸凹模间隙、刃口圆角、压边力、反顶力等，对精冲成形面质量的影响加以了分析，给出了工艺参数的影响规律，模拟结果与实际生产情况基本符合，可用于指导工艺参数优化．     

类金刚石薄膜/HgCdTe晶体界面应力的有限元分析

Micro-indention and finite element method (FEM) are used to study the stress at the interface between diamond-like carbon (DLC) film and mercury cadmium telluride (MCT) substrate, with different coating thickness, deposition temperature and indention load. The FEM simulation results show that when Young＇s modulus ratio of the coating to the substrate Ec/Es相似文献   

Pure bending of simply supported circular plate of transversely isotropic functionally graded material

INTRODUCTION In recent years, functionally graded materials (FGMs) have attracted more and more attention. Due to their continuously varying material properties in space on the macroscopic scale, FGMs, therefore, are usually superior to conventional fiber-matrix materi-als in mechanical behavior, especially for perform-ance under thermal loading. Now FGMs have been widely used in various fields including electronics, chemistry, optics, biomedicine, etc. Heretofore, volumes of literatu…     

带凸缘圆筒件壁厚与板料厚度的数值模拟分析

在传统理论计算的基础上,借助abaqus软件进行数值模拟分析,主要讨论在不同板料厚度下成形带凸缘圆筒件的应力分布和变化情况,以及壁厚的变化情况,找出其应力和壁厚随板料厚度变化的规律。验证理论计算的科学性和合理性,同时也反应数值模拟的参数比理论计算更精细化,为该类零件的成形工艺提供借鉴和参考。     

MIDAS/Civil在预应力空心板简支梁桥结构抗震分析中的应用

以有限单元法基本理论为基础,介绍了有限元通用软件MIDAS/Civil在预应力空心板简支梁桥结构抗震计算中的应用问题.采用三维有限元法,实现了预应力空心板简支梁桥的动力特性模拟,分析了在E1、E2地震作用下,桥梁各控制截面的抗弯能力、抗剪能力,以及支座厚度和抗弯稳定性等抗震性能,并提出切实可行的抗震措施,为桥梁施工质量控制提供必要的理论指导与技术支持.     

顶底角型件高强螺栓连接铝合金梁柱节点有限元分析

以顶底角型件高强螺栓连接铝合金梁柱节点为研究对象,利用有限元软件建立数值模型,并根据试验实测数据验证了有限元的准确性。探讨了轴压比、节点域厚度和顶底角型件厚度对节点力学性能的影响。对算例计算所得弯矩-转角曲线进行分析,拟合回归了三参数模型中形状系数的近似解析公式。结果表明,节点在合适的轴压比、节点域厚度和顶底角型件厚度下能表现出良好的抗震性能。提出的形状系数近似计算公式较为准确可靠,可为实际工程的连接设计方法提供理论依据。     

斜刃冲裁模的设计

在冲裁高强度材料或厚度大、周边长的工件时，由于冲裁力较大超过冲床负载，常常需要采取措施降低冲裁力。本文介绍一种较为实用的降低冲裁力的方法一斜刀冲裁法，并以温州华成电器公司的机壳落料模为例，介绍了斜刃冲裁模的基本结构设计及斜刃冲裁模冲裁力的计算方法。