三层复合铝箔的有限元分析

用MSC SuperForm软件对三层复合铝箔的轧制过程进行了有限元模型，得到了轧件的包覆板横向厚度分布特征。研究了压下量对横向厚度分布的影响，结果表明，通过改变压下量的大小，可以有效改善轧件的包覆板横向厚度分布不均的现象。     

钎焊箔芯材与包覆层变形速度差异研究

从钎焊复合铝箔热轧及冷轧过程中芯材与包覆层变形速度差异方面分析、探讨钎焊箔与包覆层厚度均匀性的关系。     

4004/3003/4004铝合金复合钎焊板包覆率研究

三层铝合金复合钎焊板是制造钎焊式热交换器的重要材料,其中4004/3003/4004是一种使用最为广泛的铝合金复合钎焊板。对4004/3003/4004铝合金复合钎焊板进行热轧复合,分析其包覆层宽度方向分布情况和上下包覆层厚度差异性,并研究不同初始包覆率下轧制后包覆率的变化规律,对实际生产中钎焊板包覆层厚度控制起到重要的指导作用。     

热轧4343/3003/7072铝合金钎焊板的组织与性能

采用热轧复合工艺生产4343/3003/7072铝合金钎焊板,利用光学显微镜、电子拉伸试验机和扫描电镜,研究了铝合金钎焊板的包覆率、显微组织和力学性能。结果表明,铝合金钎焊板的包覆层合金厚度均匀、复合界面平整,铝合金钎焊板中4343和7072铝合金包覆层的包覆率分别为9.0%和8.1%,铝合金钎焊板的抗拉强度、屈服强度和伸长率分别为118.62 MPa、56.21 MPa和32.48%。     

热轧铝基钎焊板包覆率变化规律研究

对三层4004／3003／4004铝合金钎焊板进行热轧复合,研究不同轧制阶段包覆率的变化规律,结果表明：复合钎焊板在热轧复合后其包覆层的厚度在板带宽度方向上存在不均匀性,且这种不均匀分布具有一定的规律性和遗传性。并利用回归方程推导出包覆率（％）与总变形量（％）的关系。     

钎焊复合箔"铸轧-冷轧复合"短流程生产工艺开发

采用铸轧坯料组织细化处理技术及"三步轧制法"在线表面处理-轧制复合-扩散退火处理,实现多层材料界面的冶金结合并获得均匀包覆率.通过加工率的合理设计和退火工艺优化,使复合铝箔具有良好的抗下垂性和较好的耐腐蚀性能.解决了行业内无法用铸轧法代替热轧法生产复合铝箔的难题,突破长期以来热轧法生产复合铝箔生产周期长、成材率低的瓶颈...     

金属复合轧制包覆板坯厚度的计算

通过对金属复合轧制的变形分析，导出了多层金属复合轧制的包覆板坯厚度计算公式。该式对金属复合轧制时，包覆板坯厚度的迁取提供了理论依据。对生产具有重要的现实意义。     

张力对大宽厚比铝箔板形影响的有限元分析

在铝箔宽厚比为5300的条件下，采用大型商用显式动力学有限元分析软件ANSYS／LS—DYNA模拟了铝箔轧制状态，得到了改变前后张力时，铝箔的出口厚度、轧制压力、压下方向应变的横向分布规律，分析了张力变化对铝箔板形的影响，提出铝箔轧制宜采用的最佳张力制度。     

包覆浇铸高硼不锈钢复合板的变形协调性

包覆浇铸后的复合铸坯虽然已具有冶金结合,但热轧过程中,道次变形量若确定不合理将在界面处产生附加应力,附加应力值的大小将影响热轧后复合板的界面结合情况。应用ABAQUS有限元软件对包覆浇铸304不锈钢/高硼不锈钢/304不锈钢复合铸坯的热轧过程进行了有限元模拟,有限元模拟结果显示,当道次变形量大于17%时,覆层及芯层变形协调性变差,复合板界面将遭到破坏。实际热轧试验验证了有限元模拟结果的正确性,为包覆浇铸复合铸坯的热轧提供了有利的工艺参数。     

超声波化学还原法制备超细Ni包覆Cu复合粉工艺研究

采用化学镀法以预制的Cu粉为基体,制备出了超细Ni包覆Cu复合粉体.研究了超声波对Ni包覆Cu复合粉体的转化率、包覆效果及分散性的影响.用SEM、EDS及XRD分析样品的微观形貌、成分及物相组成.结果表明:在超声条件下,获得了分散性较好的Ni包覆Cu复合粉体;不同超声条件下制备的Ni包覆Cu复合粉体中Cu、Ni含量无明...     

还原工艺对钼粉粒度和氧含量的影响

以仲钼酸铵、三氧化钼、二氧化钼和钼粉为原料,采用不同的温度和不同的料层厚度进行了还原,分析了所得钼粉的粒度、氧含量和形貌,剖析了同舟内不同层次钼粉的粒度和氧含量的变化规律。     

Nb+Ti处理的ELC-BH钢板织构的研究

系用极图分析的方法对一种Ｎｂ＋Ｔｉ处理的ＥＬＣ－ＢＨ钢板厚向各层冷轧和退火织构进行了研究，发现板厚向各层冷轧或退火织构的基本特征相似，但是它们的组分强度发生变化，并且这些变化之间存在着一定联系。     

Layer thickness effect on ductile tensile fracture

Laminated metal composites containing equal volume percentage of ultrahigh carbon steel (UHCS) and brass were prepared in three different layer thicknesses (750, 200, and 50 μm) by press- bonding and rolling at elevated temperature and were tensile tested at ambient temperature. A dramatic increase in tensile ductility (from 13 to 21 to 60 pct) and a decrease in delamination tendency at the UHCS-brass interfaces were observed as the layer thickness was decreased. The layer thickness effect on ductility is attributed to residual stress whose influence on delamination is decreased as the layer thickness is decreased. Suppression of delamination inhibits neck for- mation in the UHCS layers, allowing for extended uniform plasticity. For a given layer thick- ness, the tensile ductility decreases as the ratio of hardness of component layers is increased.     

18CrNiMo7-6合金钢表面变质层循环特性

 为了研究18CrNiMo7-6合金钢表面变质层在循环加载作用下的本构特性,对18CrNiMo7-6合金钢进行了渗碳热处理,通过化学腐蚀得到不同表面变质层厚度的圆棒试样,并分别进行单调拉伸试验和循环加载试验分析其力学性能、滞回性能、耗能能力及微观组织的区别。对不同表面变质层厚度18CrNiMo7-6合金钢在循环加载作用下的骨架曲线进行拟合,研究其与单调拉伸作用下的力学性能区别。基于Chaboche循环本构模型标定了不同表面变质层厚度试样在循环加载作用下的循环本构参数,并通过有限元软件ABAQUS进行了仿真验证。结果表明,在单调拉伸作用下,随着表面变质层厚度的增加,试样的硬度、屈服强度及抗拉强度也随之提高。在相同的应变幅值加载下,表面变质层越厚,其响应应力越大,能量耗散系数越低,材料的耗能能力越弱;Ramberg-Osgood方程能够较好地拟合不同表面变质层厚度的试样在循环加载作用下的骨架曲线;18CrNiMo7-6合金钢的主要组成成分为马氏体,随着表面变质层厚度的增加,位错密度增高;18CrNiMo7-6合金钢基体材料在循环加载作用下表现出循环硬化特征,而随着表面变质层厚度的增加,试样逐渐由没有循环软硬化现象到表现出循环软化特征;Chaboche循环本构模型对不同表面变质层厚度的18CrNiMo7-6合金钢均具有较好的适用性,能准确拟合其在循环加载作用下的力学响应。     

Mechanical properties of multilayer materials

Conclusions A multilayer composite material consisting of a soft, ductile and hard, strong component possesses, at a high level of hardness, much higher impact and tensile strengths compared with a single-layer material. A greater improvement in impact strength is exhibited by a system whose soft component, other things being equal, is more ductile. A better combination of mechanical properties is attainable in a MLC produced by the metallurgical process. The increase in impact strength is apparently due to the inhibition of crack propagation in the ductile component of a MLC and to an increase in the strength of the hard component associated with the small thickness of its layers.Translated from Poroshkovaya Metallurgiya, No. 5(233), pp. 70–74, May, 1982.     

Online Earthquake Response Test for Stratified Layers of Clay and Sand

Artificial islands often consist of layers of alluvial clay and reclaimed soil of varying order and thickness. Soft clay layers have nonlinear characteristics and can both amplify and attenuate earthquake ground motions. Liquefied ground impedes propagation of shear waves and thus attenuates the earthquake accelerations. Online testing is a method of feeding soil response characteristics directly from soil samples into a modeling algorithm. The effects of the layer thickness, configuration, and degree of consolidation on the earthquake response characteristics of alternating layers of clay and sand have been investigated. The degree of liquefaction and strain generated in sand adjacent to clay layers increased with the degree of consolidation. Clay layers attenuate the motions of sand layers for short period vibrations but amplify the long period motions, increasing the strain in overlying liquefied sand layers. Clay layers which were closer to the ground surface or of greater thickness tended to increase the surface accelerations. Normalized cumulative energy loss was larger in clay than in sand increasing with a decreasing degree of consolidation.     

Optimal Hybridization of Symmetric, Cross‐Ply Laminates against Biaxial Buckling

Optimal ratio of the thickness of the inner layers made of a low‐stiffness fiber‐reinforced material to the total laminate thickness is determined for sandwich hybrid laminates, with the objective of maximizing the buckling load for a given laminate thickness. The sandwich plate is constructed as a symmetric, cross‐ply laminate with outer layers made of a high‐stiffness fiber composite material and inner layers made of a low‐stiffness fiber‐composite material. The fiber orientations of high‐ and low‐stiffness materials (0° or 90°) are determined optimally, noting that the orientations of outer and inner layers affect the maximum buckling load in the case of hybrid laminates. The relative stiffness of outer layers to inner layers is shown to affect the optimal level of hybridization. The optimal laminate configurations are shown to be sensitive to the relative magnitudes of biaxial buckling loads as well as to the changes in the aspect ratio.     

Carotid artery wall changes in estrogen-treated and -untreated postmenopausal women

OBJECTIVE: To investigate whether the thickness of the layers of the carotid artery (externa, media, and intima) are affected by menopause and its treatment with hormone replacement therapy (HRT). METHODS: One hundred twenty-nine postmenopausal women were recruited sequentially and classified into three groups. Forty-six were taking oral HRT, 32 had estradiol implants, and 51 had never taken HRT. The three layers of the externa wall of the carotid artery were identified and measured by high-resolution ultrasound. RESULTS: Women with implants had thicker carotid artery wall measurements (0.84 +/- 0.26 mm) than the other groups. The media (0.32 +/- 0.11 mm) was significantly thicker in the implant group. This layer has a high connective tissue component, including collagen type I, collagen type III, and elastin fibers. The intima layer was thinner (0.25 +/- 0.09 mm) in the oral HRT group compared with controls (0.29 +/- 0.1 mm). A statistically significant higher intima-media ratio (1.17 +/- 0.05) was calculated for the control group, compared with both the oral HRT (0.92 +/- 0.04) and implant groups (0.94 +/- 0.03). CONCLUSION: Our findings suggest that HRT given to postmenopausal women influences differentially the layers of the carotid artery. Hormones seem to encourage thickening of the layers with the highest connective tissue component (externa and media) and to delay thickening of the atheromatous intima layer. These effects on the vascular system may be partly responsible for the cardioprotection attributed to HRT.     

The Influence of the Thickness and Areal Density on the Mechanical Properties of Carbon Fibre Reinforced Aluminium Laminates (CARAL)

A novel composite material consisting of a laminate of several thin aluminium sheets bonded with layers of carbon fibre mat/epoxy resin. Carbon fibre reinforced aluminium laminates (CARAL) offer specific advantageous properties such as better strength, fatigue, impact, corrosion resistance, fire resistance and weight savings. CARAL is a kind of fibre metal laminate system. In the present work, CARAL was prepared and experimental tests were conducted to evaluate the influence of the thickness and areal density on the mechanical properties of CARAL. Mechanical properties such as, the tensile strength and flexural strength of the laminates were increased with the increase in thickness and areal density. CARAL with four aluminium layers and three carbon fibre mat layers have superior strength than the laminates with lesser number of layers due to thickness of laminates and areal density.     

Effect of the Geometric Parameters of a Layered Powder Composite on Its Magnetic Properties

The effect of thickness of magnetic conductor and number of electrically insulating layers on the magnetic properties in an alternating field of a layered powder-metallurgy soft-magnetic material based on iron was investigated. It was determined that increasing the thickness of the magnetic conductor and frequency of the alternating current deteriorated the magnetic properties of the material. Creation of a layered structure in which ferromagnetic layers alternate with electrically insulating layers decreased specific magnetic losses.