基于ANSYS对液压支架底座的强度研究

基于液压支架底座结构特征，合理构建液压支架底座三维模型和有限元模型，以此为基础，通过ANSYS软件，从底座端载试验、底座扭转试验以及底座集中载荷试验三个角度对液压支架底座在不同工况条件下的强度性能进行有限元分析，进而根据有限元分析结果提出液压支架底座改进方案，最终将改进方案运用于工程实践，检验改进方案的有效性。     

基于有限元法的ZY6400/21/45型放顶煤液压支架强度分析

在对ZY6400/21/45型放顶液压支架进行三维建模的基础上,利用有限元仿真软件对液压支架在扭转和偏移工况下顶梁和底座的应力分布进行分析,结合分析结果对液压支架提出科学的优化建议,为提升放顶煤液压支架的工作性能与稳定性提供参考。     

液压支架的三维建模及主体结构有限元分析

论文利用Solid Works软件的建模功能和ABAQUS软件的分析功能互补,应用Solid Works软件对液压支架进行三维建模,然后再将模型导入到ABAQUS软件中进行有限元分析。在工程实际中,液压支架的损坏一般是由于顶梁和底座的偏载和扭转造成的,所以本文选取其中顶梁偏载底座扭转、顶梁扭转底座两端集中载荷这两种工况,对两柱掩护式液压支架进行三维建模和有限元分析,从而得到液压支架各处的应力应变的分布情况,并得到液压支架在这两种工况下工作过程中的薄弱点,为液压支架的设计提供了参考依据。     

基于Workbench的ZC10000型液压支架底座结构强度分析

以ZC10000型液压支架为研究对象,根据液压支架工程图建立三维模型,并根据液压支架的材料属性等创建了有限元分析模型,基于Workbench分析软件计算该型液压支架底座在两种较恶劣工况下应力分布情况,分析计算得到底座在偏载工况下底座最大应力为553.89MPa,在扭转工况下底座位移最大为20.252mm,根据计算结果提出了两条结构优化改进意见,以有效保证液压支架工作安全可靠性.     

基于有限元法的固体充填液压支架底座结构参数优化

为提高固体充填液压支架底座的强度和可靠性,以ZZC8800/20/38型六柱支撑式固体充填液压支架底座为研究对象,在满足强度要求的前提下,以减小底座质量和变形位移为优化目标,利用三维建模软件建立了底座的有限元模型,采用有限元法,在ANSYS Workbench软件中进行有限元分析,通过观察应力云图,选择液压支架底板厚度、外侧主筋板厚度、内侧主筋板I厚度、内侧主筋板II厚度为变量,对液压支架底座结构参数进行优化。结果表明,优化前后底座应力集中区的应力和变形位移变化不大,但是底座的质量明显减小,其质量减小了334.7 kg,也同时改善了底座的强度分布不均现象。     

矿井液压支架底座结构的优化设计

以ZF3880/20/30型液压支架的底座为研究对象,通过有限元仿真技术对液压支架底座结构进行优化设计.在提升液压支架底座的最大等效应力的同时,对底座进行减重设计,降低底座的设计制造成本,提升液压支架制造厂商的生产效益.优化后的底座结构最大等效应力增加了4.16％,重量减轻了19.53％.     

关于ZY86400/25.5/55型液压支架掩护梁结构优化的研究

以ZY86400/25.5/55型液压支架掩护梁为研究对象,基于ABAQUS有限元分析软件,分析计算掩护梁在扭转工况和偏载工况下的结构强度.结果 表明,其在两种工况下最大应力值均小于材料的屈服强度,但存在比较明显的应力集中情况.根据仿真分析的结果,提出了两种对掩护梁的优化改进措施,以提高液压支架结构可靠性.     

超前支护液压支架顶梁与底座的分析与研究

阐述超前支护液压支架的顶梁和底座的选择过程;对超前支护液压支架的顶梁和底座进行有限元分析,确定所需要的结构并绘制出结构图;对超前支护液压支架的顶梁和底座进行模态分析,确定了其强度符合工作要求,并能合理避开掘进机的工作频率,防止共振的产生。     

基于有限元的液压支架强度可靠性的优化分析

利用ANSYS软件对型号为ZF8000/22/35的液压支架进行建模分析,计算可靠性其及其灵敏度.通过有限元分析,得出优化液压支架可靠性的方法,对液压支架结构进一步优化设计提供有力的数据参考.     

煤矿开采液压支架底座受力仿真分析

采用ANSYS Workbench对液压支架底座进行受力仿真分析,选择液压支架底座受力最大的工况进行分析,结果表明:底座所受到的整体应力值满足底座的使用强度需求,结构存在一定的应力集中现象;液压支架底座的整体变形量较小,满足底座的设计使用要求.针对仿真分析进行一定的结构优化,在保证液压支架性能的同时,提高了使用寿命及安全性.     

Electron and light microscopy studies on the domain structures of Zn3B7O13Cl, Zn3B7O13Br and Zn3B7O13I ferroic boracites

The domain structures of Zn₃B₇O₁₃Cl, Zn₃B₇O₁₃Br and Zn₃B₇O₁₃I boracite single crystals were studied by means of polarized light in conjunction with electron microscopy. Single crystals of the three compositions were grown by chemical transport reactions in closed quartz ampoules, at a temperature of 900 °C and were examined by polarizing optical microscopy (PLM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). For both PLM and SEM, the same as‐grown samples were used without having to resort to metallization of the crystal faces. For TEM the single crystals were crushed and mounted on holey carbon films. Comparative electron microscope images were useful for revealing the domain structure of these ferroelectric/ferroelastic materials previously observed between the crossed polars of an optical microscope. X‐ray diffraction analysis of the pulverized crystals was performed for this triad of halogen boracites containing zinc as a common metal.     

Cylindrical specimens for KIC of rocks

Stress intensity factors for pairs of diametrically opposite radial cracks on the inside of a jacketed pressurized hole in a thick cylinder have been calculated by using finite element technique. Burst tests on thick cylinder rock samples under above conditions have been performed and the K_IC values for Antrim Shale and Limestone determined. The method is very convenient for rocks whose samples are often available in form of cylindrical bars drawn as cores from underground drilling.     

GT/CAD/CAPP/PDM/ERP系统集成研究

研究ETO生产方式下以成组技术为基础的CAD/CAPP/PDM/ERP的集成方法,包括面向CAD/CAPP/PDM/ERP的集成的成组信息编码,基于成组编码的CAD/PDM集成、CAPP/PDM集成和PDM/ERP集成.提出了基于成组技术的CAD/CAPP/PDM/ERP集成框架,研究了贯穿于CAD、CAPP、PDM与ERP系统的统一的成组编码方案和信息编码方案.     

基于太赫兹光谱的人参和西洋参鉴别

为了快速区分人参和西洋参,依据两者所含的人参皂苷在太赫兹波段具有不同指纹光谱,提出了一种基于人参皂苷的太赫兹光谱鉴别人参和西洋参的方法。采用MATLAB软件识别人参和西洋参的太赫兹光谱,同时根据太赫兹光谱特征并通过标准的主成分分析(PCA)区分出人参、西洋参。实验结果表明,基于太赫兹光谱的主成分分析可精确区分出人参、西洋参,并且还可以应用于其他类似物质的区分中。     

Analysis of the Rk surface roughness parameter proposals

European manufacturers have proposed a set of surface roughness parameters based on an examination of the variation in slope of the bearing ratio curve of a surface profile. It is shown, that the proposed procedure provides no useful information, and indeed is misleading, since the bearing ratio curve of even a normally-distributed random surface profile exhibits the expected variation in slope when plotted on rectangular coordinates. On the other hand, the desired information is readily obtained by a similar examination of the cumulative height distribution of a surface profile (the unity complement of the bearing ratio) when it is plotted on normal probability coordinates.     

永磁同步电机积分滑模观测器控制

对永磁同步电机观测器控制进行研究,针对传统滑模观测器存在控制精度低、系统抖振较大的不足,设计了一种永磁同步电机积分滑模观测器控制。积分滑模控制具有控制精度高、系统抖振小的特点。积分滑模观测器可以有效提高电机控制精度,增强控制系统抗干扰能力。采用饱和函数代替符号函数进行滑模控制律设计,降低控制系统固有抖振,使滑模控制动态性能提高。通过仿真验证了积分滑模观测器控制策略的可行性。     

Characterization of cast Al86Mn3Be11 alloy

An Al₈₆Mn₃Be₁₁ alloy cast into copper mould was subjected to metallographic investigation. The as-cast microstructure consisted of a quasicrystalline icosahedral phase (i-phase), Be₄AlMn phase and, occasionally, a hexagonal phase. Al-rich solid solution represented the dominant phase. The chemical compositions of phases were determined using AES. The composition of the Be₄AlMn slightly deviated from the stoichiometric composition, whereas the composition of the i-phase was approximately Al₅₂Mn₁₈Be₃₀, containing an appreciable amount of Be. The average composition of the hexagonal phase was Al₆₆Mn₂₁Be₁₃. Deep etching and particle extraction provided a deep insight into the three-dimensional morphology of the i-phase and the hexagonal phase, whereas Be₄AlMn was slightly attacked by the etchant. The i-phase was present predominantly in the form of dendrites and a rodlike eutectic phase. The hexagonal phase was primarily in the form of hexagonal platelets, whereas Be₄AlMn was rather irregular in shape. The morphology of the i-phase can be explained by predominant growth in 3-fold directions and the lowest energy of the 5-fold planes, leading to the faceting and adopting a pentagonal dodecahedron shape. The brightnesses of phases in the backscattered electron images were rationalized by determining their backscattering coefficients. TEM investigation showed considerable phason strain in the i-phase, and the polycrystalline nature of the Be₄AlMn phase.     

Investigation on the impact behavior of Al2O3-SiC-MgO nanoceramic/metal laminated composite

Lightweight laminated composites containing a ceramic front layer and a metallic backing layer were used in order to protect people, moving equipment, and mobile vehicles from high velocity impact and the increased mobility of mobile vehicles. In this study, by adding10 vol% SiC and 500 ppm MgO nanoscale particles on the microstructure of Al ₂ O ₃ matrix and applying optimum sintering conditions, ceramic performance against high-speed projectile impact was improved. To perform this investigation, a number of target samples with two different types of front layers (alumina and Al ₂ O ₃-SiC-MgO nanocomposite ceramic) were produced. Impact tests were conducted on these samples using 7.62 mm projectiles with a velocity of 820 ± 15 m/s. The amount of bulge and bending of the backing layer caused by impact tests was measured. The results of the impact tests on the samples made of Al ₂ O ₃-SiC-MgO nanocomposite ceramics and alumina were also compared and analyzed. The results indicate that the substitution of Al ₂ O ₃-SiC-MgO ceramic layer — which is proffered in this paper — instead of pure alumina ceramic layer, decreases the areal-density of the samples by at least 30% and improves mechanical properties by about a 60% increase in flexural strength and 100% growth of the energy distribution factor, which impressively increases impact energy absorption.     

Electron microscopy of crack/particle interactions in Al2O3/SiC nanocomposites

Crack/particle interactions in alumina/silicon carbide nanocomposites have been investigated by scanning electron microscopy and transmission electron microscopy, with cracks induced by Vickers microindentation. Intergranular cracks are frequently deflected into grains by SiC particles on grain boundaries inclined to the average direction of crack propagation. This mechanism is proposed to explain the change in the fracture mode from intergranular fracture for monolithic alumina to predominantly transgranular fracture for the nanocomposites. Neither stress-induced microcracking around SiC particles nor significant crack deflection by intragranular particles was found to occur in the nanocomposites. It is argued that an addition of nanoparticles may not be a promising approach for increasing the toughness of alumina.     

Near-field second harmonic imaging of the c/a/c/a polydomain structure of epitaxial PbZrxTi1–xO3 thin films

Near-field optical second harmonic microscopy has been applied to imaging of the c/a/c/a polydomain structure of epitaxial PbZr _x Ti_{1– x} O₃ thin films in the 0 <  x  < 0.4 range. Comparison of the near-field optical images and the results of atomic force microscopy and X-ray diffraction studies show that an optical resolution of the order of 100 nm is achieved. Symmetry properties of the near-field second harmonic signal allow us to obtain good optical contrast between the local second harmonic generation in c- and a-domains. Experimentally measured near-field second harmonic images have been compared with the results of theoretical calculations. Good agreement between theory and experiment is demonstrated.