非均匀地应力下井壁Von Mises应力及稳定性分析

为分析非均匀地应力作用下井壁Von Mises(米塞斯)应力及其对井壁稳定性的影响,建立了非均匀地应力作用下井壁附近岩石的力学分析模型。根据弹性力学中应力与应力函数之间的关系,应用叠加原理,导出了非均匀地应力下井壁径向应力、环向应力和剪切应力计算公式,分析了非均匀地应力对井壁稳定性的影响,确定了以钻井液密度为自变量的井壁Von Mises应力的二次拟合公式。采用拟合公式计算的井壁Von Mises应力误差小于2.5%,利用该公式可以确定井壁岩石不会破裂的钻井液密度。     

三维多粗糙峰涂层等效应力分析与表征

利用有限元方法建立了刚性平面与多粗糙峰涂层的弹性接触模型,研究了刚性平面分别与二维涂层粗糙峰、三维涂层粗糙峰的接触状态,揭示了涂层/基体弹性模量比、涂层厚度、粗糙峰问距、刚性平面压下深度对涂层粗糙峰表面、涂层/基体界面等效应力分布及涂层基体变形的影响规律.计算结果表明:压下深度对涂层粗糙峰表面最大等效米塞斯应力的影响最大,涂层厚度和涂层/基体弹性模量比的影响次之,粗糙峰间距的影响最小;增大涂层厚度,减小压下深度、粗糙峰间距和低弹性模量比,会使得最大等效应力值显著降低.     

组合式弹性片金属密封环密封特性有限元分析

利用ANSYS Workbench软件建立组合式弹性片金属密封环有限元模型,分析密封环初始压缩量、工作压力等对密封环最大Von Mises应力、接触应力大小及接触部位压力分布的影响。研究表明:组合式弹性片金属密封在不受工作压力情况下,顶块与封严片之间并不是完全接触的,不能起到密封效果,但在工作条件下,在一定的预压缩量下其顶块与封严片之间完全接触,满足密封要求;适当增加预压缩量可以提高密封环密封性能,但同时其所受的最大Von Mises应力也增大,当最大Von Mises应力大于材料的屈服极限时密封环会失效。通过计算得到弹性片的安全工作夹角范围,为组合式弹性片金属密封环的设计、安装及使用提供依据。     

齿根裂纹几何参数对齿轮强度影响的研究

在工程机械再制造过程中,齿根裂纹特征作为齿轮失效的主要检测依据之一,直接决定齿轮回收件的再制造处理方案。提出了基于缺陷建模的齿轮强度分析方法,根据齿轮回收件裂纹统计情况,设计了一组裂纹特征的几何参数,并使用齿根裂纹建模技术将其引入到齿轮副模型中,使用Ansys系统进行有限元静力分析,得到了齿轮内部最大等效应力随裂纹几何参数的变化曲线。结果表明：与无裂纹时齿根受拉侧最大等效应力108 MPa相比,裂纹处的最大等效应力变化范围为301～890 MPa,齿根裂纹有明显的应力集中作用;在相同几何参数条件下,中部裂纹处的最大等效应力大于端部裂纹处的最大等效应力,中部裂纹对应力集中的影响较大;裂纹最大等效应力随深度变化曲线斜率比随长度变化曲线斜率大,裂纹深度对最大等效应力的影响比裂纹长度强。     

Elasto-Plastic Analysis of Adhesively Bonded Symmetric Single Lap Joints Under In-Plane Tension and Edge Moments

An analysis is presented that predicts adhesive shear and peel stresses and strains in an adhesively bonded single lap joint having symmetric configuration with adhesive behavior. The single lap joint is under tension loading together with moments induced by the interactions of the geometric eccentricity and the boundary conditions of the joint. The von Mises yielding criterion is used to relate the adhesive stress components within the yielded region. The adhesive strains are computed from the relative displacements of the adherends and can be considered as an average of the strain variation through the adhesive thickness direction. Example calculations show that the predicted adhesive shear and peel stress and strain profiles are well matched to detailed finite element analysis results. Generally, the analytical model predictions are found to be more accurate when the adhesive thickness is small.     

硅锰钢中夹杂物应力场数值模拟

采用ANSYS有限元分析软件,建立含不同种类、形态夹杂物的硅锰钢有限元模型,计算在单向拉伸状态下含夹杂物的硅锰钢应力场分布,进而从宏观力学角度分析夹杂物的力学行为。结果表明,夹杂物和基体的弹性模量的差距及夹杂物的形态,对试样内的应力集中程度及最大应力影响最显著。     

Quantum inspired method of feature fusion based on von Neumann entropy

One mission of feature fusion is to obtain a complete yet concise presentation of all existing feature data by detecting and fusing the duplicate feature data. In contrast to the already developed feature fusion methods which have shown their limitations, this paper applies the theories of quantum information to feature fusion. Further, a novel and effective step-wise quantum inspired feature fusion method, which detects the duplicate feature data based on maximum von Neumann mutual information and fuses the duplicate feature data using the operations on quantum state, is developed. This same idea is also used for feature dimensionality reduction, and the corresponding models are investigated. For comparison, another quantum inspired feature fusion method based on average quantum phase is presented here. The experimental results show that the quantum inspired feature fusion method based on von Neumann entropy gives better results on completeness and conciseness than the method based on average quantum phase.     

Clustering of periodic multichannel timeseries data with application to plasma fluctuations

A periodic datamining algorithm has been developed and used to extract distinct plasma fluctuations in multichannel oscillatory timeseries data. The technique uses the Expectation Maximisation algorithm to solve for the maximum likelihood estimates and cluster assignments of a mixture of multivariate independent von Mises distributions (EM-VMM). The performance of the algorithm shows significant benefits when compared to a periodic k-means algorithm and clustering using non-periodic techniques on several artificial datasets and real experimental data. Additionally, a new technique for identifying interesting features in multichannel oscillatory timeseries data is described (STFT-clustering). STFT-clustering identifies the coincidence of spectral features over most channels of a multi-channel array using the averaged short time Fourier transform of the signals. These features are filtered using clustering to remove noise. This method is particularly good at identifying weaker features and complements existing methods of feature extraction. Results from applying the STFT-clustering and EM-VMM algorithm to the extraction and clustering of plasma wave modes in the time series data from a helical magnetic probe array on the H-1NF heliac are presented.     

小型冷室压铸机尾板减重设计方案分析

压铸机尾板是压铸机核心部件之一,其结构的优劣直接影响着压铸机生产质量和使用寿命。利用COSMOSWorks有限元软件对160 t压铸机尾板减重前后的2种方案进行对比分析,并得出了尾板的Von Mises应力、位移图解。分析结果表明减重后对尾板的刚度和挠度影响微小,减重方案切实可行。