共查询到17条相似文献,搜索用时 218 毫秒
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协同式专家系统及其在三轴转台故障诊断中的应用 总被引:1,自引:0,他引:1
针对传统的专家系统在处理多领域知识方面的缺陷,作提出了一种协同式专家系统,给出了相应的模型和结构,并提出一种裁决算法,将多个涉及不同领域的子专家系统融合起来,共同实现专家系统的多领域问题求解。以此方法构建的TRDES目前已应用于高精密三轴转台的故障诊断中,效果良好。 相似文献
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有限元模型比知识的获取和形式化是有限元模型化专家系统建立的核心。本文以信息论为工具,在总结大量工程经验和理论研究成果的基础上,建立了工程结构模型化知识系统,它分为两个层次,一是复杂结构模型化,二是简单结构模型化。后者是前者的基础,包括力学模型化、有限元模型化和网络生成三部分。这些知识均已溶人了作者开发的专家系统之中。 相似文献
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中间弱层对层合板性能影响分析 总被引:1,自引:0,他引:1
对于夹胶玻璃等结构,由于中间胶层很弱,层合板结构的层间剪切效应占主导地位。此时经典层合板理论以及整体高阶剪切位移场理论所预测的结果可能导致很大的实际误差,应采用更加精细的力学模型来分析弱层的效应。本文建立了分层位移场假设下的浅柱面层合板静力计算模型以及自振周期计算模型,并同经典层合板理论计算结果对比,分析了中间层的剪切模量、弹性模量、层合板曲率半径对层间剪切效应的影响。计算结果表明:中间层的剪切模量对层合板的受力性能有着决定性的影响,相对来说中间层的弹性模量对层合板性能的影响不太显著;当中间层与面层的剪切模量比值小于0.2时,随着中间层剪切模量的减小,两个模型的计算误差急剧增大。 相似文献
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提出了高速切削过程中诱发绝热剪切带形成的热塑性剪切波的传播机理,针对锯齿形切屑中热望性区域内的塑性梯度变形特征、动量和能量耗散情况,建立了与切削条件相关的热塑性剪切波的传播模型及剪切带宽度模型.在此基础上,通过淬硬45钢的切削实验并结合改进的Johnson-Cook本构模型分析了热塑性剪切波的传播规律,并将剪切带宽度模型与已提出的DB模型、WR模型和DM模型做了对比,结果表明,由热塑性剪切波传播理论推导的剪切带宽度模型与实验结果较其他模型吻合较好. 相似文献
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碳纤维增强塑料层合板正交层间的剪切强度 总被引:1,自引:0,他引:1
1. 前言在以往的一些复合材料性能测试标准和有关讨论层间剪切破坏的文献中,都只引入单向复合材料的层间剪切强度。然而事实证明,正交铺层间的剪切强度(称正交层间剪切强度) 要比单向铺层间的剪切强度(称单向层间剪切强度)低得多。因此,只用单向层间剪切强度不足以说明层合板的层间剪切强度,尤其是把它用作设计指标时就更不合理,也不安全。为此,我们引进了正交层间剪切强度这一新的强度指标,并设法正确地测定了它。若以此作为设计指标就保证安全。测定单向层间剪切强度已经有了较合理的方法,它是用短梁的三点弯曲来测得的。本文也提出用短梁的三点弯曲来测定正交层间剪切强度。不过试样材料是用〔0_m/90_n〕_s这类正交铺设层合板。 相似文献
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混合专家系统及其在有限元模型化中的应用 总被引:3,自引:0,他引:3
本文结合传统专家系统和人工神经网络的优势建立了混合专家系统模型,并在此基础上建立了“飞机结构机身框有限元模型化专家系统”,能够自动地实现机身框一类结构的有限元模型化,本文采用人工神经网络解决结构类型的分类和识别、采用知识系统解决单元自动选取都取得了良好的效果。 相似文献
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《European Journal of Mechanics - A/Solids》2007,26(2):337-347
This paper investigates the edge crack problem for a coating/substrate system with a functionally graded interfacial zone under the condition of antiplane deformation. With the interfacial zone being modeled by a nonhomogeneous interlayer having the continuously varying shear modulus between the dissimilar, homogeneous phases of the coated medium, the coating is assumed to contain an edge crack at an arbitrary angle to the interfacial zone. The Fourier integral transform method is used in conjunction with the coordinate transformations of basic field variables. Formulation of the proposed crack problem is then reduced to solving a singular integral equation with a generalized Cauchy kernel. The mode III stress intensity factors are defined and evaluated in terms of the solution to the integral equation. In the numerical results, the values of the stress intensity factors are plotted, illustrating the effects of the crack orientation angle for various material and geometric combinations of the coating/substrate system with the graded interfacial zone. 相似文献
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Elastodynamic analysis of a crack at an arbitrary angle to the graded interfacial zone in bonded half-planes under antiplane shear impact 总被引:2,自引:0,他引:2
A solution is provided for the elastodynamic problem of a crack at an arbitrary angle to the graded interfacial zone in bonded media under the action of antiplane shear impact. The interfacial zone is modeled by a nonhomogeneous interlayer with the spatially varying shear modulus and mass density in terms of power functions between the two dissimilar, homogeneous half-planes. Based on the use of Laplace and Fourier integral transforms and the coordinate transformations of basic field variables, formulation of the transient crack problem is reduced to solving a Cauchy-type singular integral equation in the Laplace transform domain. The crack-tip response in the physical domain is recovered via the inverse Laplace transform and the values of dynamic mode III stress intensity factors are obtained as a function of time. A comprehensive parametric study is then presented of the effects of crack obliquity on the overshoot behavior of the transient crack-tip response, by plotting the peak values of the dynamic stress intensity factors versus the crack orientation angle for various material and geometric combinations of the bonded system. 相似文献
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岩石压剪断裂核的试验研究 总被引:14,自引:0,他引:14
本文介绍了岩石压剪断裂试件切口端部微裂区的研究成果。通过白光散斑,光弹贴片测试及切片镜检,查明了该微裂区呈不对称的桑叶状,其内部岩石晶粒碎裂,形成多条裂纹,岩石压剪主破裂面沿微裂区边界面扩展。在上述结果基础上,提出了描述该微裂区的岩石压剪断裂核的形状方程。 相似文献
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The propagation of interlayer cracks and the resulting failure of the interface is a typical mode occurring in rock engineering and masonry structure. On the basis of the theory of elasto~plasticity and fracture mechanics, the shear beam model for the solution of interface failure was presented. The concept of `cohesive crack’ was adopted to describe the constitutive behavior of the cohesive interfacial layer. Related fundamental equations such as equilibrium equation, constitutive equations were presented. The behavior of a double shear beam bonded through cohesive layer was analytically calculated. The stable propagation of interface crack and process zone was investigated. 相似文献
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基于案例推理方法在惯性导航故障诊断专家系统的应用 总被引:2,自引:0,他引:2
以测量船惯性导航系统为例,为解决其故障诊断专家系统知识瓶颈问题,特别是突发、原因不详的故障,利用专家知识和以往的工作经验积累,在故障诊断专家系统中融入了基于案例的推理方法。这种推理方法把知识获取简化为领域内经验知识的收集,并以此为基础构造案例库;把基于规则的推理转化为基于案例推理,即在案例库中检索相似的经验知识。采用基于案例推理的方法,可以简化知识获取的过程,求解效率高、质量高,具有持续的学习能力,能有效提高故障诊断系统的智能化程度。文中重点介绍了构建该故障诊断专家系统的案例知识表示方法、案例的索引和检索算法等关键技术。 相似文献
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《Acta Mechanica Solida Sinica》2017,(3)
In this paper, the interlayer sliding between graphene and boron nitride(h-BN) is studied by molecular dynamics simulations. The interlayer shear force between h-BN/h-BN is found to be six times higher than that of graphene/graphene, while the interlayer shear between graphene/h-BN is approximate to that of graphene/graphene. The graphene/hBN heterostructure shows several anomalous interlayer shear characteristics compared to its bilayer counterparts. For graphene/graphene and h-BN/h-BN, interlayer shears only exit along the sliding direction while interlayer shear for graphene/h-BN is observed along both the translocation and perpendicular directions. Our results provide significant insight into the interlayer shear characteristics of 2D nanomaterials. 相似文献
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A.J. ShawP.D. Gosling 《Mechanics Research Communications》2011,38(6):463-467
A mathematical model to quantify the variation of the displacement field through the thickness of a laminated shell has been proposed previously by Beakou and Touratier (1993). Transverse shear deformations were taken into account and thickness correction factors were not required but the analysis was restricted to shallow shells (i.e. the principal radii of shell curvature were both assumed to be large relative to the shell thickness). In this technical note the later restriction is removed by replacing the Cartesian coordinate form of elasticity tensor with the more general curvilinear form. The modified laminate level model coefficients are derived from the expressions for the curvilinear transverse shear stress components by: applying zero transverse shear stress boundary conditions at the top and bottom of the shell and enforcing interlayer layer continuity at each internal lamina interface. The purpose of this model enhancement is to facilitate the development of a degenerate finite element type that can be used to compute the deformation of a non-shallow laminated shell. 相似文献