船形高频腔壳体成型工艺研究

大功率质子束加速器广泛应用在基础物理、核工业、家庭安全等领域，其中大功率波导型射频腔极为重要。船形射频腔具有最高的空载Q值和分流阻抗，是GeV质子束加速器的良好选择。船形铜射频腔体的制造，主要难点在于腔体复杂轮廓壳体的成型，为此，本文对其进行了详细的成型工艺研究。通过PAM-STAMP 2G仿真分析软件对高频腔壳体进行了模压成型数值模拟，分别分析了椭圆弧成型过程中壳体的减薄量、残余应力以及成形回弹，为实际模压成型提供了理论依据。根据模拟结果设计的高频腔椭圆壳体成型模具能够成功实现椭圆弧的实际模压成型。     

金属结构胶粘剂在鱼雷产品上应用的探讨

对鱼雷壳体试图采用胶接结构代替焊接结构,以减轻劳动强度和减少壳体变形,进行了模拟结构试验及实雷试验。模索了表面处理、接头型式对胶接结构性能影响。并进行了胶接疲劳及模拟壳体的冲击、振动、水压、气密等各项性能试验。     

燃料电池车用漩涡风机壳体辐射噪声数值预测

数值模拟燃料电池车用旋涡风机壳体的结构振动辐射噪声。首先给出燃料电池车上旋涡风机运行时振动噪声测量结果,然后使用Fluent模拟风机内部三维非定常流场,将作用在壳体表面的非定常力加载到壳体模型,使用Nastran对壳体进行动力响应计算,实现气体到结构的单向耦合。接着使用Virtual. Lab模拟风机壳体振动向外辐射的噪声,将试验测量和数值计算结果进行对比,表明此方法能够较为准确地模拟壳体的振动辐射噪声。最后采用这一方法研究散热片及结构阻尼对风机振动辐射噪声的影响。结果表明：无散热片以及增大结构阻尼系数可以降低漩涡风机壳体辐射噪声。     

单曲率多面壳体高温胀形制造球形容器工艺

提出单曲率多面壳体高温胀形制造球形容器工艺的基本思想。对内切球面直径为μ420mm,壁厚为1．2mm的低碳钢单曲率多面壳体加热到胀形温度时的温度场进行了测量,对壳体的高温胀形成形过程进行了数值模拟。壳体加热结果表明,其温度场的最大温差值为80℃,数值模拟结果表明,在壳体壁的最高温度与最低温度相差达80℃时,单曲率多面壳体可以成形为球形容器。     

TC4薄壁壳体真空等温成形研究

对TC4合金薄壁壳体真空等温成形进行数值模拟,根据模拟结果进行真空等温成形试验。以传统热冲压成形的壳体及TC4原始板材为对比,分析了真空等温成形壳体的力学性能、微观金相和杂质元素含量。结果表明,相比热冲压成形,真空等温成形的TC4合金薄壁壳体的H元素含量降低83%,O元素含量降低55%;力学性能良好,延伸率提高了50%;金相组织为均匀的等轴组织。     

纤维缠绕复合材料壳体原位成型工艺研究

热固型缠绕复合材料壳体以其优异的性能在航空、军事和工业等领域得到了广泛应用.目前,制约其应用和发展的主要瓶颈是壳体的成本和性能,而壳体成型工艺直接决定了其最终性能和成本.由于缠绕壳体为中空结构,因此可以采用加热壳体内部金属芯模或内衬的方法实现缠绕后的或正在缠绕的复合材料的固化成型,即原位成型.本文介绍复合材料壳体原位成型新工艺,建立筒型壳体内加热固化过程的数学模型,利用有限元法对筒体固化过程中的温度和固化度进行了数值模拟分析.该研究为实现壳体高效、优质且低成本成型提供新思路,为原位成型工艺设计、模拟和参数优化提供分析模型和方法.     

不同参数对压缩机壳体噪声辐射的数值分析

压缩机的噪声辐射是通过壳体的振动辐射出去,为了降低压缩机的噪声,并进一步优化壳体的声学特性,利用数值模拟方法,在合理简化模型的基础上,进行了壳体模态分析。然后,研究不同的参数(泵体支撑方式,集中力作用方向,壳体形状、厚度和阻尼)对壳体噪声辐射的影响,给出有效降低壳体噪声辐射的方法,其分析结果给压缩机壳体的设计与优化提供重要的参考依据。     

不锈钢球壳无模液压胀形过程的有限元模拟

用弹塑情限元对不锈钢球壳液胀形过程进行了数值模拟，给出了胀形过程中壳体外形和焊变化规律，分析了应力应变及残余应力分布规律，并与试验结果进行了比较。     

带壳装药爆炸毁伤混凝土的数值模拟

为研究壳体对混凝土毁伤效果的影响规律,运用AUTODYN-2D对裸装药和不同厚度钢壳装药爆炸毁伤混凝土进行了数值模拟,结果表明,裸装药爆炸毁伤混凝土后的有效破坏区半径R2值比薄壳体时的小,但比较厚钢壳体时的大,这与试验结果吻合.壳体的存在对于最终毁伤效果的影响,视钢壳体的厚度而定.     

双孔壳体正反挤压成形工艺

目的设计双孔壳体成形工艺方案,生产出合格产品。方法运用数值仿真方法,模拟双孔壳体成形过程,分析其成形趋势、应变图和应力图等,为工艺设计提供理论支撑。结果通过模拟仿真计算,优化和验证了双孔壳体挤压工艺方案的可行性和合理性。结论通过工艺方案分析、有限元模拟计算,确定了双孔壳体最终成形方案,并且制作出了合格的产品。     

复合材料夹层板壳一种等效分析方法

本文研究了复合材料夹层板壳的一种等效分析方法,首先由壳体理论导出了夹层板壳的内力和位移表达式,通过与各向异性单层板壳理论的比较,提出了二者等效的条件,从而把夹层板壳问题简化为一个等效各向异性单层板壳问题,这用有限元法很容易求解,并对一个工程实例进行了计算,证实了该方法的有效性。      

复合材料夹层板壳一种等效分析方法

本文研究了复合材料夹层板壳的一种等效分析方法,首先由壳体理论导出了夹层板壳的内力和位移表达式,通过与各向异性单层板壳理论的比较,提出了二者等效的条件,从而把夹层板壳问题简化为一个等效各向异性单层板壳问题,这用有限元法很容易求解,并对一个工程实例进行了计算,证实了该方法的有效性。     

Simulations of thermomechanical behavior of composite refractory linings

The wall of refractorized vessels are composites, made of metallic casing often containing tubes and a refractory material for the protection against the high temperature environment. The objective of the present paper is to model a two layer shell with a thermomechanical behavior equivalent to those of the 3D lining and that render possible the finite element analysis of the complete vessel. A smeared crack model is used for the damage analysis of the refractory material. The equivalent shell is made up of an exterior orthotropic layer and an interior isotropic damageable layer. The set of thermal and mechanical parameters of the equivalent shell is obtained by an inverse method in conjunction with finite element analyses of the 3D panel subjected to an appropriate set of loadings. Some validation analyses show that the identified parameters lead to shell behavior, which is in good agreement with those of the 3D wall. In the case of a simplified cyclone, it is shown that the equivalent shell permits to compute the thermomechanical behavior of a complete refractorized vessel and especially to follow the damaged zones of the refractory.     

Optimum design for buckling of plain and stiffened composite axisymmetric shell panels/shells

The buckling of plain and discretely stiffened composite axisymmetric shell panels/shells made of repeated sublaminate construction is studied using the finite element method. In repeated sublaminate construction, a full laminate is obtained by repeating a basic sublaminate, which has a smaller number of plies. The optimum design for buckling is obtained by determining the layup sequence of the plies in the sublaminate by ranking, so as to achieve maximum buckling load for a specified thickness. For this purpose, a four-noded 48-dof quadrilateral composite thin shell element, together with fully compatible two-noded 16-dof composite meridional and parallel circle stiffener elements are used.     

Finite element analysis of contact–impact between a shell of revolution and a rigid wall

In this paper an attempt is made to use a shell theory that includes transverse normal stresses to study the contact–impact behaviour involving thick shells. The problem is solved using the finite element method. The contact criterion is imposed by means of displacement and force constraints. The Lagrangian multipliers technique is used to impose these constraints. The case of a spherical shell impacting a rigid wall with a constant velocity is considered for the analysis. It is shown that the method produces accurate results with less amount of computation than the usual three-dimensional analyses. The effects of the thickness of shell, velocity of impact and modulus of the material are studied.     

复合材料大变形任意加筋壳单元

构造了用于复合材料偏心加筋壳形结构大变形分析的任意加筋壳单元。在此模型中,肋骨连同壳的整体被视为一个单元偏心加筋壳单元。肋骨可放在壳单元内的任意位置和任意方向。所构造单元的特点是在网格划分时,可不必考虑肋骨的位置,这就给网格划分带来了很大的灵活性。在壳和肋骨的方程中,引用Von-Karman大变形理论计及几何非线性的影响,按照Mindlin-Reissner一阶剪切变形理论考虑横向剪切变形。     

圆柱壳在水下爆炸载荷下的流-固耦合响应分析

研究了无限域流场中两端简支圆柱壳受球形炸药爆炸冲击载荷作用的响应特性。运用Hamilton变分原理,推导出了考虑流固耦合作用圆柱壳受水下爆炸冲击载荷作用的运动方程,并分别展开成Fourier级数的形式,最后在时域上差分离散,用Galerkin方法求解,得到了在水下爆炸冲击载荷下圆柱壳的响应分析。文章着重就圆柱壳在迎爆面和背爆面的不同位置的变形位移和变形速度进行了对比分析,同时还比较了流体动压力对结构响应的影响。并将分析结果与有限元计算软件MSC.DYTRAN计算结果比较,验证了算法的可靠性。     

Two refined non‐conforming quadrilateral flat shell elements

Two refined quadrilateral flat shell elements named RSQ20 and RSQ24 are constructed in this paper based on the refined non‐conforming element method, and the elements can satisfy the displacement compatibility requirement at the interelement of the non‐planar elements by introducing the common displacements suggested by Chen and Cheung. A refined quadrilateral plate element RPQ4 and a plane quadrilateral isoparametric element are combined to obtain the refined quadrilateral flat shell element RSQ20, and a refined quadrilateral flat shell element RSQ24 is constructed on the basis of a RPQ4 element and a quadrilateral isoparametric element with drilling degrees of freedom. The numerical examples show that the present method can improve the accuracy of shell analysis and that the two new refined quadrilateral flat shell elements are efficient and accurate in the linear analysis of some shell structures. Copyright © 2000 John Wiley & Sons, Ltd.     

铸轧辊套热膨胀及热应力的有限元分析

本文在利用已有的有限差分法求解获得铸轧辊辊套温度场的基础上,采用有限元法分析了铸轧辊辊套相应的热变形和热应力。获得了热变形结果,以及在铸轧辊中产生的各种应力情况,其中第四强度理论的最大相当应力为703.7MPa,所得结果有助于解释辊套为何需采用用高强度钢材。     

Degenerated shell element with composite implicit time integration scheme for geometric nonlinear analysis

A degenerated shell element with composite implicit time integration scheme is developed in the present paper to solve the geometric nonlinear large deformation and dynamics problems of shell structures. The degenerated shell element is established based on the eight‐node solid element, where the nodal forces, mass matrices, and stiffness matrices are firstly obtained upon virtual velocity principle and then translated to the shell element. The strain field is modified based on the mixed interpolation of tensorial components method to eliminate the shear locking, and the constitutive relation is modified to satisfy the shell assumptions. A simple and practical computational method for nonlinear dynamic response is developed by embedding the composite implicit time integration scheme into the degenerated shell element, where the composite scheme combines the trapezoidal rule with the three‐point backward Euler method. The developed approach can not only keep the momentum and energy conservation and decay the high frequency modes but also lead to a symmetrical stiffness matrix. Numerical results show that the developed degenerated shell element with the composite implicit time integration scheme is capable of solving the geometric nonlinear large deformation and dynamics problems of the shell structures with momentum and energy conservation and/or decay. Copyright © 2015 John Wiley & Sons, Ltd.