共查询到20条相似文献,搜索用时 156 毫秒
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对泰勒斯低温技术公司线性斯特林制冷机的发展现状进行总结.分别对其线性斯特林制冷机压缩机技术发展、膨胀机技术发展、膜片弹簧设计原则和可靠性增长等方面进行了总结. 相似文献
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Helical springs constitute an integral part of many mechanical systems. Usually, a helical spring is modelled as a massless, frequency independent stiffness element. For a typical suspension spring, these assumptions are only valid in the quasi-static case or at low frequencies. At higher frequencies, the influence of the internal resonances of the spring grows and thus a detailed model is required. In some cases, such as when the spring is uniform, analytical models can be developed. However, in typical springs, only the central turns are uniform; the ends are often not (for example, having a varying helix angle or cross-section). Thus, obtaining analytical models in this case can be very difficult if at all possible. In this paper, the modelling of such non-uniform springs are considered. The uniform (central) part of helical springs is modelled using the wave and finite element (WFE) method since a helical spring can be regarded as a curved waveguide. The WFE model is obtained by post-processing the finite element (FE) model of a single straight or curved beam element using periodic structure theory. This yields the wave characteristics which can be used to find the dynamic stiffness matrix of the central turns of the spring. As for the non-uniform ends, they are modelled using the standard finite element (FE) method. The dynamic stiffness matrices of the ends and the central turns can be assembled as in standard FE yielding a FE/WFE model whose size is much smaller than a full FE model of the spring. This can be used to predict the stiffness of the spring and the force transmissibility. Numerical examples are presented. 相似文献
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Finite element mapping for spring network representations of the mechanics of solids 总被引:1,自引:0,他引:1
Gusev AA 《Physical review letters》2004,93(3):034302
We present a general finite element mapping procedure for defining spring network representations of solid mechanics. The procedure is rigorous and equally suitable for setting regular and unstructured spring network models of generally anisotropic solids. We use the procedure to define close-packed triangular and simple cubic lattice spring models of isotropic 2D and 3D elastic media, respectively. We extend the study to heterogeneous solids and show that the mapped spring network approach constitutes an appealing route for incorporating subelement level constitutive equations. 相似文献
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���˴ϣ�Ƚ �죬������� �����α���� �� 《核聚变与等离子体物理》2018,38(2):192-198
参考ITER真空室制造规范,在常温下对中国聚变工程实验堆(CFETR)真空室壳体成型进行工艺预研。先根据成型经验公式计算出所研究壳体的成型模具尺寸范围,再利用有限元软件选择3组公式值附近的尺寸模拟了该成型工艺最佳模具尺寸参数,分析出最佳型面尺寸误差在±1.5mm内,并以此指导成型实验。测试了成型实验后工件减薄量、回弹量、变形率等参数,与模拟分析结果吻合度较高,验证了该成型模具设计的合理性。 相似文献
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A finite element formulation is employed to obtain the linear and non-linear frequencies of orthotropic circular plates with elastically restrained edges. Results are presented in the form of linear frequency parameters and ratios of non-linear to linear periods for several values of the spring constants, orthotropy parameter and central deflections. 相似文献
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Superconducting turbogenerators with a “double rotor structure” have a torsional natural frequency within the generator, the outer rotor moving in opposition to the inner rotor. For large machines this natural frequency may approach 100 Hz. In this paper a finite element model and simple lumped mass and spring models of the rotor, for the calculation of the undamped torsional natural frequencies, are described and compared. A method by which equivalent spring stiffnesses for both the inner and outer rotors can be derived is described, allowing one to use a rotor model with one lumped mass and equivalent spring stiffness for each of the inner and outer rotors. Such a rotor model can be readily used for studying electromagnetic interaction effects and assessing fault torques in the outer rotor and inner rotor torque tubes. 相似文献
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FUNDAMENTAL FREQUENCY OF CRACKED BEAMS IN BENDING VIBRATIONS: AN ANALYTICAL APPROACH 总被引:1,自引:0,他引:1
J. FERNÁNDEZ-SÁEZC. NAVARRO 《Journal of sound and vibration》2002,256(1):17-31
This paper presents an analytical approach to the fundamental frequency of cracked Euler-Bernoulli beams in bending vibrations. The flexibility influence function method used to solve the problem leads to an eigenvalue problem formulated in integral form. The influence of the crack was represented by an elastic rotational spring connecting the two segments of the beam at the cracked section. In solving the problem, closed-form expressions for the approximated values of the fundamental frequency of cracked Euler-Bernoulli beams in bending vibrations are reached. The results obtained agree with those numerically obtained by the finite element method. 相似文献
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G. Zen 《Journal of sound and vibration》2006,289(3):551-576
The dynamic response of an axially translating continuum subjected to the combined effects of a pair of spring supported frictional guides and axial acceleration is investigated; such systems are both non-conservative and gyroscopic. The continuum is modeled as a tensioned string translating between two rigid supports with a time-dependent velocity profile. The equations of motion are derived with the extended Hamilton's principle and discretized in the space domain with the finite element method. The stability of the system is analyzed with the Floquet theory for cases where the transport velocity is a periodic function of time. Direct time integration using an adaptive step Runge-Kutta algorithm is used to verify the results of the Floquet theory. This approach can also be employed in the general case of arbitrary time-varying velocity. Results are given in the form of time history diagrams and instability point grids for different sets of parameters such as the location of the stationary load, the stiffness of the elastic support, and the values of initial tension. This work showed that presence of friction adversely affects stability, but using non-zero spring stiffness on the guiding force has a stabilizing effect. This work also showed that the use of the finite element method and Floquet theory is an effective combination to analyze stability in gyroscopic systems with stationary friction loads. 相似文献
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The dynamic contact problem of a tensioned beam with clamped-pinned ends is analyzed when the beam contacts a moving mass–spring system. The contact and contact loss conditions are expressed in terms of constraint equations after considering the dynamic contact between the beam and the moving mass. Using these constraints and equations of motion for the beam and moving mass, dynamic contact equations are derived and then discretized using the finite element method, which is based on the Lagrange multiplier method. The time responses for the contact forces are computed from these discretized equations. The contact force variations and contact loss are investigated for the variations of the moving mass velocity, the beam tension, the moving mass, and the stiffness of the moving mass–spring system. In addition, the possibility of contact loss and safe contact conditions between the moving mass and the tensioned beam are also studied. 相似文献