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排序方式: 共有276条查询结果,搜索用时 9 毫秒
71.
72.
针对现有的附着式升降脚手架防坠落装置存在的不足,根据脚手架的结构和安装位置,设计了一种基于速度控制的制动机构——异型卡式防坠落装置.该防坠落装置主要构件是异型卡子和多爪转子,异型卡子具有独特的形状结构.当脚手架慢速提升和下降时,多爪转子作逆时针或顺时针转动,而异型卡子仅小幅摆动;当脚手架急速坠落时,多爪转子与异型卡子互... 相似文献
73.
对膜片联接的齿轮传动多跨转子系统进行了故障动态特性仿真研究.利用ANSYS有限元分析软件进行建模、仿真,根据在裂纹和碰摩故障工况下单跨转子与整个转子系统的固有频率在弯扭耦合振动下的变化情况,研究了系统的非线性动态特性和响应,以及膜片联轴器与齿轮对转子系统的影响.研究结果表明,此种情况下发生的故障对故障跨的影响比其余跨大;膜片联轴器和齿轮能够削弱或阻隔弯曲振动及裂纹故障对系统的不利影响,有助于故障诊断的定位与维修,也为产品设计提供参考. 相似文献
74.
Computation and asymptotic analysis in the impact problem 总被引:1,自引:0,他引:1
Non-linear numerical method is applied to solve the viscous-elastic-plastic material impact problem. The finite element simulation
agrees with the celebrated European crash safety analysis. The complex material stress distribution in the large deformation
has been obtained, when the impact happens. Also the posteriorestimate solver and asymptotic analysis have been used for the
sensitive pre-stage deformation before the impact happening. This part of simulation is very interesting for the passive safety
in automotive protection devices. It is an important part of the mathematical modelling.
Supported by the National Natural Science Foundation of China (No. 10871225), Partly supported by EInstitutes of Shanghai
Municipal Education Commission, N.E03004; Partly supported by Shanghai Pu Jiang Telent project [2006]118. 相似文献
75.
Dimos J. Polyzois Ioannis G. Raftoyiannis 《Archive of Applied Mechanics (Ingenieur Archiv)》2009,79(4):347-358
This paper presents a semi-analytical finite element analysis of pole-type structures with circular hollow cross-section.
Based on the principle of stationary potential energy and Novozhilov’s derivation of nonlinear strains, the formulations for
the geometric nonlinear analysis of general shells are derived. The nonlinear shell-type analysis is then manipulated and
simplified gradually into a beam-type analysis with special emphasis given on the relationships of shell-type to beam-type
and nonlinear to linear analyses. Based on the theory of general shells and the finite element method, the approach presented
herein is employed to analyze the ovalization of the cross-section, large displacements, the P-Δ effect as well as the overall
buckling of pole-type structures. Illustrative examples are presented to demonstrate the applicability and the efficiency
of the present technique to the large deformation of fiber-reinforced polymer composite poles accompanied with comparisons
employing commercial finite element codes. 相似文献
76.
R. J. Windslow 《Soft Materials》2019,17(3):228-240
ABSTRACTThe viscoelastic behavior of elastomers manifests itself in numerous ways depending on the application. In seals, the viscoelastic response of an elastomer is complex as it depends upon the specific combination of loading pressures, loading rates, chemical environment, temperature and time of loading, and ultimately long-term effects such as creep or stress relaxation can result in seal failure. One specific mechanism encountered in seals under large pressures is extrusion damage. When a seal is pressurized by a fluid, the elastomer is highly constrained; however, there is typically a very small gap between the inner and outer sealing surfaces. Over time viscoelastic creep causes the elastomer to gradually extrude into this gap until the seal ruptures. In this paper the viscoelastic creep behavior of a typical sealing elastomer, NBR, was studied. Compression creep tests were carried out over a range of strains and the measured data were used to develop a strain-dependent viscoelastic material model. The model was then implemented into a finite element analysis (FEA) simulation to study the extrusion creep behavior of an O-Ring seal. Data from the FEA model were then compared against physical test data from equivalent extrusion tests. The FEA model correlated well to the physical test data, with the strain-dependent viscoelastic material model allowing compression creep data to be used to accurately predict extrusion creep. 相似文献
77.
利用ANSYS参数化编程语言APDL建立受电弓弓头三维有限元分析模型、编制了循环加载及求解程序,模拟列车行车过程中滑板与接触线滑动接触受流.分析了滑板温升的基本规律,研究了各热源对滑板温升的影响,对比了不同材料时滑板的温升情况. 相似文献
78.
在纵、弯复合模态直线超声电机的基础上,提出并试制了一种新型的直线超声电机。通过解析法确定振子两侧直梁的长度和厚度范围;完成了H形振子的结构设计,确定了振子的柔性支撑方案。利用ANSYS软件对H形压电振子进行了优化设计。根据优化设计结果,试制了原理样机。实验结果表明:振子的实测谐振频率与有限元计算结果有一定的偏差。实测的频率比有限元计算值要低,其原因是在测试时,振子的边界条件与有限元计算时相比发生了变化。 相似文献
79.
Xiwen Jia Zihui Xia Bohong Gu 《International Journal of Solids and Structures》2013,50(22-23):3539-3554
Three-dimensional (3D) textile composites have great potential applications to aircrafts and high speed vehicles because of the high strength/weight ratios and the capabilities of manufacturing complex, net-shape preforms. This paper reports the nonlinear viscoelastic responses and damage mechanisms of one kind of 3D textile composites, named as 3D orthogonal woven composite (3DOWC) under quasi-static tensile loading based on a micro/meso-scale repetitive unit cells (RUCs) model. In the RUCs model, the resin is described with a nonlinear viscoelastic material and the fibers/tows with an elastic material. The damage initiation and propagation in resin are simulated by the post-damage constitutive models with maximum principal theory failure criteria. The fibers/tows impregnated with resin are defined by elastic transverse-isotropic material model with ultimate strengths failure of ‘expanded smeared crack’ both along and perpendicular to fibers/tows axis direction. The engineering parameters and ultimate strengths of homogenized fibers/tows filled with matrix in meso-RUCs model are transferred from the numerical analysis of the micro-RUCs. The results are compared with experimental and theoretical values of RUC deformation and damage initiation and propagation under monotonic axial loading. The methodology of establishing the nonlinear visco-elastic multi-scale model of 3D textile composites without introducing the real fabric architecture in finite element analyses is explained. With the multi-scale RUCs model, the mechanical behaviors of other kinds of 3D textile composites can also be predicted. 相似文献
80.