1、翻译部分英文原文Research on Dynamic Characteristics of EllipticalVibrating ScreenAbstractWith the screening equipment becoming larger and larger, more and more people are paying attention to the dynamic characteristics of large-scale vibrating screen. The paper utilizes finite element software ANSYS to carr
2、y on modal analysis and dynamic stress analysis of 3175 elliptical vibrating screen, and finds out the dynamic stress distribution and modal parameters. The paper puts forward concrete modal revision plan on resonance risk. After optimization, the structure can satisfy the modal, dynamic and kinemat
3、ical needs. Keywords-elliptical vibrating screen; modal analysis; dynamic stress analysis; modal modificationI. INTRODUCTION Elliptical vibrating screen integrates the advantages of circular vibrating screen and linear vibrating screen which has the best loose strength and strong transmission capaci
4、ty widely used in many fields, such as metallurgy, mine, oil, chemical industry etc. Many scientists have exploited a variety of elliptical screening equipment according to spot application features 1 2 3.With the development of the computer, finite element method provides an effective way to solve
5、the strength of complicated structure 7 8.3175 elliptical screen is taken as the research object, and the paper analyzes the structural mode and stress distribution of the screen box, and proposes an improvement program on the structure based on finite element analysis software ANSYS78.II. SIMPLIFIC
6、ATION AND ESTABLISHMENT OF MODELThe simulation model in finite element analysis must represent the physical prototype and properly simplify the structure. Model in the paper mainly refers to geometry modeling, nodes and elements generating. Concrete modeling must consider factors as follows: All cha
7、mfers, fillets, rivets and welding spots are ignored which are not the major factors in the paper. Because the screen box is made up of riveting/welding steel plates, the paper uses shell element SHELL18 to plot the major structure and controls grid size as 80mm (sifter dimension 3100mm750
8、0mm); Spring element COMBIN14 is used to plot the spring; and mass element MASS21 is used to plot mass point on behalf of the excitation box, the big and small eccentric blocks. Considering the actual installation of excitation box,the paper uses regional rigidization method to connect mass element
9、with the installation surface of vibration exciter rigidly.The finite element analytical model of vibrating screen is shown in Fig. 1.Figure 1. Finite element analytical model of 3175 vibrating screen boxIII. LOAD HANDING The four exciting forces generated by eccentric blocks driven by motor are for
10、ce vectors changing with the sine rule,ends of whose track are round, so the paper can utilize harmonic response analysis in ANSYS to solve the question. Defining a complete harmonic loads needs to input three pieces of information: amplitude, phase angle and forcing frequency range. ANSYS harmonic
11、response analysis needs to decompose harmonic load into real part and imaginary part,and load them separately. The computational formulas of real part and imaginary part are shown in Fig.2. Figure 2. the computational formulas of real part and imaginary partAccording to excitation principle of force
12、d synchronous elliptical vibrating screen, in combination with Fig.3, two exciting forces generated by eccentric blocks are set as 1 F and 2 F respectively which have no changes in size and rotatearound their center doing the reverse isokinetic rotation. 1 F and 2 F are projected to x and y axis, an
13、d x F1 x F2 y F1 y F2 change with sine/cosine rule. The paper converts the four forces into sine form and calculates corresponding real part and imaginary part based on harmonic analysis loading method.Figure 3. exciting forcesThe specific calculations are as follows: Centrifugal inertial force gene
14、rated by two eccentric blocks: F 2m r 2 2 74 0.153 77.492 135864N 1 1 1 = = = (1) F 2m r 2 2 47 0.120 77.492 67680N m ,m mass of the big and small eccentric blocks, everyvibration exciter has two eccentric blocks rotational velocity 1 2 r , r eccentricity of two eccentric blocks The forces are decom
15、posed in orthogonal wayF does clockwise rotation relative to coordinate system,and initial phase angle is located in negative semi-axis of x axis in coordinate system as is shown in Fig. 3. Therefore, the paper must reverse x-axis in nodes coordinate system of 1 F operational nodes, and then decompo
16、se two exciting forces toward x and y direction in their coordinate system. The formulas of transforming every force into sine form are as follows:Inside = 79phase difference angle of two eccentric blocks The forces are decomposed into real part and imaginary partThe starting time is set t = 0, then the real part and ima
