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Experimental Modal Analysis of Fan Vibration Frequency Lijun Wang 1, a, Zhiyang Pan1,b 1 College of Engineering,Northeast Agricultural University, Harbin 150030, China a wljszf@163.com, b356816982@qq.com Keywords: Threshing prior to cutting, Combine harvester, Fan, Vibration frequency,Experimental modal analysis Abstract: Fan is used for pneumatic conveying grain in the 4ZTL-1800 combine harvester threshing prior to cutting.
Its basic function is to separate cells, short stems and other miscellaneous materials from grain when they come from the preliminary cleaning system.
Inlet diameter is 348 mm, Outlet size is 222×372mm, Type of impeller is centrifugal, Type of blade is straight, Number of blade is 6.
Acknowlegments This work was financially supported by the Supporting Plan Project for Youth Scholar Backbone of General Universities of Heilongjiang Province（1251G011）, Science Start-up Supporting Project for Doctor to Settle Heilongjiang Province（LBH-Q10147） References [1] Enchen Jiang: A Stripping Unit and Pneumatic Conveying System for Grain Harvesting.

Introduction The strength of metallic materials is improved by grain refinement and this has been well described by the Hall Petch relationship [1, 2].
Many studies have shown that ultra-fine grain sizes, in the submicrometer or even nanometer range, may be achieved by imposing extremely large plastic strains through processing by severe plastic deformation (SPD) [3-6].
Finite Element Analysis The grain refinement in ECAP is dependent on the accumulated stresses in the final work piece through multipass ECAP.
Results and Discussions: 4.1 Load measurements: The maximum load required for ECAP is plotted against the number of pressing in Fig 1.
The hardness values first decreased and then gradually increased with increasing number of passes.

The rare earth has no obvious influence on coating grain and spangle size.
Numerous research results show that the addition of appropriate rare earth would be helpful to improve the flowability of Zn-5%Al bath, purify the bath, refine the coating grain and enhance corrosion resistance and so on [1-2].
Table1 Target bath component % Sample number RE Si Al Zn 00 0.00 1.55 54.37 44.08 08 0.08 1.54 54.11 44.24 12 0.12 1.55 54.17 44.25 16 0.16 1.55 54.23 44.25 22 0.22 1.55 54.13 44.11 Experiment Method.
It indicates that the grain of coating was not refined by the addition of rare earth in this experimental condition.
The grain of coating was not refined by the addition of rare earth

The flank wear of CBN inserts were measured after predetermined number of passes.
Scanning electron microscopy images show that on the flank surface of the tool small holes appear in such places that were previously occupied by CBN grains, which show that the CBN grains pluck out from the tool surface due to adhesive wear.
Thanks to the plucking out the edge of tool is continuously renewed during cutting, because from the deeper layers of flank wear land sharp grains come into the surface continuously [4, 7].
During the cutting after a predetermined number of passes optical microscopy images were made with Zeiss discovery V8 optical microscope of the worn flank surface and edge chamfering and the flank wear of cutting inserts were measured.
Szabó, Stability Criteria and Break out of Grains of Super-Hard of Grinding Tools, Journal of Materials Processing Technology.

Although the CrMoV steel has a certain degree of reheat crack trend, it possibly happens only under coarse grain and high tensile stress whereas doesn’t happen with normal condition. 52MPa 39MPa Fig.5 Pipe-step model and its outer surface stress Table.1 Chemical composition analysis of the base metal Sample number Chemical composition（%） Element C Si Mn S P Cr Mo V Base metal near the crack 0.12 0.24 0.68 0.012 0.014 1.11 0.22 0.22 Weld seam near the crack 0.09 0.52 0.77 0.020 0.025 0.98 0.37 0.24 Metallurgical microstructure observation.
Observation showed that the crack originated at the melting line then propagated along coarse grain zone where lots of intergranular cracks were found.
Fig.6 Lots of cracks within coarse grain zone Fig.7 SEM of microcrack within coarse grain zone SEM observation.
It can be found from Fig.7 that the crack in coarse grain zone was transverse type and consists of a cluster of holes that form a macrocrack when connected.
Those cracks locate only within coarse grain zone and belong to reheat crack.

For produce a large number of micro-defects, which form large internal residual stress, it appears work-hardening and the hardness is high.
Recrystallization is a process of form new strain-free equiaxed grains through the formation and growth of crystal nuclei.
In a relatively short annealing time, although most of the residual stress within the organization has been eliminated, the recrystallization process has not completed, some of the grains still present orientation after deformation, which indicate that old distorted grains have not completely disappeared, as shown in Figure3(a).
This may be due to the increase in the size of grain with the time extended, and at the same time, the carbide that has been broken in organization began to grow up in ferrites.
It is indicate that when the sample in tension, plastic deformation is generated under the tensile stress, grains begin to slip and scalability has been greatly improved.

There is number of successful applications of fibre reinforced composites in automotive, aircraft, space and energetic industry [1-7].
The grains were approximately ten times bigger after the annealing and average grain size was around 500 nm.
Note that alumina grains are not present there anymore.
Elongated alumina grain is also marked as an example.
The main change can be seen in significant grain growth.

This mismatch causes the formation of a layer, which differs in depth and in the size of the formed grain.
Due to the inhomogeneity in the depth and due to the great number of the grain, the inhibition layer is destroyed selectively giving rise to an outburst formation of Fe-Zn phases (Fig. 2).
Number 1 refers to outburst formation.
Amongst them the diffusion of zinc through the inhibition layer combined with the precipitation of oxide at the grain boundary of the inhibition layer, seems to explain sufficiently the breakdown of the Fe2Al5 layer.
Number 1 refers o the ZnFe phases.

The irreversible trend increases as the number of the chlorine atoms decreases.
We attribute this inconsistency to the different structure of the grown diamond film, because the grain size of our deposited diamond film is much larger than that reported by Muna (about 50-100nm) [13].
The larger diamond crystal has less grain boundary formed mainly by sp2 phase, which evidently impacts the overpotential of the electrode.
So the slopes of the lines decrease as the Cl atom number in the benzene ring increases.
As the number of the chlorine atoms decreases, the reaction becomes more irreversible.

Analysis of the thermomechanical properties [8] indicates that a great number of oxide and carbide materials will crack at laser treatment.
Cobalt grains form a dendritic structure, which is typical for crystallization from melt.
The growing cobalt grains push carbide particles.
Finally, the carbides are left between the cobalt grains.
The number of the balls generally decreases with increasing the scanning velocity.