The spot welding structure that is based on mode experiment is limited of yuan of model build reach amend
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1 least square answer the development course that the analysis experienced mode of experiment of brief introduction of frequency domain law a few years, spend development for much freedom from odd freedom, by odd input only output development is much input to be outputted more, by local estimation development is integral estimation, new method emerges in endlessly. The least square that uses extensively at present answer exponential law (PolyLSCE, abbreviation LSCE) with law of least square frequency domain (LSFD) , can have tackled problem of major mode parameter identification, but interference rejection ability is poorer, to believing the data of ratio of a confusion of voices, stable state pursues more disorder. To solve above problem, the professor such as university AUWERAER of Belgian Lu Wen and GUILLAUME puts forward least square answer frequency domain law (Least Squares Complex Frequency Domain Method, abbreviation LSCF, commercial name is PolyMAX) , introduce model of disperse time frequency domain, used the operation skill of fast recurrence, have a lot of advantages than the method previously. Because have better interference rejection ability, stable state,pursue clear and clean, it is at present accepted optimal experiment mode analyses one of methods [2] . 3.
This experiment uses 2 experiments position only place is stimulated brace up structure of some spot welding undertakes the satellite with many bits of Shi Zhenfang suspensory to flexibility law mode analysis, omit important mode of the structure for guarantee against, many drive chose to nod hand-in-hand travel on the structure the drive of many direction. The mode computation result according to initiative model is decorated in the add up to on the structure measure a place 66, measure a dot to if the graph is shown 4 times,arrange a plan. The SCADS-X III that the experiment uses Belgian LMS firm and software of Test Lab 9B collect system and analytic software as data. Graph 4 measure a dot to arrange a plan 3.
3 tests result uses PolyMAX method to answer function to frequency from 0 undertake to 1000Hz mode analysis can get some measures bit of stable state to pursue 5. Graph stable state of 5 mode vibration shape pursues Nextpage pursues to all stable state undertake an analysis, before summing up what exist possibly 10 rank if natural frequency expresses 2 to show: The commonly used method that has test and verify as a result to mode analysis is mode decides criterion (MAC is worth) , use at comparing the consistency of vibration shape. It two mode relevant degree with [0, a numerical value between 1] expresses: MAC value is more adjacent 1 those who express two mode vector is relevant degree taller, be equal to when MAC 1 state both linear is relevant, be equal to 0 to state linear has nothing to do. Before this experiment 10 rank value of vibration shape MAC is shown 6 times like the graph, blame advocate yuan maximum is 8.
5, make clear each rank sex of vibration shape orthogonality is better. If typical mode vibration shape pursues 7- graph is shown 9 times. Graph 6 before 10 rank vibration shape MAC is worth 3.
4 will experiment quite as a result with initiative computation result and finite yuan computation undertakes comparative as a result, if the watch shows 3 times: By more knowable: Have 3 in all rank mode forecasts an error to exceed project precision to ask -- 5% , the biggest error is 18% ; Calculate a result with chronometer the 7th rank, the 9th rank did not appear in test result, the reason that analyses a likelihood has two: (1) trial error. Do not have in the experiment this two rank mode is aroused come, caused mode losing; (2) emulation error. Be built finite yuan of feature that the model did not reflect a structure well and truly, caused mode to spill over. In considering initiative model, did to spot welding simplify processing, be opposite then the correction of the model very be necessary. 4. Finite yuan the model amends reach result analysis to have 3 kinds commonly usedly about spot welding model: (1) Chan Liang model. The component join that the positional part that it orders in solder uses one flexibility or rigid bridge will be soldered rises, perhaps will decorate the node that is in in dot of the solder on two weldment to incorporate directly have connective objective thereby. (2) ACM2 model. This model is in two weldment by perpendicular at be being soldered hexahedral unit of the surface parts to be comprised at join of appearance of two substance be solderinged through RBE3 unit. (3) CWELD model. This solder orders a model by have specific cut unit of flexible Tie Maxin Ke Liang to form, on two solder side that unit node is located in bridge to be soldered respectively [3] . This Nextpage anthology uses the most commonly used CWELD model, the method building a model that if the graph is shown 10 times,uses, after amending finite if yuan of model pursues 11 are shown. Graph 10 CWELD builds modular method to pursue 11 after amending finite yuan of model to examine solder nucleus dimension is opposite the influence of mode, here chose dimension of nucleus of 3 kinds of solder to have consideration, if the contrast with test result expresses 4 to show. By contrast knowable, solder nucleus size is more distinct to the influence of mode. Forecast frequency as solder nucleus diameter reduce and reduce, and be close to actual measurement frequency more and more, forecast precision to be with the model of 1mm of solder nucleus diameter among them highest, before 6 rank of mode frequency the biggest forecast an error by original 18% fell 8.
2% . The likelihood in considering an experiment puts the error that be in, of the 1mm of solder nucleus diameter after the article thinks to amend finite yuan of model precision is contented project requirement, can use effectively adumbrative satellite the trends of structure of some spot welding is answered. 5. Conclusion the article is integrated experiment of finite Yuan Jianmo, mode and model are amended wait for relevant job, obtained finally to forecast precision taller finite yuan of model. Summarize afore-mentioned works, gotten main verdict is as follows: (1) use mode experiment to be opposite finite yuan the model undertakes repairing acquisition high accuracy just about finite the effective method of yuan of model. Use LMS Test.
Lab system will do mode test, the operation is convenient and quick, the result is accurate and reliable. (2) the volume of dimension of nucleus of the solder in spot welding model is more remarkable to the influence of block mould condition, mode frequency as solder nucleus diameter reduce and reduce. (3) the article considered his only to spot welding model the impact of solder nucleus measure to block mould condition, the action area of CWELD unit remains to study further to the influence of mode. Remain to study further about the applicable circumstance of 3 kinds of models of spot welding and the comparison that forecast precision at the same time. CNC Milling