A Brief Discussion onCAEApplication of technology and multi axis tensile testing machine in automotive sealing products

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summary：This article mainly introducesRubber sealing products for automobilesThe development of CAE technology and the application of multi axis tensile testing machines in finite element analysis, through the combination of these two technologies, can fully utilize computer simulation selection, reduce costs and shorten research and development cycles, and orderly promote the realization of the ideal of "green cars".

keywords：Rubber sealing products; Finite element analysis;CAE； Isometric stretching

With the continuous development of automotive industry technology, especially with the increasing public attention to environmental issues, the demand for green new energy and green new materials in automobiles is growing rapidly,The concept of "green cars" has also deeply penetrated people's hearts, and the greening of the entire car inevitably requires the green transformation of all systems and components used in it^[1].

According to the "Automotive Sealing Strip IndustryAccording to the research report on the 11th Five Year Plan, each car needs to consume an average of about 70 meters of sealing strips^[2]Moreover, consumers have increasingly high demands for automotive sealing strips. In addition to excellent sealing and environmental isolation functions, relevant requirements have also been put forward for its comfort, decorative safety, durability, and environmental friendliness. This also requires more rational structural design and superior craftsmanship for future sealing strips

modernCAE technology has been widely applied in the research and design of various products, and can assist in defect analysis and quality improvement at the beginning of product design, becoming the mainstream design analysis method at present. Due to the complex assembly relationship of automotive seals, the product may experience significant deformation during use, making its engineering solution more difficult than typical products. utilizeCAE analysis and design of sealing strip structureandDeformation behavior under stress,canvia computersimulationAnalysis and verification of the stress and strain experienced by the sealing strip during the loading processandOptimize and improve the sealing stripknotStructure and Material DesignReduce research and development costs, shorten the research and development cycle, and improve the level of product manufacturing technology and production efficiency. In recent yearsUtilize relevant softwareSqueezingThe export modelrunner designandThe analysis of the noise isolation performance of sealing strips has begun to be applied.

At present, automotive sealing strips are mainly made of EPDM rubber（EPDM）And thermoplastic elastomers（TPE）Mainly, some products also usePVCtexture of material.Finite element analysis of automotive sealing strip structure, based on the connection between the sealing strip and the vehicle bodyotherThe interaction form of components,canClassified as compression, insertion and extraction, sliding, bending, andvarious, multiple, diverse, a variety ofComposite form.

Currently comparingAdvanced sealing strip enterprises,All can be achievedThe synchronous design and modification of sealing strips and automotive body sheet metal fully utilize computer simulation methods for design selection, reducing costs and shortening development cycles.

andOther metallic materialsDifferent, the sealing strip is basically made of rubber, and the direction of the rubber long-chain molecules is randomly distributed, presenting aTypical nonlinearitymaterialfeatureAnd it exhibits strong dependence on stress, time, environment, etc., and will harden or soften as the product agesTherefore，InCAEdesigntimeFirstly, we need toChoose the most suitable oneMaterial constitutive model to characterize material propertiesThen, by testing the materials, a series of basic physical property parameters are obtainedMaterial characteristic curve，andestablishedThe material model achieves a good match. ComprehensiveStructural analysis of sealing strips for structural modeling and boundary conditionsofsensitivedegreeSet reasonable boundary conditions，Improve the simulation accuracy of the deformation characteristics of sealing strip structures and provide valuable guidance for the design of sealing strip structures.

With the continuous in-depth study of the constitutive relationship of rubber materials, various material constitutive models based on different theories have been established. includingMooney RivlinmodelTheBLatz-imodelTheKnowlesmodelTheOgdenmodelTheYeahModels, etcWhen rubber materialDuring the occurrencelarge deformationtimeUsually treated as a hyperelastic material, a constitutive model based on strain energy density function can be used to describe it^[3].

In研究Material constitutive relationshipat the same time，People are also starting tofocus onHow tomaterialMake more reasonable decisionsexperimentthusObtain more complete and realistic material characteristic curves,andVerify the applicability of the material model through subsequent finite element analysis，Reduce errors and verify the accuracy of the material model in expressing material properties. Therefore, accurate and rich material data must be obtained before finite element analysis.

sealing stripThe rubber materialin practiceworking conditionChineseforce-bearing-transformComplex and variable, any single stress-The strain state cannot fully simulate the real deformation of materials, and requires multiple methods“pure”The material curve under strain state is used to jointly fit the material model. The rubber material tests in the laboratory mainly include uniaxial tensile test, plane shear test, uniaxial compression test, equiaxed tensile test, etc^[4].

whileUniaxial compression testtimeDue to the sampleTest the pressure plateintervaloffriction力During the compression process, the sample is subjected tocannotFree and uniformofExpansion,ThereforepresentexistThe non pure compressive strain state of tensile and shear strains.And during this processUnable to determineitsCoefficient of friction,soThe experimental data cannot be effectively corrected. Ideal SingleaxisThe deformation characteristic of uniformly increasing the radius of the compressed specimen and maintaining a cylindrical shape is equivalent to the state of uniformly distributed radial tension on the cylindrical surface. Therefore,Isometric tensile test can be used instead of uniaxial compression test.

For example, it can be done throughCAEAnalysis can evaluate the mechanical response and stress distribution of sealing strips during experiments and use, and automatically analyze and determine the failure location and structural safety fatigue performance of the structure design through test data results, thereby achieving the prediction of product service life.

summary

currentlyFinite element analysis of rubber materials, both domestically and internationallytemporarilyLack of unified material testing standardsInstead, traditional methods are adoptedexperimentequipmentandtestfixtureUnable to obtain accurate material property testing data, thus unable to establish accurate and detailedBasic material database and its impact on the accuracy of subsequent analysis work. Thereforealsourgently needIntroduce as soon as possibleunifiedtestStandard,Use equiaxed tensile test data as much as possible，Can effectively improveCAEAnalyze the efficiency and level of design, reduce research and development cycles, and improve product quality.

References：

[1] Cai Zengwei, Yu HanshengThe rise and development of green passenger car seals[J] Special Rubber Products, 2002, 23 (6): 40-43

[2] FanChenggao. The design trend of sealing strips in automobiles[J] Research and Development, 2010, (2)：68-69．

[3] Kuang Zhenbang. Fundamentals of Nonlinear Continuum Mechanics[M] Xi'an: Xi'an Jiaotong University Press, 1989

[4] Measuring rubber and plastic friction for rubber, Axel Products Testing and Analysis Report[EB/OL].

[5] Huang Yanmin. Research on the Improvement of Car Door Sealing Strip Structure Based on Simulation Analysis[D].Shanghai: Shanghai Jiao Tong University,2010.