Sag analysis of an automotive roller blind system in terms of the variation in the production process

In the automotive industry large roof opening systems are developed enabling bright and friendly passenger compartments. For strong solar radiation these systems require a blind system that in most case are realized by a roller blind system made out of a fabric.

In the development and production of such systems the main challenge is to find a good compromise between a tight strained, “good-looking” fabric and the pre-tension forces that can lead to noise, strength or high operational force issues. Hereby the compensation of the strong variation of the fabric stiffness is the key problem in the production.

In the presentation an analysis approach is shown to assess the variations in the production in terms of used processes and materials. Base for this analysis is a Monte-Carlo analysis that considers the relations between sag, tension & operational force and clamping distance. Analytical formulas were validated by a numerical model. The FEA model included the anisotropy of the material, the curved boundaries and of course the tension in the fabric. The load application is done by gravity and the relation between maximum sag and reaction forces is evaluated.

Beside the theoretical investigations a lot of test data was required like determination of the fabric stiffness, impact of further parts and friction coefficients. Hereby the effort was increase because not only the size but also the variation of the factor needs to be described.

Tolerance analysis results of involved parts, assy and processes complete the input for the MC-Analysis.

The Author

Author: R. Peter, Inteva Products
Co-Author: D. Bernhardt, Inteva Products

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