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System Identification of Quasi-static Foam Behavior and its Application in H-point Prediction
Technical Paper
2003-01-2207
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Hip joint location (H-point) is an important design specification used by car seat manufacturers. Since most of the modern car seats are full-foam seats, the H-point location is primarily dependent on the quasi-static behavior of foam which is a highly nonlinear and viscoelastic material. In this work, a constitutive model is developed for flexible polyurethane foam. The stiffness characteristics of foam are described by a polynomial in displacement and the viscoelastic behavior is described by a convolution of the response with a kernel which is assumed to be a sum of exponentials. A system identification procedure, based on linear least squares fitting and ARMA modeling, is developed to identify the parameters from data collected in quasi-static foam experiments. Once identified, these models of foam are incorporated into two dimensional multi-degree-of-freedom seat occupant models to determine the static equilibrium position of an occupant in a seat from which the H-point location is determined. A graphical user interface is developed to facilitate study of the influence of changes in system parameters and also to visualize the settling of the occupant in the seat.
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Citation
Ippili, R., Davies, P., and Bajaj, A., "System Identification of Quasi-static Foam Behavior and its Application in H-point Prediction," SAE Technical Paper 2003-01-2207, 2003, https://doi.org/10.4271/2003-01-2207.Also In
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