A Study on Automotive Seat Cushions having Multi-hardness Distribution for the Elderly

Objectives: Recent trends show an increase in driving by the elderly and most of them drive with a poor posture. In this study, not only the tests for body pressure but also the tests to identify characteristics of the seat itself were conducted. Methods/Statistical Analysis: Static load tests were conducted first to derive the seat-inherent characteristics such as deflection and hardness, etc. of the seat cushion as a function of loads for the automotive seat, and measurement tests for body pressure were conducted to secure body pressure data of the elderly. Combining the above two test results, final hardness values were obtained through which seat cushion pattern models having 8-hardness distributions could be derived. Findings: As a result, curves and functional equation for the two variables were derived through deflection as a function of measured loads. Also, hardness values at each point of the cushion could be found from the slopes of the curves mentioned, with the appearance of the phenomenon where the slope showed a steep increase in a particular region. This was affirmed to have occurred due to a difference in thicknesses of the cushion. Secondly, concentrated regions of body pressure per subject were affirmed and analyzed in the body pressure tests. By combining two test results, a total of 11 seat cushion pattern models could be derived, of which pattern analyses were conducted for 3 types observed with many personnel. Improvements/Applications: When the cushions are produced on the basis of the above pattern, it is considered possible to more ideally distribute the weight and to improve comfort upon seating compared with the commercial cushions.