Using Failure Mode and Effects Analysis to design a comfortable automotive driver seat.
Given enough time and use, all designs will fail. There are no fail-free designs. This is especially true when it comes to automotive seating comfort where the characteristics and preferences of individual customers are many and varied. To address this problem, individuals charged with automotive seating comfort development have, traditionally, relied on iterative and, as a result, expensive build-test cycles. Cost pressures being placed on today's vehicle manufacturers have necessitated the search for more efficient alternatives. This contribution aims to fill this need by proposing the application of an analytical technique common to engineering circles (but new to seating comfort development), namely Design Failure Mode and Effects Analysis (DFMEA). An example is offered to describe how development teams can use this systematic and disciplined approach to highlight potential seating comfort failure modes, reduce their risk, and bring capable designs to life.
The influence of car-seat design on its character experience.
Producing higher efficiency cars with less and lighter materials but without compromising safety, comfort and driving pleasure might give a competitive advantage. In this light, at BMW a new light weight car-seat concept was developed based on the human body contour. A possibility to increase the comfort is using a seat which elicits positive tactile experiences. However, limited information is available on seat characteristics and tactile experiences. Therefore, this study describes the contour of three different car-seat designs, including a light weight seat, and the recorded corresponding emotion and tactile experience of 21 persons sitting in the seats. Results show that the new light weight car-seat concept rated well on experienced relaxedness, even with the lack of a side support. The most important findings are that hard seats with rather high side supports are rated sporty and seats that are softer are rated more luxurious.
Gender differences in thermal comfort and mental performance at different vertical air temperatures
The purpose of this study was to investigate the effects of a thermal environment where air temperature closer to the ground was lower compared to that above on thermal comfort and mental performance in both sexes. Temperatures at the upper and lower parts of the body were controlled independently using a climatic box placed in a climatic chamber. Sixteen healthy subjects (8 males and 8 females) were exposed to the four conditions with various temperature differences between the upper (25°C) and lower part of the body (16, 19, 22, or 25°C). Skin temperature and subjective votes were measured, and two kinds of task using a computer were performed during exposure. Skin temperature on the back for females was higher than that for males during exposure, and the decrease in thigh skin temperature for females under lower air temperature conditions was significantly larger than that for males. A significant difference in thermal comfort at the beginning of the exposure was indicated between genders, especially in the 16 and 19°C conditions, so females became aware of thermal discomfort before males. Although the score of mental performance based on perceptual speed for females was higher than that for males, there was no significant effect from the different vertical air temperatures. The effect of the unequal thermal environment, where air temperature closer to the ground was lower than above, on skin temperature and thermal discomfort for females was significantly higher compared to males.