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A comprehensive comparison between an air-inflated seat cushion designed for truck seats and a commonly used foam cushion is provided, using a single-axis test rig designed for seat dynamic testing. Different types of tests were conducted in order to evaluate various aspects of each type of cushion; in terms of their response to narrowband (single frequency) dynamics, broadband input of the type that is commonly used in the trucking industry for testing seats, and a step input for assessing the damping characteristics of each cushion. The tests were conducted over a twelve-hour period—in four-hour intervals—measuring the changes that occur at the seat cushion over time and assessing how these changes can affect the metrics that are used for evaluating the cushions. The tests indicated a greater stiffening of the foam cushion over time, as compared with the air-inflated cushion that showed almost no change in stiffness when exposed to a static weight for twelve hours.

Two alternative methods are presented for studying the comfort, and possibly fatigue, effects of vehicle seats, in particular truck seats that include a seat suspension. The methods, named “aPcrms” and “SPD%” for the purpose of this study, are based on analyzing the pressure profile at the seat cushion/human body interface in a manner that accounts for the contact area, pressure distribution, and change in contact pressure. The alternative methods are compared with methods suggested in the past for vehicle seats, using a laboratory test rig and a truck seat with a conventional foam cushion and an air-inflated seat cushion. The results show that the proposed methods better highlight the human comfort differences between the two cushion types, and provide objective measures that better correlate with subjective measures from a separate field study on the same types of seats.