Pressure Paper refers to a pressure indicating sensor film that can measure pressure between any two surfaces that touch, mate, or impact. Pressure Paper is synonymous with the following other terms: Fuji Paper, Fuji Prescale®, Fuji Prescale® Film, Fuji Pressure Film, Fuji Pressure Paper, Nip Impression Paper, Prescale®, Prescale® Film, Prescale® Fuji Film, Pressure Indicating Film, and Pressure Measurement Film.
K. Ogawa from Kyoto University and T. Yokoyama of Okayama University of Science reported on the use of Pressure Paper in their treatise entitled, “Visualization of Impact Force Using Pressure Sensitive Paper”. This work was performed to clarify the response of Pressure Paper to high-velocity collisions such as the impact of a golf ball.
Fig 1: Structure and Mechanism of Pressure Sensitive Paper
Fig 2: Microstructure of Pressure Sensitive Paper by SEM
The structure of the Pressure Paper is shown in Figure 1. When subjected to pressure, the Pressure Paper reveals the pressure distribution against it. Like Litmus paper, the color intensity of the Pressure Paper film is directly related to the amount of pressure applied to it, the greater the pressure, the more intense the color. Figure 2 shows the microstructure of the Pressure Paper.
From this study, Ogawa and Yokoyama concluded that the pressure of short-duration impacts can leave colored impressions on the Pressure Paper. However, the intensity of color is much greater when the Pressure Paper is subjected to continuous pressure. Therefore, these researchers developed a dual sheet method to identify the pressure distribution in the dynamic contact of flying objects.
In general, the duration of impacts, such as T1, T2, T3, changes the relation of pressure to depth of color for the respective Pressure Papers as shown in Figure 3. Two sensitivities of Pressure Papers are layered on the contact surface. When the color densities of a and b are recorded, one can find the point where the pressures (Pa3 and Pb3) and the duration of impact (T3) are identical both for the papers.
Fig 3: Schematic Presentation of Dual-Sheet Method to Simultaneously Evaluate Duration and Magnitude of Impact