Pressure Profile

Please refer to the following Application Glossary topics that provide additional information on the Pressure Profile of items: Contact Pressure Mapping, Nip Pressure Profile, Pressure Mapping, Surface Force Mapping, Surface Force Profiling, Surface Pressure Distribution, Surface Profiling, and Surface Stress Profiling.

Pressure is exerted between two items that are in contact with one another. The Pressure Profile is the pressure distribution over the entire contact area. For a static situation, such as two items bolted together, pressure does not change with time. The pressure may differ from point to point within the contact area due to surface irregularities or lack of parallelism, but the Pressure Profile will be not be time dependent.

For dynamic events, such as an impact, the pressure between any two opposing points within the contact area may vary with time. Thus, the Pressure Profile is time-dependent, changing from point to point within the contact area and changing with time.

A medical study utilizing a dynamic Pressure Profile was performed by Stephen D. Fening, Morgan H. Jones, Vasilios Moutzouros, Brandon Downs, and Anthony Miniaci of the Cleveland Clinic in Cleveland, OH. This study was titled, “Method for Delivering a Controlled Impact to Articular Cartilage in the Rabbit Knee”. The intent of the study was “…to develop a mechanical model for delivering controlled impact injuries to an articular cartilage surface, with the ability to control peak contact pressure while maintaining a constant rate of loading across all impact levels.”

Figure 1 illustrates the impact apparatus with a close-up of the impact interface. Figure 2 is a typical Pressure Profile from 25-MPa impact. The values obtained from the Pressure Profile curve were: time to peak pressure, peak pressure, rate of pressure application, and impulse (area under the curve).

Impact Apparatus

Fig 1: Impact Apparatus with Close-up of Impact Interface

Impact Pressure

Fig 2: Typical Pressure Profile from a 25-MPa Impact

Pressurex-micro® supersensitive pressure film was placed between the contact surfaces to verify proper alignment prior to impact. Pressurex-micro® is a unique, affordable, and easy to use tool that reveals relative pressure distribution between two contacting, mating, or impacting surfaces. This pressure indicating sensor film is thin (20 mils), which enables it to conform to curved surfaces. It is ideal for invasive intolerant environments and tight spaces not accessible to conventional electronic transducers. Data from actual impact tests were collected using a single-axis load cell. These data were then graphed to obtain the Pressure Profile.