Plots of ice pressure versus area have often been used to generalize various ice-structure interaction processes. The nature of local ice pressures on ships and structures is characterized by a relation of decreasing ice pressure with increasing contact area. In this paper two types of pressure-area relations have been defined. One pressure-area relation describes the process of ship penetration into an ice feature or ice feature impingement on a structure. The other pressure-area relation describes the spatial distribution of pressure at an instant in time. The cases examined in this paper show that even though the two types of relations demonstrate similar trends of decreasing pressure with increasing area, they are quite different in nature.
The pressure-area relation has been developed as a useful means of examining many types and sources of ice load data. From this data a trend of decreasing ice pressure with increasing contact area has emerged, sometimes referred to as an area effect. Sanderson (1988) made one of the first comprehensive compilations of pressure-area data, covering areas from 10–4 m2 to 106 m2. This compilation encompasses many sources, ranging from small-scale laboratory tests to geophysical scale processes. More recently Masterson and Frederking (1993) prepared a compilation of data in the context of local ice loads. It covered the range 10- 1 m2 to 102 m2, and relates to local ice loading on offshore structures and ship hulls. Reviewing these papers and their data sources has revealed that there are several types of "pressure-area" definitions in use. For example, one type of pressure-area relation is developed by taking the maximum force exerted on a structure with the corresponding ice thickness and structure width to define a contact area and pressure, which then plots as one point on a pressure area graph.
