Thought about the exponential item in formulas calculating tensile strength for high-porosity materials

The difference of exponential item in any formula will greatly affect the calculation result. This is the same for the formula which calculates the tensile strength for high-porosity materials. Namely, the calculation result is very sensitive to the value used for this exponential item. The value used for this exponential item is analyzed and discussed, and 1.25 used as this exponential value is believed to be more suitable or reasonable than 1.5 (or 3/2) for the high-porosity metal material with moderate plastisity, like nickel foam.