Question

What is major difference between "hammer efficiency" and "coefficient of restitution" at what time using Haley's formula in pile driving?

Answer

Hammer effectiveness refers to ratio of kinetic energy of hammer to rate energy. In spirit, there are undoubtedly sure energy losses made by hammer itself prior to real impact on driven pile. For example, these losses can include misalignment of hammer, energy losses because of guiding friction, mistaken dropping height etc

Coefficient of compensation refers to a price indicating strain energy through collision regained after bodies reverted back to their unique shapes. If coefficient of restitution is like to unity, it means that collision is flexible and all energy has been returned after impact action. Thus, this is an index showing degree impact action in terms of flexibility.