A marine engineer tests a heavy-duty silicone elastomer mooring strap designed to absorb kinetic energy from waves. The strap is subjected to a cycle of tension loading up to 50 kN50\text{ kN}50 kN and subsequent unloading.
The force-extension behavior of the strap during this cycle is shown in the graph below:
Explain how the loading and unloading curves on this graph demonstrate that the elastic behavior of the silicone strap differs fundamentally from that of a standard steel spring.