The purpose of the midspan shrouds is to prevent the fan blade from twisting due to the aerodynamic loads on the airfoils.
▲The CFM56-5B engine of the Airbus A320 had mid-span shrouds on the fan blades.
Furthermore, their need for mid-span shrouds was to dampen fan blade vibrations due to the heavier titanium used.
Protruding from both sides of the fan blade, these shrouds interlocked with shrouds on adjacent blades to form a continuous ring which provided torsional rigidity and dampened vibration.
The presence of shrouds sometimes caused a problem called “Fan-blade shingling”.