A rotor assembly (60, 360, 460, 660) for a gas turbine engine comprising: a rotatable hub (62, 362, 462) including a main body extending along a longitudinal axis, and including an array of annular flanges (62B, 362B, 462B) extending about an outer periphery (62C, 462C) of the main body to define one or more annular channels (62D, 462D) along the longitudinal axis; an array of airfoils (66, 166, 266, 366, 466, 566, 566', 666, 766) circumferentially distributed about the outer periphery (62C, 462C), each one of the airfoils (66...766) including an airfoil section (66A, 166A, 266A, 366A, 466A, 566A, 666A, 766A) extending from a root section (66B, 266B, 366B, 466B, 566B, 666B, 766B) received in the one or more annular channels (62D, 462D), wherein the airfoil section (66A...766A) extends between a leading edge and a trailing edge in a chordwise direction and extends between a tip portion (66C, 266C, 466C, 766C) and the root section (66B... 766B) in a radial direction, the airfoil section (66A...766A) defines a pressure side and a suction side separated in a thickness direction; an array of platforms (70, 270, 370, 470, 670, 770) releasably secured to the hub (62, 362, 462), wherein each of the platforms (70...770) is dimensioned to abut against adjacent airfoils (66...766) of the array of airfoils (66...766); a plurality of retention pins (68, 168, 368, 468, 568, 668) each extending through the root section (66B... 766B) of a respective one of the airfoils (66...766) and through each of the annular flanges (62B, 362B, 462B) to mechanically attach the root section (66B...766B) to the hub (62, 362, 462); and characterised by at least one damping element (487, 487', 587, 587', 687, 787) that applies a compressive load to at least one component of the rotor assembly (60, 360, 460, 660) in response to a control signal to stiffen the at least one component, wherein the airfoil section (66A... 766A) includes a metallic sheath (72, 172, 272, 372, 472, 572, 672) that defines an internal cavity receiving a composite core (74, 174, 274, 474, 574, 774), and the at least one damping element (487...787) is a plurality of damping elements (487...787) each received in the internal cavity of a respective one of the airfoils (66...766). a rotatable hub (62, 362, 462) including a main body extending along a longitudinal axis, and including an array of annular flanges (62B, 362B, 462B) extending about an outer periphery (62C, 462C) of the main body to define one or more annular channels (62D, 462D) along the longitudinal axis; an array of airfoils (66, 166, 266, 366, 466, 566, 566', 666, 766) circumferentially distributed about the outer periphery (62C, 462C), each one of the airfoils (66...766) including an airfoil section (66A, 166A, 266A, 366A, 466A, 566A, 666A, 766A) extending from a root section (66B, 266B, 366B, 466B, 566B, 666B, 766B) received in the one or more annular channels (62D, 462D), wherein the airfoil section (66A...766A) extends between a leading edge and a trailing edge in a chordwise direction and extends between a tip portion (66C, 266C, 466C, 766C) and the root section (66B... 766B) in a radial direction, the airfoil section (66A...766A) defines a pressure side and a suction side separated in a thickness direction; an array of platforms (70, 270, 370, 470, 670, 770) releasably secured to the hub (62, 362, 462), wherein each of the platforms (70...770) is dimensioned to abut against adjacent airfoils (66...766) of the array of airfoils (66...766); a plurality of retention pins (68, 168, 368, 468, 568, 668) each extending through the root section (66B... 766B) of a respective one of the airfoils (66...766) and through each of the annular flanges (62B, 362B, 462B) to mechanically attach the root section (66B...766B) to the hub (62, 362, 462); and characterised by at least one damping element (487, 487', 587, 587', 687, 787) that applies a compressive load to at least one component of the rotor assembly (60, 360, 460, 660) in response to a control signal to stiffen the at least one component, wherein the airfoil section (66A... 766A) includes a metallic sheath (72, 172, 272, 372, 472, 572, 672) that defines an internal cavity receiving a composite core (74, 174, 274, 474, 574, 774), and the at least one damping element (487...787) is a plurality of damping elements (487...787) each received in the internal cavity of a respective one of the airfoils (66...766).