A bearing assembly for a rotatable shaft, the bearing assembly comprising: a bearing housing; a bearing located within the bearing housing having an axis of rotation and arranged to receive a rotatable shaft; a first spring bar that couples the bearing to the bearing housing, the first spring bar being configured to tune vibrations of the rotatable shaft; and a first piezoelectric actuator disposed between the bearing housing and the first spring bar, the first piezoelectric actuator being configured to extend in a first direction, wherein extension of the piezoelectric actuator in the first direction displaces the first spring bar relative to the bearing housing.

A gas turbine engine including a support structure including a conduit coupled to a static support. The conduit defines an end wall between which a fluid is contained within a volume defined by the conduit. An effort variable provided to the support structure modulates a stiffness of the support structure.

An actuation system 100 comprises a fluid supply 130 that is fluidly connected to a position control actuator 110. The output of the position control actuator is determined by the fluid supply. The fluid supply is controlled by a piezoelectric actuator 150.

A centrifugal pump with adaptive pump stages includes an impeller configured to provide kinetic energy to fluid flow through the pump. The impeller has multiple geometric dimensions. The pump includes a diffuser connected to the impeller that is configured to convert the kinetic energy provided by the impeller into static pressure energy to flow the fluid through the pump. The pump includes an adaptive material attached to the impeller that is configured to modify, during operation of the pump, a geometric dimension to modify fluid flow through the pump.

A centrifugal pump with adaptive pump stages includes an impeller configured to provide kinetic energy to fluid flow through the pump. The impeller has multiple geometric dimensions. The pump includes a diffuser connected to the impeller that is configured to convert the kinetic energy provided by the impeller into static pressure energy to flow the fluid through the pump. The pump includes an adaptive material attached to the impeller that is configured to modify, during operation of the pump, a geometric dimension to modify fluid flow through the pump.

An airfoil for a gas turbine engine according to an example of the present disclosure includes, among other things, an airfoil section that extends from a root section. The airfoil section extends between a leading edge and a trailing edge in a chordwise direction and extends between a tip portion and the root section in a radial direction. The airfoil section defines a pressure side and a suction side separated in a thickness direction, and the airfoil section includes a metallic sheath that defines an internal cavity receiving a composite core. The root section defines at least one bore dimensioned to receive a retention pin. At least one damping element is received in the internal cavity and that selectively causes the airfoil section to stiffen.

A blisk assembly for vibration dampening includes a disk portion extending circumferentially about a central axis of the blisk, a plurality of blades integrally coupled to the disk, and a piezoelectric damping ring that includes a damping ring and a plurality of piezoelectric elements coupled to the damping ring. The disk portion includes a groove configured to receive the piezoelectric damping ring. As a result of centrifugal forces applied to the piezoelectric damping ring during rotation of the blisk assembly, mechanical energy may be generated at one or more of the plurality of piezoelectric elements, which is converted to electrical energy and transmitted to another one or more of the plurality of piezoelectric elements. Accordingly, the one or more of the piezoelectric elements having received the electricity can convert the electricity to mechanical energy to provide vibration damping.

A blisk assembly for vibration dampening includes a disk portion extending circumferentially about a central axis of the blisk, a plurality of blades integrally coupled to the disk, and a piezoelectric damping ring that includes a damping ring and a plurality of piezoelectric elements coupled to the damping ring. The disk portion includes a groove configured to receive the piezoelectric damping ring. As a result of centrifugal forces applied to the piezoelectric damping ring during rotation of the blisk assembly, mechanical energy may be generated at one or more of the plurality of piezoelectric elements, which is converted to electrical energy and transmitted to another one or more of the plurality of piezoelectric elements. Accordingly, the one or more of the piezoelectric elements having received the electricity can convert the electricity to mechanical energy to provide vibration damping.

Systems and methods include providing an aircraft with a fuselage and a convertible engine disposed within the fuselage. The convertible engine is operable as a turbofan engine in a thrust mode and a turboshaft engine in a shaft power mode. The convertible engine includes a housing, an engine core having a low pressure turbine shaft, and a bypass fan system. The bypass fan system includes a bypass fan having a fan clutch. The fan clutch selectively couples at least a portion of the bypass fan to the low pressure turbine shaft when the convertible engine is operated in the thrust mode and decouples at least a portion of the bypass fan from the low pressure turbine shaft when the convertible engine is operated in the shaft power mode.

A centrifugal pump with adaptive pump stages includes an impeller configured to provide kinetic energy to fluid flow through the pump. The impeller has multiple geometric dimensions. The pump includes a diffuser connected to the impeller that is configured to convert the kinetic energy provided by the impeller into static pressure energy to flow the fluid through the pump. The pump includes an adaptive material attached to the impeller that is configured to modify, during operation of the pump, a geometric dimension to modify fluid flow through the pump.