Actuator

An actuator comprising:

• a fiber material having a fiber axis direction;
• a volume change part housed in the housing part, the volume change being a solid polymer material configured to be isotropically expanded by external input of heat energy when having no restriction to an outer shape thereof;
• and
• a frame structure part that forms a frame structure surrounding a housing part, the frame structure having a tubular structure of a combination of one or more fibers and surrounding the housing part, and being stretched more easily in a width direction perpendicular to the fiber axis direction than in the fiber axis direction, the frame structure part being configured to deform to contract the housing part in a first direction along the fiber axis direction, and widen the housing part in second direction different from the first direction along with the increasing of the volume of the volume change part,
• wherein the frame structure part has a higher Young's modulus than a Young's modulus of the volume change part, and
• the actuator outputs tensile force in the fiber axis direction of the fiber material by the external input of the heat energy.

An actuator comprising:

• a volume change part housed in the housing part, the volume change part being configured to increase a volume thereof by external input of external energy except mechanical energy;
• a frame structure part that forms a frame structure surrounding a housing part, the frame structure part being configured to deform to contract the housing part in a first direction and widen the housing part in second direction different from the first direction along with the increasing of the volume of the volume change part;
• and
• a fiber material,
• wherein the frame structure part has a higher Young's modulus than a Young's modulus of the volume change part,
• the actuator outputs tensile force in a fiber axis direction of the fiber material by the external input of the external energy,
• the first direction is a direction along the fiber axis direction,
• the housing part has an anisotropic shape, with a maximum width in the first direction of the housing part longer than a maximum width in the second direction of the housing part,
• the fiber material is composed of at least a polymer material including a plurality of crystalline portions in which polymer chains are regularly arranged, a plurality of tie molecule domains in which polymer chains extend to connect the plurality of crystalline portions to each other, and a plurality of amorphous portions in which polymer chains are irregularly arranged,
• the plurality of tie molecule domains include a plurality of first tie molecule domains extending in a first direction as the first direction and a plurality of second tie molecule domains extending in the first direction,
• the plurality of first tie molecule domains and the plurality of second tie molecule domains are disposed alternately one by one in a second direction perpendicular to the first direction,
• one second tie molecule domain among the plurality of second tie molecule domains and one first tie molecule domain among the plurality of first tie molecule domains form a first space therebetween, the one first tie molecule domain being positioned adjacent to the one second tie molecule domain on one side in the second direction,
• the one second tie molecule domain and one first tie molecule domain among the plurality of first tie molecule domains form a second space therebetween, the one first tie molecule domain being position adjacent to the one second tie molecule domain on another side in the second direction,
• the plurality of crystalline portions include a plurality of first crystalline portions disposed in the first space and a plurality of second crystalline portions disposed in the second space,
• the plurality of amorphous portions include a plurality of first amorphous portions disposed in the first space and a plurality of second amorphous portions disposed in the second space,
• the plurality of first crystalline portions and the plurality of first amorphous portions are, in the first space, disposed alternately one by one in the first direction,
• the plurality of second crystalline portions and the plurality of second amorphous portions are, in the second space, disposed alternately one by one in the first direction,
• one first crystalline portion among the plurality of first crystalline portions in the first space faces, in the second direction, one second amorphous portion among the plurality of second amorphous portions in the second space, and one second crystalline portion among the plurality of second crystalline portions in the second space faces, in the second direction, one first amorphous portion among the plurality of first amorphous portions in the first space,
• each of the plurality of amorphous portions has a longer length in the first direction than a length in the first direction of each of the plurality of crystalline portions,
• the volume change part is one amorphous portion among the plurality of amorphous portions,
• the frame structure part is a part of the plurality of crystalline portions and the plurality of tie molecule domains that surrounds the one amorphous portion, and
• the polymer material has a density of higher than 0 g/cm3 and lower than 1.03 g/cm3.