Stiffening assembly

A stiffening assembly comprising:

• a flexible outer tube extending along a longitudinal axis, the flexible outer tube being flexible inwardly toward the longitudinal axis when subjected to an applied vacuum;
• a flexible inner tube extending along the longitudinal axis;
• and
• a plurality of longitudinal beams extending between the flexible outer and inner tubes and separate from the flexible outer and inner tubes,
• wherein the stiffening assembly is adjustable between a flexible state in which the plurality of longitudinal beams is movable between the flexible outer and inner tubes and a stiffened state in which the applied vacuum clamps the plurality of longitudinal beams between the flexible outer and inner tubes such that transfer of shear forces between the plurality of longitudinal beams stiffens the stiffening assembly,
• wherein the plurality of longitudinal beams are positioned around the longitudinal axis to form a tubular arrangement such that the plurality of longitudinal beams are equidistant from the longitudinal axis when the stiffening assembly is in the stiffened state,
• wherein each of the longitudinal beams of the plurality of longitudinal beams has a trapezoid shape cross section,
• wherein a first longitudinal beam of the plurality of longitudinal beams has a first side surface, and a second longitudinal beam of the plurality of longitudinal beams has a second side surface, and
• wherein in the stiffened state, the first side surface of the first longitudinal beam abuts the second side surface of the second longitudinal beam to form the tubular arrangement.

A stiffenable surgical instrument comprising:

• a flexible outer wall;
• a flexible guide tube extending through the outer wall along a longitudinal axis, the flexible outer wall configured to flex toward the flexible guide tube;
• and
• a plurality of stacks of longitudinal beams extending between the flexible outer wall and the flexible guide tube, each stack in the plurality of stacks of longitudinal beams comprising an inner beam and an outer beam, the inner beam being closer to the longitudinal axis than the outer beam,
• wherein the surgical instrument is adjustable between a flexible state in which the plurality of stacks of longitudinal beams is movable between the flexible outer wall and the flexible guide tube and a stiffened state in which an applied vacuum compresses the flexible outer wall toward the flexible guide tube and compresses the plurality of stacks of longitudinal beams toward the longitudinal axis such that transfer of shear forces between each longitudinal beam in the plurality of stacks of longitudinal beams stiffens the surgical instrument, and
• wherein the plurality of stacks of longitudinal beams are positioned around the longitudinal axis to form a tubular arrangement such that the inner beam in each stack of the plurality of stacks of longitudinal beams is equidistant from the longitudinal axis when the surgical instrument is in the stiffened state.