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Related Concept Videos

Torque01:10

Torque

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Torque is an important quantity for describing the dynamics of a rotating rigid body. We see the application of torque in many ways in the world, such as when pressing the accelerator in a car, which causes the engine to apply additional torque on the drivetrain. Here, we define torque and provide a framework to create an equation to calculate torque for a rigid body with fixed-axis rotation.
Torque can be considered as the rotational counterpart to force. Since forces change the translational...
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Electro-mechanical Systems01:19

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Electromechanical systems are intricate configurations that effectively combine electrical and mechanical elements to achieve a desired outcome. Central to many of these systems is the DC motor, a device that converts electrical energy into mechanical motion, enabling various applications ranging from simple fans to complex robotic mechanisms.
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Net Torque Calculations01:19

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When a mechanic tries to remove a hex nut with a wrench, it is easier if the force is applied at the farthest end of the wrench handle. The lever arm is the distance from the pivot point (the hex nut in this case) to the person’s hand. If this distance is large, the torque is higher. Only the component of the force perpendicular to the lever arm contributes to the torque. Therefore, pushing the wrench perpendicular to the lever arm is more advantageous. If multiple people apply force to...
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Mechanical Systems01:22

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Mechanical systems are analogous to to electrical networks where springs and masses play similar roles to inductors and capacitors, respectively. A viscous damper in mechanical systems functions similarly to a resistor in electrical networks, dissipating energy. The forces acting on a mass in such systems include an applied force in the direction of motion, counteracted by forces from the spring, a viscous damper, and the mass's acceleration. This interplay of forces is mathematically...
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Torque Free Motion01:15

Torque Free Motion

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The torque-free motion refers to the movement of a rigid body in space when no external torques are acting upon it. This type of motion can be observed in environments where there are no external forces or frictions, like in outer space. For example, a rotation of Mars in space is a torque-free motion. Mars is an axisymmetric object, meaning it has an axis of symmetry along which it rotates, designated as the z-axis. The rotating frame of reference is defined such that the center of mass of...
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Torque On A Current Loop In A Magnetic Field01:13

Torque On A Current Loop In A Magnetic Field

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The most common application of magnetic force on current-carrying wires is in electric motors. These consist of loops of wire, which are placed between the magnets with a magnetic field. When current flows through the loops, the magnetic field applies torque, which causes the shaft to rotate, thus converting electrical energy to mechanical energy.
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Torque-dense photomechanical actuation.

Mahnoush Babaei1, Junfeng Gao2, Arul Clement2

  • 1Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA.

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Summary
This summary is machine-generated.

Light-powered soft actuators generate high torque densities using patterned polymer shells. These novel photoactuators can be shaped into various mechanisms for remote operation.

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Area of Science:

  • Soft robotics
  • Materials science
  • Polymer physics

Background:

  • Tethered electromechanical systems are limited by physical connections.
  • Light-actuated systems offer potential for contactless control.
  • Photoresponse in polymers is typically limited by light penetration depth.

Purpose of the Study:

  • To develop light-powered actuators with high torque density.
  • To explore the fabrication and actuation of molecularly patterned polymer shells.
  • To demonstrate the potential for light-controlled soft machines.

Main Methods:

  • Fabrication of azobenzene-functionalized liquid crystalline polymer shells.
  • Unstructured irradiation to induce photostrain gradients.
  • Analysis of shell morphogenesis and strain focusing.
  • Design and demonstration of light-powered mechanisms (levers, lifters, grabbers).

Main Results:

  • Achieved torque densities of ~10 N m kg-1 at ~102 rad s-1.
  • Demonstrated spontaneous bifurcation of shells into jointed mechanisms.
  • Observed hierarchical strain focusing at creases.
  • Showcased light-powered actuation and regulation of soft machines.

Conclusions:

  • Confinement of molecularly patterned shells enables torque-dense photoactuation.
  • The design framework allows for parameterizable morphogenesis based on geometry.
  • Light-powered actuators offer a viable alternative to tethered systems for soft machines.