Why Machines That Bend Are Better

Compliant mechanisms are components that bend and are found in satellite thrusters, plastic tools, and micro mechanical switches.

Traditionally flexibility in machines was considered bad, but researchers are learning to use flexibility to advantage rather than avoid it.

Professor Larry Howell from mechanical engineering literally wrote the most cited book on compliant mechanisms.

Compliant mechanisms are used in safing and arming systems for nuclear weapons to prevent accidental detonation.

A compliant gripper is a single piece of plastic that can break chalk and amplify force by a ratio of thirty to one.

One pound of input force produces thirty pounds of output force, demonstrating significant mechanical advantage.

• Single piece construction compared to traditional vice grips with multiple components • Can be produced via injection molding for minimal cost • Can be extruded and cut for efficient manufacturing

Compliant mechanism switches have been tested in fatigue machines and can withstand over a million cycles without failure.

Compliant mechanisms reduce part count by using bendy parts instead of separate hinges, bearings, and springs.

Simple design allows use of different production processes including injection molding, extrusion, and cutting.

Micro mechanical switches achieve in one plastic piece what normally requires springs, hinges, and multiple rigid plastic pieces.

Manufacturing cost drops to cents due to simplified design and efficient production methods.

Despite being made of flexible parts, compliant mechanisms can produce very precise motion, which seems counterintuitive.

Traditional hinges suffer from backlash because a pin in a hole has play that allows movement reversal delay.

• No backlash from flexible design • Reduced wear compared to traditional mechanisms • Minimal lubrication requirements • Better performance than rigid counterparts

Compliant mechanisms are used in wind tunnels to control model angle and movement without displacing position.

Building compliant mechanisms at microscopic level on chips required silicon fabrication, despite silicon being as brittle as glass.

Once the design was perfected for silicon, it could be produced in less ideal materials like PLA.

• Uses photo-lithography process similar to computer chip manufacturing • Enables significantly smaller proportions than traditional mechanisms • Allows etching details at microscopic scale

Design files are available online for users to 3D print compliant mechanisms themselves in various materials.

Compliant mechanisms are more portable and lightweight due to simplified design, making them perfect for space applications.

A 3D printed titanium hinge developed with NASA can replace bearings for deploying solar panels.

• Solid titanium piece achieves plus-minus 90 degree bending (180 degree deflection total) • No alloy or special treatment needed for flexibility • Single piece design eliminates multiple components

Titanium, normally rigid, can bend dramatically when designed as a compliant mechanism.

A titanium device for NASA allows two motor inputs to direct a thruster in any direction using flexible beams.

• Single piece titanium achieves thruster directional control • No pinch points for fuel lines or electrical lines • One thruster replaces two separate units

A flexible outer part on a spinning device expands outward due to centrifugal force and engages a drum for power transmission.

Plastic version shows the mechanism visually while steel version demonstrates the actual application used in devices like chainsaws.

The device prevents random vibrations from earthquakes from inadvertently disabling safeties and arming nuclear weapons.

• Must be made as small as possible • Traditional methods and Swiss watch manufacturing reached their limits • Compliant mechanisms solved the miniaturization challenge

Hardened stainless steel device contains components the size of a human hair, representing extreme miniaturization.

Device operates at 72 Hertz with a rotor wheel rotating a notch when proper inputs are given; an arming laser detects when the hole lines up with the beam.

The device must maintain perfectly predictable performance even after sitting unused in a silo for decades.

Prototypes were designed, made, and tested before being handed over for classified military use.

After testing, the technology went 'behind the fence' where military operations remain classified and undisclosed to the public.

The actual deployment and use of these devices on nuclear weapons is not publicly confirmed by the researchers.

The host became serious about home security after a nearby house break-in during a police helicopter incident.

• Base station • Camera • Multiple sensors

• Installation takes about one hour • 24/7 professional monitoring • Police dispatch available in break-in events

• Intuitive user interface • Door open reminders • Fair pricing with no contracts or hidden fees • Works without Wi-Fi or power via backup systems