A suction cup, also known as a sucker, is a device or object that uses the negative fluid pressure of air or water to adhere to nonporous surfaces, creating a partial vacuum. [1]
Suction cups occur in nature on the bodies of some animals such as octopuses and squid, and have been reproduced artificially for numerous purposes. [2]
The working face of the suction cup is made of elastic, flexible material and has a curved surface. [3] When the center of the suction cup is pressed against a flat, non-porous surface, the volume of the space between the suction cup and the flat surface is reduced, which causes the air or water between the cup and the surface to be expelled past the rim of the circular cup. The cavity which develops between the cup and the flat surface has little to no air or water in it because most of the fluid has already been forced out of the inside of the cup, causing a lack of pressure. The pressure difference between the atmosphere on the outside of the cup and the low-pressure cavity on the inside of the cup keeps the cup adhered to the surface.
When the user ceases to apply physical pressure to the outside of the cup, the elastic substance of which the cup is made tends to resume its original, curved shape. The length of time for which the suction effect can be maintained depends mainly on how long it takes for air or water to leak back into the cavity between the cup and the surface, equalizing the pressure with the surrounding atmosphere. This depends on the porosity and flatness of the surface and the properties of the cup's rim. A small amount of mineral oil or vegetable oil is often employed to help maintain the seal.
The force required to detach an ideal suction cup by pulling it directly away from the surface is given by the formula:
where:
This is derived from the definition of pressure, which is:
For example, a suction cup of radius 2.0 cm has an area of (0.020 m)2 = 0.0013 square meters. Using the force formula (F = AP), the result is F = (0.0013 m2)(100,000 Pa) = about 130 newtons.
The above formula relies on several assumptions:
Artificial suction cups are believed to have first been used in the third century, B.C., and were made out of gourds. They were used to suction "bad blood" from internal organs to the surface. Hippocrates is believed to have invented this procedure.[ citation needed ]
The first modern suction cup patents were issued by the United States Patent and Trademark Office during the 1860s. TC Roche was awarded U.S. Patent No. 52,748 in 1866 for a "Photographic Developer Dipping Stick"; the patent discloses a primitive suction cup means for handling photographic plates during developing procedures. In 1868, Orwell Needham patented a more refined suction cup design, U.S. Patent No. 82,629, calling his invention an "Atmospheric Knob" purposed for general use as a handle and drawer opening means. [4] [5]
Suction cups have a number of commercial and industrial applications:
On May 25, 1981, Dan Goodwin, a.k.a. SpiderDan, scaled Sears Tower, the former world's tallest building, with a pair of suction cups. He went on to scale the Renaissance Center in Dallas, the Bonaventure Hotel in Los Angeles, the World Trade Center in New York City, Parque Central Tower in Caracas, the Nippon TV station in Tokyo, and the Millennium Tower in San Francisco. [10] [11] [12]
In physics, the Coriolis force is an inertial force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the left of the motion of the object. In one with anticlockwise rotation, the force acts to the right. Deflection of an object due to the Coriolis force is called the Coriolis effect. Though recognized previously by others, the mathematical expression for the Coriolis force appeared in an 1835 paper by French scientist Gaspard-Gustave de Coriolis, in connection with the theory of water wheels. Early in the 20th century, the term Coriolis force began to be used in connection with meteorology.
Cavitation in fluid mechanics and engineering normally refers to the phenomenon in which the static pressure of a liquid reduces to below the liquid's vapour pressure, leading to the formation of small vapor-filled cavities in the liquid. When subjected to higher pressure, these cavities, called "bubbles" or "voids", collapse and can generate shock waves that may damage machinery. These shock waves are strong when they are very close to the imploded bubble, but rapidly weaken as they propagate away from the implosion. Cavitation is a significant cause of wear in some engineering contexts. Collapsing voids that implode near to a metal surface cause cyclic stress through repeated implosion. This results in surface fatigue of the metal, causing a type of wear also called "cavitation". The most common examples of this kind of wear are to pump impellers, and bends where a sudden change in the direction of liquid occurs. Cavitation is usually divided into two classes of behavior: inertial cavitation and non-inertial cavitation.
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Types of friction include dry, fluid, lubricated, skin, and internal.
Pressure measurement is the measurement of an applied force by a fluid on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressure and vacuum. Instruments used to measure and display pressure mechanically are called pressure gauges,vacuum gauges or compound gauges. The widely used Bourdon gauge is a mechanical device, which both measures and indicates and is probably the best known type of gauge.
A vacuum is space devoid of matter. The word is derived from the Latin adjective vacuus meaning "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often discuss ideal test results that would occur in a perfect vacuum, which they sometimes simply call "vacuum" or free space, and use the term partial vacuum to refer to an actual imperfect vacuum as one might have in a laboratory or in space. In engineering and applied physics on the other hand, vacuum refers to any space in which the pressure is considerably lower than atmospheric pressure. The Latin term in vacuo is used to describe an object that is surrounded by a vacuum.
Radiation pressure is mechanical pressure exerted upon a surface due to the exchange of momentum between the object and the electromagnetic field. This includes the momentum of light or electromagnetic radiation of any wavelength that is absorbed, reflected, or otherwise emitted by matter on any scale. The associated force is called the radiation pressure force, or sometimes just the force of light.
Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects to float on a water surface without becoming even partly submerged.
In fluid dynamics, the drag coefficient is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water. It is used in the drag equation in which a lower drag coefficient indicates the object will have less aerodynamic or hydrodynamic drag. The drag coefficient is always associated with a particular surface area.
Suction is the day-to-day term for forces experienced by objects that are exposed to the movement of gases or liquids moving along a pressure gradient. Contrary to popular belief, however, the forces acting in this case do not originate from the lower pressure side, but from the side of the higher pressure.
Buoyancy, or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object. The pressure difference results in a net upward force on the object. The magnitude of the force is proportional to the pressure difference, and is equivalent to the weight of the fluid that would otherwise occupy the submerged volume of the object, i.e. the displaced fluid.
Archimedes' principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially, is equal to the weight of the fluid that the body displaces. Archimedes' principle is a law of physics fundamental to fluid mechanics. It was formulated by Archimedes of Syracuse.
Fluid statics or hydrostatics is the branch of fluid mechanics that studies fluids at hydrostatic equilibrium and "the pressure in a fluid or exerted by a fluid on an immersed body".
An injector is a system of ducting and nozzles used to direct the flow of a high-pressure fluid in such a way that a lower pressure fluid is entrained in the jet and carried through a duct to a region of higher pressure. It is a fluid-dynamic pump with no moving parts except a valve to control inlet flow.
Daniel Goodwin is an American climber best known for performing gymnastic-like flag maneuvers and one-arm flyoffs while free soloing difficult rock climbs on national TV and for scaling towering skyscrapers, including the Sears Tower, the John Hancock Center, the World Trade Center, the CN Tower, and the Telefónica Building in Santiago, Chile.
A surgical drain is a tube used to remove pus, blood or other fluids from a wound, body cavity, or organ. They are commonly placed by surgeons or interventional radiologists after procedures or some types of injuries, but they can also be used as an intervention for decompression. There are several types of drains, and selection of which to use often depends on the placement site and how long the drain is needed.
Airwatt or air watt is a measurement unit of the effectiveness of vacuum cleaners which refers to airflow and the amount of power (watts) a vacuum cleaner produces and uses. It can also be referred to as a measurement of the energy per unit time of the air flowing through an opening, which is related to the energy that electricity carries through the power cable (wattage).
An end effector is the device at the end of a robotic arm, designed to interact with the environment. The exact nature of this device depends on the application of the robot.
Nano-suction is a technology that uses vacuum, negative fluid pressure and millions of nano-sized suction cups to securely adhere any object to a flat non-porous surface. When the nano-suction object is pressed against a flat surface, millions of miniature suction cups create a large vacuum, generating a strong suction force that can hold a tremendous amount of weight. The nature of the technology allows easy removal without residue, and makes it reusable.
Microsuction tape is a material for sticking objects to surfaces such as furniture, dashboards, walls, etc. One side is usually attached to the base surface by a classical adhesive. Objects are attached to the other side by pressing them against the tape. They stick to the tape due to small bubbles (cavities) on the surface of the tape. These contain air, which is squeezed out when the surface of an object is pressed against the surface of the tape. Due to sealing properties of the material, when the object is pulled off the surface, a vacuum is created in the cavities. Due to external air pressure, this creates a force that prevents the object from being removed from the surface, a mechanism similar to that of a suction cup.
The self-sealing suction cup is a suction cup that exerts a suction force only when it is in physical contact with an object. Unlike most other suction cups, it does not exert any suction force when it is not in contact with an object. Its grasping ability is achieved entirely through passive means without the use of sensors, valves, or actuators.
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