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Torsion Box
A torsion box consists of Sandwich theory, two thin layers of material (skins) on either side of a lightweight core, usually a grid of beams. It is designed to resist Torsion (mechanics), torsion under an applied load. A hollow core door is probably the most common example of a torsion box (stressed skin) structure. The principle is to use less material more efficiently. The torsion box uses the properties of its thin surfaces to carry the imposed loads primarily through tension while the close proximity of the enclosed core material compensates for the tendency of the opposite side to buckle under compression. Torsion boxes are used in the construction of structural insulated panels for houses, wooden table (furniture), tables and doors, skis, snowboards, and airframes - especially wings and vertical stabilizers. See also * Tubular bridge and Fairbairn steam crane, Fairbairn crane, the Victorian invention of the multiple torsion box, for the construction of bridges and crane ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandwich Theory
Sandwich theoryPlantema, F, J., 1966, Sandwich Construction: The Bending and Buckling of Sandwich Beams, Plates, and Shells, Jon Wiley and Sons, New York.Zenkert, D., 1995, An Introduction to Sandwich Construction, Engineering Materials Advisory Services Ltd, UK. describes the behaviour of a beam, plate, or shell which consists of three layers—two facesheets and one core. The most commonly used sandwich theory is linear and is an extension of first order beam theory. Linear sandwich theory is of importance for the design and analysis of sandwich panels, which are of use in building construction, vehicle construction, airplane construction and refrigeration engineering. Some advantages of sandwich construction are: * Sandwich cross sections are composite. They usually consist of a low to moderate stiffness core which is connected with two stiff exterior facesheets. The composite has a considerably higher shear stiffness to weight ratio than an equivalent beam made of only the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torsion (mechanics)
In the field of solid mechanics, torsion is the twisting of an object due to an applied torque. Torsion is expressed in either the pascal (Pa), an SI unit for newtons per square metre, or in pounds per square inch (psi) while torque is expressed in newton metres (N·m) or foot-pound force (ft·lbf). In sections perpendicular to the torque axis, the resultant shear stress in this section is perpendicular to the radius. In non-circular cross-sections, twisting is accompanied by a distortion called warping, in which transverse sections do not remain plane. For shafts of uniform cross-section unrestrained against warping, the torsion is: : T = \frac \tau= \frac G \varphi where: * ''T'' is the applied torque or moment of torsion in Nm. * \tau (tau) is the maximum shear stress at the outer surface * ''J''T is the torsion constant for the section. For circular rods, and tubes with constant wall thickness, it is equal to the polar moment of inertia of the section, but for other shape ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Table (furniture)
A table is an item of furniture with a raised flat top and is supported most commonly by 1 or 4 legs (although some can have more), used as a surface for working at, eating from or on which to place things. Some common types of table are the dining room table, which is used for seated persons to eat meals; the coffee table, which is a low table used in living rooms to display items or serve refreshments; and the bedside table, which is commonly used to place an alarm clock and a lamp. There are also a range of specialized types of tables, such as drafting tables, used for doing architectural drawings, and sewing tables. Common design elements include: * Top surfaces of various shapes, including rectangular, square, rounded, semi-circular or oval * Legs arranged in two or more similar pairs. It usually has four legs. However, some tables have three legs, use a single heavy pedestal, or are attached to a wall. * Several geometries of folding table that can be collapsed into a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Door
A door is a hinged or otherwise movable barrier that allows ingress (entry) into and egress (exit) from an enclosure. The created opening in the wall is a ''doorway'' or ''portal''. A door's essential and primary purpose is to provide security by controlling access to the doorway (portal). Conventionally, it is a panel that fits into the doorway of a building, room, or vehicle. Doors are generally made of a material suited to the door's task. They are commonly attached by hinges, but can move by other means, such as slides or counterbalancing. The door may be able to move in various ways (at angles away from the doorway/portal, by sliding on a plane parallel to the frame, by folding in angles on a parallel plane, or by spinning along an axis at the center of the frame) to allow or prevent ingress or egress. In most cases, a door's interior matches its exterior side. But in other cases (e.g., a vehicle door) the two sides are radically different. Many doors incorporate locking ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snowboard
Snowboards are boards where the user places both feet, usually secured, to the same board. The board itself is wider than most skis, with the ability to glide on snow."snowboarding." Dictionary.com Unabridged (v 1.1). Random House, Inc. 17 Mar. 2009. . Snowboards widths are between 6 and 12 inches or 15 to 30 centimeters. Snowboards are differentiated from monoskis by the stance of the user. In monoskiing, the user stands with feet inline with direction of travel (facing tip of monoski/downhill) (parallel to long axis of board), whereas in snowboarding, users stand with feet transverse (more or less) to the longitude of the board. Users of such equipment may be referred to as ''snowboarder''s. ''Commercial snowboards'' generally require extra equipment such as bindings and special boots which help secure both feet of a snowboarder, who generally ride in an upright position. These types of boards are commonly used by people at ski hills, mountains, backcountry, or resorts for le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airframe
The mechanical structure of an aircraft is known as the airframe. This structure is typically considered to include the fuselage, undercarriage, empennage and wings, and excludes the propulsion system. Airframe design is a field of aerospace engineering that combines aerodynamics, materials technology and manufacturing methods with a focus on weight, strength and aerodynamic drag, as well as reliability and cost.Michael C. Y. Niu (1988). ''Airframe Structural Design''. Conmilit Press LTD. History Modern airframe history began in the United States when a 1903 wood biplane made by Orville and Wilbur Wright showed the potential of fixed-wing designs. In 1912 the Deperdussin Monocoque pioneered the light, strong and streamlined monocoque fuselage formed of thin plywood layers over a circular frame, achieving . First World War Many early developments were spurred by military needs during World War I. Well known aircraft from that era include the Dutch designer Anth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wing
A wing is a type of fin that produces lift while moving through air or some other fluid. Accordingly, wings have streamlined cross-sections that are subject to aerodynamic forces and act as airfoils. A wing's aerodynamic efficiency is expressed as its lift-to-drag ratio. The lift a wing generates at a given speed and angle of attack can be one to two orders of magnitude greater than the total drag on the wing. A high lift-to-drag ratio requires a significantly smaller thrust to propel the wings through the air at sufficient lift. Lifting structures used in water include various foils, such as hydrofoils. Hydrodynamics is the governing science, rather than aerodynamics. Applications of underwater foils occur in hydroplanes, sailboats and submarines. Etymology and usage For many centuries, the word "wing", from the Old Norse ''vængr'', referred mainly to the foremost limbs of birds (in addition to the architectural aisle). But in recent centuries the word's meaning has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertical Stabilizer
A vertical stabilizer or tail fin is the static part of the vertical tail of an aircraft. The term is commonly applied to the assembly of both this fixed surface and one or more movable rudders hinged to it. Their role is to provide control, stability and trim in yaw (also known as directional or weathercock stability). It is part of the aircraft empennage, specifically of its stabilizers. The vertical tail is typically mounted on top of the rear fuselage, with the horizontal stabilizers mounted on the side of the fuselage (a configuration termed "conventional tail"). Other configurations, such as T-tail or twin tail, are sometimes used instead. Vertical stabilizers have occasionally been used in motor sports, with for example in Le Mans Prototype racing. Function Principle The vertical tail of an aircraft typically consists of a fixed vertical stabilizer or fin on which a movable rudder is mounted. A trim tab may similarly be mounted on the rudder. Together, their role ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tubular Bridge
A tubular bridge is a bridge built as a rigid box girder section within which the traffic is carried. Famous examples include the original Britannia Bridge over the Menai Strait, the Conwy railway bridge over the River Conwy, designed and tested by William Fairbairn and built by Robert Stephenson between 1846 and 1850, and the original Victoria Bridge in Montreal. Conwy and Britannia Bridges The Conwy railway bridge carries the North Wales coast railway line across the River Conwy between Llandudno Junction and the town of Conwy. The wrought iron tubular bridge was built by Robert Stephenson to a design by William Fairbairn, and is similar in construction to Stephenson's other famous tubular bridge, the Britannia Bridge across the Menai Strait. It was officially opened in 1849, but had been completed in 1848. Being the first tubular bridge to be built, the design needed much testing on prototypes to confirm that it would be capable of carrying heavy locomotives, the testing bei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fairbairn Steam Crane
A Fairbairn crane is a type of crane of an 'improved design', patented in 1850 by Sir William Fairbairn. There are numerous hand-powered versions around the world and one surviving steam-powered example in Bristol Docks, England. Innovative design The crane's innovation was in the use of a curved jib, made of riveted wrought iron platework to form a square-section box girder. This curved jib could reach further into the hold of a ship, clear of the deep gunwales alongside the quay. Designing a strong curved jib required Fairbairn's advanced theoretical understanding of the mechanics of a box girder. The tension forces were carried by the outer, convex surface of the girder which was made of back plates being chain-riveted together. The inner surface carried a compressive load. To avoid plate crumpling, it was made as a cellular structure: an inner plate and webs formed three rectangular cells, effectively box girders in their own right. The character of a box girder is to r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
