Space-frame

In the past a limitation on this process was that it tended to be restricted to shapes which were symmetrical about an axis of rotation and from which the mandrel could be easily extracted. However, in recent years there have been major advances through the use of collapsible or expendable cores and in particular through the development of computer-controlled winding equipment. The latter has opened the door to a whole new range of products which can be filament wound - for example, space-frame structures. Braiding machines for complex shapes are shown in Fig. 4.76. 

In this section we discuss the idea of degrees of freedom of motion of simple structures, with emphasis on space frames and trusses. These simple structures are often easily understood and exhibit simple and predictable behavior. They can also be structurally efficient and thus make a valuable group of structures interesting in astronomy. 

Space frames are structures made up of nodes and struts. When the struts that connect the nodes together are slender, the axial stiffness of the strut becomes the dominant form of stiffness, and the bending stiffness that might be achieved in the attachment of a strut to a node is usually very much smaller, and can often be ignored. 

Global Electric Motor s two-seat GEM car is a NEV, with a top speed of 25 mph and a curb weight of 1100 pounds with batteries. A 72-volt shunt GE motor is used with front wheel drive. Six 12-volt deep-cycle batteries are used with hydraulic brakes, independent front wheel suspension, rack and pinion steering, aluminum welded space frame and composite and thermoplastic body. It seats two or four with a price of 7,000 to 9,000. 

Crystals growing on a substrate may be oriented every which way that is, the direction axes of individual crystallites can be randomly distributed. However, where one particular axis is oriented or fixed in nearly one direction, we speak about a single texture. When two axes are thus fixed or oriented, we speak about double texture. Monocrystalline orientation refers to a scenario in which there are three such nearly oriented axes, including epitaxial films. Orientation here is viewed with respect to any fixed (in space) frame of reference. Crystal planes and directions are illustrated in Figure 16.5. A brief discussion of the enumeration of these elements follows. 

Staff Audi To Get Aluminum Space Frame,5 Adv. Mat. Proc., 9 (January 1992). Staff Forecast 92—Aluminum, Adv. Mat. Proc., 17 (Januaiy 1992). 

An easy way of visualizing the structure of fullerenes is to make a physical model, for example, to assemble equal angle planar trivalent connectors and equal length plastic tubes. Mechanically, the polyhedron-like structure so obtained can be considered as a space frame with equal rigid nodes and equal elastic bars such that three bars meet and form angles of 120° at each node. The closed net shape arises by deformation of the bars in a state of self-stress. The edges of the polyhedron obtained... 

A simple way to appreciate the shape of fullerene is to construct a physical model in which rigid planar trivalent nodal connectors represent the atoms and flexible plastic bars (tubes) of circular cross-section represent the bonds. From a mechanical point of view the model may be considered as a polyhedron-like space frame whose equilibrium shape is due to self-stress caused by deformation of bars. We suppose that the bars are equal and straight in the rest position and that they are inclined relative to each other at every node with angle of 120°. The material of the bars is assumed to be perfectly elastic and that Hooke s law is valid. All the external loads and influences are neglected and only self-stress is taken into account. Then we pose the question What is the shape of the model subject to these conditions To answer this question we apply the idea used for coated vesicles by Tarnai Gaspar (1989). 

Let us first investigate this mechanical problem for the model of C28 having tetrahedral symmetry (Kroto 1988), and arrange the structural elements in a plane and join the corresponding bar ends and nodes. As a result, a ball-like space frame... 

Figure 7. The equilibrium of the space frame modelling C28. (a) The primal curved-edged polyhedron formed from bars. (6) The dual polyhedron formed from moments. 

Figure 9. Arrangement of bars of the space frame modelling C240 on a face of the icosahedron.

Figure 10. The equilibrium shape of the space frame modelling C24. ...

There have been many intereshng approaches to overeome the shortage of high quality, large dimension hmber. Engineers have turned to trusses, I-beams, and space frames to achieve what had previously been aeeomplished by solid timber beams. Composites like glulam and the new produets diseussed below provide substitute elements that can be incorporated into the kinds of modem designs just alluded to. The thmst in the development of these new produets has been improved... 

Here J is the total angular momentum, with projection M along the space-frame z-axis... 

This may be called a body-frame label set. Alternatively one may use the space-frame labels v, j, and / of the initial collision pair, where / is the orbital angular momentum quantum number of the relative translational motion of FF with respect to H2. The quantum number l is constrained by (137)... 

Over the last three years, the Ford Motor Company has produced several thousand Ford GT automobiles with an FSW central tunnel assembly (Fig. 13.35). This tunnel houses and isolates the fuel tank from the interior compartment and contributes to the space frame rigidity. The top aluminum stamping is joined to two hollow aluminum extrusions along the length of the tuimel, using a linear FSW lap joint. The use... 

RRIM polyurethanes are widely used for body panels. Bayflex 150 (of Bayer) was chosen by Pontiac for its 1987 Fiero, a well-publicized all-plastic car. The car s panels hang from a metal space frame. Bayflex 150 is used on vertical panels while the bonnet and roof are made of sheet molded components. Bayflex 150 is said to offer a number of advantages (improved thermal stability, stiffness, impact resistance, and dimensional stability) over conventional ureas without their processing limitations. 

Arciszewski, T. (1991). Joint for space frame, Canada, Patent No. 1,291,626. 

Fig. 19 Single-scattering refinements of the EXAFS for Cr(II) supported on S948-500 (a, b) and S948-800 (c, d). Frames (a) and (c) show the data dotted lines) and curve fits solid lines) in k -weighted -space. Frames (b) and (d) show the FT magnitudes upper dotted lines), imaginary components lower dotted lines) and curve fits solid lines) in R space...

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