Stiffening buildings

Under this programme 25% of the stiffeners and adjacent plate material in bulk carriers will be examined with thickness measurements being taken at upper, lower and mid points in both face and web plates of the stiffeners and associated end brackets. The extent of thickness measurement applied to transverse bulkheads has also been increased. In addition. Classification has revised the scantling requirements for new buildings to nominate thicker material in the bottom structure and at the transverse watertight bulkheads of the No 1 cargo holds. 

Spheres, spheroids, and toroids use steel or concrete saddles or are suppoi ted by columns. Some may rest directly on soil. Horizontal cyhndrical tanks should have two rather than multiple saddles to avoid indeterminate load distribution. Small horizontal tanks are sometimes supported by legs. Most tanks must be designed to resist the reactions of the saddles or legs, and they may require reinforcing. Neglect of this can cause collapse. Tanks without stiffeners usually need to make contact with the saddles on at least 2.1 rad (120°) of their circumference. An elevated steel tank may have either a circle of steel columns or a large central steel standpipe. Concrete tanks usually have concrete columns. Tanks are often supported by buildings. 

For the composite spoiler design, the bottom is a variable-thickness skin on one side in Figure 1-33, but with composite materials that construction is not difficult. We do not have to chem-mill a composite material to change its thickness. All we do is stop building up the material in layers in the middle, but continue to build it up at the sides. That s a very natural process for composite materials and does not involve a costly machining operation. Instead of machined extruded stiffeners, a honeycomb core is placed on the inside of the laminae. That honeycomb... 

A low melting entropy is experienced if the intramolecular motions of the polymer are hindered, for example, the free rotation of chain segments. This is preferentially be done by stiffening of the polymer chain. Table 2.12 shows a selection of building blocks for temperature-resistant polymers. 

The hand building finish is not only one of the oldest but also one of the most important kind of finishes. Very different natural and synthetic polymers are used for an astonishing variety of hand effects. The main effects of fullness and stiffness enable a very interesting hand design, often in combination with other finishes. Softness and hardness or stiffness are incompatible contrasts, but there are -especially with the filling finish - many fluent transitions. Filling products can be combined as well with softeners as with stiffening products. 

Hand building finishes that retain their stiffening and fullness effects after repeated launderings are considered to be durable. These products are usually aqueous emulsions of polymers that form water-insoluble films on the fibre surface when dried. The three main types of products are vinyl acetate-containing polymers, acrylic copolymers and thermosetting polymers. 

DANFIRM VA is used primarily in finishing baths for fabric stiffening. It is a very efficient and economical hand builder. It tends to produce a stiff, full leathery hand as opposed to the thin, crisp hand produced by polyvinyl alcohol and starch derivatives. Being nonionic in nature, it is highly compatible with a wide variety of resins, softeners, catalysts and other finishing bath components. DANFIRM VA has excellent running properties and will not present roll and clip build-up problems. 

An example of this effect is illustrated in Figure 10, which shows a series of stress-strain curves as a fiinction of time for a material made with tri-ethoxysilane-end-capped PTMO(2000) (50 wt %) in conjunction with titanium isopropoxide (30 wt %) and TEOS (20 wt %). Over a period of many days, the material clearly stiffens in terms of modulus build-up hence, the time-dependent mechanical characteristics would have to be recognized for any application. However, such materials can be further cured thermally to achieve a more stable mechanical response with time. Therefore, if this aging phenomenon is noted, it can be dealt with accordingly. 

It is becoming clear that to meet the OEM s requirements which now nearly always have a combination of problems, these problems will be resolved by building up the substrate as the circuit is produced. Different layers will be added to cope with high speed signals, or to stiffen the board or to modify the thermal expansion. Heat removal will be done through heat pillars or openings in the dielectric. In Japan, fibre optical cables are being... 

Coherent reflections at the top and bottom boundaries of the plate give way for a set of standing acoustic waves between the two main surfaces of the plate. Due to the piezoelectric nature of quartz two sets of resonance frequencies exist for each mode, depending on the electrical boundary conditions. The first set corresponds to a plate with open-circuit boundary conditions. From the physical point of view charges will be collected on the electrodes building up a potential difference and hence an electrical field from the electrical point of view the electrodes are unconnected. This resonance is termed anti-resonance in the piezoelectric literature and parallel resonance in electronics literature. The second set of resonance frequencies corresponds to a plate with short-circuit boundary conditions. The electrodes are connected and a potential difference cannot be built up. The respective names are resonance in piezoelectric and series resonance in electronics Hterature. The differences arise from piezoelectric stiffening accompanied by differences in the sound velocity. The anti-resonance (parallel) frequencies of each of the three acoustic modes are completely decoupled giving ... 

The design in Fig. 8.33c is an improvement on the concepts illustrated in Fig. 8.336. Here the bottom cross leg has been removed. That permits the upper portions to become nominal wall thickness (A). The inside radii (C3) have been increased to equal the nominal wall thickness, which is the ideal configuration. The outside radii are the inside radii plus a wall thickness (E = C3 + A). A stiffening rib has been added at the center of the part. Its height should not exceed the nominal wall thickness (H < A). Its thickness (J) should be designed using the same parameters as elsewhere where there are material build-ups (D = 1.25A). If the rib is greater than described by this equation, a sink will appear where there is a dashed line. This can be masked by... 

Turvey G J (2(X)7), Analysis of bending tests on CFRP-stiffened pultruded GRP beams. Proceedings of the Institution of Civil Engineers Structures and Buildings, Vol. 160, No. 1, pp. 37-49. 

---