Injection-molded windows
Utilizing a patented molding/bonding technique, researchers have developed a plastic alternative to vehicle glass. Said to be more durable, easier to shape, and lighter in weight, the new material comprises an impact-resistant polypropylene core sandwiched between two scratch-resistant and weather-proof polymer skins.
Three stages make up the "Poly glaze" molding/bonding technique: First, skin material enters the mold through the outer ring of a concentric dispenser. The inner dispenser then injects core material inside the skin. A final injection of skin material seals the core.
Different material/thickness combinations serve different purposes. For example, filling the gap between the two skins with a less expensive polymer reduces price; a combination of recycled core material with a virgin polymer creates an environmentally friendly composition.
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A materials ratio of 80:20, core to skin, results in a 3.2 mm thick core sandwiched between two 0.4 mm skins with no refracting problems at the boundaries.
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Kerry Kirwin, Warwick Mfg. Group; Coventry UK CV4 7AL; Tel: +44 24 7652 8444; esrrh@atcmail.wmg.warwick.ac.uk .
Electrically
tuned shock
An electro-rheological fluid (ERF), which increases its viscosity under the influence of an electric field, varies the damping characteristics of RheDamp shock absorbers.
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RheDamp works with flow resistors in the form of spiral channels.
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Piston motion pushes the ERF, a silicone oil containing fine polyurethane particles, through a spiral channel around the piston circumference. The plastic strip forming the channel insulates the piston, which acts as the positive electrode, from the cylinder that forms the negative electrode. An insulated wire running down the piston rod connects the piston to the electrical controller. When a high-voltage, low-power pulse is applied to the electrodes, the ERF increases viscosity and the piston moves more slowly. On removal of the electric field, the ERF quickly reverts to its former viscosity.
With reaction times of around one msec, piston speed characteristics can be changed mid-stroke. When built into vehicles, RheDamp shocks tune the car suspension to "hard & sporty" or "soft & comfortable" depending on the driver's preference.
Lucien Johnston, Fluid Mechatronics, DKP/D, Schenck Pegasus GmbH; Landwehrstrasse 55 D-64293; Tel: +49 6151 32 2304; Fax: +49 6151 32 1825; johnston@csd.de .
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