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Well, I got that figure by making the foolish mistake of using a diameter as a radius. I believe the correct circumference should be .59 inches. Thanks.

Just to refresh on the loads I'm talking about here, our load is about 3 pounds. The screw will create a hole in the plastic about the size of its 1/8" shaft diameter. The (outside) thread diameter is 3/16" and will spread this shear / tension load over a circumference of 1.18". Doesn't this...

Ugh! I miss the predicatability of concrete and steel already. The "sure" things at this point are thermoplastics (for cost), lowest possible water absorption, and best over-all strength, creep, and fatigue characteristics. Polypropylene, Polyethylene are fielded and should be tested (with...

True. But cost is a driver and I doubt there'd be interest in stepping up to Thermosets unless we come to the conclussion that the less expensive options won't work.

Seems to me that if screw pullout is the primary mode of failure the best approach would be to go with fibers (well-bonded with the plastic resin). Hopefully their strength would also allow us to drop back to a more reasonable factor of safety. I'm imagining that a 1/8" screw will sever some...

Screw holes will not be preformed, ice between components is not a concern, and the tolerances of the associated construction materials will not be a problem with differential thermal movement. Long-term cold-flow and brittleness leading to rupture are my major worries. The former could be...

Yes, lawn sprinkler systems remain in the freeze zone (after draining in the fall) and have about a 20-year life (according to a manufacturer). They don't see the range of temps a plastic on the outside of a wall would see, however, nor do they experience the shear loads of a fastener under...

Thanks, Mike. I built the Univision Network building in Miami and we lost our antennae dishes during Andrew. Did not realize a test center also went away. There are quite a few plastic construction materials and I'm trying to choose products that will likely perform best over time. Current...

Hey, Pat, I'm just a Civil Engineer (licensed) trying to figure out the best plastic for use in a building material. What I've found so far is ZIP for age testing of anything. My thinking is that thousands of cycles of freeze-thaw, under load, will affect the length of time I can expect a...

It's been awhile since I enjoyed the "tact" of non-civil engineers. Refreshing! Plastic (HDPE and PP, mostly) is being sold in many construction products. These molded shapes, typically grids with a folded edge about 1/8" thick, hold metal fasteners and are subject to shear and freeze-thaw...

UV is not a concern, so what is another reservation on the Acetal? Its strength, fatigue resistance, and low cost are all promising. As for other factors with PET/PBT, what might some of those be?

Don't mean to "string" anybody along, sorry. The only data I can think to add is that the finished piece will be a thin (~1/8") strip designed to hold a screw in zero to 100 degree (F) temperatures. My only considerations are long term structural performance and cost. Product is currently...

What plastic / reinforcement would be suggested for a structural (shear / pullout loaded) application able to perform over 50+ years and 3,000+ freeze-thaw cycles. The plastic will be protected from UV and must be injection moldable at low cost.