12 research outputs found
Vibrating soap films: An analog for quantum chaos on billiards
We present an experimental setup based on the normal modes of vibrating soap
films which shows quantum features of integrable and chaotic billiards. In
particular, we obtain the so-called scars -narrow linear regions with high
probability along classical periodic orbits- for the classically chaotic
billiards. We show that these scars are also visible at low frequencies.
Finally, we suggest some applications of our experimental setup in other
related two-dimensional wave phenomena.Comment: 5 pages, 7 figures. Better Postscript figures available on reques
Effect of hot-wet aging on the pin-bearing strength of a pultruded material with polyester matrix
This paper presents test results to show the effect of hot-wet conditioning on the pin-bearing strength of a pultruded fiber reinforced polymer material. Knowledge of this strength property, taking account of any reduction over the service lives of structures, is required to reliably calculate bearing strength when designing bolted connections. Pin-bearing strength is determined using an in-house test method with batches of nominally identical specimens, cut from the web of a 203 x 203 x 9.53 mm wide flange shape. This shape is from the 1525 series
of Creative Pultrusion Inc., having a polyester based matrix. Specimens were immersed prior to strength testing under water for 3000 hours at the constant temperature of 40° C. The paper discusses the accelerated aging protocol and its relation to service life, and an explanation is given to why the material was aged for an unknown number of service years. Variables in the
test matrix are the direction of the bearing force (0°, 45° and 90° to the direction of pultrusion) and plain pin diameter (four sizes from 9.7 mm to 25.4 mm). Comparing aged pin-bearing strengths with equivalent strengths for non-aged material it is found that the average reduction in characteristic strength (calculated in accordance with Eurocode 0) of the 12 batches, is in the range of 18 to 31%. The extent of strength reduction is found to be
independent of pin size, except when the diameter is 25.4 mm. For the 0o situation a comparison is made between the characteristic strengths for the four pin diameters
determined using BS EN 1990:2002 and ASTM D7290 to show that the latter Weibull distribution values are lower, and by 4 to 18%