News about Science, Technology and Engineering at Iowa State University

News about Science, Technology and Engineering at Iowa State University

Hitting the road As the saying goes, "Iowa only has two seasons -- winter and road construction." But with a new technology in asphalt paving, called Superpave, the frequency of road repairs could decrease, along with costs to taxpayers. To stay on the leading edge of technology, Iowa State's civil engineering program and the Asphalt Paving Association of Iowa (APAI) teamed up to modernize the university's asphalt paving lab. The new high-tech research and testing equipment includes a gyratory compactor, which compacts asphalt mixtures, simulating their conditions on highways, in order to study the effects of the relative proportions of asphalt, aggregate and air voids. Other equipment will test and measure the response of asphalt to summer and winter environmental conditions while accounting for the age-hardening process.

Asphalt application has been the same since World War II, says civil and construction engineering assistant professor Brian Coree. In the old system, engineers used the same asphalt mix for an Iowa road as for a highway in New Mexico. With Superpave, New Mexico and Iowa roads would have entirely different mixes appropriate to their environmental and traffic conditions, but they would retain the same long-lasting performance.

"Asphalt roads in the past had a typical lifetime of 18 to 20 years," says Renee White, technical representative with APAI. "Superpaved roads will have 5 to 10 more years of life." She said at least 15 pilot projects using Superpave have been constructed in Iowa and that by the year 2000, all new projects will be done with Superpave technology. For more information, contact Coree at (515) 294-3973, White at (515) 222-0015, or Mitch Mihavolich, Engineering Communications, (515) 294-4344.

Adding more metal to the mix Mixing a metal and a ceramic together to form a composite may seem simple, but it can be almost as difficult as mixing oil and water. The composites formed may be difficult to machine, and they may separate or more readily suffer impact failures. But researchers at Iowa State University and Ames Laboratory have developed a method to strengthen metals with other metals producing a stronger, lighter weight material.

Called metal-metal composites by researchers Alan Russell and Scott Chumbley, the material is made by using a formable matrix material for the bulk of the composite, then adding ribbons of another formable metal within the matrix. The ductility of the composites allows them to be processed in such a way that the second phase particles, initially tens of microns thick, become just tens of nanometers thick. This increases the strength of the composite by 6 to 10 times.

Metal-metal composites are strong for their weight, very resistant to heat, and flexible enough to be processed into a variety of shapes. A 45-millimeter thick cable of an aluminum metal-metal composite can support as much as 190 tons, according to Russell. The materials have potential applications in high performance aircraft and automotive structures, surgical implants, microprocessors and electric power generation tethers for spacecraft. The process is inexpensive and easily scaleable to tonnage quantities of material using conventional metal processing equipment. For more information, contact Russell at (515) 294-3204, Chumbley at (515) 294-7903, or Anita Rollins, IPRT Information, (515) 294-1113.

A Veishea first On April 17 and 18, Ames Laboratory will open its doors to Veishea visitors who want a look at the replica of the Atanasoff-Berry Computer (ABC), the first electronic digital computer. Veishea is Iowa State University's spring festival.

The original ABC was built by John Vincent Atanasoff, a physics and mathematics professor at Iowa State University, with the help of Clifford Berry, an engineering graduate student, between 1939 and 1942. To preserve the legacy of Atanasoff and Berry, a team of Ames Laboratory and ISU scientists, technicians, faculty and students constructed a full-size working replica of the ABC. Vintage gears, vacuum tubes, drums and IBM punches that distinguished the ABC in its time were used to make the model authentic to the original.

John Gustafson, Ames Laboratory computational scientist who worked on the reconstruction project, says, "John Atanasoff did for computing what the Wright brothers did for aviation. He was the first to apply electronics to computing. He was the first to invent digital storage, or computer memory as we know it. No one understood, including Atanasoff, the impact his invention would eventually have."

Ames Lab's Veishea open house display featuring the ABC will be in Room 205 TASF and will be open to the public on Friday, April 17, from noon to 4 p.m., and Saturday, April 18, from 9 a.m. to 5 p.m. For more information on the replica contact Gustafson at (515) 294-9294, or Steve Karsjen, Ames Lab Public Information, (515) 294-5643.

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