Mechanical Engineering

ho are you going to call when you need to balance the air conditioning needs of a 42-foot long dinosaur, people-eating lions, Somalian wild asses, a pair of elephants and thousands of museum visitors and staff?

Chicago's Field Museum of Natural History hired Associate Professor Doug Reindl (left) and Professor Sanford Klein (right) to study the heating, ventilation, humidity and air conditioning systems in their massive, century-old structure. Reindl summarized the challenge: "How are we managing to destroy in a few decades artifacts that have lasted hundreds of years? And how can we prevent that? We can either put artifacts in a secure, safe environment and keep people out or we can compromise and put them in a display where people can see them."

Their work was further complicated by the fact that 95 percent of the museum's collections are in storage. These collections must be preserved while remaining accessible to scientists.

Reindl, Klein and graduate student Janeen Ault set up monitors throughout the building to collect a year's worth of information on the building's climate. They also researched the heating, ventilation and air-conditioning systems used by other museums. The team's recommendations include replacing seals on exterior emergency doors, relocating thermostats to more representative locations, demolishing a wall restricting air movement from one exhibit hall to another, and adding humidifying equipment.

Klein and Reindl also recommended reducing intake of outside air. A significant amount of damaging air pollution comes from nearby Chicago traffic and parking lots. Contaminants from auto exhaust react chemically with the artifacts causing irreversible damage.

Improving the safety of automobiles--one joint at a time

Automobile manufacturers strive to improve the quality and safety standards of cars with every new model. Through her work in laser materials processing and intelligent manufacturing, Assistant Professor Elizabeth Smith is contributing to that effort by making the welded joints in automobiles and other products stronger and safer.

Lasers provide a precise, flexible source of intense energy for materials processing applications such as welding, cutting, forming and heat-treating. Smith uses small microphones to monitor the acoustic signals generated during the laser welding process. With this approach, she can identify the quality of the laser-welded joints and identify defects that may not have been found otherwise.

Smith's interest in intelligent manufacturing is not limited to industrial laser applications. Manufacturing operations, in general, can be made more robust and reliable through the integration of monitoring systems. Sensors can be applied for real-time process control of both traditional and non-traditional manufacturing operations. For example, acoustic signals can be used to monitor machining operations like turning and milling.

Smith's research in laser materials processing extends beyond automotive applications, encompassing electronics manufacturing and novel microfabrication techniques, with applications in microelectromechanical systems, biomedical devices and more.

Strength and efficiency through flexibility

Elastic deformation is generally considered undesirable in the design of conventional rigid-link mechanisms which rely on rigid members and localized joints to translate forces and motions. Assistant Professor Joel Hetrick is working with compliant mechanisms: structures which utilize elastic deformation to emulate the behavior of traditional rigid mechanisms.

For applications requiring moderately small motions, compliant mechanisms have many advantages over traditional devices, including the elimination of friction, wear and backlash associated with mechanical joints. In addition, the monolithic nature of compliant mechanisms makes them easy to fabricate and can minimize or altogether eliminate assembly requirements.

Hetrick recently created a novel micro-compliant displacement multiplier for Sandia National Laboratories. When coupled with an electrostatic actuator, the compliant displacement multiplier efficiently amplifies the actuator displacement by a factor of 10, while requiring one-fifth the chip area of a standard direct-drive actuator. The new actuator-multiplier is being investigated for use in a variety of MEMS applications which require high-speed, compact actuation.

Hetrick is now focused on automating design of compliant mechanism and smart material systems. The combination of these systems could enable a host of new devices including minimally invasive surgical tools, better microfluidic pumps and valves, and faster, more efficient optical devices.

Neil A. Duffie (Chair)
240 Mechanical Engineering
1513 University Avenue
Madison, WI 53706-1572

Tel: 608/262-0665
Fax: 608/265-2316
E-mail: bruckert@engr.wisc.edu
www.engr.wisc.edu/me