Bernard R. Tittmann, Schell professor of engineering science and mechanics,
uses the prototype ultrasonic scanner, or acoustic microscope he developed
along with C. Miyasaka, postdoctoral scholar.
Photo: Greg Grieco
Bernard R. Tittmann, Schell professor of engineering science and mechanics,
uses the prototype ultrasonic scanner, or acoustic microscope he developed
along with C. Miyasaka, postdoctoral scholar.
Photo: Greg Grieco
By Barbara Hale
Public Information
Engineers have developed a prototype ultrasonic scanner, or acoustic microscope, that can image the interior of a material as it responds to temperature changes by melting, deforming or solidifying.
The new device, a modified Olympus UH3 Scanning Acoustic Microscope, is the first to enable researchers to peer nondestructively below a material's surface not only at room temperature, but also over a range of up to 400 degrees centigrade.
The device was developed by C. Miyasaka, a visiting postdoctoral scholar, and Bernhard R. Tittmann, the Schell professor of engineering science and mechanics.
Tittmann said the new device could potentially be used to study a broad range of materials. For example, microelectronics companies may be able to use the device to look for defects below the surface of computer chips or to study structural detail in integrated circuits. The device also could be used to study the grains and grain boundaries of complex materials or to optimize the distribution of liquid and solid in a semi-solid material.
The first material the team has studied is a laminate, called PEEK, composed of eight layers of graphite-reinforced plastic and adhesive. PEEK is widely used in truck bodies, boats, planes, golf clubs, tennis rackets and other consumer products. In the application the team investigated, PEEK was being considered by an international consortium for use as a material from which to manufacture the turbine blades in the first stage of aircraft engines.
The consortium hoped to decrease the weight of the engines while still maintaining strength and durability. However, during testing, the blades failed as the result of soft body or simulated "bird strike" impacts, but there were no telltale external marks on the blades to indicate that any damage was present.
At the request of the consortium, the researchers used their prototype acoustic microscope to image each of the eight layers in the turbine blades individually and to identify areas of delamination or separation that led to the failures. Also, by using the new temperature range feature of the modified microscope, the team was able to heat the sample and watch the delaminations close or "heal."
"The resolution of the microscope at temperatures up to about 100 degrees is comparable to that achieved by optical microscopes. At higher temperatures and lower frequencies, the resolution is on the order of a tenth of a millimeter," Tittmann said.
The researchers equipped the prototype device with several modifications that enable it to operate in its broad, nearly 400-degree temperature range. They surround the sample with a heat-tolerant fluid, racing car oil, which acts as a coupling medium. The acoustic waves are focused with a new type of low-absorption, ceramic lens and they have added a specially developed thermal barrier between the hot container and the transducer.
"The results clearly demonstrate the usefulness of scanning acoustic microscopy with temperature control," Tittman said. "The technique is completely nondestructive and lends itself for field development."
When Pennsylvania buck season begins on Nov. 30, an estimated 1 million
hunters will head for the woods. Both hunters and landowners need to keep
safety in mind, said an expert in the College of Agricultural Sciences.
"Many hunters use the property of farmers and other landowners," said Earle Robbins, Penn State Cooperative Extension agent in Tioga County. "Cooperation and mutual understanding between hunters and hosts is the key to keeping everyone involved safe and satisfied."
Following are hints from Robbins for both hosts and hunters:
* Make sure your guests are responsible and mature. If you have any doubts, refuse permission to hunt on your property.
* Tell your guests how you expect the land to be treated.
* Check your property and warn hunters about hazards, posting warning signs if needed. If you want parts of your land left alone, say so.
* Never assume you have a right to hunt on property not posted with "no trespassing" signs. Always ask permission to hunt on private property.
* Ask the landowner about potential hazards on the property and whether any sections are off-limits.
* Obey the owner's rules and respect his or her property.
* Hunters must strictly follow Pennsylvania Game Commission rules on safety. Wear at least 250 square inches of fluorescent orange material on the head, chest and back.
* Unload guns and leave the actions open when you are transporting them to and from the hunting area.
* Remember that it's illegal to hunt within 150 yards of any occupied residence, camp, industrial or commercial building, or school or playground without permission.
Finally, Robbins advises hunters and their hosts to promote safety by reporting violations and injuries to the Pennsylvania Game Commission as soon as possible.
"If you have questions about specific hunting regulations, contact the game commission," Robbins said. He also recommends A Digest of Pennsylvania Hunting and Trapping Regulations, published by the game commission. "It's an excellent summary of regulations and offers many safe hunting tips."
If you're taking a youngster deer hunting for the first time Nov. 30, make sure he or she understands some important safety rules, said Earle Robbins, Penn State Cooperative Extension agent in Tioga County.
Robbins offers these hunting safety tips:
* Make sure firearms are in good working order, and barrels and chambers are free of obstructions. Guns must be sighted properly and have the proper size ammunition.
* Familiarize yourself with the hunting site, so that you will know what's beyond your target.
* Assume every firearm is loaded. "When you pick up a gun, the first thing you should do is check it for ammunition," Robbins said. "When you pass a firearm to someone else, leave the action open so there is no chance of it firing."
* Always keep track of where your gun is pointed, and keep your finger off the trigger until it's time to fire at your target. Never aim your gun at anything you do not plan to shoot.
* Don't shoot until you're absolutely sure of your target. Shooting at a sound or an undefined shape is inviting tragedy.
* Unload your gun before climbing trees, scaling fences and logs, or jumping over ditches.
* If you have shot a deer and are preparing to dress it, don't forget to unload your gun.
* Never engage in horseplay using a gun.