9. Foiled Again

a bearing	підшипник	hypersonic	надзвуковий
foil	фольга	to absorb	поглинати
film	плівка	a shock	удар
thrust	тяга	delicate	чутливий
to exceed	перевищувати	stiffness	жорсткість
ultimate	граничний	damping	демпфування
yield strength	міцність	to toss	кидати
a shaft	вал	to match	вирівнювати
to crack	тріскатись	gradually	поступово
spring-loaded	пружинний	airborne	що перебуває у повітрі
journal lining	опорна підкладка	to prevent	запобігати
coated	покритий	to survive	витримати
lubricant	змазка	a missile	ракета
revolution	оберт	a turbocharger	турбокомпресор
to clock in	обертатись	to cut back on	скорочувати

Foil bearings are making explosive progress, according to Hooshang Heshmat, an ASME Fellow and founder of Mohawk Innovative Technology Inc. in Albany, N.Y.

Foil bearings run on a thin film of air that enables them to achieve very high rotational speeds. How high? According to Heshmat, he once ran a 50-pound-thrust turbine engine so fast that it exceeded the ultimate yield strength of the shaft, which cracked and exploded into thousands of pieces. Nor was it any ordinary shaft: It was made of 440C, a high-carbon chromium bearing steel used in the Space Shuttle’s main engine.

The key to foil bearing performance lies in its foil. The shaft rests on a spring-loaded foil journal lining coated with solid lubricant. Once it starts moving, it rides on the foil until it moves fast enough to generate the air pressure needed to push the foil away. At this point, the shaft is riding on a film of air. Foil bearings use no liquid lubricants.

The technology was invented 50 years ago. In the early days, foil bearings could support maximum loads of only about 10 pounds per square inch at room temperature. Today, Mohawk has bearings that carry loads up to 100 pounds per square inch and operate at temperatures as high as 1,700°F. The smallest foil bearings are 4 mm in diameter and achieve 1 million revolutions per minute. The largest bearings are 235 mm diameter and clock in at hypersonic speeds of more than 600 meters per second.

Mohawk’s latest bearings take advantage of two key innovations. The first has to do with the bearing’s ability to absorb shocks without failing. This involves a delicate balance of stiffness and damping. Heshmat likens it to tossing a child into the air. “As the baby starts coming down, you match his speed with your hands to slow him down gradually before catching him,” he explained. “We’ve designed the foil and springs around the shaft to achieve multilevel stiffness and damping to do just that.”

Heshmat’s team has also developed an innovative foil coating. It fulfills two important functions. First, it acts as a solid lubricant to smooth the startup of the bearing before it goes airborne. This prevents wear. The same coating also acts as a thermal barrier, enabling the foils to survive for tens of thousands of hours at temperatures up to 1,700°F.

The military funded much of Mohawk’s research for use in missiles, rockets, and jet engines.

Lubrication-free bearings could make possible turbochargers for diesel engines. As today’s diesel turbochargers age, oil leaks into the engine and comes out as particulates. Environmental regulations limit particulate emissions, such as the black soot that diesels emit as they warm up to operating temperatures. While foil bearings could double the cost of turbochargers, they would allow diesel manufacturers to cut back on the equipment now needed to capture particulate emissions.

Speech Patterns

to have something (nothing) to do with smth.	мати (не мати) відношення до чогось
I’m sure he has something to do with medicine.	Я певен, що він має якесь відношення до медицини.
This problem has nothing to do with us.	Ця проблема нас ніяк не стосується.

Exercise 1. Say whether the statements are TRUE or FALSE.

1. Foil bearings run on a film of oil. 2. Heshmat made an experiment with a turbine engine to check the strength of the shaft. 3. The shaft used in the experiment was made of cast iron. 4. The technology of foil bearings was invented 20 years ago. 5. The smallest foil bearings are less than 1 sentimetre in diameter. 6. Heshmat compares the operation principles of the bearings with tossing a child into the air. 7. Foil coating enables to prevent overheating. 8. The military are going to use the foil bearings in submarines.

Exercise 2. Give synonyms to the following words from the text:

progress, ultimate, ordinary, main, performance, to support, to achieve, stiffness, to toss, innovative, regulation.