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Fixture explores the reliability of bellows used in precision in inertial systems. The fixture establishes the ability of the bellows to withstand repetitive over-stress pressure cycling at elevated temperatures. It is applicable in quality control and reliability programs.
Classical method of presenting fatigue data in plots of alternating stress vs number of deflection cycles is applied to bellows formed of various metals, including corrosion-resistant steel, nickel alloys, and aluminum alloys. The expected life of a new bellows design can then be determined before fabrication and testing.
Report presents test data on the bending fatigue life of notched sheet specimens. The influence of a surface irregularity on the fatigue life of a metal bellows is evaluated, with emphasis on accidental defects in ducting bellows which are impossible to avoid short of completely eliminating human contact.
To prevent fatigue due to flow-induced vibrations in metal bellows connected to ducts carrying liquid hydrogen, a study was made which shows that the flexure lines are in general a function of the vibration coupling between the fluid and bellows structure, and the nature of the external environment.
Bellows seal rotary drive device was developed which allows high torque transmission through sealed compartments. Bearing friction which would normally be carried by sealing bellows in comparable devices is absorbed by universal-gimbal joint. It can be used to transmit high torque, low speed, rotary motion through sealed barriers to prevent contamination or escape of fluids.
Thin cover of corrosion-resistant steel (CRES) protects metal bellows and ducts against hydrogen embrittlement. Bellow current carries hydrogen at high pressure and currently is used in the engine of Space Shuttle.
Results of theoretical and experimental investigations of bellows typical of those found in space shuttle external tanks are presented. Correlation parameters are identified which generalize the alternating stress calculations cited in an earlier study. Alternating stress amplitudes and mean stress levels form the basis of a fatigue analysis incorporating seven ordinate charts for 347 stainless steel, alloy 21 6-9, and Inco 718. A crack propagation model is included with a program for computing bellows fatigue life. Two phase flow and material hardness properties are discussed.
Adjustable leaf spring increases maximum operating pressure of pump from 2 to over 60 psi (13 to over 400 kN/m2). Small commercial bellows pump using ac-powered electromagnet to vibrate bellows at mechanical resonance modified to operate over wider pressure range.
The bellows flow excitation mechanism and results of comprehensive test program are summarized. The analytical model for predicting bellows flow induced stress is refined. The model includes the effects of an upstream elbow, arbitrary geometry, and multiple piles. A refined computer code for predicting flow induced stress is described which allows life prediction if a material S-N diagram is available.
SHELL computer program developed to calculate changes in volume of bellows caused by changes in internal pressure. Input to program consists of tables describing bellows material, geometry of convolutions, and loading. Output gives displacements and changes in volume used for analysis of POGO or of water hammers. Written in FORTRAN 77.
A high-temperature hybrid seal is constructed of multiple elements to meet the many demands placed on the seal. The primary elements are: a central high-temperature bellows, a braided ceramic sheath covering the bellows, an outer abrasion resistant sheath covering the ceramic sheath, and a structurally-sound seal-end termination.
A miniature optically ignited actuation device has been demonstrated using a laser diode as an ignition source. This pyrotechnic driven motor provides between 4 and 6 lbs of linear force across a 0.090 inch diameter surface. The physical envelope of the device is 1/2 inch long and 1/8 inch diameter. This unique application of optical energy can be used as a mechanical link in optical arming systems or other applications where low shock actuation is desired and space is limited. An analysis was performed to determine pyrotechnic materials suitable to actuate a bellows device constructed of aluminum or stainless steel. The aluminum bellows was chosen for further development and several candidate pyrotechnics were evaluated. The velocity profile and delivered force were quantified using an non-intrusive optical motion sensor.
Load transfer to end flanges for prevention of bellows buckling in tunnel fuel tank
Control of electrolyte level in nickel-cadmium cells with metal and plastic bellows
Dynamic instability of undamped bellows face seals in cryogenic liquid
Bellows restraints, thrust-vector attitude-control gimbal devices, and tube clamp descriptions
Dynamic instability in undamped bellows face seals operating in cryogenic environment with torsional oscillation and diametrical rocking as primary motion