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Cyclic shear device for interfaces and joints with pore water pressureRigby, Douglas Bertrand, 1956- January 1988 (has links)
An improved multi degree-of-freedom direct shear device has been designed and constructed to test interfaces and joints under pore water pressure. Any two structural (concrete, steel, wood) or geologic (soil, rock) materials may be tested in the device as long as the top specimen is solid. The apparatus is designed to hold a 7.5-inch diameter 3-inch thick upper sample and a 9-inch diameter 3-inch thick lower sample. A normal stress of 400 psi (2.7 MPa) and a shear stress of 550 psi (3.9 MPa) can be developed at the interface. Test loading may be static, quasi-static, or cyclic, and constant or variable stiffness loading is available. A stiff reaction frame was designed to house the device and is described. The electro-hydraulic system is capable of supporting cyclic testing at 30 Hz. A new computer-controlled data acquisition and control system is also described.
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TESTS OF GUSSET PLATE CONNECTIONS.Chakrabarti, Sekhar Kumar. January 1983 (has links)
No description available.
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DRIFT AND MOMENT DISTRIBUTIONS IN BRACED FRAMES.Otu, Sunday Ekum. January 1984 (has links)
No description available.
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Cyclic load tests of composite beam-column connectionsDunberry, Max. January 1982 (has links)
No description available.
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Cyclic load tests of composite beam-column connectionsDunberry, Max. January 1982 (has links)
No description available.
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Slab-column connections with misplaced reinforcementLai, Wai Kuen (Wai Kuen Frank) January 1983 (has links)
No description available.
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Slab-column connections with misplaced reinforcementLai, Wai Kuen (Wai Kuen Frank) January 1983 (has links)
No description available.
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Flexural strength of reinforced concrete external column-beam jointsYue, Hon-fai, Peter., 余漢輝. January 1973 (has links)
published_or_final_version / Civil Engineering / Master / Master of Philosophy
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Reliability of Solder Joints in Embedded Packages Using Finite Element MethodsYunusa, Valeri Aisha 26 July 2018 (has links)
Solder joints serve as both mechanical and electrical connections between elements in a package. They are subjected to shear strains generated as a result of the different behaviors of the elements in the package (tension and compression) due to the differences in coefficients of thermal expansion during service conditions.
Some of the causes of solder joint failures are due to the following:
Vibration: small rapid displacements of parts of the assembly. This is not necessarily an issue with electronic components but larger parts like automobiles.
Humidity: the package being exposed to water or ionic species can undergo corrosion if an electrical bias exists resulting in electrical opens or electrical shorts if the corrosion products are electrically conductive.
Thermal Aging: this occurs during the lifetime of the solder interconnects, the package can be exposed to high ambient temperature or high dissipated heat during use. The micro-structure of the solder joint becomes more coarse and brittle.
Mechanical Shock: the package undergoes shock during a short term exposure to high loads.
Thermo-mechanical fatigue: this type of failure arises as a result of the solder joints going through cyclic strains, due to different coefficients of thermal expansion of individual components in the package during service.
The most prevalent long-term reliability issues that can cause interconnect failure are thermal aging and thermo-mechanical fatigue. This study aims to evaluate the reliability of solder joints using finite element method, considering solder joint failure due to thermo-mechanical fatigue.
Three variations of the BGA (Ball Grid Array) package are evaluated using the finite element analysis. The SAC305 series lead (pb) free alloy of 96.5% tin, 3% silver, and 0.5% copper is employed for this study.
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Viscoelastic relaxation in bolted thermoplastic composite jointsSchmitt, Ron R. 12 1900 (has links)
Results from a research program to investigate the long term effects of
through-the-thickness fastener clamp-up force (preload) relaxation on the
strength of mechanically fastened joints for two graphite/thermoplastic
composite materials (Dupont's IM6/KIII and ICI-Fiberite's IM8/APC(HTA)) are
summarized and compared with analytical methods. An experimental program
was conducted in which 56 mechanically fastened single-shear joints were
tested. Phase I static tests established joint bearing strength as a function of
clamp-up force for two types of fasteners (protruding head and countersink) with
no relaxation of preload. Phase II testing monitored short-term fastener preload
relaxation (up to 1 ,000 hours), with special bolt force sensor washers. Inservice
parameters included were temperature, in-plane loads, and torque. The
jOints were tested to failure at the end of the relaxation time period to determine
any subsequent effect on joint strength.
Phase I test results indicated that joint bearing strength increased by as
much as twenty-eight percent over the clamp-up force range of a Ibs (fingertight)
to 3,500 Ibs for both materials. Fastener head type, material, and
temperature also affected the resultant bearing strength. For Phase II, fastener
clamp-up force at room temperature (78°F) relaxed an average of six percent
from the initial value during the short-term test period. The relaxation was
projected to be as high as fourteen and sixteen percent at 100,000 hours for
HTA and Kill, respectively. The elevated temperature condition (250°F)
significantly increased the relaxation rate with the projected 100,000 hour
relaxation amount being as high as thirty-seven percent for HTA and sixty
percent for Kill. Comparison of the Phase II bearing strengths to the Phase I
results indicated that portions of the data correlated well, while others did not. It
was concluded that relaxation of the clamp-up force over the short-term time
period did not significantly lower the bearing strength of either material,
however an extended exposure to 250°F could affect the bearing strength. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Aerospace Engineering.
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