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Shaker force measurements using voltage and current

Description: In a previous paper (Smallwood and Coleman, 1993), equations were developed which would allow the force into a test item during a vibration test to be measured using voltage and current measurements from the input to an electrodynamic shaker. To accomplish this, the voltage and current required to drive the shaker with no load and with a known mass were required. In this paper, the equations are generalized to cover the case where the measurements are made with several (at least 2) load conditions. It is not required that one of the conditions be the no load condition. The equations are written in a form where the known loads are not required to be a simple mass, but can be a complex impedance. For the case of more than two load conditions, a least squares solution is found.
Date: October 1, 1996
Creator: Smallwood, D.O.
Partner: UNT Libraries Government Documents Department

Microstructural changes in eutectic tin-lead alloy due to severe bending

Description: Severe plastic deformation in an eutectic tin-lead alloy is studied by imposing fast bending at room temperature, in an attempt to examine the microstructural response in the absence of thermally activated diffusion processes. A change in microstructure due to this purely mechanically imposed load is observed: the tin-rich matrix phase appears to be extruded out of the narrow region between neighboring layers of the lead-rich phase and alterations in the colony structure occur. A micromechanism is proposed to rationalize the experimental observations.
Date: February 29, 2000
Partner: UNT Libraries Government Documents Department

Ceramic powder compaction

Description: With the objective of developing a predictive model for ceramic powder compaction we have investigated methods for characterizing density gradients in ceramic powder compacts, reviewed and compared existing compaction models, conducted compaction experiments on a spray dried alumina powder, and conducted mechanical tests and compaction experiments on model granular materials. Die filling and particle packing, and the behavior of individual granules play an important role in determining compaction behavior and should be incorporated into realistic compaction models. These results support the use of discrete element modeling techniques and statistical mechanics principals to develop a comprehensive model for compaction, something that should be achievable with computers with parallel processing capabilities.
Date: December 31, 1995
Creator: Glass, S. J.; Ewsuk, K. G. & Mahoney, F. M.
Partner: UNT Libraries Government Documents Department

Ceramic granule strength variability and compaction behavior

Description: Diametral compression strength distributions and the compaction behavior and of irregular shape 150--200 {mu}m ceramic granules and uniform-size 210 {mu}m glass spheres were measured to determine how granule strength variability relates to compaction behavior of granular assemblies. High variability in strength, represented by low Weibull modulus values (m<3) was observed for ceramic granules having a distribution of sizes and shapes, and for uniform-size glass spheres. Compaction pressure data were also analyzed using a Weibull distribution function, and the results were very similar to those obtained from the diametral compression strength tests for the same material. This similarity suggests that it may be possible to model granule compaction using a weakest link theory, whereby an assemblage of granules is viewed as the links of a chain, and failure of the weakest granule (i.e., the weakest link) leads to rearrangement and compaction. Additionally, with the use of Weibull statistics, it appears to be possible to infer the variability in strength of individual granules from a simple pressure compaction test, circumventing the tedious task of testing individual granules.
Date: August 1, 1995
Creator: Glass, S.J.; Ewsuk, K.G. & Readey, M.J.
Partner: UNT Libraries Government Documents Department

Tensile properties of amorphous diamond films

Description: The strength and modulus of amorphous diamond, a new material for surface micromachined MEMS and sensors, was tested in uniaxial tension by pulling laterally with a flat tipped diamond in a nanoindenter. Several sample designs were attempted. Of those, only the single layer specimen with a 1 by 2 {micro}m gage cross section and a fixed end rigidly attached to the substrate was successful. Tensile load was calculated by resolving the measured lateral and normal forces into the applied tensile force and frictional losses. Displacement was corrected for machine compliance using the differential stiffness method. Post-mortem examination of the samples was performed to document the failure mode. The load-displacement data from those samples that failed in the gage section was converted to stress-strain curves using carefully measured gage cross section dimensions. Mean fracture strength was found to be 8.5 {+-} 1.4 GPa and the modulus was 831 {+-} 94 GPa. Tensile results are compared to hardness and modulus measurements made using a nanoindenter.
Date: December 2, 1999
Creator: Lavan, D.A.; Hohlfelder, R.J.; Sullivan, J.P.; Friedmann, T.A.; Mitchell, M.A. & Ashby, C.I.
Partner: UNT Libraries Government Documents Department

Correlation of Nanoindentation and Conventional Mechanical Property Measurements

Description: A series of model ferritic alloys and two commercial steels were used to develop a correlation between tensile yield strength and nano-indentation hardness measurements. The NanoIndenter-II{reg_sign} was used with loads as low as 0.05 g{sub f} (0.490 mN) and the results were compared with conventional Vickers microhardness measurements using 200 and 500 g{sub f} (1.96 and 4.90 N) loads. Two methods were used to obtain the nanohardness data: (1) constant displacement depth and (2) constant load. When the nanohardness data were corrected to account for the difference between projected and actual indenter contact area, good correlation between the Vickers and nanohardness measurements was obtained for hardness values between 0.7 and 3 GPa. The correlation based on constant nanoindentation load was slightly better than that based on constant nanoindentation displacement. Tensile property measurements were made on these same alloys, and the expected linear relationship between Vickers hardness and yield strength was found, leading to a correlation between measured changes in nanohardness and yield strength changes.
Date: February 14, 2001
Creator: Rice, P. M.
Partner: UNT Libraries Government Documents Department

Superconducting link bus design for the accelerator project for upgrade of LHC

Description: The Accelerator Project for Upgrade of LHC (APUL) is a U.S. project participating in and contributing to CERN's Large Hadron Collider (LHC) upgrade program. Fermi National Accelerator Laboratory in collaboration with Brookhaven National Laboratory was developing sub-systems for the upgrade of the LHC final focus magnet systems. Part of the upgrade called for various lengths of superconducting power transmission lines known as SC Links which were up to 100 m long. The SC Link electrically connects the current leads in the Distribution Feed Boxes to the interaction region magnets. The SC Link is an extension of the magnet bus housed within a cryostat. The present concept for the bus consists of 22 power cables, 4 x 13 kA, 2 x 7 kA, 8 x 2.5 kA and 8 x 0.6 kA bundled into one bus. Different cable and strand possibilities were considered for the bus design including Rutherford cable. The Rutherford cable bus design potentially would have required splices at each sharp elbow in the SC Link. The advantage of the round bus design is that splices are only required at each end of the bus during installation at CERN. The round bus is very flexible and is suitable for pulling through the cryostat. Development of the round bus prototype and of 2 splice designs is described in this paper. Magnetic analysis and mechanical test results of the 13 kA cable and splices are presented.
Date: June 1, 2011
Creator: Nobrega, F.; Brandt, J.; Cheban, S.; Feher, S.; Kaducak, M.; Kashikhin, V. et al.
Partner: UNT Libraries Government Documents Department

Development of Self-Expanding Idealflo (tm) Sandcontrol Technology

Description: Development of Self-Expanding Idealflo{trademark} Sandscreen Technology was a successfully executed design-by-analysis through field demonstration project. This final report is presented as a two-part progression of concept development and manufacturing activities. The first part, conceptual development activities, discusses novel specifications creation and non-linear analytical design generation. The second part, manufacturing, contains achievement related information for detailed-design, fabrication, mechanical testing, and field demonstration activities.
Date: September 30, 2007
Creator: Spray, Jeff A.
Partner: UNT Libraries Government Documents Department

Interlaminar strains at the free edge of a hole in laminated composites: An experimental study

Description: Free-edge effects in laminated composite materials were studied experimentally using high-sensitivity moire interferometry. Six laminates from two material systems were tested in uniaxial compression on an electro-mechanical testing machine. Interlaminar deformations were measured on a ply-by-ply basis at the straight free-edge and, for the first time, on the cylindrical surface of a hole. Strain distributions were determined with high fidelity for the hole surface and the straight free edge of the thick composite panels. Comparisons were made on a ply-by-ply basis for the transverse and tangential strains at the horizontal centerline of the hole (90{degree} location) and the corresponding plies at the straight boundaries.
Date: December 31, 1993
Creator: Boeman, R. G.
Partner: UNT Libraries Government Documents Department

Hall-Petch hardening in pulsed laser deposited nickel and copper thin films

Description: Very fine-grained Ni and Cu films were formed using pulsed laser deposition on fused silica substrates. The grain sizes in the films were characterized by electron microscopy, and the mechanical properties were determined by ultra-low load indentation, with finite-element modeling used to separate the properties of the layers from those of the substrate. Some Ni films were also examined after annealing to 350 and 450 C to enlarge the grain sizes. These preliminary results show that the observed hardnesses are consistent with a simple extension of the Hall-Petch relationship to grain sizes as small as 11 nm for Ni and 32 nm for Cu.
Date: January 3, 2000
Creator: Knapp, J.A.; Follstaedt, D.M.; Banks, J.C. & Myers, S.M. Jr.
Partner: UNT Libraries Government Documents Department

Strength testing of hot gas filters: Volume 6. Final report

Description: The strength of various ceramic hot gas filter materials has been evaluated by four laboratories: Argonne National Laboratory, DuPont Lanxide, Southern Research Institute and Babcock and Wilcox. The filter materials under study include (a) a Nextel{trademark}/SiC composite filter (from 3M), (b) PRD-66, an all oxide layered microstructure of alumina, mullite, cordierite and some amorphous material by DuPont Lanxide, (c) a Babcock and Wilcox material consisting of an oxide composite of chopped fibers (Saffil) and continuous Nextel fibers, (d-f) monolithic and recrystallized SiC materials and an alumino/aluminosilicate material by IFPM, and (g) a monolithic SiC by the Pall Corporation. Not all four organizations tested each of the materials. PRD-66 was tested by three of the four. Four tests were used to evaluate properties of the candle filter materials. They included (a) the C-ring test, (b) the O-ring test, (c) the burst test and (d) the axial compression test. Each organization identified above did not perform all four tests. The objective of the study described here was to (a) provide an evaluation of the test methods used for hot gas filters to determine which is best for hot gas filter evaluation and (b) evaluate the discrepancies in results from tests run at different laboratories. No material ranking was made here, nor requested.
Date: June 9, 1998
Creator: Faber, K.T.
Partner: UNT Libraries Government Documents Department

A New Technique for Dynamic Load Distribution When Two Manipulators Mutually Lift a Rigid Object. Part 1, the Proposed Technique

Description: A general framework for solving the dynamic load distribution when two manipulators hold a rigid object is proposed. The underspecified problem of solving for the contact forces and torques based on the object`s equations of motion is transformed into a well specified problem. This is accomplished by augmenting the object`s equations of motion with additional equations which relate a new vector variable quantifying the internal contact force and torque degrees of freedom (DOF) as a linear function of the contact forces and torques. The resulting augmented system yields a well specified solution for the contact forces and torques in which they are separated into their motion inducing and internal components. A particular solution is suggested which enables the designer to conveniently specify what portion of the payload`s mass each manipulator is to bear. It is also shown that the results of the previous work are just a special case of the general load distribution framework described here.
Date: April 1, 1994
Creator: Unseren, M. A.
Partner: UNT Libraries Government Documents Department

Mechanical properties of S-65C grade beryllium at elevated temperatures

Description: Tensile property measurements and fractographic analysis of S-65C beryllium are reviewed. Tests were performed on specimens oriented in the longitudinal and transverse directions with respect to the direction of vacuum hot pressing. Specimens were tested in air at RT, 100 C, 200 C, 300 C, 415 C and 500 C at an initial strain rate of 1.1 {times} 10(sup {minus}4) per second. Ductility of the material was strongly affected by the test temperature, exhibiting a peak ductility at 300 C. The material displayed a yield point phenomenon which was most pronounced at this same temperature. Scanning electron microscopy was performed on the resulting fracture surfaces and observations are reported.
Date: November 1, 1997
Creator: Goods, S.H. & Dombrowski, D.E.
Partner: UNT Libraries Government Documents Department

Solid Freeform Fabrication Using the Wirefeed Process

Description: Direct metal deposition technologies produce complex, near net shape components from CAD solid models. Most of these techniques fabricate a component by melting powder in a laser weld pool, rastering this weld bead to form a layer, and additively constructing subsequent layers. This talk describes a new direct metal deposition process, known as WireFeed, whereby a small diameter wire is used instead of powder as the feed material to fabricate components. Currently, parts are being fabricated from stainless steel. Microscopy studies show the WireFeed parts to be fully dense with fine microstructural features. Initial mechanical tests show stainless steel parts to have good strength values with retained ductility.
Date: July 22, 1999
Creator: Buchheit, T. E.; Crenshaw, T. B.; Ensz, M. T.; Greene, D. L.; Griffith, M. L.; Harwell, L. D. et al.
Partner: UNT Libraries Government Documents Department

Determining a Method to Pressure Test a Novel Type of Glass

Description: A novel type of glass made with a double ion exchange process is more reliable and fractures in a unique manner compared to glass currently available in the market. The novel glass is unique because it disintegrates into a powder instead of fracturing into shards and splinters, and it fails over a very narrow range of stresses. Potential applications for this glass include using it in removable valves because the powdered glass does not produce obstructions when it breaks, and in other applications that require safety glass. A 20,000-psi MTS pressure system was used to determine the possible techniques for pressure testing the strength of a collection of disk-shaped glass samples. Ordinary (i.e., not ion exchanged) glass samples, 0.962 inches in diameter and 0.07 inches thick, were fractured with linearly increasing pressures to determine the best methods. The best method for testing novel glass samples, with the same size and shape as the ordinary glass, will be implemented. The final results of this ongoing project will be used to ascertain if the novel glass is suitable for potential applications.
Date: August 19, 1999
Creator: Rice, Catherine Diane
Partner: UNT Libraries Government Documents Department

Characterization of Min-K TE-1400 Thermal Insulation

Description: Min-K 1400TE insulation material was characterized at Oak Ridge National Laboratory for use in structural applications under gradient temperature conditions. Initial compression testing was performed at room temperature at various loading rates ranging between 5 and 500 psi/hour (&#8776;35 and 3500 kPa/hour) to determine the effect of sample size and test specimen geometry on the compressive strength of Min-K. To determine the loading rates that would be used for stress relaxation testing, compression tests were next carried out at various levels followed by stress relaxation under constant strain at temperatures of 650, 850, and 900oC. Additional high temperature compression testing was performed with samples loaded at a rate of 53 psi/hour (365 kPa/hour) in three load steps of 50, 100 and 200 psi (345, 690, and 1380 kPa) with quick unload/load cycles between steps and followed by a hold period in load control (3 to 100 hours) to allow for sample creep. Testing was carried out at 190, 382, 813, and 850oC. Isothermal stress relaxation testing was performed at temperatures of 190, 382, 813, and 850oC and initial loads of 100 and 200 psi (690 and 1380 kPa). Gradient stress relaxation testing was intended to be performed at temperatures of 850/450oC and 450/190oC with initial loads of 100 or 200 psi (690 and 1380 kPa) performed under constant strain utilizing a twelve-step loading scheme with loading every half hour at a rate of 5.56% strain/hour.
Date: July 1, 2008
Creator: Hemrick, James Gordon; Lara-Curzio, Edgar & King, James
Partner: UNT Libraries Government Documents Department

Adjustable Shock Test Sled for Haversine Pulses at 250 fps

Description: New test requirements were developed by Sandia National Laboratory to simulate a regime of shock testing not previously performed at the Kansas City Plant operated by Honeywell Federal Manufacturing & Technologies. These environments were unique in that they involved amplitude of shock >1000g with relatively long pulse durations (greater 5 ms but less than 10 ms) and involved velocity changes up to 235 ft/sec. Ten months were available to develop, design, manufacture and prove-in this new capability. We designed a new shock sled to deliver this new family of shock environments in a laboratory test. The performance range of the new sled includes five specific shocks (1000 g – 8 ms, 1300 - 6 ms, 1500 g – 5.4 ms, 1950 g – 6 ms, 2250 g – 5.4 ms; all haversine shaped), and it also incorporates adjustability to accommodate new shocks within this range. These shock environments result in velocity changes ranging from 160 fps to 250 fps. The test sled accommodates test articles weighing up to 20 lbs and measuring up to 10” along any axis.
Date: May 5, 2008
Creator: Hartwig, Troy; Hower, Brent & Seaholm, Aaron
Partner: UNT Libraries Government Documents Department

A multiaxial viscoplastic model for advanced Si{sub 3}N{sub 4} ceramics

Description: A uniaxial creep/creep rupture model developed previously based on results obtained from uniaxial tensile creep tests of an advanced Si{sub 3}N{sub 4} ceramic has been refined and upgraded in multiaxial form to facilitate general applications. Severity of asymmetric creep behavior in tension compared to that in compression observed in recent experimental results mandates this revision. The tensorial formulation follows the plasticity theories developed for soils. Material sensitivity to pressure, asymmetry between tension and compression, changes of material structure due to hardening of grain boundary phase, and deformation induced volumetric swelling attributable to cavity and void formations have all been considered. Provisions for such features in the proposed multiaxial model are shown to have improved modeling flexibility.
Date: April 1, 1996
Creator: Ding, J.L.; Liu, K.C. & Brinkman, C.R.
Partner: UNT Libraries Government Documents Department

Fracture testing and analysis of adhesively bonded joints for automotive applications

Description: In 1992, the Oak Ridge National Laboratory (ORNL) began a cooperative effort with the Automotive Composites Consortium (ACC) to conduct research and development that would overcome technological hurdles to the adhesive bonding of current and future automotive materials. This effort is part of a larger Department of Energy (DOE) program to promote the use of lighter weight materials in automotive structures for the purpose of increasing fuel efficiency and reducing environmental pollutant emissions. In accomplishing this mission, the bonding of similar and dissimilar materials was identified as being of primary importance to the automotive industry since this enabling technology would give designers the freedom to choose from an expanded menu of low mass materials for component weight reduction. This paper concentrates on the details of developing accurate fracture test methods for adhesively bonded joints in the automotive industry. The test methods being developed are highly standardized and automated so that industry suppliers will be able to pass on reliable data to automotive designers in a timely manner. Mode I fracture tests have been developed that are user friendly and automated for easy data acquisition, data analysis, test control and test repeatability. The development of this test is discussed. In addition, materials and manufacturing issues are addressed which are of particular importance when designing adhesive and composite material systems.
Date: December 31, 1994
Creator: Boeman, R. G. & Warren, C. D.
Partner: UNT Libraries Government Documents Department

Quantification of damage evolution for a micromechanical model of ductile fracture in spallation of copper

Description: Detailed quantitative measurements of damage evolution in an incipiently spalled and recovered 10100 OFHC copper sample of 30 {micro}m grain size are described. The free surface velocity is shown. The total porosity of the sample as a function of distance from the spall plane is reported. The observed and true volumetric size distribution of voids and the observed size distribution of clusters of voids are also calculated and presented.
Date: September 1, 1997
Creator: Thissell, W.R.; Zurek, A.K.; Tonks, D.L. & Hixson, R.
Partner: UNT Libraries Government Documents Department

Fracture of hard thin films using nanoindentation and nanoscratch techniques: A materials and mechanics approach

Description: Thin films are used in many applications where special properties are needed to insure performance and reliability. Of particular interest are thin tantalum nitride films. They are used extensively in microelectronic applications because of their long term stability and low thermal coefficient of resistance. They are sputter deposited which produces films with a high structural defect content and high compressive residual stresses both of which can alter the physical and mechanical properties of microelectronic thin films. Although these films are strong heat generators, they exhibit no changes in structure or composition of the interface with aluminum oxide substrates that degrade performance or reliability. However, the use of high power density components is driving a move to replace aluminum oxide with aluminum nitride for greater heat transfer. 6 This replacement substrate creates concern as residual stresses and long-term operation could induce detrimental changes along the thin film interface not observed in aluminum oxide devices. As a result, the authors employed nanoindentation and continuous nanoscratch testing to determine the effects of the intrinsic compressive residual stresses on the properties and fracture resistance of the thin tantalum nitride films. These techniques sample small volumes of material while preserving the production configuration of a free surface. Although nanoscratch tests lack a rigorous derivation of stress distributions and strain energy release rates, good approximations for strain energy release rates can be obtained using mechanics-based models for blister formation where residual stresses dominate interfacial fracture behavior. When combined with scanning and transmission electron microscopy, the results define structure-property relationships and resistance to fracture of these hard films.
Date: March 19, 1998
Creator: Moody, N.R.; Medlin, D.; Hwang, R.Q.; Boehme, D.; Venkataraman, S. & Gerberich, W.W.
Partner: UNT Libraries Government Documents Department
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