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Strength of Welded Joints in Tubular Members for Aircraft

Description: "The object of this investigation is to make available to the aircraft industry authoritative information on the strength, weight, and cost of a number of types of welded joints. This information will, also, assist the aeronautics branch in its work of licensing planes by providing data from which the strength of a given joint may be estimated. As very little material on the strength of aircraft welds has been published, it is believed that such tests made by a disinterested governmental laboratory should be of considerable value to the aircraft industry" (p. 323).
Date: February 6, 1930
Creator: Whittemore, H. L. & Brueggeman, W. C.
Partner: UNT Libraries Government Documents Department

Strength of Welded Aircraft Joints

Description: "This investigation is a continuation of work started in 1928 and described in NACA-TR-348 which shows that the insertion of gusset plates was the most satisfactory way of strengthening a joint. Additional tests of the present series show that joints of this type could be improved by cutting out the portion of the plate between the intersecting tubes. T and lattice joints in thin-walled tubing 1 1/2 by 0.020 inch have somewhat lower strengths than joints in tubing of greater wall thickness because of failure by local buckling. In welding the thin-walled tubing, the recently developed "carburizing flux" process was found to be the only method capable of producing joints free from cracks" (p. 177).
Date: August 12, 1936
Creator: Brueggeman, W. C.
Partner: UNT Libraries Government Documents Department

Special Welding Techniques : Final Summary Report

Description: From foreword: This is the final report on Special Welding Techniques. The work of the third and final year is discussed in detail, and the accomplishments of the first two years are summarized.
Date: January 1957
Creator: Mueller, John; Maxwell, William & Siltanen, James
Partner: UNT Libraries Government Documents Department

Summary of Results of Tests Made by Aluminum Research Laboratories of Spot-Welded Joints and Structural Elements

Description: "Available information concerning spot welding as a means of joining aluminum-alloy parts has been summarized and comparisons have been made of the relative merits of spot-welded and riveted aluminum-alloy structural elements. The results indicated that spot welding was as satisfactory as riveting insofar as resistance to static loads is concerned. Spot welds showed slightly lower resistance to impact loads but definitely lower resistance to repeated loads than rivets" (p. 1).
Date: November 1942
Creator: Hartmann, E. C. & Stickley, G. W.
Partner: UNT Libraries Government Documents Department

New Equipment for Testing the Fatigue Strength of Riveted and Welded Joints

Description: "The mechanical and electrical construction of a new experimental instrument for fatigue testing riveted and welded joints is described. This experimental device has the advantage of being able to stress, even with comparatively low magnetic exciter force, structural components in alternate bending by resonance vibrations up to incipient fatigue failure (p .1)".
Date: July 1940
Creator: Müller, W.
Partner: UNT Libraries Government Documents Department

Lamb-wave inspection of welds in stainless steel tubes

Description: An ultrasonic Lamb-wave inspection technique was developed for use in inspecting the gas tungsten arc (GTA) welds in small diameter stainless steel tubes for lack of penetration. The particular technique was employed because of the ability to introduce the sound into the material a distance from the weld. A conventional shear-wave technique was tried without success. (auth)
Date: December 26, 1973
Creator: Schrick, G. W.
Partner: UNT Libraries Government Documents Department

Neural Network Modeling of Weld Pool Shape in Pulsed-Laser Aluminum Welds

Description: A neural network model was developed to predict the weld pool shape for pulsed-laser aluminum welds. Several different network architectures were examined and the optimum architecture was identified. The neural network was then trained and, in spite of the small size of the training data set, the network accurately predicted the weld pool shape profiles. The neural network output was in the form of four weld pool shape parameters (depth, width, half-width, and area) and these were converted into predicted weld pool profiles with the use of the actual experimental poo1 profiles as templates. It was also shown that the neural network model could reliably predict the change from conduction-mode type shapes to keyhole-mode shapes.
Date: November 16, 1998
Creator: Iskander, Y.S.; Oblow, E.M. & Vitek, J.M.
Partner: UNT Libraries Government Documents Department

Towards predicting weld metal microstructure from fundamentals of transport phenomena

Description: Heat transfer and fluid flow during manual metal arc welding Of low alloy steels were investigated by solving the equations of conservation of mass, momentum and energy in three dimensions. Calculated cooling rates were coupled with an existing phase transformation model to predict the microstructure in low alloy steel welds. The computed results were found to be in good agreement with experimentally observed microstructures. The agreement indicates significant promise for predicting spatial distribution of weld metal microstructure from the fundamentals of transport phenomena.
Date: June 1, 1995
Creator: Mundra, K.; DebRoy, T.; Babu, S. S.; David, S. A. & Paul, A. J.
Partner: UNT Libraries Government Documents Department

Fatigue Strength and Related Characteristics of Spot-Welded Joints in 24S-T Alclad Sheet

Description: Report presenting an investigation on spot-welded 24S-T Alclad. The report is divided into five parts, including an investigation of tension fatigue measurements, lap-joint samples spot-welded by different companies, fatigue strengths of wire-stitched lap-joint samples, data on similar samples with different spot spacings, and the results of compression fatigue tests for stiffened panels with purposely overheated spot welds.
Date: December 1943
Creator: Russell, H. W.
Partner: UNT Libraries Government Documents Department


Description: A statistically designed experiment was conducted as part of a six sigma project for Fill Stem Manufacturing and Pinch Weld Processing. This multi-year/multi-site project has successfully completed a screening study and used those results as inputs to this optimization study. Eleven welds were made using fairly tight current and cycle range. The welds demonstrate increased burst strength, longer closure length, more net displacement, and improved bond rating with increased current. However, excessive melting remains a concern from a processing viewpoint and may cause adverse metallurgical interactions. Therefore, the highest current levels specified cannot be utilized. A Validation Study is proposed for the Defense Programs Inert Facility.
Date: September 6, 2006
Creator: Korinko, P & Karl Arnold, K
Partner: UNT Libraries Government Documents Department

High power ultrasonic bond strength evaluation

Description: S>Bond strength of diffusion and adhesive bonds has long remained one of the unsolved problems facing the materials testing industry. Many techniques are available for the detection of unbonds but these tend to become inaccurate when the unbonded surfaces are in intimate contact. Weak bonds in almost all cases cannot be distinguished from bends which approach base material strengths. One must usually resort to destructive testing of samples cut from production parts to obtain bond strength information. This is not the most satisfactory method from a cost and reliabilily standpoint. The accuracy of this data is also in some doubt since the cutting procedure itself may disturb the bond and the residual stress pattern of the part. The ultrasonic approach has the potential of eliminating many of the limitations of existing bond testing technlques. The system is based on the use of high power ultrasonic waves to stress the bond interface with an acoustic pressure sufflcient to break bonds of below minimum allowable strengths. Acceptable production parts may be 100% inspected with no detrimental effects. The technique, equipment, and transducers developed for this test as well as tests which indicate the feasibility of the method are described. Suggestions for further development are also included. (auth)
Date: October 1, 1973
Creator: Becker, F.L.
Partner: UNT Libraries Government Documents Department

Pulse shaping effects on weld porosity in laser beam spot welds : contrast of long- & short- pulse welds.

Description: Weld porosity is being investigated for long-pulse spot welds produced by high power continuous output lasers. Short-pulse spot welds (made with a pulsed laser system) are also being studied but to a much small extent. Given that weld area of a spot weld is commensurate with weld strength, the loss of weld area due to an undefined or unexpected pore results in undefined or unexpected loss in strength. For this reason, a better understanding of spot weld porosity is sought. Long-pulse spot welds are defined and limited by the slow shutter speed of most high output power continuous lasers. Continuous lasers typically ramp up to a simmer power before reaching the high power needed to produce the desired weld. A post-pulse ramp down time is usually present as well. The result is a pulse length tenths of a second long as oppose to the typical millisecond regime of the short-pulse pulsed laser. This study will employ a Lumonics JK802 Nd:YAG laser with Super Modulation pulse shaping capability and a Lasag SLS C16 40 W pulsed Nd:YAG laser. Pulse shaping will include square wave modulation of various peak powers for long-pulse welds and square (or top hat) and constant ramp down pulses for short-pulse welds. Characterization of weld porosity will be performed for both pulse welding methods.
Date: October 1, 2007
Creator: Ellison, Chad M. (Honeywell FM&T, Kansas City, MO); Perricone, Matthew J. (R.J. Lee Group, Inc., Monroeville, PA); Faraone, Kevin M. (BWX Technologies, Inc., Lynchburg, VA) & Norris, Jerome T.
Partner: UNT Libraries Government Documents Department

Feasibility of eddy current measurement of ferrite content in stainless steel welds

Description: A phase-sensitive eddy current system was used to measure the presence of ferrite in an austenitic stainless steel matrix. Measurements were made on pressed powder specimens and on a weld in Type 304L stainless steel. The data obtained showed that small amounts of ferrite, on the order of 1 to 3%, could easily be detected. Variation in ferrite with position within the weld was also detected with good reproducibility. Absolute values for the ferrite content were not obtained as accurate standards for calibration were not available. (auth)
Date: December 17, 1973
Creator: Lassahn, G. D. & Moment, R. L.
Partner: UNT Libraries Government Documents Department

Development of ultrasonic methods for examining stainless steel welds. Interim progress report

Description: Spurious ultrasonic (UT) signals obtained during the examination of austenitic stainless steel welds in LMFBR components have emphasized the need to develop more effective UT methods to supplement the examination processes presently employed during fabrication, and for use during subsequent in-service inspection of LMFBR plants. This interim report documents the first year's effort on a program that was designed to investigate this problem and develop viable solutions. Sixty-eight weld samples were acquired, cataloged, and subjected to a series of ultrasonic, radiographic, and metallographic examination procedures. It was determined that although spurious UT noise signals could usually be associated with major dendritic grain growth patterns, the existence and magnitude of some of the observed noise signals could not be explained simply on the basis of dendritic microstructure. The results obtained during application of a series of ultrasonic and radiographic characterization procedures are included, in addition to photomicrographs and photomicrographic montages taken in the vicinity of numerous sites which produced ultrasonic noise signals of various amplitudes. A concurrent investigation was conducted to evaluate the performance of conventional ultrasonic examination procedures. These results are compared with the laboratory investigation results, and a brief outline of future work planned under this program is presented. (auth)
Date: November 1, 1975
Creator: Peterson, R.O.; Spanner, J.C. & Mech, S.J.
Partner: UNT Libraries Government Documents Department

Feasibility study on infrared electro-thermal NDE of stainless steel

Description: Electro-thermal examination, a branch of thermal testing (TT), is a promising method being developed for NDE of stainless steel welds. This report describes the first phase of development; i.e., preliminary demonstration and laboratory evaluation of the method's sensitivity to notches in Type 304 stainless steel plate specimens. It also includes a description of the basic principles, together with a description of the hardware and experimental results showing that electrical discharge machined notches down to 0.16 cm (0.06 in.) long x 0.08 cm (0.03 in.) deep were detected. A qualitative technique for interpreting the test results to determine whether defects are at the surface or deeper within the material is demonstrated. (auth)
Date: November 1, 1975
Creator: Green, D.R. & Hassberger, J.A.
Partner: UNT Libraries Government Documents Department

Analytical prediction of the location of ductility dip cracking in the trans-varestraint test

Description: Some NiCrFe weld metals exhibit decreased ductility over a temperature range known as the {open_quotes}ductility dip{close_quotes} temperature (DDT) range. Ductility dip cracking (DDT) is a phenomenon which occurs in a zone bounded by the DDT range on its sides and a threshold plastic strain on its bottom as shown in figure 1. Figure 1 illustrates how ductility varies as weld metal cools from the solidus temperature for materials with and without a ductility dip. The purpose of this work is to demonstrate the ability to predict the location of the DDC in a Trans-Varestraint Test (TVT) for a specimen machined from a weld deposited EN52 plate. The DDC predictions require a combination of Trans-Varestraint testing and finite element analysis. The test provides the threshold value of externally applied nominal strain below which DDC does not occur. The analysis provides the corresponding threshold local or peak strain. The threshold local plastic strain level and the DDT range are used to predict the location of the DDC. The ultimate purpose of this work is to evaluate susceptibility of highly constrained, component welds to DDC. Test results for Trans-Varestraint Testing for a weld deposited EN52 plate are reported in reference. The ability to predict the location of the DDC in the Trans-Varestraint Test using the techniques reported herein is demonstrated by showing good comparison between the analytical results and the test data.
Date: May 1, 1997
Creator: Singh, I.; Kroenke, W. & Cola, M.
Partner: UNT Libraries Government Documents Department

Closure Welding Design and Justification for Canister S00645 (Bent Flange)

Description: This report provides the design basis and justification for a closure welding technique using the manual Gas Tungsten Are Welding (GTAW) process. Other aspects affecting closure of Canister S00645, e.g., shielding, facility and administrative requirements, etc., are addressed elsewhere.
Date: December 21, 1998
Creator: Cannell, G.R.
Partner: UNT Libraries Government Documents Department

Modeling and design of energy concentrating laser weld joints

Description: The application of lasers for welding and joining has increased steadily over the past decade with the advent of high powered industrial laser systems. Attributes such as high energy density and precise focusing allow high speed processing of precision assemblies. Other characteristics of the process such as poor coupling of energy due to highly reflective materials and instabilities associated with deep penetration keyhole mode welding remain as process limitations and challenges to be overcome. Reflective loss of laser energy impinging on metal surfaces can in some cases exceed ninety five percent, thus making the process extremely inefficient. Enhanced coupling of the laser beam can occur when high energy densities approach the vaporization point of the materials and form a keyhole feature which can trap laser energy and enhance melting and process efficiency. The extreme temperature, pressure and fluid flow dynamics of the keyhole make control of the process difficult in this melting regime. The authors design and model weld joints which through reflective propagation and concentration of the laser beam energy significantly enhance the melting process and weld morphology. A three dimensional computer based geometric optical model is used to describe the key laser parameters and joint geometry. Ray tracing is used to compute the location and intensity of energy absorption within the weld joint. Comparison with experimentation shows good correlation of energy concentration within the model to actual weld profiles. The effect of energy concentration within various joint geometry is described. This method for extending the design of the laser system to include the weld joint allows the evaluation and selection of laser parameters such as lens and focal position for process optimization. The design of narrow gap joints which function as energy concentrators is described. The enhanced laser welding of aluminum without keyhole formation has been demonstrated.
Date: April 1997
Creator: Milewski, J. O. & Sklar, E.
Partner: UNT Libraries Government Documents Department

Joining of melt-textured YBCO : a direct contact method.

Description: We report a method for making weld joints, capable of transmitting high supercurrent densities, in bulk samples of melt textured YBCO. The joining procedure is carried out in a flowing atmosphere of O{sub 2} to eliminate problems associated with nitrogen gas, which can become trapped in the joint. No filler or fluxing material is used. The method can be used to join large areas (several cm{sup 2}) that are capable of transmitting supercurrent densities exceeding 10{sup 4} A/cm{sup 2}.
Date: December 19, 2001
Creator: Chen, L.; Claus, H.; Paulikas, A. P.; Zheng, H. & Veal, B. W.
Partner: UNT Libraries Government Documents Department