Investigating Ultrasound-Induced Acoustic Softening of Aluminum 6061

2014 ◽  
Author(s):  
Qing Mao ◽  
James M. Gibert ◽  
Georges Fadel
Keyword(s):  
Stress Reduction ◽  
Experimental Studies ◽  
Tensile Tests ◽  
Ultrasonic Waves ◽  
Test Machine ◽  
Acoustic Softening ◽  
Softening Process ◽  
Noise Factors ◽  
Longitudinal Ultrasonic Waves ◽  
Energy Activation

Blaha and Langenecker are the first to document the phenomena known as “acoustic softening”: a significant reduction of static stress in tensile tests when applying longitudinal ultrasonic waves to various metals. Based on experimental observations, they hypothesized that acoustic heating due to internal friction and energy activation at dislocations was responsible for this temporary weakening of the material. Later research studies investigating the acoustic softening process used different experimental setups leading to alternative theories of the softening process such as superposition of static and dynamic stress. The variation in the design of the experiments leads to significant differences in observations, causing differing interpretations of the results and the formation of competing theories. We reviewed previous experimental studies and found that the optimum setup is similar to Blaha’s and Langenecker’s. Their setup minimizes noise factors such as friction at the oscillator specimen interface, which could contribute to heating and stress reduction. Therefore, we present our experimental setup composed of an MTS tensile test machine and a Branson ultrasonic welder to study the softening of aluminum 6061 and discuss our own results and how they compare with those in the literature. Additionally, we investigate the applicability of competing theories of softening based on our experimental data.

Calculation And Experimental Substantiation Of Optimal Design Of The Welded Joint Of Plates On Соver Plates

2020 ◽  
pp. 17-24
Keyword(s):  
Welded Joint ◽  
Experimental Studies ◽  
Engineering Calculation ◽  
Tensile Tests ◽  
Physical Nonlinearity ◽  
Steel Plates ◽  
Optimal Parameters ◽  
Actual Problem ◽  
Numerical Research ◽  
Cover Plates

The article is devoted to the actual problem of assigning optimal parameters for connecting steel plates on cover plates with angular welds that are widely used in construction practice. The article presents the results of a comprehensive study of operation of a welded assembly of the plates connection on cover plates. An algorithm is proposed for determining the optimal parameters of a welded joint with fillet welds on the cover plates, which makes it possible to obtain a strength balanced connection. The results of full-scale tensile tests of models were presented. These results confirmed the correctness of the assumed design assumptions, and made it possible to obtain a form of destruction, not characteristic and not described in the normative literature, expressed by cutting the main elements along the length of the overlap in the joint. The possibility of such a form of destruction was confirmed by the results of numerical research in a nonlinear formulation. The optimal parameters of the nodal welded joint determined by engineering calculation are confirmed by experimental studies, as well as by the results of numerical experiments on models of calculation schemes, taking into account the physical nonlinearity of the material operation. The obtained dependence for determining the bearing capacity of the joint by the cut-off mechanism and the expression for limiting the overlap length of the cover plates will make it possible to predict the nature of the fracture and design equally strong joints.

Transmission of Ultrasonic Waves Via Optical Silica Glass Fiber Doped by 7.5% of TiO2 with the Use of Power Sandwich Transducer

2011 ◽  
Vol 36 (1) ◽  
pp. 141-150 ◽  
Author(s):  
Sylwia Muc ◽  
Tadeusz Gudra
Keyword(s):  
Optical Fibre ◽  
Output Signal ◽  
Optical Waveguides ◽  
Experimental Studies ◽  
Signal Amplitude ◽  
Capacitive Sensor ◽  
Ultrasonic Waves ◽  
Sandwich Type ◽  
Type Transducer ◽  
Simultaneous Transmission

Abstract The possibility of acoustic wave propagation in optical waveguides creates new prospects for simultaneous transmission of laser beams and ultrasonic waves. Combined laser-ultrasonic technology could be useful in e.g. surgical treatment. The article presents the results of experimental studies of transmission of ultrasonic wave in optical fibres, the core of which is doped by 7.5% of TiO2, using a sandwich-type transducer. It also presents amplitude characteristics of an ultrasonic signal propagated in the optical fibre. Authors studied the effect which the length of the fibre has on the achieved output signal amplitudes. They presented the relation of the output signal amplitude from a capacitive sensor to the power applied to the sandwich-type transducer. The obtained results were compared with the results produced when using an optical fibre with a core doped by 3% of GeO2, in order to select optical fibre suitable for simultaneous transmission of ultrasonic waves and laser rays.

Determination of the foaming parameters of polyurethane compositions from the velocity of longitudinal ultrasonic waves

1979 ◽  
Vol 15 (3) ◽  
pp. 316-317 ◽  
Author(s):  
V. M. Mel'nikov ◽  
�. A. Putnin'sh ◽  
V. O. Putninya ◽  
V. P. Karlivan
Keyword(s):  
Ultrasonic Waves ◽  
Longitudinal Ultrasonic Waves

Heat Treatment Effects on Static and Dynamic Mechanical Properties of Sintered SINT D30 Powder Metal

2013 ◽  
Vol 592-593 ◽  
pp. 643-646 ◽  
Author(s):  
Marko Šori ◽  
Tomaž Verlak ◽  
Srečko Glodež
Keyword(s):  
Mechanical Properties ◽  
Complex Geometry ◽  
Low Cost ◽  
Surface Hardness ◽  
Load Ratio ◽  
Tensile Tests ◽  
Test Machine ◽  
Strain Diagram ◽  
Powder Metal ◽  
Sintered Steel

Low cost, low material waste and good accuracy in components with complex geometry are the main reasons for powder metallurgy to be considered as a promising manufacturing process for the future. Like wrought steel, sintered steel can also be heat treated to increase surface hardness and to improve strength. This paper compares mechanical properties of the hardened sintered steel with the sintered steel of the same powder metal SINT D30. Firstly, the static strength of both samples is determined by quasi-static tensile tests. Results are compared in stress strain diagram and they show that the tensile strength of the hardened sintered steel SINT D30 can surpass 700 MPa. The main focus of this study is however fatigue behaviour of the sintered steel. Both sets of samples are tested on a pulsating test machine with the load ratio of R = 0. The first sample is subjected to a load that corresponds to 90 % of the yield strength and is then gradually lowered to achieve one million stress cycles without breakage. Obtained results are then presented as Wöhler curves and compared in S-N diagram.

The relation between the velocity of longitudinal ultrasonic waves and the strengths of rocks and ores in the sheregesh deposit (Gornaya Shoriya)

1966 ◽  
Vol 2 (4) ◽  
pp. 425-427
Author(s):  
V. V. Andrievich ◽  
S. E. Mogilevskaya ◽  
S. T. Nakhrov ◽  
G. P. Starkov
Keyword(s):  
Ultrasonic Waves ◽  
Longitudinal Ultrasonic Waves

The Effect of Hydrostatic Pressure on Physical Properties and Microstructure of Spruce and Cherry

Holzforschung ◽  
2000 ◽  
Vol 54 (1) ◽  
pp. 83-92 ◽  
Author(s):  
Voichita Bucur ◽  
Simone Garros ◽  
Claire Y. Barlow
Keyword(s):  
Hydrostatic Pressure ◽  
Structural Damage ◽  
Untreated Wood ◽  
Average Density ◽  
Ultrasonic Waves ◽  
Ultrasonic Velocities ◽  
Main Effect ◽  
Natural Wood ◽  
Effect Of Hydrostatic Pressure ◽  
Longitudinal Ultrasonic Waves

Summary The effect of hydrostatic pressure on the density, the ultrasonic velocities and the microstructure of spruce and cherry wood has been studied. Generally speaking, under hydrostatic pressure wood becomes less heterogeneous and less anisotropic than natural wood. In spruce, crushing and buckling of the thin-walled cells in the earlywood takes place. This also has the effect of disrupting the medullary rays, which assume a zig-zag path through the structure. Cherry has a much more homogeneous structure, and the main effect of the hydrostatic pressure is compaction of the vessels by buckling of the walls. The fibres are scarcely affected by the treatment. The width of the earlywood zone decreased after the application of pressure by 26% in spruce, and by 11% in cherry. The average density was increased by the hydrostatic pressure by 26% for spruce and by 46% for cherry. The densitometric profile of spruce demonstrates significant changes following the pressure treatment, with the minimum density DMin increasing and the maximum density DMax decreasing. For cherry, the densitometric profile is shifted rather uniformly towards higher densities, and the annual ring profile is spatially slightly compacted but otherwise similar to that of untreated wood. The anisotropy of wood (expressed by the ratio of acoustic invariants) decreased by 56% for spruce and by 33% for cherry. The structural damage in spruce is predominantly found in the radial (R) direction, and this corresponds to a reduction of 73% in the velocity of the longitudinal ultrasonic waves in the radial direction, VRR. In cherry, the structural damage is mainly in the transverse, T direction. The velocity of the longitudinal ultrasonic waves in the transverse direction, VTT is reduced by 44%. The medullary rays in cherry seem to be the most important anatomical feature influencing the propagation of ultrasonic waves.

Additive Manufacturing of Porous Ceramics with Foaming Agent

2021 ◽  
pp. 1-21
Author(s):  
Zipeng Guo ◽  
Lu An ◽  
Sushil Lakshmanan ◽  
Jason Armstrong ◽  
Shenqiang Ren ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Ambient Pressure ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Cost Effective ◽  
Tensile Tests ◽  
Porous Ceramics ◽  
Foaming Agent ◽  
Printing Quality ◽  
And Control

Abstract The macro-porous ceramics has promising durability and thermal insulation performance. As porous ceramics find more and more applications across many industries, a cost-effective and scalable additive manufacturing technique for fabricating macro-porous ceramics is highly desirable. Herein, we reported a facile additive manufacturing approach to fabricate porous ceramics and control the printed porosity. Several printable ceramic inks were prepared, the foaming agent was added to generate gaseous bubbles in the ink, followed by the direct ink writing and the ambient-pressure and room-temperature drying to create the three-dimensional geometries. A set of experimental studies were performed to optimize the printing quality. The results revealed the optimal process parameters for printing the foamed ceramic ink with a high spatial resolution and fine surface quality. Varying the concentration of the foaming agent enables the controllability of the structural porosity. The maximum porosity can reach 85%, with a crack-free internal porous structure. The tensile tests showed that the printed macro-porous ceramics possessed enhanced durability with the addition of fiber. With a high-fidelity 3D printing process and the precise controllability of the porosity, we showed that the printed samples exhibited a remarkably low thermal conductivity and durable mechanical strength.

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