WorldWideScience

Sample records for duralumin

  1. Suppression of Fatigue Crack Propagation of Duralumin by Cavitation Peening

    Directory of Open Access Journals (Sweden)

    Hitoshi Soyama

    2015-08-01

    Full Text Available It was demonstrated in the present paper that cavitation peening which is one of the mechanical surface modification technique can suppress fatigue crack propagation in duralumin. The impacts produced when cavitation bubble collapses can be utilised for the mechanical surface modification technique in the same way as laser peening and shot peening, which is called “cavitation peening”. Cavitation peening employing a cavitating jet in water was used to treat the specimen made of duralumin Japanese Industrial Standards JIS A2017-T3. After introducing a notch, fatigue test was conducted by a load-controlled plate bending fatigue tester, which has been originally developed. The fatigue crack propagation behavior was evaluated and the relationship between the fatigue crack propagation rate versus stress intensity factor range was obtained. From the results, the fatigue crack propagation rate was drastically reduced by cavitation peening and the fatigue life of duralumin plate was extended 4.2 times by cavitation peening. In addition, the fatigue crack propagation can be suppressed by 88% in the stable crack propagation stage by cavitation peening.

  2. An optimal open/closed-loop control method with application to a pre-stressed thin duralumin plate

    Science.gov (United States)

    Nadimpalli, Sruthi Raju

    The excessive vibrations of a pre-stressed duralumin plate, suppressed by a combination of open-loop and closed-loop controls, also known as open/closed-loop control, is studied in this thesis. The two primary steps involved in this process are: Step (I) with an assumption that the closed-loop control law is proportional, obtain the optimal open-loop control by direct minimization of the performance measure consisting of energy at terminal time and a penalty on open-loop control force via calculus of variations. If the performance measure also involves a penalty on closed-loop control effort then a Fourier based method is utilized. Step (II) the energy at terminal time is minimized numerically to obtain optimal values of feedback gains. The optimal closed-loop control gains obtained are used to describe the displacement and the velocity of open-loop, closed-loop and open/closed-loop controlled duralumin plate.

  3. Research on Microstructure and Weld Penetration of LY12 Duralumin Alloy Welded Joint under TIG Welding and A-TIG Welding%LY12硬铝合金TIG与A-TIG焊接接头组织和熔深的研究

    Institute of Scientific and Technical Information of China (English)

    王燕; 魏晓红; 胡宗智

    2011-01-01

    针对Al-Cu-Mg系共晶型高强度LY12硬铝合金,进行了TIG与A-TIG焊接接头组织特征和熔深变化规律的研究.结果表明,在相同焊接规范下,TIG与A-TIG焊接接头焊缝区金相组织均为树枝状晶,热影响区金相组织均为等轴晶,差别在于A-TIG焊接接头组织晶粒较粗大.高倍显微镜下的金相组织显示,A-TIG焊缝区和热影响区中强化相数量比TIG焊多,且比TIG焊粗大.另外由于活性剂的加入,电弧产生收缩,热量集中,使得A-TIG焊熔深比TIG焊大.%This paper have researched the microstructure characteristics and weld penetration change law of welded joint of Al-Cu-Mg system eutectic type high strength LY12 duralumin alloy under TIG welding and A-TIG welding. Results showed that the weld zone microstructure of TIG welding and A-TIG welding was dendritic crystal and the heat-affected zone microstructure of TIG welding and A-TIG welding was equiaxed crystal under the same welding specification. The difference was that the microstructure of A-TIG welded joint was coarser. The microstructure under advanced microscope showed that the weld zone and heat-affected zone of A-TIG had more strengthening phase than TIG and the strengthening phase of A-TIG was coarser than that of TIG. The weld penetration of A-TIG was deeper than TIG which had been caused by the addition of surfactant which leaded to arc constriction and heat concentration.

  4. Study of the effect of silver in the mechanical properties and electrical conductivity of duralumins (Al-4%Cu-0.5%Mg

    Directory of Open Access Journals (Sweden)

    Reinaldo Correa-Avendaño

    2014-01-01

    Full Text Available En este trabajo se evalúa el efecto del contenido de plata de las aleaciones base Al-Cu en la microestructura, la resistencia a la tracción, la resistencia eléctrica y el incremento de la temperatura con el paso de la corriente eléctrica (efecto Joule. Para tal fin, fueron evaluadas las aleaciones Al-4%Cu-0,5%Mg con contenidos de plata en proporciones del 1,5%, 2,5% y 3,5%. El endurecimiento por precipitación se llevó a cabo mediante tratamientos térmicos de homogenización por solución sólida. El análisis de la microestructura se realizó mediante el microscopio óptico y SEM, además, se realizó análisis de dureza Vickers, ensayos de resistencia a la tracción y pruebas de conductividad eléctrica, las cual se compararon con la aleación A356-T6. Los resultados de esta investigación muestran que el aumento de la plata en la aleación aumenta la resistencia la tracción y disminuye su resistividad. Mediante el análisis del SEM y EDS se observó la fase ɵ (CuAl2, Al6(Cu, Fe y Al7Cu2Fe.

  5. Effect of heat treatment on the inhibition of the acidic corrosion aluminium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Khamis, E. (Alexandria Univ. (Egypt). Dept. of Chemistry); El-Gamal, M. (Alexandria Univ. (Egypt). Dept. of Material Science); El-Toukhy, A. (Alexandria Univ. (Egypt). Dept. of Material Science); Atea, M. (Alexandria Univ. (Egypt). Dept. of Material Science)

    1994-12-01

    The effect of heat treatment on the inhibition of acid corrosion of duralumin has been studied using gasometry, mass loss measurements and potentiodynamic technique. All the data reveal that the duralumin generally developed good corrosion resistance after heat treatment and the corrosion rate ranked as follows: Non treated > Naturally aged > quenched. This improvement in the corrosion resistance was attributed to the structural homogeneity of the heat-treated alloys. The presence of some selected aryl and alkyl triazoline derivatives at the threshold concentration of 5 x 10[sup -3] M indicate that these compounds retard the corrosion rate of duralumin and the extent of inhibition depends on the molecular structure of the inhibitors. Polarization curves show that the triazoline compounds act as mixed-type inhibitors affecting both the cathodic and anodic processes. Moreover, there is no noticeable difference in the degree by which the triazoline derivatives inhibit the corrosion of pure aluminium and heat treated duralumin alloy. (orig.)

  6. Research on a new type of precision cropping method with variable frequency vibration

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Aiming at the cropping operations widely applied in practical industry production, a new method of bar cropping is presented. The rotational speeds of actuating motor of eccentric blocks are controlled by a frequency-changer, and the shearing die provides the bar with the controllable force, frequency and amplitude of vibration. By utilizing the stress concentration at the bottom of V shape groove on the bar, the low stress bar cropping is realized. The bar cropping experiments of duralumin alloy and steel ...

  7. A theoretical study of the influence of technological friction stir welding parameters on weld structures

    Science.gov (United States)

    Astafurov, Sergey; Shilko, Evgeny; Kolubaev, Evgeny; Psakhie, Sergey

    2015-10-01

    Computer simulation by the movable cellular automaton method was performed to study the dynamics of friction stir welding of duralumin plates. It was shown that the ratio of the rotation rate to the translational velocity of the rotating tool has a great influence on the quality of the welded joint. A suitably chosen ratio of these parameters combined with an additional ultrasonic impact reduces considerably the porosity and the amount of microcracks in the weld.

  8. Modeling of the mechanical behavior of aluminum alloys with friction stir welds

    Science.gov (United States)

    Balokhonov, Ruslan R.; Romanova, Varvara A.; Batukhtina, Ekaterina E.

    2015-10-01

    The deformation and fracture of a macroscopic duralumin sample with a friction stir weld are investigated numerically under compressive loading applied to the sample surface. A boundary-value problem is solved using a dynamic plane strain approximation. The weld zone structure corresponds to that observed experimentally and is taken into account explicitly in calculations. The mechanisms of the plastic strain localization and crack propagation operating in different zones of the weld are examined.

  9. Positron annihilation study of the hardening behavior in Al-Cu based alloy by electron and heavy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Hori, Fuminobu; Kobayashi, Ippei; Iwase, Akihiro [Department of Materials Science, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531 (Japan); Saito, Yuichi; Ishikawa, Norito; Oshima, Takeshi, E-mail: horif@mtr.osakafu-u.ac.j [JAEA Tokai, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan)

    2010-04-01

    Al-Cu based alloy, which is generally called duralumin (JIS2017), was irradiated with 10 MeV Iodine ions, 200 MeV Xenon ions and 3 MeV electrons at room temperature respectively. The micro Vicker's hardness and positron annihilation coincidence Doppler broadening (CDB) measurements have been performed before and after irradiation. Only in the case of ion irradiation, the Vicker's hardness increases with increasing ion dose. Nevertheless, there was no difference in the profile CDB spectrum for before and after irradiation. On the other hand, we found that the micro hardness of this alloy, which was Xe ion irradiated and subsequently annealed at 423 K, is greater than that of age hardened alloy without irradiation. CDB ratio curve of the age hardened Duralumin is clearly different in the electron momentum range around 0.015-0.025 mc from that of the ion irradiated alloy. The results of three-dimensional atom probe (3DAP) also show that a lot of small clusters were found after ion irradiation but large precipitations have found in annealed Duralumin. These results reveal that a number of small clusters formed in this alloy after ion irradiation, and they should strongly affects the micro hardness.

  10. The impact of permanent magnetic fields on photomultiplier HAMAMATSU R7899-20 used in a hadron calorimeter of LHCb experiment

    Science.gov (United States)

    Dmitrenko, V. V.; Vorobyev, K. A.; Vlasik, K. F.; Grachev, V. M.; Muravyev-Smirnov, S. S.; Novikov, A. S.; Ulin, S. E.; Uteshev, Z. M.; Shustov, A. E.; Petrenko, D. V.; Chernysheva, I. V.; Shmatkov, I. A.

    2017-01-01

    The influence of a permanent magnetic field strength up to 40 Gs (4 mT) to operation PMT HAMAMATSU R7899-20 with its standart magnetic screens and without them is investigated. This PMT is used in a hadron calorimeter of LHCb experiment at CERN. It is shown that the use of a protective housing made of steel in joint its use with permalloy screen significantly reduces screening efficiency. It proposed to use a protective housing made from non-magnetic material (duralumin) electrolytic coated with a multilayered film as magnetic shield. This solution can be used in a hadron calorimeter, the CERN installations SHiP.

  11. The influence of an external cavity on the emission spectrum of a mercury germicidal lamp

    Science.gov (United States)

    Solomonov, V. I.; Surkov, Yu. S.; Gorbunkov, V. I.

    2016-09-01

    The spectrum of emission from the cylindrical duralumin cavity of a TUV 8wG8 T5 UV industrial germicidal mercury lamp is studied. It is shown that, due to reflection from the inner surface of the cavity and reabsorption in the gas discharge, the resonance line of a mercury atom is significantly weakened. The dependence of the resonance line intensity on the discharge current has a maximum, and the discharge current corresponding to the intensity maximum depends on the reflection coefficient of the inner surface of the cavity.

  12. Investigation of tribological and mechanical properties of metal bearings

    Indian Academy of Sciences (India)

    Bekir Sadik Ünlü

    2009-08-01

    Copper, aluminum and tin–lead based alloys are widely used as journal bearing materials in tribological applications. Bronze and brass are widely used as journal bearing materials for copper based alloys. Zamacs find applications as journal bearing materials for zinc based alloys, while duralumines are chosen as journal bearing materials for aluminum based alloys. In addition, white metals are widely used as journal bearing materials for tin–lead based alloys. These alloys ensure properties expected from journal bearings. In this study, tribological and mechanical properties of these journal bearings manufactured by metals were investigated. SAE 1050 steel shaft was used as counter abrader. Experiments were carried out in every 30 min for a total of 150 min by using radial journal bearing wear test rig.

  13. An Analytical Approach on Thermally Induced Vibrations of Nonhomogeneous Tapered Plate

    Directory of Open Access Journals (Sweden)

    Anupam Khanna

    2013-01-01

    Full Text Available A mathematical model to control the vibrations of a rectangular plate is constructed with an aim to assist engineers in designing and fabrication of various structures used in the field of science and technology, mostly used in satellite and aeronautical engineering. The present study is related to the analysis of free vibrations of nonhomogeneous rectangular plate clamped at all the four edges. Authors studied the bilinear effect of thickness as well as temperature variations in both and directions. Variation in Poisson's ratio is also considered linearly in -direction due to nonhomogeneity. Rayleigh-Ritz method is used to analyze the frequencies for the first two modes of vibrations for different values of thermal gradient, nonhomogeneity constant, taper constants and aspect ratio. All the numerical computations have been performed for an alloy of aluminum, that is, duralumin. All the results are presented in the form of graphs.

  14. Study on precision cutting technology of complex shape microparts

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Relatively to non-traditional and high-energy-beam micro-manufacturing technique, the micro-cutting technology has many merits. For instance, the machining range is bigger, the cost of equipments is much lower, and the productivity and machining accuracy are higher. Therefore, the micro-cutting technology will take an important effect on the machining technique of complex shape microparts. In this paper, based on selfly-developed machine tool, the precision cutting technology of complex shape microparts made of metal material was studied by analyzing the modeling method on complex shape, the means of toolpaths layout and the optimal selection for cutting parameters. On the basis of above work, a typical duralumin specimen of high precision, low surface roughness and complex shape micropart was manufactured. This result will provide favorable technical support for farther research on the micro-cutting technology.

  15. Research on a new type of precision cropping method with variable frequency vibration

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Aiming at the cropping operations widely applied in practical industry production, a new method of bar cropping is presented. The rotational speeds of actuating motor of eccentric blocks are controlled by a frequency-changer, and the shearing die provides the bar with the controllable force, frequency and amplitude of vibration. By utilizing the stress concentration at the bottom of V shape groove on the bar, the low stress bar cropping is realized. The bar cropping experiments of duralumin alloy and steel show that the shear surface has no radial distortion and deviation angle, the cutting force is lower and the die life is longer compared with the common bar cropping method. According to the special feature of cutting surface obtained by the new method, a new method of measurement is proposed and applied to assess the cutting surfaces obtained by the different control curves of frequency. The results show that the linear decrease control method is the best.

  16. Fastening of a High-Strength Composite Rod with a Splitted and Wedged End in a Potted Anchor 2. Finite-Element Analysis

    Science.gov (United States)

    Kulakov, V. L.; Terrasi, G. P.; Arnautov, A. K.; Portnov, G. G.; Kovalov, A. O.

    2014-03-01

    A finite element analysis is carried out to determine the stress-strain state of anchors for round rods made of a high- modulus, high-strength unidirectional carbon-fiber reinforced plastic. The rods have splitted ends in which Duralumin wedges are glued. Three types of contact between the composite rods and a potted epoxy compound are considered: adhesion, adhesion-friction, and friction ones. The corresponding three-dimensional problems in the elastic statement are solved by the finite-element method (FEM) with account of nonlinear Coulomb friction. An analysis of stresses on the surface of the composite rod revealed the locations of high concentrations of operating stresses. The results of FEM calculations agree with experimental data.

  17. Spectrophotometric determination of titanium with tannin and thioglycollic acid and its application to titanium-treated steels and ferrous and non-ferrous alloys.

    Science.gov (United States)

    Banerjee, S

    1986-04-01

    A sensitive spectrophotometric method for the determination of titanium by formation of its complex with tannin and thioglycollic acid at pH 4 has been developed. The intense yellow colour is measured at 400 nm and the system obeys Beer's law over the range 0.2-5 ppm titanium in the solution measured. The method is applicable to titanium-treated steels, stainless steels, permanent magnet alloys and duralumin alloys. The interference of Co, Ni, Cr, Mn, V, Mo and W can be eliminated by prior separation of titanium by controlled addition of cupferron in the presence of thioglycollic acid (TGA). Copper can be quantitatively separated by precipitation with TGA and determined complexometrically with EDTA, with PAN as indicator. Niobium interferes even in traces.

  18. Method and device for electroextraction of heavy metals from technological solutions and wastewater

    Science.gov (United States)

    Khalemsky, Aron Mikhailov; Payusov, Sergei Abramovic; Kelner, Leonid; Jo, Jae

    2005-05-03

    The basic principles of the method for heavy metals electroextraction from technological solutions and wastewater includes pretreating to remove Chromium-6 and high concentrations of heavy metals and periodically treating in a six-electrode bipolar cylindrical electroreactor made of non-conducting material to achieve lower accepted levels of impurities. Six cylindrical steel electrodes form two triode stacks and are fed with three-phase alternating current of commercial frequency (50-60 Hz), which can be pulsed. Each phase of the three-phase current is connected to three electrodes of one triode stack or in parallel to two triode stacks. The parallel connection of three-phase current to two triode stacks is performed so that the same phase of the three phase current is connected in parallel with each two opposite electrodes of six electrodes located along the periphery, or with two adjacent electrodes. A bipolar stationary aluminum electrode is situated in the inter-electrode space. In one of the embodiments, the bipolar electrode is made of a perforated heat-resistant plastic container filled with secondary aluminum and duralumin scrap. In another embodiment, the bipolar electrode of aluminum or duralumin scrap may be made without a perforated container and is placed in the inter-electrode space as a bulk scrap. In this case, to prevent shorts, each of six steel electrodes is placed in isolated perforated plastic shell with holes of 5 mm in diameter. Non-ferrous metals are extracted in a form of ferrite-chromites, and aluminates as well as hydroxyl salts deposited in the inter-electrode space without electrolysis deposits on electrodes. Deposits are separated from solution by known methods of filtration.

  19. Negative reflection of Lamb waves at a free edge: Tunable focusing and mimicking phase conjugation

    Science.gov (United States)

    Gérardin, Benoît; Laurent, Jérôme; Prada, Claire; Aubry, Alexandre

    2016-07-01

    The paper studies the interaction of Lamb waves with the free edge of a plate. The reflection coefficients of a Lamb mode at a plate free edge are calculated using a semi-analytical method, as a function of frequency and angle of incidence. The conversion between forward and backward Lamb modes is thoroughly investigated. It is shown that, at the zero-group velocity (ZGV) frequency, the forward $S_1$ Lamb mode fully converts into the backward $S_{2b}$ Lamb mode at normal incidence. Besides, this conversion is very efficient over most of the angular spectrum and remains dominant at frequencies just above the ZGV-point. This effect is observed experimentally on a Duralumin plate. Firstly, the $S_1$ Lamb mode is selectively generated using a transducer array, secondly the $S_{2b}$ mode is excited using a single circular transducer. The normal displacement field is probed with an interferometer. The free edge is shown to retro-focus the incident wave at different depths depending on the wave number mismatch between the forward and backward propagating modes. In the vicinity of the ZGV-point, wave numbers coincide and the wave is retro-reflected on the source. In this frequency range, the free edge acts as a perfect phase conjugating mirror.

  20. Coda reconstruction from cross-correlation of a diffuse field on thin elastic plates

    Science.gov (United States)

    Hejazi Nooghabi, Aida; Boschi, Lapo; Roux, Philippe; de Rosny, Julien

    2017-09-01

    This study contributes to the evaluation of the robustness and accuracy of Green's function reconstruction from cross-correlation of strongly dispersed reverberated signals, with disentangling of the respective roles of ballistic and reverberated ("coda") contributions. We conduct a suite of experiments on a highly reverberating thin duralumin plate, where an approximately diffuse flexural wave field is generated by taking advantage of the plate reverberation and wave dispersion. A large number of impulsive sources that cover the whole surface of the plate are used to validate ambient-noise theory through comparison of the causal and anticausal (i.e., positive- and negative-time) terms of the cross-correlation to one another and to the directly measured Green's function. To quantify the contribution of the ballistic and coda signals, the cross-correlation integral is defined over different time windows of variable length, and the accuracy of the reconstructed Green's function is studied as a function of the initial and end times of the integral. We show that even cross-correlations measured over limited time windows converge to a significant part of the Green's function. Convergence is achieved over a wide time window, which includes not only direct flexural-wave arrivals, but also the multiply reverberated coda. We propose a model, based on normal-mode analysis, that relates the similarity between the cross-correlation and the Green's function to the statistical properties of the plate. We also determine quantitatively how incoherent noise degrades the estimation of the Green's function.

  1. A rotary ultrasonic motor using radial bending mode of ring with nested PZT excitation

    Institute of Scientific and Technical Information of China (English)

    Ying-xiang LIU; Jun-kao LIU; Wei-shan CHEN; Xiao-hui YANG

    2012-01-01

    This study presents and verifies a new idea for constructing a rotary traveling wave ultrasonic motor (USM) that uses the radial bending mode of a ring.In the new design,20 trapezoid cross section slots are cut symmetrically in the outer surface of a thick duralumin alloy ring,where 20 PZT stacks are nested.In each slot,two wedging blocks are set between the PZT stack and the two sides of the slot respectively to apply preloading on the PZT ceramics.Two radial bending modes of the stator that have a phase difference of a quarter wavelength on space are generated by using the d33 operating mode of the PZT elements,and then a flexural traveling wave is formed by the superimposing of two standing waves whose amplitudes are equal and phases are different by 90° temporally.Two conical rotors are pressed to each end of the ring type stator by a coiled spring.The finite element method (FEM) simulation is developed to validate the feasibility of the proposed motor.The maximal speed and torque of the prototype are tested to be 126 r/min and 0.8 N·m,respectively.

  2. A T-shape linear piezoelectric motor with single foot.

    Science.gov (United States)

    Liu, Yingxiang; Chen, Weishan; Yang, Xiaohui; Liu, Junkao

    2015-02-01

    A new T-shape piezoelectric motor using the hybrid of two orthogonal longitudinal vibrations is proposed in this work. Six pieces of PZT ceramic plates are bonded on the upside and downside surfaces of a T-shape duralumin alloy base respectively to form the proposed motor. Elliptical movement can be generated on the driving tip by applying sine and cosine voltages to the PZT elements. The horizontal displacement of the driving tip will push the runner while the vertical displacement can overcome the preload. Finite element method is used to accomplish the design and analysis process. The resonance frequencies of the two vibration modes are tuned to be close by modal analysis, while the motion trajectory of the driving tip is observed by transient analysis. After the fabrication of a prototype, the vibration characteristics and mechanical output ability are measured. The no-load speed and the maximum output thrust force of the proposed motor are tested to be 718 mm/s and 3.5 N under an exciting frequency of 53.1 kHz. The proposed T-shape piezoelectric motor exhibits merits of simple structure, easy to realize miniaturization, easy to be fabricated, and high power-to-weight ratio.

  3. LY12铝合金试件拉伸声发射信号特征分析与状态识别%Acoustic Emission Signature Analysis and State Recognition for LY12 Tensile Aluminum Alloy Specimen

    Institute of Scientific and Technical Information of China (English)

    丁立伟

    2014-01-01

    Taking LY12 duralumin with high strength as the research object , the acoustic emission testing sys-tem was employed to investigate acoustic emission signal feature of the tensile aluminum alloy specimen in elas -tic, yield, plastic deformation and fracture stages so that the relationship between specimen and acoustic emis -sion signal feature can be found; meanwhile , the independent experiment on the operating conditions of the pressure-maintaining and the repeated load was implemented and the laws of acoustic emission signal with dif -ferent working conditions were analyzed .The test results show that good corresponding relationship between LY12 aluminum alloy specimen and acoustic emission signal feature can be found .%以高强度硬铝LY12为研究对象,利用声发射试验系统研究拉伸铝合金试件在弹性、屈服、塑性变形和断裂阶段的声发射信号特征,揭示了试件状态与声发射信号特征间的关系。同时对保压和重复加载典型工况进行独立试验,分析不同工况下声发射信号的规律。试验结果表明:LY12铝合金试件状态与声发射信号特征之间存在着良好的对应关系。

  4. Thin layer Characterization by ZGV Lamb modes

    Energy Technology Data Exchange (ETDEWEB)

    Ces, Maximin; Clorennec, Dominique; Royer, Daniel; Prada, Claire, E-mail: maximin.ces@espci.fr [Laboratoire Ondes et Acoustique, ESPCI- Universite Paris 7- CNRS UMR 7587, 10 rue Vauquelin, 75231 Paris Cedex 05- France (France)

    2011-01-01

    Ultrasonic non-destructive testing of plates can be performed with Lamb modes guided by the structure. Non contact generation and detection of the elastic waves can be achieved with optical means such as a pulsed laser source and an interferometer. With this setup, we propose a method using zero group velocity (ZGV) Lamb modes rather than propagating modes. These ZGV modes have noteworthy properties, in particular their group velocity vanishes, whereas their phase velocity remains finite. Thus, a significant part of the energy deposited by the pulsed laser can be trapped in the source area. For example, in a homogeneous isotropic plate and at the minimum frequency of the S{sub 1}-Lamb mode a very sharp resonance can be observed, the frequency of which only depends on the plate thickness, for a given material. In fact, other ZGV modes exist and the set of ZGV resonance frequencies provide a local and absolute measurement of Poisson's ratio. These non-propagating modes can also be used to characterize multi-layered structures. Experimentally, we observed that a thin (500 nm) gold layer deposited on a thick (1.5 mm) Duralumin plate induces a sensitive down-shift of the set of ZGV resonance frequencies. This shift, which is typically 5 kHz for the S{sub 1}-Lamb mode at 1.924 MHz, can be approximated by a formula providing the layer thickness. Thickness down to 100 nm can be estimated by this method. Such a sensitivity with conventional ultrasound inspection by acoustic microscopy would require an operating frequency in the GHz range.

  5. Noncontact ultrasonic transportation of small objects over long distances in air using a bending vibrator and a reflector.

    Science.gov (United States)

    Koyama, Daisuke; Nakamura, Kentaro

    2010-05-01

    Ultrasonic manipulation of small particles, including liquid droplets, over long distances is discussed. It is well known that particles can be trapped at the nodal points of an acoustic standing wave if the particles are much smaller than the wavelength of the standing wave. We used an experimental setup consisting of a 3-mm-thick, 605-mm-long duralumin bending vibrating plate and a reflector. A bolt-clamped Langevin transducer with horn was attached to each end of the vibrating plate to generate flexural vibrations along the plate. A plane reflector with the same dimensions as the vibrating plate was installed parallel to the plate at a distance of approximately 17 mm to generate an ultrasonic standing wave between them and to trap the small particles at the nodal lines. The acoustic field and acoustic radiation force between the vibrator and reflector were calculated by finite element analysis to predict the positions of the trapped particles. The sound pressure distribution was measured experimentally using a scanning laser Doppler vibrometer. By controlling the driving phase difference between the two transducers, a flexural traveling wave can be generated along the vibrating plate, and the vertical nodal lines of the standing wave and the trapped particles can be moved. The flexural wave was excited along the vibrator at 22.5 kHz. A lattice standing wave with a wavelength of 35 mm in the length direction could be excited between the vibrator and the reflector, and polystyrene spheres with diameters of several millimeters could be trapped at the nodal lines of the standing wave. The experimental and calculated results showed good agreement for the relationship between the driving phase difference and the positions of the trapped particles. Noncontact transportation of the trapped particles over long distances could be achieved by changing the driving phase difference. The position of the trapped particles could be controlled to an accuracy of 0.046 mm/deg. An

  6. 瞬态热冲击环境下超硬铝合金7A04的力学性能%MECHANICAL PROPERTIES OF SUPER-HIGH STRENGTH Al ALLOY 7A04 AT TRANSIENT HEATING

    Institute of Scientific and Technical Information of China (English)

    吴大方; 潘兵; 王岳武; 赵寿根; 杨洪源; 黄良

    2011-01-01

    使用瞬态气动热实验模拟系统对超硬铝合金7A04在不同瞬态高温热冲击条件下的力学性能进行了气动热模拟和热载联合实验研究,得到7A04在热、力学环境共同作用下的高温强度极限和承载时间等重要表征参数.实验结果表明:超硬铝合金7A04在短时热冲击环境下的强度极限比航空材料手册中长时间恒温下测量的强度极限有明显提高,这为航空航天材料和结构在短时高速热冲击环境下承载能力的提升和结构优化设计提供了可靠依据.%Super-hard aluminum alloy 7A04 (Al-Zn-Mg-Cu), whose ultimate strength is higher than that of duralumin, belongs to a class of aluminum alloys with highest ultimate strength tested at room temperature. As it can be utilized as structural material of various heating components such as rocket liquid storage tank and missile wing, super-hard aluminum alloy 7A04 has been widely used in the field of aerospace engineering. However, the ultimate strength and other token mechanical parame ters of aluminum alloy 7A04 at transient high-temperature heating environment are still unclear to us, as these key mechanical parameters are lacking in existing strength design handbook. Experimental characterization of these critical parameters of aluminum alloy 7A04 is undoubtedly meaningful to the reliability estimation, life prediction and security design of the high-speed flight vehicle. In this paper, by combining transient aerodynamic heating simulation system and material testing machine, the high-temperature ultimate strength, loading time and other mechanical properties of super-hard aluminum alloy 7A04 under different transient heating temperature and loading conditions were inves tigated Experimental results revealed that the ultimate strength and loading capability of aluminum alloy 7A04 subjected to transient thermal heating were much higher than those tested in a long-time stable high-temperature environment. The

  7. Study of the Effect of Process Parameters on Mechanical Properties and Microstructure of Al-Cu and SiCp Reinforced Metal Matrix Composite

    Directory of Open Access Journals (Sweden)

    SERAJUL HAQUE

    2012-12-01

    Full Text Available The high cost of fabrication hindered the actual application of metal matrix composite (MMC despite of their high stiffness, strength, corrosion resistance, wear resistance, non-reactivity with chemicals and so many other tailored quality which are never obtained in alloy of metals. In this study, a modest attempt has been made to find out the process parameters at which best mechanical properties of Al6061, 4%Cu and reinforced 5% SiCp ceramic MMC can be obtained. Addition of 4% Cu in Al6061 is more or less comparable to the composition of duralumin, which is widely used in aerospace applications. SiCp is hard and having linear thermal expansion at high temperature. With reinforcement of SiCp in Al-Cu alloy, it can be postulated thathardness of MMC retains at high temperature applications. An analysis of Variance (ANOVA was used for analysis of data with the help of SPSS (Version-17.0 software. Independent parameters are three levels of pouring rates (1.5cm/s, 2.5 cm/s and 3.5 cm/s, material type (Al6061+4%Cu alloy and Al+4%Cu, reinforced 5%SiCp MMC processed using stir casting technique and dependent parameters are hardness and impact strength, which is found that at different pouring rates material hardness and impact strength are highly significant. At pouring rate of 2.5 cm/s and 700±5°C pouring temperature, optimum values of hardness and impact strength are observed as compared to other values of pouring rates (1.5 cm/s and 3.5 cm/s. With reinforcement of 5% SiC trend of mechanical properties is same, buthardness and impact strength of MMCs are increased by 25% and 20% respectively. Also it is observed from scanning electron microscopy (SEM that at pouring rate 2.5 cm/s a better homogeneity can be obtained.

  8. Uso de fijador externo en la inestabilidad de la pared torácica anterior (volet esternal: Presentación de un caso Use of the external fixative in the instability of the anterior thoraxic wall (sternal volet: A case report

    Directory of Open Access Journals (Sweden)

    Orestes N Mederos Curbelo

    2005-03-01

    external stabilization was attained by an equipment that is utilized in our hospital and that is reusable and may be applied to any thoracic instability independently of its localization. The fixative is made of malleable duralumin plates that make possible its adaptability and introduce a way of treatment in the bilateral thoracic lesions with external instability, a complex situation in which it may be a useful instrument for treatment

  9. Portable Test Equipment for Infrared Systems%便携式红外系统检测仪

    Institute of Scientific and Technical Information of China (English)

    曹海源; 孙斌; 韦尚方; 黎伟; 初华

    2015-01-01

    In light of the miniaturization and portability demand for test equipment of infrared system,the basic composition of test equipment was analyzed,as well as the key parts for miniature design.The design of infrared collimator was optimized by optimizing the design parameters,adopting the optical path design of off-axis parabolic multiple reflections,and selecting duralumin as the machining material of lens,which effectively reduces the volume of optical path system as well as the weight of infrared collimator.A small high-effective black-body radiation source structure was constructed by using red copper radiant surface,thermoelectric refrigerator,cooling fins,etc.,and a temperature-controlled driving circuit was designed,realizing the small lightweight surface source black-body.Overall weight of the test equipment developed is less than 15 kg,which realizies the goal of miniaturization and portability with desired application effect.%针对红外系统检测设备的小型便携化需求,分析了检测仪的基本组成及对其进行小型设计的重点部位,分别从优化设计指标、采用离轴抛物面多次反射光路设计、选用硬铝作为镜片加工材质等方面对红外平行光管进行了优化设计,有效减小了光路系统的体积,减轻了平行光管的重量。采用紫铜辐射面、热电制冷器、散热片等构造了小型高效的黑体辐射源结构,设计了温度控制驱动电路,实现了小型轻量的面源黑体。所研制的检测仪整机重量小于15 kg,实现了小型便携,并取得了理想的应用效果。