• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Test specimen for determining material properties by means of ultrasonic stress, which is designed substantially rod-shaped and at least one of its two ends can be coupled to an ultrasonic horn. Ultrasound creates standing sound waves in the sample. These samples consist of two materials which are interconnected by an interface (3) and whose aspect ratios correspond substantially to the ratio of the wavelengths of ultrasonic propagation in the respective materials.
    公开号:AT512637A4
    申请号:T9082012
    申请日:2012-08-22
    公开日:2013-10-15
    发明作者:Elmar Dr Tschegg；Stefanie Dr Tschegg
    申请人:Elmar Dr Tschegg；Stefanie Dr Tschegg；
    IPC主号:
    专利说明:

    Ultrasonic test specimens for the measurement of fatigue and fracture mechanical values of material composites made of different materials.
    The invention relates to test specimens for the determination of mechanical and fracture mechanical characteristics with the ultrasonic fatigue technique, It are produced with this longitudinal (axial), or torsional, or composite mechanical waves. The sample is generally attached at one end to the ultrasonic horn with the opposite end free. This creates an alternating stress of the sample about the middle load zero. If the sample is also attached to the second end, the application of a constant or variable preload is possible. The second sample end is for this purpose e.g. to a Umversalprüfmaschine, or coupled to a second Ultraschallhom (double oscillator method).
    In resonance mode, the sample length corresponds to half the wavelength (λ / 2) of the standing ultrasonic wave in the relevant material. To create a standing wave, the samples must be tuned accordingly. The strain and stress are sinusoidally distributed at resonance along the sample (that is, in the longitudinal direction), and the maximum of strain and strain is in the longitudinal center of the sample. This maximum is used to calculate the fatigue and fracture mechanical values (such as fatigue strength or stress intensity factors). For the mentioned alternating stress with superimposed constant or variable tensile, compressive, torsional load, the coupling takes place at points of even multiples of half the wavelength (λ / 2), so that a resonance stress is ensured. For certain special cases, operation is also possible with non-matched samples. Thus, the samples do not resonate, but a continuous wave is created by the sample being shorter than λ / 2 and attached to the second end so that the wave is reflected off the fixed end. The resulting strains and stresses are not sinusoidally distributed - with the maxima in the longitudinal center - along the sample length, but usually approximately linear. Since the strain / voltage curve depends on the selected sample length, separate calibration measurements must be carried out for each sample length.
    The samples (both resonant and non-resonant samples) may be rod-shaped with circular (circular or elliptical), rectangular or square cross-section, or be formed as hollow cylinders. Watch glass or dumbbell specimens of round or square cross-section may also be used (Stanzl S.E., Fatigue Testing at Ultrasonic Frequencies, Journal of the Society of Environmental Engineers, 25-1, 1986, 11-16). For determination of fracture mechanical characteristics (stress intensity factors, etc.), notched specimens (e.g., AT Patent No. 378,853) are used.
    So far, samples for testing with the ultrasonic fatigue method have been made consistently of the same material (which may also be a composite material composed of different materials). There is no publication in which the examination of specimens obtained at the point of the maximum of the strain and stress amplitude consists of two or one of the following: ·············································································· · »· · ♦« · * ♦ · ·
    Consist of several materials with which the described ultrasound technique is reported. This is a disadvantage for the ultrasonic fatigue process.
    There are many connections in the art between different materials (metals, different alloys with different thermal and mechanical treatment, plastics, wood, ceramics, building materials, etc.). Today, new connections are made between the different materials (such as laser and electron welding, soldering and gluing techniques). For the industry, this is a new incentive, e.g. in the automotive industry, in the aircraft, medical and cryogenic technology as well as space research is vehemently pursued. So far, testing of composite samples (i.e., the interfaces between materials) with ultrasonic technology has not been possible.
    The object of the invention is to overcome this disadvantage by adapting the shape and dimensions of the ultrasonic samples to produce a stationary mechanical shaft which enables the determination of the fatigue properties and the fracture mechanical values of the interfaces of different materials. Young's modulus, or shear modulus and shape of the sample should thus allow the formation of a standing ultrasonic wave, or should be possible even in non-resonant stress using the above-mentioned suitable experimental guide the interface test.
    The impedances of the two materials must not be too different, i. the ratio of the impedances should not be more than ten times. If the ratio of the impedances were greater, the resulting wave would be reflected in part at the interface, and a measurement of the mechanical and fracture mechanical values would therefore no longer be valid.
    The usual (consisting of only one material) samples consist of one piece. On the other hand, the length must be different for different materials, due to the different densities and moduli of elasticity, or shear moduli to achieve a standing mechanical shaft. In essence, the dimensions of the samples corresponding to 11 / I2 = λ] / λ2 and 11 = λ] / 4 ΐ2 = λι / 4 (for resonance stress) must match those of the ultrasonic wave.
    For the dumbbell and watch glass samples, both the shape and length must be adjusted.
    Shape and length are determined by computer programs developed for the different sample forms (rod-like, cylindrical, dumbbell, watch-glass-shaped).
    The progress made by the invention is that the fatigue behavior (Wöhler curves, fatigue strength) and the fracture mechanics values (stress intensity factors, threshold values, fatigue crack propagation velocities) of the interfaces of two or more different materials are determined under a cyclic load. This is important for the automotive industry (body parts), aeronautical engineering and space research, for which, as a joining technique, e.g. want to use the laser technology. 2
    In boiler construction, the exploding technique (the two materials are connected by a blast explosive) is used. Also for testing of coatings (color and protective layers against corrosion), in the joining technique and in certain processes of the thin-film industry is interested in such tests. Samples are bonded with adhesives or other methods, with knowledge of mechanical and fracture mechanics values of utmost importance. Even several interfaces can be tested during the test.
    This is especially true for interfaces of two materials that are subject to cyclic loading in the industry, especially if the workpieces are to have a long service life.
    The test specimens according to the invention can have different lengths and shapes. They may have a free end (zero mean voltage) or be coupled at both ends to the ultrasonic apparatus (by screw connection, soldering, welding, clamping) for non-zero mean voltages, where the voltage amplitudes may be constant or variable. They can easily be used to detect crack initiation (fatigue data), lifetime and fatigue crack growth. They are also suitable for multiaxial loading (tension, compression, shear or torsion) and can be used up to the lowest and highest temperatures.
    In order to avoid transversal oscillations in ultrasonic mode, the samples must be sufficiently stiff, which is achieved by suitable sample thicknesses or shapes.
    The invention will be explained below with reference to illustrated embodiments. 1 shows the stress and strain behavior of the test specimens with interfaces of different materials. In FIGS. 2 to 4, non-notched and notched specimens with interfaces of different materials are shown. FIG. 5 shows non-notched and notched dumbbell and watch glass samples with interfaces of different materials.
    FIG. 1 shows the stress (1) and expansion curves (2) of a smooth sample with an interface (3) between two materials. Wherein the entire length of the specimen consists of two parts 1ι = λι / 4 U-λζ / 4 or (2n + l) λ (0 <ΐ € Γ2 ^ 4, with \ and U
    In Figure 2 smooth (a) and notched (b) rod-shaped specimens with square cross-section of two materials (4,5) with interfaces (3) and notches (6) are shown.
    FIG. 3 shows cylindrical smooth (a) and notched (b) test specimens of two materials (4, 5) with interfaces (3) and notches (6).
    In FIG. 4, notched bar-shaped test specimens with a rectangular cross-section of two materials (4, 5) with interfaces (3) and with notches (6) are shown.
    In Figure 5 dumbbell and Uhrglasprüfkörper of two materials (4,5) with interfaces (3) with (6) and without notches are shown.
    权利要求:
    Claims (3)
    [1]


    1. Test specimen for determining material properties by means of ultrasound stress, which essentially has a rod shape and can be coupled to an ultrasound horn at least with one of its two ends, characterized in that in that it consists of two bar sections of different material interconnected by means of a boundary layer, the aspect ratio of which substantially corresponds to the ratio of the wavelengths of ultrasonic propagation in the respective materials.
    [2]
    2. Test specimen according to claim 1, characterized in that the length (h; L) of each rod section substantially corresponds to an odd multiple of the quarter of the wavelength (λι; λ2) of the ultrasonic propagation in this rod section.
    [3]
    3. Test specimen according to claim 1, whose lengths (L; 12) are determined separately in the case of non-resonance stress for different combinations of materials in a respective suitable test procedure.

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    同族专利:
    公开号 | 公开日
    EP2700939A2|2014-02-26|
    AT512637B1|2013-10-15|
    EP2700939A3|2014-03-12|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US20050166678A1|2002-07-19|2005-08-04|Pozuelo Cleofe C.|Method and device for examining fatigue resistance of metallic materials at ultrasonic frequencies and constant temperature|
    DE102005016038B3|2005-04-07|2006-12-28|Infineon Technologies Ag|Micro connections, e.g. joints, cyclic shear load testing method, e.g. for use between sample holders, involves producing relative movement against workpieces under utilization of mass inertia of respective other workpieces|
    DE102007038479A1|2007-08-14|2009-02-19|Materia Consult Gmbh|Test specimen material's fatigue characteristic evaluating method, involves detecting deformation-induced, micro-structural changes in material of test specimen during predetermined measurement period |
    AT378853B|1981-05-29|1985-10-10|Elmar Dr Tschegg|TEST BODY FOR DETERMINING BREAKMECHANICAL CHARACTERISTICS|CN105738017B|2016-02-29|2018-07-06|江苏科技大学|Constituent content influences the modification method of assessment metal material skin stress|
    CN105973983A|2016-05-09|2016-09-28|西北工业大学|Method for designing ultrasonic torsion fatigue testing specimen with uniform section|
    CN105891340B|2016-06-03|2018-10-12|江苏科技大学|Crystallite dimension influences the modification method of assessment material stress|
    法律状态:
    2019-04-15| MM01| Lapse because of not paying annual fees|Effective date: 20180822 |
    优先权:
    申请号 | 申请日 | 专利标题
    AT9082012A|AT512637B1|2012-08-22|2012-08-22|Ultrasonic test specimen for the measurement of fatigue and fracture mechanical values of material composites made of different materials|AT9082012A| AT512637B1|2012-08-22|2012-08-22|Ultrasonic test specimen for the measurement of fatigue and fracture mechanical values of material composites made of different materials|
    EP13176530.7A| EP2700939A3|2012-08-22|2013-07-15|Ultrasound test body for measuring the fatigue and mechanical fracture values of composite materials comprising different materials|
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