ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Collection
Keywords
Publisher
Years
  • 1
    Electronic Resource
    Electronic Resource
    Laser excitation through fiber optics for NDE (1987)
    Springer
    Journal of nondestructive evaluation 6 (1987), S. 57-64 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; fiber optics ; lasers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract This paper describes experiments designed to generate acoustic waves by using a laser pulse, transmitted through fiber optics, to thermally shock the surface of a steel specimen. The purpose of this effort was to explore the noncontacting generation of Rayleigh surface waves appropriate to the interrogation of structures for the detection of subcritical defects, with the ultimate goal of developing an efficient laser-based nondestructive evaluation technique utilizing flexible fiber optics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566697
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Fiber optic sensing for ultrasonic NDE (1987)
    Springer
    Journal of nondestructive evaluation 6 (1987), S. 135-146 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; fiber optics ; lasers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract An innovative approach to nondestructive evaluation (NDE) using noncontacting optical sensors has demonstrated. In this effort a single mode optical fiber interferometer (OFI) was used to sense the presence and form of Rayleigh waves traveling along the surface of a steel test bar at a velocity of nearly 3mm/µs. Acousto-optic time-domain data was successfully used to detect the presence and locate the position of a test “flaw” (a machined slot) in the bar, and spectrum analysis was used to estimate its geometry and size. This approach has many potential applications in the ultrasonic evaluation of real flaws in structures with complex geometries. Coupled with the authors' earlier work demonstrating the feasibility of generating acoustic waves in metals using laser light pulses transmitted through the fiber optic probes, this latest achievement points to the development of a fully noncontacting, fiber optic based thermal-acousto-photonic (TAP) NDE system, with potential applications to the reliability testing of many important structures where composition, scale, geometry, or restricted access preclude the use of conventional NDE techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568009
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Application of photoelasticity to a weld-penetration problem (1975)
    Springer
    Experimental mechanics 15 (1975), S. 73-80 
    Details
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The need for more information on the “initiation period” in fatigue tests of weld specimens with penetration defects is discussed and the literature which relates the elasticity stress-concentration factor and Irwin's stress-intensity factor is reviewed. A series of photoelasticity tests on two-dimensional plane-stress models of typical penetration defects is described. In particular a method for casting “ready to use” very narrow defects is explained. The results are presented in a graph of stress-concentration factor against defect length. This graph has a “knee” at defect length-to-plate thickness ratios around 0.2. Below the “knee”, the stress-concentration factor changes very little with changes in defect length but, for lengths beyond the knee, i.e., ratios larger than 0.2, the stress concentrations increase linearly with defect length. It is concluded that such a critical defect length should have a strong effect on fatigue life of defective welds and that it may constitute a first approach to the specification of an “acceptable” level of penetration defects for production processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02319740
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Resistance strain gages as physiological transducers on trees (1976)
    Springer
    Experimental mechanics 16 (1976), S. 329-336 
    Details
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A tree responds to its environment in several ways. One important way is through changes in the rate of transfer of water through the stems of the tree as it transpires. These changes induce extremely small variations in internal water stress and, therefore, in the size of the capillaries through which the water moves. The overall effect is minute changes in the diameter of the stems. By monitoring these changes, it is possible to observe an immediate response of the tree to its environment. This paper describes how electrical-resistance strain gages, bonded directly to the bark of a living-tree trunk, were used to measure these changes. It discusses bonding techniques, circuit design, instrumentation and the response of a red-maple tree to diurnal variations in its environment. Substantial changes in the circumference of the trunk, as large as 1900 microstrains, were observed on a 4-cm-diam tree during a daily cycle when the tree was under physiological stress. The overall results indicated good correlation with classical botanical theory and prior experimental data on the subject. In addition to its primary purpose, the paper illustrates the benefits possible from interdisciplinary cocperation and interaction between the fields of experimental mechanics and physical botany as related to forestry. The method described has potential importance in many aspects of tree husbandry. These include capabilities for remote sensing of forest-tree growth, maximizing seedling growth in large nursery operations, and efficient water management in orchards for maximum productivity with minimum irrigation. It may also provide a helpful new technique for use in basic studies in plant and tree physiology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02330249
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Dynamic photoelasticity as an aid in developing new ultrasonic-test methods (1982)
    Springer
    Experimental mechanics 22 (1982), S. 147-154 
    Details
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A prerequisite for the development of quantitative ultrasonic-inspection techniques for surface flaws is a thorough understanding of the ways in which elastic waves interact with defects. Analytical and numerical approaches are presently inadequate. Experimental methods are needed for a better understanding of wave interactions with real geometries. This paper describes how dynamic photoelasticity was used to study the interaction between Rayleigh waves and slots. To fully interpret the interactions between an incident Rayleigh wave and a surface slot, the problem was subdivided as follows: first, the reflections and mode conversions of a Rayleigh wave at a corner were studied. This simulated the Rayleigh-wave interaction with a slot opening. Then, the interaction when a Rayleigh wave ran off the tip of a slot was observed, and, finally, the total interaction with slots perpendicular to the surface was studied. The results for these three cases are presented. It is suggested that the most important property of a Rayleigh wave that can be used to size surface and near-surface defects is the subsurface particle motions. These motions persist up to a depth of the order of a wavelength. The shape (that is, the frequency spectrum of the transmitted wave) should, therefore, be affected by the depth of the slot. Spectroscopic analysis is applied to the photoelastic data to develop a simple method for sizing slots. Results from ultrasonic tests on slots in steel confirm the validity of the suggested method. By applying contemporary concepts of signal processing to photoelastic data, a powerful new area of experimental investigation is introduced. It promises to overcome the current inability of scatter theories to predict the interactions between real-life defects and acoustic waves as used in ultrasonic testing. Applications of this approach will improve the quantitative ability of ultrasonic-inspection methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02325544
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Three-dimensional strain distributions in upset rings by photoplastic simulation (1981)
    Springer
    Experimental mechanics 21 (1981), S. 361-370 
    Details
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The changes in internal diameter that occur when a hollow disk, or ring, is plastically deformed by axial compression have been proposed as a method for measuring interface friction during metal forming. The adoption of this test method has been delayed because the three-dimensional strains in such rings are not known. This paper describes how an experimental method using photoplastic simulation was used to obtain the three-dimensional strains for a particular ring geometry. It presents proot of highly nonuniform strains and also shows that the division between flow inward and flow outward occurs at different radii through the thickness of the ring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02324797
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Material properties in thermal-stress analysis (1981)
    Springer
    Experimental mechanics 21 (1981), S. 295-301 
    Details
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract With simple techniques and not too-costly laboratory equipment, the significant material properties in modeling transient thermal stresses by photothermoelasticity are evaluated. The results are presented for a room-temperature-cured epoxy, a hot-cured epoxy and a polycarbonate. The materials tested are also evaluated on their applicability to a transient-thermal-stress analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02325769
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Three-dimensional strains in rolled slabs by photoplastic simulation (1982)
    Springer
    Experimental mechanics 22 (1982), S. 441-447 
    Details
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Small polyester billets are used to model the deformations that occur during the hot rolling of slabs of aluminum. The billets are rolled to a retained reduction of around 11 percent. They are then sliced along principal planes and the three-dimensional strains are plotted over a transverse cross section of the deformed billet. The extent of this nonuniformity in the strains is clearly shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02325421
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Half-fringe photoelasticity: A new approach to whole-field stress analysis (1983)
    Springer
    Experimental mechanics 23 (1983), S. 304-313 
    Details
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper presents a new method for whole-field stress analysis based on a symbiosis of two techniques—classical photoelasticity and modern digital image analysis. The resulting method is called ‘half-fringe photoelasticity (HFP)’. Classical photoelasticity demands materials with high birefringence, which leads to extensive use of plastics as model materials. Since the behavior of these materials is often different from that of the prototype materials, their use distorts the similitude relationships. In many contemporary problems this distortion is untenable. HFP offers a way out of this dilemma. It permits materials and loads to be chosen so that no more than one half of a fringe order appears in the area of interest. Thus, for example, glass, which behaves linearly up to high stress levels and over a wide range of temperatures, could be used as model material. Alternatively, models from polymeric materials could be used under very low load in order to stay within the linear part of the stress-strain diagram and to prevent large deformations. The half-fringe-photoelasticity system, which is described here, utilizes the resulting low levels of birefringence for effective stress analysis. This paper describes the system. It outlines a calibration routine and illustrates its application to two simple problems using glass models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02319257
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Effects of impedance mismatch on the strength of waves in layered solids (1974)
    Springer
    Experimental mechanics 14 (1974), S. 129-137 
    Details
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This research program was conducted to study the effects of acoustic-impedance mismatch between materials in a layered elastic solid on the amplitudes of the head waves generated at the interface as a stress wave develops and propagates in one of the layers. Dynamic photoelasticity methods were employed. The isochromatic-fringe patterns used for analysis were recorded with a Cranz-Schardin multiple-spark camera operating at a framing rate of approximately 188,000 exposures per second. Acoustic-impedance ratios from a low of 1.7∶1 to a high of 17.4∶1 were studied. Small charges of lead azide were used to generate the original dilatational (P 1) wave. Results of the study confirm the existence of all waves predicted by theory except for theP 1 P 1 waves reflected from the free surface and from the interface near the source in the low-impedance layer. In the region near the explosive detonation, the head waves are important since they have significant magnitudes for certain impedance ratios and they appear to attenuate at a rate much lower than the rate associated with the incidentP 1 wave or the reflectedP 1 S 1 waves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02322835
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...