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
  • American Institute of Physics (AIP)  (5)
Collection
Publisher
Years
  • 1
    Electronic Resource
    Electronic Resource
    Absolute stress determination in orthotropic materials from angular dependences of ultrasonic velocities (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 1547-1556 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper we describe a method to determine absolute plane stresses in orthotropic materials from the angular dependence of ultrasonic velocities. No prior information on material anisotropy (texture) is required since the stress dependent elastic constants and stresses are found simultaneously from velocity data using least-squares optimization. In the optimization algorithm no relation between the stress dependent elastic constants and stresses is assumed and therefore they are considered as uncoupled variables, but it is shown that the iteration process converges to the correct (coupled) values. The method is applicable for stress measurements in materials which have undergone a complicated (possibly plastic) history of loading and unloading; thus it can be used to determine both applied and residual stresses. To check the proposed technique we use synthetic sets of experimental data for different degrees of anisotropy and stress levels. Calculations using these synthetic data show that when the principal stress directions coincide with the symmetry axes the angular velocity data in the plane perpendicular to the stress plane may be used for reconstruction of both stress components. When the stress is off the symmetry axis, the shear and the difference of the normal stress components may be determined from the angular dependence of the velocities in the plane of stresses. In both cases the stress determination accuracy depends only on the accuracy of velocity measurements and is independent of stress level and material anisotropy. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360248
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Models for ultrasonic characterization of environmental degradation of interfaces in adhesive joints (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4643-4650 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper we discuss two models of environmental degradation of adhesive joints developed from experimental observation of the joint failure mode. It is found that after severe degradation, failure is dominated by the interfacial mode, i.e., by failure at the interface between adhesive and adherend. The fraction of failure in the interfacial mode was found to be related to the joint strength and to be proportional to the frequency shift of a minimum in the spectrum of the reflected ultrasonic signal. One model considers an interface as an interphase in the form of a nonhomogeneous layer composed of two phases: "soft'' which is viscoelastic (degraded part of the interphase) and "stiff'' corresponding to the nondamaged interphase. Increase of the "soft'' phase fraction corresponds to the process of degradation in the interphase. The second model describes degradation in a form of disbonds filled by absorbed water at the interface. The disbonded interface is modeled by transverse spring boundary conditions, with the complex spring stiffness representing the quality of the bond. The influence of different disbond growth scenarios is considered. Advantages and drawbacks of these models are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357301
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Fiber-matrix interphase characterization in composites using ultrasonic velocity data (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4121-4129 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A nondestructive method is introduced to determine the effective elastic moduli of fiber-matrix interphases from measured composite moduli. The composite moduli are obtained by measuring the angular dependences of ultrasonic longitudinal and transverse phase velocities in planes along and perpendicular to the fibers. Three independent interphase effective moduli are found using micromechanical multiphase models which were applied after averaging composite transverse moduli to account for the composite orthotropy. Sensitivity analysis shows that errors in the calculated interphasial moduli are approximately ten times those in the composite moduli. Experiments are performed on Si3N4 ceramic and Ti-24Al-11Nb intermetallic matrix composites reinforced with carbon coated silicon carbide fibers. The experimental interphasial moduli for the intermetallic composites agree with literature data after accounting for the interphase microstructure. The interphasial moduli for ceramic composites are lower than those for the intermetallic composite due to imperfect mechanical contact between the interphase and the porous matrix. The use of the method to assess the interphase degradation is demonstrated for interphasial oxidation damage. The analysis helps to determine the morphology of the damaged interphase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357362
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Splitting of domain of angles for incident wave vectors in elastic anisotropic media (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 3672-3677 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An anomalous phenomenon in the reflection and refraction of elastic waves on an interface between anisotropic crystals is analyzed. Due to the deviation of the ray (energy flow) direction from the wave normal for elastic waves in crystals, the domain of permissible incident angles splits into disjoint pieces for certain crystal cuts. This may lead to the existence of grazing angles at three different wave-vector angles. The grazing angle is defined as the angle at which the ray vector of the incident wave is parallel to the interface. To clarify this interesting phenomenon, numerical calculations were made for the (001) plane of a Ni crystal, based on a calculational procedure developed previously for study of the reflection and refraction of elastic waves in crystals. For each of the two split domains of incident angle there appear two branches of the reflection coefficient for the slow quasi-transverse wave corresponding to the same slowness surface. The value of the energy conversion of the incident wave into each of these reflected waves depends on the closeness of the direction of the displacement vector in these waves to the incident displacement direction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.336748
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Turnover temperatures of ST-cut quartz with sputtered-deposited thin layers of SiO2 and ZnO (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 6191-6193 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of sputter-deposited thin layers of ZnO and SiO2 on the turnover temperature of an ST-cut quartz surface-acoustic-wave delay line is studied. Upward shifts of the turnover temperature are obtained with SiO2 . Downward shifts are obtained for ZnO. It was found that the turnover temperature is linearly dependent on the thickness of the overlays over the temperature range −90–80 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343559
    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...