Room temperature internal friction (Q sup-1) values of the 0.00002-0.00003 range were achieved with lunar rock 70215,85 by thorough outgassing procedures in ultrahigh vacuum. Results are presented on the temperature dependence of Q-1 as... more
Room temperature internal friction (Q sup-1) values of the 0.00002-0.00003 range were achieved with lunar rock 70215,85 by thorough outgassing procedures in ultrahigh vacuum. Results are presented on the temperature dependence of Q-1 as measured in the range 25 C to 600 C along with some data on the change in Q-1 with pressure in ultrahigh vacuum. The temperature dependence shows the existence of an internal friction peak at around 200 C followed at high temperatures by an extensive region with flat Q-1 (approximately 0.001); the work at ultrahigh vacuum shows decreases in the internal friction with decreases in ambient pressure even in the range 10 to the -8 to 10 to the -10 power torr.
The viscoelastic response of commercial Al–Zn–Mg and Al–Cu–Mg alloys was measured with a dynamic-mechanical analyzer (DMA) as a function of the temperature (from 30 to 425°C) and the loading frequency (from 0.01 to 150 Hz). The... more
The viscoelastic response of commercial Al–Zn–Mg and Al–Cu–Mg alloys was measured with a dynamic-mechanical analyzer (DMA) as a function of the temperature (from 30 to 425°C) and the loading frequency (from 0.01 to 150 Hz). The time-temperature superposition (TTS) principle has proven to be useful in studying mechanical relaxations and obtaining master curves for amorphous materials. In this work, the TTS principle is applied to the measured viscoelastic data (i.e., the storage and loss moduli) to obtain the corresponding master curves and to analyze the mechanical relaxations responsible for the viscoelastic behavior of the studied alloys. For the storage modulus it was possible to identify a master curve for a low-temperature region (from room temperature to 150°C) and, for the storage and loss moduli, another master curve for a high-temperature region (from 320 to 375°C). These temperature regions are coincidental with the stable intervals where no phase transformations occur. Th...
The creep of a dislocation on its glide plane is essentially controlled by three different stress fields: the external applied stress, the internal stress field due to a multi-scale hierarchy of different obstacles (the structural defects... more
The creep of a dislocation on its glide plane is essentially controlled by three different stress fields: the external applied stress, the internal stress field due to a multi-scale hierarchy of different obstacles (the structural defects acting on the dislocation by short-or long-range interactions) and the thermal stress field due to thermal fluctuations. The dislocation glide dynamics involves solution of a string equation, which can be written as a Langevin equation. In this paper, it is shown that general analytical solutions of this equation can be found, allowing calculation of the plastic strain rate and the amplitude-dependent internal friction (ADIF), by using simple assumptions concerning the multi-scale hierarchy of obstacles and the mechanisms of Brownian dislocation creep through the different kinds of interacting obstacles. It is also shown that several experimental observations are well explained by this approach.
Abstract Beydag dam is under construction on Kucukmenderes River for irrigation purposes. Due to the scarcity of core material and liquefaction of alluvium at the dam site, the original design was changed to Roller Compacted Concete (RCC)... more
Abstract Beydag dam is under construction on Kucukmenderes River for irrigation purposes. Due to the scarcity of core material and liquefaction of alluvium at the dam site, the original design was changed to Roller Compacted Concete (RCC) from rockfill dam with claycore. ...
Amorphous alloys were first developed over 40 years ago and found applications as magnetic core or reinforcement added to other materials. The scope of applications is limited due to the small thickness in the region of only tens of... more
Amorphous alloys were first developed over 40 years ago and found applications as magnetic core or reinforcement added to other materials. The scope of applications is limited due to the small thickness in the region of only tens of microns. The research effort in the past two ...
The shear strength of alpine permafrost soils can be expressed in terms of internal friction φ' and cohesion c utilizing a Mohr-Coulomb failure criterion as for many other soils. The challenges lie in the correct parameterization, in... more
The shear strength of alpine permafrost soils can be expressed in terms of internal friction φ' and cohesion c utilizing a Mohr-Coulomb failure criterion as for many other soils. The challenges lie in the correct parameterization, in other words the assignment of realistic values for the chosen parameters φ' and c. Because the strength of frozen soils depends on the temperature, a correlation of the effective angle of internal friction φ' and cohesion c with temperature- dependent parameters, such as the volumetric ice content wi, is proposed. The correlations are based on laboratory tests carried out on undisturbed samples of alpine permafrost soils. Utilizing an example calculation, this paper provides guidance in dealing with limit equilibrium slope stability analysis and assistance in selecting appropriate soil parameters.
A continuum glassy polymer model applicable to dynamic loading J. Appl. Phys. 112, 083511 (2012) Effects of mechanical contact stress on magnetic properties of ferromagnetic film J. Appl. Phys. 112, 084901 (2012) Pyramidal dislocation... more
A continuum glassy polymer model applicable to dynamic loading J. Appl. Phys. 112, 083511 (2012) Effects of mechanical contact stress on magnetic properties of ferromagnetic film J. Appl. Phys. 112, 084901 (2012) Pyramidal dislocation induced strain relaxation in hexagonal structured InGaN/AlGaN/GaN multilayer J. Appl. Phys. 112, 083502 (2012) Resonant frequency analysis of Timoshenko nanowires with surface stress for different boundary conditions J. Appl. Phys. 112, 074322 (2012) Additional information on Appl. Phys. Lett. Journal Homepage: http://apl.aip.org/ Journal Information: http://apl.aip.org/about/about_the_journal Top downloads: http://apl.aip.org/features/most_downloaded Information for Authors: http://apl.aip.org/authors
Increasing settlement activities of people in mountanious regions and the appearance of extreme climatic conditions motivate the investigation of landslides. Within the last few years a significant rising of disastrous slides could be... more
Increasing settlement activities of people in mountanious regions and the appearance of extreme climatic conditions motivate the investigation of landslides. Within the last few years a significant rising of disastrous slides could be registered which generated a broad public interest and the request for security measures. The FWF (Austrian Science Fund) funded project `KASIP' (Knowledge-based Alarm System with Identified Deformation
Abstract. We have measured qualitative elastic properties of basalt and Berea sandstone from room temperature down to 4 K using Resonant Ultrasound Spectroscopy (RUS). A simple elastic solid should show a monotonic increase in the elastic... more
Abstract. We have measured qualitative elastic properties of basalt and Berea sandstone from room temperature down to 4 K using Resonant Ultrasound Spectroscopy (RUS). A simple elastic solid should show a monotonic increase in the elastic constants as temperature decreases. The basalt sam-ples show this gross behavior while the sandstone shows a very unexpected anomalous regime between 40 K and 200 K where the elastic constants decrease with decreasing temper-ature. Both rocks show temperature-dependent structure in both the modulus and internal friction, and also signicant hysteresis, indicating history and rate-dependent properties. This data provides insight into the time and energy scales of dynamical eects observed in sandstones. The low tem-perature range (4K{300K) is of interest due to the renewed interest in Mars and Lunar rocks.
The overall mechanics of fold-and-thrust belts and accretionary wedges along compressive plate boundaries is considered to be analogous to that of a wedge of soil or snow in front of a moving bulldozer. The material within the wedge... more
The overall mechanics of fold-and-thrust belts and accretionary wedges along compressive plate boundaries is considered to be analogous to that of a wedge of soil or snow in front of a moving bulldozer. The material within the wedge deforms until a critical taper is attained, ...
