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Hold Periods (hold + period)

Distribution by Scientific Domains

Polymers and Materials Science	80%

Selected Abstracts

Timing and the Holding Periods of Institutional Real Estate

REAL ESTATE ECONOMICS, Issue 2 2003
David Collett
Literature on investors' holding periods for securities suggests that high transaction costs are associated with longer holding periods. Return volatility, by contrast, is associated with shorter holding periods. In real estate, high transaction costs and illiquidity imply longer holding periods. Research on depreciation and obsolescence suggests that there might be an optimal holding period. Sales rates and holding periods for U.K. institutional real estate are analyzed, using a proportional hazards model, over an 18-year period. The results show longer holding periods than those claimed by investors, with marked differences by type of property and over time. The results shed light on investor behavior. [source]

Crack Growth in Soda,Lime,Silicate Glass near the Static Fatigue Limit

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2002
Sheldon M. Wiederhorn
The atomic force microscope (AFM) was used to explore the nature of features formed on the surfaces of cracks in soda,lime,silicate glass that were held at stress intensity factors below the crack growth threshold. All studies were conducted in water. Cracks were first propagated at a stress intensity factor above the crack growth threshold and then arrested for 16 h at a stress intensity factor below the threshold. The stress intensity factor was then raised to reinitiate crack growth. The cycle was repeated multiple times, varying the hold stress intensity factor, the hold time, and the propagation stress intensity factor. Examination of the fracture surface by optical microscopy showed surface features that marked the points of crack arrest during the hold time. These features were identical to those reported earlier by Michalske in a similar study of crack arrest. A study with the AFM showed these features to be a consequence of a bifurcation of the crack surface. During the hold period, waviness developed along the crack front so that parts of the front propagated out of the original fracture plane, while other parts propagated into the plane. Crack growth changed from the original flat plane to a bifurcated surface with directions of as much as 3° to 5° to the original plane. This modification of crack growth behavior cannot be explained by a variation in the far-field stresses applied to the crack. Nor can the crack growth features be explained by chemical fluctuations within the glass. We speculate that changes in crack growth direction are a consequence of an enhancement in the corrosion rate on the flank of the crack at stresses below the apparent crack growth threshold in a manner described recently by Chuang and Fuller. [source]

On the mechanisms of fatigue facet nucleation in titanium alloys

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 11 2008
F. P. E. DUNNE
ABSTRACT A crystal plasticity model for near-alpha hcp titanium alloys embodying a quasi-cleavage failure mechanism is presented and employed to investigate the conditions necessary in order for facet nucleation to occur in cold-dwell fatigue. A model polycrystal is used to investigate the effects of combinations of crystallographic orientations (and in particular, a rogue grain combination), the essential role of (cold) creep during hold periods in the loading cycle and the more damaging effect of a load hold rather than a strain hold in facet nucleation. Direct comparisons of model predictions are made with dwell fatigue test results. More generally, the crystal model for faceting is found to be consistent with a range of experimental observations. [source]

Factors influencing the service-like thermomechanical fatigue test cycle endurance of 1% CrMoV rotor steel

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 11 2003
B. MASSEREY
ABSTRACT Service-like thermomechanical fatigue tests have been performed in order to characterize the endurance of 1% CrMoV rotor steel under such transient thermal conditions. The key features of these tests are low strain rates (,10,5 s,1) and longer hold periods. In all testpieces, ratcheting with progressive section reduction is observed in the central portion of the gauge length accompanied by local amplification of the strain range. The finite-element-based analysis of this phenomenon allows the measured endurances to be rationalized with those determined from isothermal tests. Post-test inspection has revealed the development of two concurrent damaging mechanisms in the testpieces: (i) fatigue at the surface and (ii) creep in the interior. Different methods of damage calculation for creep,fatigue interaction are applied and compared in their predictive capabilities. [source]

Variation in cyclic oxidation testing practice and data: The European situation before COTEST

MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 1 2006
S. Osgerby
Abstract A survey of existing testing practice and pre-existing data was conducted to provide a starting point for the COTEST project on cyclic oxidation testing. The main parameters within the test that need to be controlled were identified as: control of test environment; temperature stability during hold periods; heating and cooling rates; specimen preparation; and post test evaluation. Existing experimental facilities were surveyed to establish the full range of variability within these parameters. [source]