Crack simulation

D 5293 in Used Lubricating Oils and Determination of Selected Elements in Base Oils by ICP-AES Apparent Viscosity of Engine Oils Between -5 and -30 °C Using the Cold-Cracking Simulator... 

Figure 21 Schematic representation of Abraham s crack simulation.

Chloride-induced reinforcement corrosion and concrete cracking simulation was investigated by Chen and Mahadevan [35] using Faraday s law to develop a... 

Two-Dimensional Mixed Mode Crack Simulation Using the Material Point Method. 

As stated above for catalytic cracking simulation under the reaction conditions of FCCs a bench scale internal recycle batch reactor was proposed by de Lasa (1991, 1992). It has to be pointed out that this objective is not easy nor straight forward considering the complex fluid-dynamic... 

The cracking simulation model developed by the Laboratorium voor Petrochemische Techniek contains 1680 reaction networks for some 550 hydrocarbons. The components involved in the model are normal and iso-paraffins and olefins up to C25, 5- and 6-ring naphthenes up to C20 and aromatics up to C20. The computation of the reaction networks for the heavy components requires many hours. 

Simulations about Eddy Current Distributions and Crack Detection Algorithms for a SQUID Based NDE System. 

In this paper we present simulations and measurements of several types of excitation coils, which match the special requirements for a SQUID based eddy current NDE system. We note however that all calculations presented here on penetration depths, current distributions and crack-detecting algorithms are also useful for conventional eddy current testing systems. 

The simulation of the actual distortion of the eddy current flow caused by a crack turns out to be too time consuming with present means. We therefore have developed a simple model for calculating the optimum excitation frequencies for cracks in different depths of arbitrary test sarriples Using Equ. (2.5), we are able to calculate the decrease in eddy current density with increasing depth in the conductor for a given excitation method, taking into account the dependence of the penetration depth c on coil geometry and excitation frequency. 

We have perfomied some simulations of the eddy current distribution in a test object for a spiral coil and a circular one (see Fig. 4.1). Both coils had 9 turns and the excitation current was 6 mA. Figs. 4.1 show the cross section of the sample at the location of the crack and the amplitude of the eddy current density. One observes a 1.5 higher current density at the sides of the crack for the case of the circular coil. 

For precise 3D-FEM simulations, a huge number of nodes is required (>30,000), which results in calculation times of several hours (sun spare 20) for one model. In order to decrease the number of nodes, we took advantage of the symmetry of the coils and calculated only a quarter or half of the test object. The modelled crack has a lenght of 15 mm, a height of 3 mm and is in a depth of 5 mm. The excitation frequency was 200 Hz. 

Heat is used to darken amber, ivory, and jade to simulate age. Pieces of amber and tortoiseshell can be reconstmcted, ie, joined under heat and moderate pressure. By careful heating in oil, milky amber can be clarified when the gas and water within small bubbles diffuse out of the stone. If heating is rapid, the attractive sun-spangle cracking shown in Figure 1 results. 

Colored Impregnations. Colored oil to fill cracks is used on gemstones primarily to improve color, most frequendy on emerald. Colored oil is also used to simulate other stones, most frequendy quartz. Depending on the dye used, the colors may fade, in addition to the problems associated with colodess oiling. 

Figure 2.3.1 (Wachtel, et al, 1972) shows the ARCO reactor that tried to simulate the real reaction conditions in a fluid cracking unit. This was a formal scale-down where many important similarities had to be sacrificed to get a workable unit. This unit was still too large for a laboratory study or test unit, but instead was pilot-plant equipment that could still give useful empirical results Since this serves a very large industry, it may pay off to try it, even if it costs a lot to operate.

Figure 2.3.2 (Kraemer and deLasa 1988) shows this reactor. DeLasa suggested for Riser Simulator a Fluidized Recycle reactor that is essentially an upside down Berty reactor. Kraemer and DeLasa (1988) also described a method to simulate the riser of a fluid catalyst cracking unit in this reactor.

Catalytic crackings operations have been simulated by mathematical models, with the aid of computers. The computer programs are the end result of a very extensive research effort in pilot and bench scale units. Many sets of calculations are carried out to optimize design of new units, operation of existing plants, choice of feedstocks, and other variables subject to control. A background knowledge of the correlations used in the "black box" helps to make such studies more effective. 

A pecuhar sohd phase, which has been discovered not too long ago [172], is the quasi-crystalline phase. Quasi-crystals are characterized by a fivefold or icosahedral symmetry which is not of crystallographic type and therefore was assumed to be forbidden. In addition to dislocations which also exist in normal crystals, quasi-crystals show new types of defects called phasons. Computer simulations of the growth of quasicrystals [173] are still somewhat scarce, but an increasing number of quasi-crystalline details are studied by simulations, including dislocations and phasons, anomalous self-diffusion, and crack propagation [174,175]. 

R. Mikulla, F. ICrul, P. Gumbsch, H.-R. Trebin. Numerical simulations of dislocation motion and crack propagation in quasicrystals. In A. Goldmann,... 

T. Hoshide, K. Kusuura. Life prediction by simulation of crack growth in notched components with different microstructures and under multiaxial fatigue. Fatigue Fract Eng Mater Struct 27 201, 1998. 

T. Hoshide. Simulation of microstructural effects on cracking behavior in biaxial fatigue. Mater Sci Res Int 5 119, 1997. 

Sheeks, C. J., Moshier, W. C., Ballinger, R. G., Latanison, R. M., Pelloux, R. M. N., Fatigue crack growth of Alloys X750 and 600 in simulated PWR and BWR environments , Proc. 1st Int. Conf. on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors, Myrtle Beach, USA, 22-25 Aug. 1983, NACR pp. 701-25 (1984)... 

Pre-cracked specimens are sometimes useful for other reasons than the analysis that they afiford in relation to stress-intensity factors. Such applications may be associated with the simulation of service situations, the relative ease with which stress-corrosion cracks can be initiated at pre-cracks or the advantages that sometimes accrue from the propagation of a single crack. The claim that has sometimes been made of pre-cracked specimen tests-that they circumvent the initiation stage of cracking in plain specimens, erroneously assumed invariably to be related to the creation of a corrosion pit that provides a measure of stress concentration approaching that... 

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