292
292
May 22, 2011
05/11
by
Reddy, E. S.; Abumeri, G. H.; Chamis, C. C.; Murthy, P. L. N
texts
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The ice impact problem on an engine blade made of layered composite is simulated. The ice piece is modeled as an equivalent spherical object and has the velocity opposite to that of the aircraft with direction parallel to the engine axis. Near the impact region and along the leading edge, the blade is assumed to be fully stressed and undergoes large deflection. A specified portion of the blade around the impact region is modeled. The effect of ice size and velocity on the average leading edge...
Topics: DATA PROCESSING, OPTICAL MEASUREMENT, POSITION (LOCATION), RADIATION MEASUREMENT, ZENITH,...
265
265
Jul 12, 2010
07/10
by
Hopkins, D. A.; Chamis, C. C
texts
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A computational capability for predicting the nonlinear thermomechanical structural response of fiber-reinforced superalloy (FRS) turbine blades is described. This capability is embedded in a special purpose computer code (COBSTRAN) developed at the NASA Lewis Research Center. Special features of this computational capability include accounting for: fiber/matrix reaction, nonlinear and anisotropic material behavior, complex stress distribution due to local and global heterogeneity, and residual...
Topics: ALUMINUM, ABSORPTIVITY, FAILURE ANALYSIS, SPACE SHUTTLE MAIN ENGINE, SURFACE TEMPERATURE,...
249
249
Jul 25, 2010
07/10
by
Wilt, T. E.; Murthy, P. L. N.; Chamis, C. C
texts
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A procedure is described to computationally simulate composite laminate fracture toughness in terms of strain energy release rate. It is also used to evaluate the degradation in laminate structural integrity in terms of displacements, loss in stiffness, loss in vibration frequencies and loss in buckling resistance. Specific laminates are selected for detail studies in order to demonstrate the generality of the procedure. These laminates had center delaminations, off-center delaminations, and...
Topics: CERAMICS, CONSOLIDATION, PRESSING, SILICON NITRIDES, SLURRIES, PH FACTOR, SILICON OXIDES,...
246
246
Jul 21, 2010
07/10
by
Chamis, C. C.; Hopkins, D. A
texts
eye 246
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A set of thermoviscoplastic nonlinear constitutive relationships (1VP-NCR) is presented. The set was developed for application to high temperature metal matrix composites (HT-MMC) and is applicable to thermal and mechanical properties. Formulation of the TVP-NCR is based at the micromechanics level. The TVP-NCR are of simple form and readily integrated into nonlinear composite structural analysis. It is shown that the set of TVP-NCR is computationally effective. The set directly predicts...
Topics: EARTH ORBITAL ENVIRONMENTS, EXPERIMENTATION, INTERPLANETARY DUST, LOW EARTH ORBITS, OPTICAL...
224
224
May 23, 2011
05/11
by
Gotsis, P. K.; Chamis, C. C.; Minnetyan, L
texts
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Defect-free and defected composite thin shells with ply orientation (90/0//-75) made of graphite/epoxy are simulated for damage progression and fracture due to internal pressure and axial loading. The thin shells have a cylindrical geometry with one end fixed and the other free. The applied load consists of an internal pressure in conjunction with an axial load at the free end, the cure temperature was 177 C (350 F) and the operational temperature was 21 C (70 F). The residual stresses due to...
Topics: SOLAR FLARES, SUN, IMAGING TECHNIQUES, FORBUSH DECREASES, SUNSPOTS, X RAYS, COLLIMATORS
363
363
May 31, 2011
05/11
by
Chamis, C. C.; Abumeri, G. H
texts
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The response to high velocity impact of a composite blade is probabilistically evaluated. The evaluation is focused on quantifying probabilistically the effects of uncertainties (scatter) in the variables that describe the impact, the blade make-up (geometry and material), the blade response (displacements, strains, stresses, frequencies), the blade residual strength after impact, and the blade damage tolerance. The results of probabilistic evaluations results are in terms of probability...
Topics: STATISTICAL ANALYSIS, KNOWLEDGE, FUNCTIONS (MATHEMATICS), HYPOTHESES, INFERENCE, BIOASSAY,...
