Structural analysis applications

An account is given of the application of computer codes for the efficient conduct of three-dimensional inelastic analyses to aircraft gas turbine combustor, turbine blade, and turbine stator vane components. The synergetic consequences of the program's activities are illustrated by an evaluation of the computer analyses of thermal barrier coatings and of the Space Shuttle Main Engine's High Pressure Fuel Turbopump turbine blading. This software, in conjunction with state-of-the-art supercomputers, can significantly reduce design-task burdens

Multiaxial Cyclic Thermoplasticity Analysis with Besseling's Subvolume Method

A modification was formulated to Besseling's Subvolume Method to allow it to use multilinear stress-strain curves which are temperature dependent to perform cyclic thermoplasticity analyses. This method automotically reproduces certain aspects of real material behavior important in the analysis of Aircraft Gas Turbine Engine (AGTE) components. These include the Bauschinger effect, cross-hardening, and memory. This constitutive equation was implemented in a finite element computer program called CYANIDE. Subsequently, classical time dependent plasticity (creep) was added to the program. Since its inception, this program was assessed against laboratory and component testing and engine experience. The ability of this program to simulate AGTE material response characteristics was verified by this experience and its utility in providing data for life analyses was demonstrated. In this area of life analysis, the multiaxial thermoplasticity capabilities of the method have proved a match for the actual AGTE life experience

Component specific modeling

The objective is to develop and verify a series of interdisciplinary modeling and analysis techniques that have been specialized to address three specific hot section components. These techniques will incorporate data as well as theoretical methods from many diverse areas including cycle and performance analysis, heat transfer analysis, linear and nonlinear stress analysis, and mission analysis. The new methods developed will be integrated to provide an accurate, efficient, and unified approach to analyzing combustor burner liners, hollow air-cooled turbine blades, and air-colled turbine vanes. For these components, the methods developed will predict temperature, deformation, stress, and strain histories throughout a complete flight mission

Component specific modeling

The objective was to develop and verify a series of interdisciplinary modeling and analysis techniques specialized to address hot section components. These techniques incorporate data as well as theoretical methods from many diverse areas, including cycle and performance analysis, heat transfer analysis, linear and nonlinear stress analysis, and mission analysis

Nonlinear analysis of an axisymmetric structure subjected to non-axisymmetric loading

The development of the SHELPC finite element computer program is detailed. This program is specialized to simulate the nonlinear material behavior which results from combustor liner hot streaks. This problem produces a nonlinear Fourier Series type loading on an axisymmetric structure. Example cases are presented

The 3D inelastic analysis methods for hot section components

The objective of this research is to develop an analytical tool capable of economically evaluating the cyclic time dependent plasticity which occurs in hot section engine components in areas of strain concentration resulting from the combination of both mechanical and thermal stresses. The techniques developed must be capable of accommodating large excursions in temperatures with the associated variations in material properties including plasticity and creep. The overall objective of this proposed program is to develop advanced 3-D inelastic structural/stress analysis methods and solution strategies for more accurate and yet more cost effective analysis of combustors, turbine blades, and vanes. The approach will be to develop four different theories, one linear and three higher order with increasing complexities including embedded singularities

First look analyses of five cycles of ERTS-1 imagery over County of Los Angeles: Assessment of data utility for urban development and regional planning

Significant results have been obtained from the analyses of ERTS-1 imagery from five cycles over Test Site SR 124 by classical photointerpretation and by an interactive hybrid multispectral information extraction system (GEMS). The synopticity, periodicity and multispectrality of ERTS coverage, available for the first time to LA County planners, have opened up both a new dimensionality in data and offer new capability in preparation of planning inputs. Photointerpretation of ERTS images has produced over 25 overlays at 1:1,000,000 scale depicting regional relations and urban structure in terms of several hundred linear and areal features. To mention only one such result, a possible new fault lineament has been discovered on the northern slope of the Santa Monica mountains in the scene 1144-18015, composited of MSS bands 4, 5, 6,. GEMS analysis of the ERTS products has provided new or improved information in the following planning data categories: urban vegetation; land cover segregation; man-made and natural impact monitoring; urban design; and suitability. ERTS data analysis has allowed planners to establish trends that directly impact planning policies. This new source of information will not only assist current methods to be more efficient, but permits entirely new planning methodologies to be employed

Coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures

Accomplishments are described for the third years effort of a 5-year program to develop a methodology for coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures. These accomplishments include: (1) structural analysis capability specialized for graded composite structures including large deformation and deformation position eigenanalysis technologies; (2) a thermal analyzer specialized for graded composite structures; (3) absorption of electromagnetic waves by graded composite structures; and (4) coupled structural thermal/electromagnetic analysis of graded composite structures

An Empirical Test of a Free-Will Centered, Phenomenological Approach to Organizational Behavior Education: Working Paper Series--97-04

This paper presents the initial validation of a Free-will Centered, Phenomenological Approach to Organizational Behavior Education. This approach is based on a subjective science which operates in a subjective truth system. This truth is a truth of value--of what is truly valuable for the quality of human experience. The theory predicts that a classroom aimed at teaching such knowledge would result in students moving in the direction of becoming self-actualizing persons, and this paper summarizes a test of the validity of this prediction. Specifically a group of college seniors was exposed to the theory and suitable pre, post and six-month follow-up measures were taken to determine the effect (if any) of the experience upon them. In general, the prediction that learning the theory would result in movement toward being a self-actualizing person was found to be valid. Thus, we can, in a course in organizational behavior, actually help students become healthier human beings, and, presumably also, then, better managers and leaders

Structure and evolution of an oceanic megamullion on the Mid-Atlantic ridge at 27°N

Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2001Megamullions in slow-spreading oceanic crust are characterized by smooth "turtle-back" morphology and are interpreted to be rotated footwalls of long-lived detachment faults. Megamullions have been analyzed in preliminary studies, but many questions remain about structural and tectonic details of their formation, in particular how the hanging wall develops in conjugate crust on the opposing side of the rift axis. This study compares the structure of an off-axis megamullion complex and its conjugate hanging wall crust on the Mid-Atlantic Ridge near 27°N. Two megamullion complexes, an older (Ml) and younger (M2), formed successively on the west side of the rift axis in approximately the same location within one spreading segment. Megamullion M1 formed while the spreading segment had only one inside comer on the west flank, and megamullion M2 formed after the segment developed double inside comers west of the axis and double outside comers east of the axis. The older megamullion formed between ~22.3 and ~20.4 Ma, and the younger megamullion formed between ~20.6 and ~18.3 Ma; they are presently ~200-300 km off-axis. Reconstruction poles of plate rotation were derived and plate reconstructions were made for periods prior to initiation of the megamullion complex (anomaly 6Ar, ~22.6 Ma), after the termination of mega mullion M1 and during the development of megamullion M2 (anomaly 5E, ~19 9 Ma), and shortly following the termination of megamullion M2 (anomaly 5C, ~17.6 Ma). These reconstructions were used to compare morphological and geophysical features of both flanks at each stage of the megamullions' development. Megamullion M1's breakaway occurred at ~22.3 Ma and slip along this detachment fault continued and propagated northward at ~20.6 Ma to form the northern portion ofM2. The exhumed footwall of mega mullion M1 has weak spreading-parallel lineations interpreted as mullion structures on its surface, and it forms an elevated plateau between the enclosing segment boundaries (non-transform discontinuities). There was an expansion southward of the detachment fault forming megamullion M2 at ~ 20.1 Ma. It either cut a new detachment fault through megamullion M1, stranding a piece of megamullion M1 on the conjugate side (east flank), or it linked into the active detachment fault that was forming megamullion M1 or propagated into its hanging wall. The expanded detachment of mega mullion M2 and the termination of mega mullion M1 occurred during a time when the enclosing spreading segment roughly doubled in length and formed two inside comers. Megamullion M2 developed prominent, high-amplitude (~600 m) mullion structures that parallel the spreading direction for more than 20 km at each inside comer. Its detachment fault was abandoned ~ 18.6 Ma in the south and ~ 18.3 Ma in the north. The gravity of this area demonstrates a consistent pattern of higher gravity corresponding to inside comers with thinner crust, apparently caused by fault exhumation of deep lithosphere, and lower gravity values corresponding to outside comers, indicating thicker crust, most likely a result of volcanic accretion. The gravity pattern of the area also helps with interpreting evolution of the megamullion complex. The southern section of megamullion M1 exhibits a series of inside-comer highs and elevated gravity values while the northern section has lower gravity values until megamullion M2 began to form. This change coincides with the change of the northern segment edge from an outside comer to an inside comer. During the formation of megamullion M2, a gravity high developed over the center of the megamullion. After the termination of megamullion M2, the gravity values of both the northern and southern sections of the spreading segment decrease. This pattern suggests exhumation of higher-density lithosphere during formation of M1 and M2, and a return to more normal ridge-axis conditions following termination of the megamullion complex. The gravity of conjugate crust is consistently more negative, slightly decreasing in value during the formation of megamullion M2. This suggests that crust on the east flank is significantly thicker than that on the west flank, and that rift-axis magmatism may have slightly increased at the time that megamullion M2 formed. We modeled gravity of an idealized structural cross-section of megamullion M2 to investigate possible structure and composition of the megamullion. Models with different detachment-fault angles and degrees of serpentinization of exhumed mantle that may be present in the megamullion were compared to Residual Mantle Bouguer Anomaly (RMBA) profiles. All models show gravity peaks slightly skewed towards the termination because higher-density rock is exposed closer to the termination than to the breakaway. Four models that varied the detachment fault angle show small variations that are unresolvable in the actual gravity data. Thus, the gravity profile of a megamullion is not diagnostic of its detachment fault angle from 30° to 60°/90°. Models that varied the degree of serpentinization of a lithospheric wedge beneath the megamullion show that slight variations in density give rise to large changes in the modeled gravity profiles. Comparison of model results against gravity profiles taken across megamullion M2 indicate that the magnitude of the gravity high associated with the megamullion is best explained by densities between 2800 kg/m3 and 3000 kg/m3 in the main body of the megamullion. This corresponds to peridotite serpentinized approximately 50%, or to gabbro (~2800 kg/m3).This study was supported by ONR grant N00014-90-J-1621 and by NSF grant OCE-950356