HYBRID EXPERIMENTAL - NUMERICAL STRESS ANALYSIS (TWO-DIMENSIONAL, THREE-DIMENSIONAL, ISOTROPY, ORTHOTROPY, THIN PLATES)

A hybrid (experimental + numerical + analytical) stress analysis technique combining either displacement or stress data with a mathematically continuous series and which satisfies equilibrium is developed and shown to be very efficient. Satisfying equilibrium generates relationships among the coefficients of the assumed series representation, thereby eliminating many of these coefficients. Such a procedure reduces the amount of experimental input data required for complete stress analysis. It also improves accuracy and reduces computer costs. The remaining independent coefficients of the assumed representation are evaluated for a given segment of the body using experimentally measured data and least-squares. The method can be used to analyze the complete structure or only a region of concern. Employing least-squares smooths the experimental data so that a "best fit" solution is obtained. This utilization of experimental data as input into a numerical technique can reduce both experimental and numerical requirements and thus saves laboratory effort and computation time. Sometimes only sparse experimental data are available in critical areas causing inaccuracies in a purely experimental solution in this vicinity. To counteract this, the proposed method enables experimental data to be taken elsewhere and used as input to help obtain the solution in areas where little experimental data are available.; The technique described above has been developed in Chapter 2 through Chapter 4 for two- and three-dimensional isotropic and orthotropic materials. Application of the method to solve thin plate problems (isotropic and orthotropic composite) is illustrated in Chapter 5. Chapter 6 develops and applies the hybrid method to separate the stresses from isopachics (stress sum contours). Extension of the method to separate the stresses in two- and three-dimensional photoelasticity is illustrated in Chapter 7. In the case of the latter, the need to evaluate isochromatics and isoclinics at common locations is illuminated, as is the need to determine fractional fringe orders.; The technique has been substantiated by solving a variety of problems, and the results compared with available theoretical and other experimental results.; Appendix E contains brief summaries of three pieces of research conducted at the University of Wisconsin-Madison. This research, cyclic behavior of composites at room and cryogenic temperature, was also undertaken as part of my Research Assistanceship with the Applied Superconductivity Center. (Abstract shortened with permission of author.)...