| Compressive and Shear Buckling Analysis of Metal Matrix Composite Sandwich Panels Under Different Thermal Environments |
93 |
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| Authors:
William L. Ko; Raymond H. Jackson; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION EDWARDS CA DRYDEN FLIGHT RESEAR CH CENTER
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 | Combined inplane compressive and shear buckling analysis was conducted on flat rectangular sandwich panels using the rayleigh-ritz minimum energy method with a consideration of transverse shear effect of the sandwich core. the sandwich panels were fabricated with titanium honeycomb core and laminated metal matrix composite face sheets. the results show that slightly slender (along the unidirectional compressive loading axis) rectangular sandwich panels have the most desirable stiffness-to-weight ratios for aerospace ... |
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| Combined Compressive and Shear Buckling Analysis of Hypersonic Aircraft Structural Sandwich Panels |
MAY 91 |
38 pages |
| Authors:
William L. Ko; Raymond H. Jackson; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION EDWARDS AFB CA DRYDEN FLIGHT RE SEARCH CENTER
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 | The combined-load (compression and shear) buckling equations were established for orthotropic sandwich panels by using the Rayleigh-Ritz method to minimize the panel total potential energy. The resulting combined-load buckling equations were used to generate buckling interaction curves for super- plastically-formed/diffusion-bonded titanium truss-core sandwich panels and titanium honeycomb-core sandwich panels having the same specific weight. The relative combined-load buckling strengths of these two types of sandwich panels are compared with consideration ... |
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| Stress Concentration Around a Small Circular Hole in the HiMAT Composite Plate |
DEC 85 |
18 pages |
| Authors:
William L. Ko; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER
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| When an infinite isotropic plate containing a circular hole is subjected to remote uniaxial tension, the tangential stress along the boundary of the circular hole will reach a value three times the remote tensile stress at two boundary points lying on the hole diameter perpendicular to the loading axis. Namely, the maximum tangential stress concentration factor is 3, which is independent of the hole size. For anisotropic materials, such as ... |
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| Comparison of Structural Behavior of Superplastically Formed/Diffusion- Bonded Sandwich Structures and Honeycomb Core Sandwich Structures |
JUN 80 |
35 pages |
| Authors:
William L. Ko; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION EDWARDS AFB CA DRYDEN FLIGHT RE SEARCH CENTER
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| This paper discusses a new superplastically formed/diffusion-bonded (SPF/DB) orthogonally corrugated core sandwich structure and compares its structural behavior with that of a conventional honeycomb core sandwich structure. The stiffness and buckling characteristics of the two types of sandwich structures are compared under conditions of equal structural density. Under certain conditions, the SPF/DB orthogonally corrugated core sandwich structure is slightly more efficient than the optimum honeycomb core (square- cell core) sandwich ... |
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| Elastic Constants for Superplastically Formed/Diffusion-Bonded Corrugated Sandwich Core |
MAY 80 |
82 pages |
| Authors:
William L. Ko; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION EDWARDS AFB CA DRYDEN FLIGHT RE SEARCH CENTER
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| This paper presents formulae and associated graphs for evaluating the effective elastic constants for a superplastically formed/diffusion-bonded (SPF/ DB) corrugated sandwich core. The results were used in the comparison of structural stiffnesses of the above sandwich core and a honeycomb core under conditions of equal sandwich core density. It was found that the stiffness in the thickness direction of the optimum SPF/DE corrugated core (that is, triangular truss core) was ... |
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| magnetic field leakage due to a surface crack |
SEP 75 |
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| Authors:
William L. Ko; philip h. francis
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| this paper presents some calculations of the magnetic leakage field sensed by a hall probe in the vicinity of a surface crack in a ferromagnetic material. it is shown that the peak vertical component of the magnetic leakage field can be related to the parameters of classical fracture mechanics. for the crack lengths greater than about 40 times .0010 in. the theory correlates rather well with experimental data taken from ... |
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| Thermo-Mechanical Behavior of Composites. |
JUN 1974 |
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| Authors:
U. S. Lindholm; William L. Ko; Phillip H. Francis; Andrew Nagy; Sol R. Bodner; SOUTHWEST RESEARCH INST SAN ANTONIO TEX DEPT OF MATERIALS SCIENCES
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| Part I derives elastic solutions for stress concentration pro-blems in filamentary materials containing different cracks. The derived theories for crack extension differ only for small cracks. Experimental data are compared to the theoretical results. Part II ESTABLISHES A CRITERION FOR TIME DEPENDENT FAILURES BASED ON RESULTS OF INCREMENTAL ACCUMULATION OF DAMAGE IN ACCORDANCE WITH THE INCREMENTAL FLOW LAW DESCRIBING THE INELASTIC DEFORMATION. (AE-PL) |
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| A Study of the Dynamic Strength and Fracture Properties of Rock. |
AUG 1973 |
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| Authors:
James Lankford; William L. Ko; Ulric S. Lindholm; SOUTHWEST RESEARCH INST SAN ANTONIO TEX
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| The report summarizes the results of a study aimed at developing a quantitative failure strength criterion for Dresser basalt, as well as gaining better understanding of the basic fracture mechanisms involved in fracture. Tests were performed over a temperature range of 77-1400K, a strain rate range of .0001-1000 sec minus 1, pressures of 0-100 KSI, and under a variety of uniaxial and biaxial stress states. Failure theories were analyzed, and ... |
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| EFFECTS OF AIR BLAST LOADING ON A PIER. |
SEP 1967 |
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| Authors:
Young C. Kim; Thorbjorn Karlsson; William L. Ko; SCIENCE ENGINEERING ASSOCIATES INC SAN MARINO CALIF
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| An experimental program designed to study the effects of air blast loading on a pier is described. A pier model was tested in a six foot diameter horizontal shock tube under four different test situations simulating pier on a beach with water, pier on a dry beach in a Mach reflection region, pier in deep water, and a pier on a dry beach in a region of regular reflection. The ... |
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