Metoda Kaustyk - Nowa Metoda Doświadczalna Badania Osobliwości Pola Naprężenia
W pracy opisane są podstawy nowej metody, zwanej metoda kaustyk służącej do analizy osobliwych pól napreżeń. Podane są też przykłady zastosowań. W metodzie tej promień światła pada na powierzchnie próbki w otoczeniu osobliwości pola napreżeń. Przepuszczone lub odbite promienie świetlne, wskutek gwałtownych zmian grubości płytki oraz zmian współczynnika załamania, ulegają rozproszeniu. Po zrzutowaniu na odpowiedni ekran skupiają się one wzdłuż pewnej krzywej osobliwej. Krzywa ta, zwana kaustyka zawiera istotne informacje o osobliwości pola napreżeń. W ten sposób osobliwość pola napreżeń zostaje przekształcona w osobliwość optyczną, która może być zbadana na ekranie. Pomiar geometrycznych parametrów kaustyki pozwala wyznaczyć parametry osobliwego pola napreżeń. Podano szereg zastosowań metody do rozwiazywania zagadnień tyczących: 1) pęknięć, 2) obciążeń skupionych i rozłożonych, 3) osobliwości w wierzchołkach kompozytów (wielokątów). Otrzymane w powyższy sposób wyniki doświadczalne dobrze zgadzają się z analiza teoretyczna.
References
P. S. THEOCARIS and E. E. GDOUTOS, Surface topography by the method of caustics, Applied Optics, 15, 6, pp. 1629-1638, 1976.
P. S. THEOCARIS and E. E. GDOUTOS, An interferometric method for the direct evaluation of principal stresses in plane-stress fields, J. Physic, Ser. D. 7, pp. 472-482, 1974.
P. S. THEOCARIS, Dependence of the stress-optical coefficients on the mechanical and optical properties of polymers, J. Strain Analysis, 8, 4, pp. 267-276, 1973.
P. S. THEOCARIS, The reflected shadow method for the study of constrained zones in cracked plates, Applied Optics, 10, pp. 2240-2247, 1971.
N. I. MUSKHELISHVILI, Some basic problems of the mathematical theory of elasticity, Sec. Ed. Noordhoff 1963.
M. BORN and E. WOLE, Principles of optics, Pergamon Press, Oxford 1970.
E. G. COKER and L. N.G. FILON, A treatise on photoelasticity, Cambridge at the University Press.
P. S. THEOCARIS, Local yielding around a crack-tip in plexiglas, J. Appl. Mech., Trans. ASME, Ser. E, 37, 2, pp. 409-415, 1970.
P. S. THEOCARIS, Constrained zones in cracked plates by the method of caustics, Procced. Nat. Acad. Athens. 46, pp. 116-130, 1971.
P. S. THEOCARIS, Interaction of cracks with other cracks or boundaries, Materialprüfung, 13, 8, pp. 264-269, 1971.
P. S. THEOCARIS, New methods based on geometric optics for the solution of fracture mechanics problems, Technical Annals, 41, 3/549, pp. 145-153, 1972.
P.S. THEOCARIS and E. E. Gdoutos, An optical method for determining opening -mode and edge- sliding mode stress intensity factors, J. Appl. Mech., 39, 1, pp. 91-97.
P.S. THEOCARIS, A new technique for viewing deformation zones at crack-tips, by D. Hoeppner, V. Danford and D. E. Pettit, Exp. Mech., 11, 6, pp. 280-283, 1971 discussion by P.S.
Theocaris. Exp. Mech., 12, 5, pp. 247-249, 1972.
P. S. THEOCARIS and N. IOAKIMIDIS, Some properties of generalized epicycloids applied to fracture mechanics, Zeitsch. ang. Math. and Phys., 22, 5, pp. 876-890, 1971.
P. S. THEOCARIS, An optical method for the determination of constrained zones at crack-tips, Proc. Intern. Symposium of Exp. Mech., Waterloo, Canada, June 1972, pp. 511-530, 1972. Fracture tougness testing and its applications, ASTM Special Technical Publication 381.
P. S. THEOCARIS, The method of caustics for the study of cracked plates made of viscoelastic materials, Proc. 3rd Intern. Conf. Fracture, München, Germany, VII, 512, 1973.
P.S. THEOCARIS, The method of caustics for the study of cracked plates made of viscoelastic materials, Int. J. Mech. Sci., 16, pp. 855-865, 1974.
P. S. THEOCARIS, The reflected-shadow method for the study of constrained zones in cracked birefringent media, J. Strain Anal. 7, 2, pp. 75-83, 1972.
P. S. THEOCARIS, Interaction between collinear asymmetric cracks, J. Strain Anal., 7, 7, 3, pp. 186-193, 1972.
P. S. TREOCARIS, Constrained zones in a periodic array of collinear equal cracks, Int. J. Mech. Sci., 14, 2, pp. 79-94, 1972.
P. S. THEOCARIS, A theoretical consideration of the constrained zones in an array of interacting collinear and asymmetric cracks, Acta Mechanica, 17, 3-4, pp. 169-189, 1973.
P. S. THEOCARIS, Complex stress-intensity factors at bifurcated cracks, J. Mech. Phys. Solids, 20, pp. 265-279, 1972.
P. S. THEOCARIS and C. BLONTZOU, Symmetric branching of cracks in plexiglas, Material-prüfung, 15, 4, pp. 123-130, 1973.
P. S. THEOCARIS, Asymmetric branching of cracks, J. Appl. Mech., 1977.
P. S. THEOCARIS and N. IOKIMIDIS, The symmetrically branched crack in an infinite elastic medium, ZAMP, 1977.
P. S. THEOCARIS and N. IOAKIMIDIS, Numerical integration methods for the solution of singular integral equations, Quart. Appl. Math., 1977.
P. S. THEOCARIS, Stress intensity factors of stationary cracks in cylindrical shells under internal pressure, Proc. First: Intern. Conference on Structural Mechanics in Reactor Technology, (Paper G6/7, Berlin, 1972) 4, G, pp. 487-505, 1972.
P. S. THEOCARIS and C. THIREOS, Stress intensity factors m cracked cylindrical shells under tension, J. of Fracture, 12, 1976.
P. S. THEOCARIS, Stress intensity factors in yielding materials by the method of caustics, Intern. J. Fract. Mech., 9, 2, pp. 185-197, 1973,
P. S. TREOCARIS and E. E. GDOUTOS, Verification of the validity of the Dugdale-Barenblatt model by the method of caustics, Engin. Fracture Mechanics, 6, 3, pp. 523-535, 1974. P. S. THEOCARIS and E. E. GDOUTOS, The modified Dugdale-Baremblatt model adapted 1o various fracture configuration m metals, Intern, J. Fract. Mech., 10, 4, pp. 549-664, 1974.
P.S. THEOCARIS, Ductile fracture in glass polymers, Int. J. Mechanical Sciences, 17, pp. 475- 485, 1975.
F. KATSAMANIS, D. RAFTOPOULOS and P.S. THEOCARIS, Static and dynamic stress intensity factors by the method of transmitted caustics, J. of Eng. Mat. and Tech. 1977.
D. RAFTOPOULOS, F. KATSAMANIS and P. S. THEOCARIS, Stress intensity factors at statically dynamically loaded tension specimens.
P. S. THEOCARIS and F. KATSAMANIS, Response of craks to impact by caustics, Engin. Fract. Mech., 1977.
P. S. THEOCARIS, Determination of crack-opening displacement by the method of caustics, J. Strain Analysis, 9, 3, pp. 197-205, 1974.
P. S. THEOCARIS, An optical stress-rosette based on caustics, Applied Optics, 12, 2, pp. 380-387, 1973.
P. S. THEOCARIS, Stress singularities at concentrated loads, Proc. 3rd Intern. Congress on Exp. Stress Analysis and Experimental Mechanics, 13, 12, pp. 511-518, 1973.
P. S. THEOCARIS, Stress singularities due to uniformly distributed loads along straight boundaries, Intern. J. Solids and Structures, 9, 5, pp. 655-670, 1973.
P. S. THEOCARIS and C. RAZEM, Determination of arbitrarily distributed loads by the method of caustics, J. Strain Analysis, 1977.
P. S. THEOCARIS, Stress and displacement singularities near corners, J. of Appl. Math. and Physics, 26, pp. 77-98, 1975.
P.S. THEOCARIS, Partly unbounded interfaces between dissimilar materials under normal and shear loading, Acta Mechanica, 24, pp. 99-115, 1976.
T. D. DUDDERAR and R. O'REGAN, Measurement of the strain field near a crack tip in poly-methylmethacrylate by holographic interferometry, Experimental Mechanics, 11, 2, pp. 49-56, 1971.
P. S. THEOCARIS, The determination of mode stress-intensity factors by holographic interferometry, Further comments on a discussion by Founey (Exp. Mech., 14, pp. 69-70, 1974) on a paper by Dudderar and O'Regan (Exp. Mechanics, 13, 4, pp. 145-149, 1973), Exp. Mech., 15, 4, pp. 150-152, 1975.