Journal of Theoretical
and Applied Mechanics
2, 1, pp. 45-59, Warsaw 1964
and Applied Mechanics
2, 1, pp. 45-59, Warsaw 1964
Doraźne badania własności mechanicznych i elastooptycznych materiałów używanych w elastooptyce
Przebieg pierwszego krajowego Sympozjum na temat „Elastooptyka i jej Zastosowania”, zorganizowanego w 1962 r. przez Oddział Warszawski Polskiego Towarzystwa Mechaniki Teoretycznej i Stosowanej, uwypuklił dużą przydatność metod elastooptyki do rozwiązywania różnorodnych zadań techniki. Celem badań przeprowadzonych w Pracowni Analizy Naprężeń było przyjęcie metody, która umożliwiałaby jednoczesne wyznaczanie elastooptycznej stałej materiałowej oraz współczynnika sprężystości podłużnej. W związku z tym badania te nie miały charakteru szczegółowej analizy naukowej elastooptycznych i mechanicznych własności materiałów używanych w elastooptyce. Ograniczono się również, na razie, do badań w temperaturze pokojowej. W dalszych etapach będą prowadzone badania omawianych własności w temperaturze „zamrażania naprężeń” oraz badania zjawisk reologicznych zarówno dla temperatury pokojowej, jak i temperatury „zamrażania naprężeń”.
TESTING OF MECHANICAL AND PHOTOELASTIC PROPERTIES OF THE PHOTOELASTIC MATERIALS
The object of the present tests is the adoption of one of a known method of investigation the mechanical and photoelastic properties to the simultaneous determination of the photoelastic constant K and the Young modulus E. The experimental methods have been tested on the epoxy resins (polymerized in the Laboratory of Stress Analysis of the Institute of the Fundamental Engineering Research of the Polish Academy of Sciences), VP-1527, BT-61893, CR-39, and Dekorit. The diagrams and tables show the dependence of the unit strain and K on stresses for the tested materials. The following conclusions result from the above experiments: 1. The values of constant K and modulus E considerably depend upon: a) the change of temperature, b) the differences in the conditions in which the material is stored and on the given lot of material, c) time, d) the assumed method of testing. 2. In this connection the necessity presents itself of the properties of photoelastic materials. 3. The method of “half-plane” is particularly useful for the determination of K, because: a) it is not tedious and does not require cutting of any scaling model, b) is non-destructive, c) the Young modulus E can be determined simultaneously. As regard, the determination of E this method has not yet be verified experimentally but one can suppose that it will be useful in practice, at least for the determination of E in the temperature of “freezing” and for the resins with low values of E.
TESTING OF MECHANICAL AND PHOTOELASTIC PROPERTIES OF THE PHOTOELASTIC MATERIALS
The object of the present tests is the adoption of one of a known method of investigation the mechanical and photoelastic properties to the simultaneous determination of the photoelastic constant K and the Young modulus E. The experimental methods have been tested on the epoxy resins (polymerized in the Laboratory of Stress Analysis of the Institute of the Fundamental Engineering Research of the Polish Academy of Sciences), VP-1527, BT-61893, CR-39, and Dekorit. The diagrams and tables show the dependence of the unit strain and K on stresses for the tested materials. The following conclusions result from the above experiments: 1. The values of constant K and modulus E considerably depend upon: a) the change of temperature, b) the differences in the conditions in which the material is stored and on the given lot of material, c) time, d) the assumed method of testing. 2. In this connection the necessity presents itself of the properties of photoelastic materials. 3. The method of “half-plane” is particularly useful for the determination of K, because: a) it is not tedious and does not require cutting of any scaling model, b) is non-destructive, c) the Young modulus E can be determined simultaneously. As regard, the determination of E this method has not yet be verified experimentally but one can suppose that it will be useful in practice, at least for the determination of E in the temperature of “freezing” and for the resins with low values of E.