ON THE APPLICABILITY OF THE LOAD SEPARATION CRITERION TO ACRYLONITRILE BUTADIENE/STYRENE TERPOLYMER RESINS/

Load separation constitutes the basis for the experimental evaluation of the J-integral by using the single-specimen technique. The objectiv e of this present paper is to investigate the applicability of the loa d separation criterion for evaluating the ductile fracture mechanics p arameters of acrylonitrile/butadiene/styrene (ABS) terpolymers. This c riterion allows the load to be represented as the product of two separ ate functions, namely a material deformation function and a crack geom etry function. Load separation implies a method for J-integral evaluat ion by using only a single load-displacement measurement. The original method for evaluating J used an energy-rate interpretation, which req uired several load-displacement measurements to be made for identical specimens with varying crack lengths. J methodology based on load sepa ration introduces new parameters, i.e. eta, eta(el) and eta(pl), which greatly simplify the calculation of J and constitute the basis for th e J-R multiple specimen technique. Recently, a method for both the exp erimental determination of the eta-factors and the verification of loa d separation, which is based on separation constants, has been propose d for the testing of steel. This method allows the calibration of the eta-factors in new test specimen geometries. This present paper attemp ts to evaluate experimentally whether the principle of load separation is valid when testing ABS polymers in a bending configuration in orde r to obtain a valid single J-testing method, and to calculate the eta plastic factor experimentally by using this new simple method based on the load separation criterion in non-growing-crack measurements. In a ddition, a new approach based on the load separation principle which a llows not only the calculation of J from a single specimen, but also t he calculation of J-R curves from one test measurement has recently ap peared. This approach is called the 'normalization method' and has alr eady been applied to the J-testing of two rubber-toughened nylons and one ABS polymer. However, load separation has only demonstrated for di fferent specimen geometries in steels. In addition, the load separatio n in ABS terpolymers has been verified in this present paper for growi ng cracks, by using an experimental procedure available in the literat ure. Copyright (C) 1996 Elsevier Science Ltd.