ESTIMATION OF THE RESISTANCE AGAINST STABLE CRACK INITIATION AND UNSTABLE CRACK PROPAGATION USING R-CURVES AND STABILITY ASSESSMENT DIAGRAMS IN DUCTILE POLYMERIC ABS-MATERIALS

摘要

The toughness behaviour of various ABS-materials under impact-like loading was characterized using different experimental and approximative methods of fracture mechanics to determine critical J-values, crack resistance curves and J-T{sub}J stability assessment diagrams. By use of J-T{sub}J stability assessment diagrams, critical values as resistance against unstable crack initiation can be calculated, also if unstable crack propagation can not be directly observed because of limited specimen boundaries and defined loading conditions respectively. Because stable crack propagation is followed by an unstable one, two 'brittle-totough' transitions (BTT) are observed for impact-resistant plastics like ABS. Whereas the 'tough-to-high impact' transition is caused by the matrix, the conventional 'brittle-to-tough' transition is sensitive to the structure and the deformation mechanisms.