The study of crack resistance of the PP composites with alc on the basis of the stress intensity factor
Dariusz Kwiatkowski, Jacek Nabiałek
Quarterly No. 4, 2009 pages 369-372
DOI:
keywords: composites, crack mechanics, stress intensity factor
abstract In the composites reinforced polymer fillers, there are problems of stress concentration at the border filler-warp. These stresses have a great impact on the crack resistance. The reduction in the strength of the material in relation to its theoretical strength is associated with the presence of various defects. The results of examinations of the influence of a talc content in PP composites on the stress intensity factor have been presented in this article. The RESLEN PPH polypropylene and compo- sites warp material with talc was used in this work. Composite with a maximum content of 25% of talc powder was produced at the two screw extruder in POLIMARKY Rzeszów company. The test specimens from PP composites with 5, 10, 15 and 25% talc content were injected using Krauss-Maffei KM65-160 C1 injection molding machine. Injection molding machine is equipped with high-level control system called C4. To determine the stress intensity factor, the sample three point bending, as indicated by SENB (Single Edge Notch Bend). Crack resistance examination were carried out using a special device allowing measurements of basic parameters of crack mechanics, such as: stress intensity factor, gap divergence and J integral. As far as crack resistance was adopted by a critical value of stress intensity factor. Designation of critical stress intensity factor is related to the designation of critical load PQ. Graphically this relies on the location on obtained graph of the load in the function of the displacement of the secant, oblique for 5% with relation to of the earlier appointed tangent to the graph. Secant leave by 5% is equivalent to the search for the point at which the gap has increased its length by 0.2% compared to its initial length. Please also remember to check the limit of non-linearity and the ratio of the graph of force against the PQ maximum power Pmax, so that the latter does not exceed the critical by more than 10%. The place of intersection of the secant PQ per-formance graph sets. The impact of graphic content in the form of talc filler on the stress intensity factor KQ in PP composites was presented.