Study On Impact Fracture Of UPVC

UPVC material is widely used in the structural engineering to replace metal, as a kind of high strength, corrosion resistance of macromolecular material. But comparing with metal, the research of the mechanical properties of UPVC material is less, especially its study of impact fracture. Therefore, in order to study fracture performance of UPVC material, get its development regularity of the crack, and provide support for establishing fracture criterion under impact load, the research of this paper is carried on.In this paper, using high-speed image acquisition system, using digital image correlation technique, the crack extension rule of the UPVC material are studied under different impact heights. And with the scanning electron microscope (SEM), the fracture morphology is analyzed, from the micro level of UPVC material, high-speed expansion of crack is studied under impact load.The results of this study are the following aspects:1.Respectively at the height of the role of 250mm,500mm,750mm shock, have been pure â… -crack specimens, with compound (deviation from the center of the specimen 20mm) crack specimens and have complex (deviation from the center of the specimen 40mm) relationship with the extended amount of crack propagation velocity of the specimen between the cracks.1) In the same impact height, cracks began to expand complex than pure â…  Crack earlier in composite crack under impact loading easier to crack;2) At the impact of different heights, pure and complex type â…  crack crack crack at different times, different crack velocity. The higher impact height, the shorter the time the crack tip crack.2. The impact load, use Vic2D got the crack tip displacement field before crack initiation. I have a pure specimen UPVC Crack in impact load, which the crack tip when no cracking displacement field is symmetrical. The complex has two (one for the eccentric 20mm, that eccentric 40mm) displacement field showed a strip of UPVC crack specimen near the loading point to the impact of migration.3. Through the microstructure analysis on fracture surface of UPVC material, the results are the following aspects:1) Fatigue sectional area and high-speed spline expansion area has a relatively clear dividing line, and the cross-sectional area of rapid expansion fatigue sectional area than smooth.2) The impact load, UPVC material fracture under impact loading in the form of a typical brittle fracture. The impact of rapid expansion of pure type I fracture specimens for high-speed ratio deviation Extension composite impact fracture specimens of 40mm to rough.