The Mesoscopic Crack Resistance And Analysis Of Steei

Steel is typical of engineering material, with good processing properties andthermal performance and the best weldability.The corrosion damage fracture is one ofthe major modes of the material and structure failures.In this article, we analyzethree-point bending beam with prefabricated crack and the fracture strength ofunidirectional tensile through micro observation and fracture criterion, the fracturefailure behavior are studied of two kinds of typical materials that cast iron and Q235steel, and then discuss the theory that the bearing capacity of structure containingdefects estimation methods and verify the theoretical results, then contrast themechanical properties of materials before and after the sea water corrosion.The mainresearch contents are as follows:1. The analytical calculation was carried out on the mesoscopic cracks, then receivethe displacement or deformation distribution near the crack, and then compare theexperimental value and the theory value of the cast iron materials.2. Using universal testing machine tests on different incision depth with the seawaterand low carbon steel specimen without seawater by three point bending experiments,discusses the law of unloading and the size effect of fracture toughness, and putsforward calculation methods of the largest bearing capacity of the structure combinedwith double K criterion theory.3. According to the electronic tracking test of strain gauge on a series of specimens,experimental data analyze the displacement of crack front opening damage zone,theneutral layer position in front of the ligament of the mild steel three point bendingbeam with precast cracks, and the endpoint location of the damage zone along withthe change of load regulation.4.Simple tension experiments are conducted on low carbon steel with differentcutting opening size by Scanning Electron Microscopy (SEM), the experiment gives the changes of its macroscopic mechanical properties under different circumstances andmaterials’ microstructure characteristics.All kinds of mechanical parameters arecalculated by the experimental data, such as the stress intensity factor and toughnessnear the specimen cutting, the crack propagation length and the stress intensity factorand other parameters changing with the load.5.Using the ABAQUS finite element analysis software to simulate the uniaxial tensilespecimen, and acquirethestress and strain distribution of the prefabricated crack tip.