Study On Damage Evolution Mechanism And Ballistic Performance Of SiC_3D/Al Composite

SiC ceramic skeleton reinforced Al metal composites (SiC3D/Al composites) arecharacterized by both of ceramic skeleton and metallic matrix’s connectivity in spatialdirection, which makes full use of the ceramic’s high specific strength stiffness and themetal’s high toughness, resulting in the more excellent as well as a marked difference in themechanism of dynamic damage evolution under the condition of armor-piercing impactcompared with ceramic materials. In the thesis, the test that a7.62mm armor-piercing bulletpenetrated the target made of SiC3D/Al composites with a high speed, together with theSplit Hopkinson Press Bar dynamic compression experiment, combining with thenumerical simulation technique, the process of dynamic damage evolution under the impactload was researched in depth from both the micro and macro scales. Subsequently, theeffect of macro-micro dynamic damage mechanism and microstructure on the process ofdynamic damage evolution was systematically investigated, as well as the forecastingmethod of anti-impact properties of SiC3D/Al composites containing damage under thecondition of the second bullet’s high-speed impact was explored.The main research achievements are as follows:(1)The macroscopic damage mechanisms for SiC3D/Al composites under the impact ofhigh-speed projectile were proposed, namely: two relatively upper and lower cone fracturesat the point of impact of SiC3D/Al composites target were formed, and between them therewas damage concentrated area, of which the damage evolution controlled the dwellingprocess of the interactions between projectiles and targets; the structure was almostunbroken in the region surrounding the cone fractures while where existed net broken zonewhich had an direct influence on the anti-impact properties under the condition of thesecond bullet’s high-speed impact. The establishment of the macroscopic damagemechanism gave a clear orientation to improve energy consumption in the process ofdwelling and the anti-impact properties of SiC3D/Al composites target.(2)The microscopic damage mechanisms for SiC3D/Al composites under the impact ofhigh-speed projectile were established, that was: the initial damage appeared near SiC/Al micro interface where generated shear stress concentration caused by the shock load; onthe direction of maximum shear stress, damage mainly propagated along the ceramic/metalinterface, or extended through the ceramic phase, forming a belt-fracture zone withcoordination deformation ability and a certain width; under complex stress field inside thetarget plate, the belt-fracture zone could absorb vast impact energy by forming net form,avoiding the generating of brittle fracture behavior under high speed in the traditionalceramic. The establishment of the microscopic damage mechanism revealed internal reasonthat the SiC3D/Al composites target had the ability of high damage energy dissipation andhigh structure integrity.(3)The influence rule of ceramic phase content, the metallic phase and SiC/Alinterface characteristics on the dynamic mechanical properties and damage evolutioncharacteristics of SiC3D/Al composites was obtained. From the view of improving thecomposite target structural integrity and increasing energy dissipation by high damage,the ideal microstructure characteristics that high ductility metallic phase, the moderatebinding force for ceramic/metal interface and80%of ceramic volume content were putforward as a useful reference for the design of new high damage composite materials.(4)The statistical method of target damage degree based on the microstructure ofcomposites target was established, and the radial distribution function of target damagedegree under the penetration of the first projection was obtained, and then, the forecastingmethod of anti-impact properties of composites target containing damage under thecondition of the second bullet’s high-speed impact was proposed based on the damagedegree and the residual dynamic hardness. The above methods were employed to predictthe anti-impact properties of the different positions of―SiC3D/Al+steel‖composite armorunder the condition of the second bullet’s high-speed impact after the penetration of thefirst projection, and the predicted results were agreeable to the corresponding experimentalones, providing an important means of podcasting the anti-multi impact properties ofcomposite armor.