b'Development of Multi-Axial Failure Criteria for Nuclear Grade SiC f -SiC mCompositesPrincipal Investigator: Xinyu Huang, University of South Carolina (UofSC) Team Members/Collaborators: Jingjing Bao, UofSC; George Jacobsen, General Atomics (GA)The project revealedM echanical strength ofcandidate for numerous core silicon carbide (Si)Cf-SiCmstructural components, such as composite tube is typicallyaccident tolerant fuel cladding and failure threshold ofevaluated under uniaxial tensionchannel box. Complex state of stress SiCf-SiCm compositeand internal pressure (burst)can develop in SiCf-SiCm composite cladding under complexloading. Under more complexfuel cladding. In addition to the loading conditions. loading scenarios, such as combinedself-equilibrated eigenstress due to bending and pressurization, thethermal gradient and irradiation principal stress direction can pointswelling, stresses can be induced by to directions off the hoop or thedifferential pressure loading and axial direction. Axial tensile andother concentrated external loading. internal burst strength do not provideIt is the objective of this programadequate information to determineto develop multiaxial failure mechanical failure threshold forcriteria for nuclear grade SiCf-SiCm the clad tube. In this project, UofSCcomposites which will allow more utilized five types of tests to helprigorous mechanical failure trace out a failure envelope for theanalysis of fuel rod under complex SiCf-SiCm composite tube. Theseloading conditions.tests include internal pressure test, combined internal pressure- Accomplishments: tension test, torsion test, combinedUofSC developed and validated tension-torsion test, and uniaxialcapabilities to conduct tension, tension test. The combined loadingtorsion, internal pressure, combined conditions can steer the 1st principaltension-torsion, and combined stress (highest tensile stress) ininternal pressure torsion tests. In between hoop and axial directioncombined loading tests, proportional thus allowing us to generate aload control was implemented with multi-axial failure envelope. the proportional-integral-derivative controller operating under a Project Description:master-slave mode. The applied Continuous SiC fiber-reinforcedloads (e.g., torsion and pressure, SiC matrix (SiCf-SiCm) compositeor tension and pressure) are kept with engineered weak fiber-matrixproportional during the test. The interphase has demonstrated greatlytest rig and its different loading improved mechanical toughnessmodes were validated by testing while preserving other beneficialaluminum samples and comparing characteristics of monolithic -SiC.the measured properties with well-These attributes can significantlyknown mechanical properties of improve the accident tolerancealuminum. Satisfactory results were of the light water reactor (LWR),obtained. During testing, the applied thus making it a highly promisingload (and or pressure) are monitored 70 2022|AFC ACCOMPLISHMENTS'