A PRIORI ASSESSMENT FOR FLIGHT QUALIFIED STRUCTURAL INTEGRITY

摘要

GENOA-Progressive Failure Analysis (GENOA-PFA), a virtual design/analysis software, facilitates aerospace design meeting static load, fatigue spectrum, durability and damage tolerance (D&DT), and reliability requirements of FAR 25 and associated advisories. The GENOA-PFA software successfully predicted damage tolerance limits and failure criteria of the Mini Space Technology Plane (MIST) by using a building-block strategy to numerically:1) calibrate material strength and stiffness properties with data from tape and fabric composite coupon tests, and 2) predict the D&DT (involving damage initiation, accumulation, and residual strength) of the full scale test article under combined longitudinal, torsional and shear loads. GENOA-PFA used finite element models (FEMs) to analyze subcomponents made of composite materials, taking into account ply drop-off, voids, and fiber volume ratios. Details of composite thickness, lay-up configuration, voids and flaws were provided by Boeing Tulsa Division from results of ultrasonic jet flow machine inspection of fuselage crown, side, and bottom areas. Verification was achieved by successfully predicting test results of 1) residual strength (within 2.0 percent), 2) multiple crack initiation and growth locations, and 3) strain measurements. It was shown that global fracture initiation and fracture propagation occur at maximum and minimum of me Total Energy Release Rate (TDERR) values, respectively.