Keenan Valentine Introduction & Stress Analysis

Introduction I  The ASCEND team at Arizona State University is designing, optimizing, and building an autonomous Unmanned Aerial Vehicle (UAV) to compete in a 2010 UAV aerial imaging contest.  The objectives of the contest are: (1) to fly an UAV via remote control non- stop for minutes in a square search area of 1 square miles, and (2) use onboard/remote human detectors to locate and identify targets marked by colored alphabets Courtesy of Ted Hench

Introduction II  Additional contest rules: (1) fly between 100 and 750 feet above ground, (2) fly over way points (GPS), (3) some targets are along route/some are not, and (4) better performance = higher score

Stress Analysis I  Geometry: (1) Clark Y airfoil, (2) a wingspan of 10+ feet, (3) a chord length of 12+ inches, (4) tubular fuselage, and (5) standard tail.  Critical Points: (1) entire wing, (2) wing attachment to fuselage, (3) tail attachment to fuselage, and (4) landing gear.  Method: (1) FEA, (2) analytical bounds, and (3) testing  Challenges: (1) non-isotropic material, (2) complex geometry, (3) unpredictable loads and (4) FEA error (accuracy and precision)

Stress Analysis II  Solutions: (1) use isotropic analysis with minimum material strength, (2) CAD modeling, (3) safety factor, and (4) grid refinement/convergence studies, and (5) analytical approximations to determine solution limits.  Results: (1) adding internal structural ribs to wing, and (2) smooth out notches to decrease stress concentrations and yielding.  Conclusion: structural analysis is critical to the success of the UAV ictures/rib.gif