ANALYTICAL DETERMINATION OF THE CRITICAL IMPACT LOCATION FOR WING LEADING EDGE UNDER BIRDSTRIKE

Abstract

THE WING LEADING EDGE IS ONE OF THE AIRCRAFT STRUCTURES WHICH ARE VULNERABLE TO BIRDSTRIKE. THEREFORE, FEDERAL AVIATION REGULATION HAS CLEAR REQUIREMENTS OF ANTI-BIRDSTRIKE PERFORMANCE FOR WING LEADING EDGE. HOWEVER, THE IMPACT LOCATION IS NOT SPECIFIED IN AVIATION REGULATION. THE FOREFRONT OF THE WING LEADING EDGE IS SELECTED AS A CRITICAL LOCATION FOR THE BIRDSTRIKE IN MOST RESEARCHES. BUT THE RATIONALITY OF THE SELECTION IS NOT GIVEN. THIS PAPER PROPOSES AN ANALYTICAL METHOD FOR DETERMINING THE CRITICAL LOCATION THAT CAUSES THE MOST SEVERE DAMAGE UNDER IMPACT DUE TO BIRDSTRIKE. THE ANALYSIS IS BASED ON THE CONCEPT OF EFFECTIVE IMPACT, I.E. THE COMPONENT OF THE BIRD VELOCITY PERPENDICULAR TO THE SURFACE OF WING LEADING EDGE. A BIRDSTRIKE MODEL IS ESTABLISHED USING PAM-CRASH AND USED TO VALIDATE THE ANALYTICAL PREDICTION. THE NUMERICAL MODEL PROVES ITS EFFECTIVENESS COMPARED TO THE BIRDSTRIKE TEST. THE RESIDUAL COMPRESSIVE STRENGTH OF THE SPAR WHEN THE BIRDSTRIKE IS AT THE CRITICAL IMPACT LOCATION DETERMINED BY THE PROPOSED METHOD IS 44.5% OF THAT AT THE TRADITIONAL IMPACT LOCATION. MOREOVER, THE CRITICAL PENETRATING VELOCITY OF THE TRADITIONAL IMPACT LOCATION IS NOT THE LOWEST. IN OTHER WORDS, THE TRADITIONAL IMPACT LOCATION IS NOT THE WEAKEST. AIRWORTHINESS VERIFICATION EXPERIMENT OF BIRDSTRIKE ON WING STRUCTURE SHOULD PAY ATTENTION TO THIS ASPECT.