Foreign Object Damage Analysis of Aircraft Structural Materials

Present day aircraft industry is focusing on weight reduction and fuel usage optimization which would ultimately lead to greener aero structures. The major challenge is the material selection by considering the design, operation and accidental scenarios. Composites have been considered along with advanced aluminum alloys for aero structures. One of the extreme operational scenarios is foreign object damage onto aircraft outer surfaces. The papers focus on the impact capability analysis of composites and aluminum alloys. Overall methodology of meeting the certification requirement is discussed using numerical tools. Finite Element of an aircraft windshield & surround structure for the bird-strike requirement according to the Federal Aviation Administration (FAA) Certification Specifications is discussed. Various methods of bird modeling and impact analysis is presented. Analysis is made based on the obtained numerical results. The Analysis Software used for the impact analysis were LS-Dyna and Ansys along with Hyper-mesh was used for pre-processing (Mesh). The geometry is developed using Catia. The objective of the paper is to bring out the simulated impact strength of the aircraft panels get an insight into the impact strength while meeting other criteria. Analysis high lights the need for considering extreme operation scenario like bird strike (Impact) while aiming for better material options for aircraft structures. New Materials for aircraft structures have been developed to meet the growing demands of the weight reduction and better fuel usage optimization. While the research has been focusing on the strength and density aspect of material options like aluminum and composites extreme operational scenario like Foreign Objects Damage will induce high impact loads onto to structures. The criteria are addressed in FAA regulations. As the problems impact highly non linear in nature certification based on numerical results has been a challenge. Future materials development model should be directed to address the impact loads that areexpected during operation [1]. Focus of static strength and density criteria should also include the dynamic failure mechanisms like bird strike. In current work existing models of bird in numerical tools like LSDYNA is used. Meeting the Certification requirement can be better understood by using numerical tools. This is help us in final applicability og material while choosing design direction. Due to increased air traffic in recent decade’s bird strike is seen as major threat to air safety. In addition higher flight speed (high Mach) is leading to higher kinetic energy and huge impulsive force generation during the impact conditions. The probability of bird hit on outer surfaces of the aircraft is high based on earlier experience. The date available in the open literature shows the projected parts of fight need attention. The loss of life due to bird strike has been recorded to be significantly high number. Among the all components of aircraft front facing components of an aircraft which include the nacelles, windshield, wind leading edge, compressor blade, et care often most susceptible to such strikes. It is therefore critical to ensure that the different structural parts are able to withstand such high velocity impact for safe landing of the aircraft after the strike This essentially requires maintaining integrity while undergoing plastic deformation. Table1. Aircraft components and FAR Sections