Lightning Strike Ignition Hazard Modeling for Composite Fasteners
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Solution Overview
Problem
Lightning strikes on composite structures in aircraft can lead to ignition hazards due to high current concentrations at conductive fasteners, which are not effectively addressed by existing testing methods, leading to costly and time-consuming testing matrices.
Innovation Solution
A physics-based modeling system and method to predict ignition hazards by simulating pressure rise and volatilization at the interface between conductive and decomposable members, using current waveforms, material parameters, and interface geometry to determine the probability of ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extensive physical testing matrices are conducted to assess ignition hazards, then reliability of safety assessment is improved, but loss of time and manufacturing cost increase significantly
Solution Approach 1:
The patent creates a computational model that replicates the physical testing process through simulation. The model uses material properties, geometry, and lightning strike parameters to predict ignition hazards without requiring physical prototypes. This virtual copy allows multiple test scenarios to be evaluated rapidly on computers, eliminating the time-consuming nature of physical testing while maintaining assessment reliability.
Solution Approach 2:
The patent replaces the mechanical/physical testing system with a computational modeling system. Instead of conducting physical lightning strike tests on composite structures, the invention uses numerical simulations that solve heat transfer equations and material decomposition models to predict ignition risks. This substitution eliminates the need for specialized test equipment, physical prototypes, and extensive testing facilities.
2Reliability
If extensive physical testing matrices are conducted to assess ignition hazards, then reliability of safety assessment is improved, but manufacturing cost increases
Solution Approach 1:
The computational model serves as a virtual replica of the physical testing process, allowing safety assessments to be performed through simulation rather than physical experimentation. This eliminates costs associated with manufacturing test specimens, setting up test facilities, consuming test materials, and operating expensive testing equipment, while still providing reliable safety predictions.
Solution Approach 2:
The patent substitutes the expensive physical testing infrastructure with a computational system that runs on standard computing hardware. The model uses readily available material property data and standard numerical methods to predict ignition hazards, eliminating the need for specialized test equipment, controlled environments, and expert personnel required for physical lightning strike testing.
3Measurement precision
If physical testing is used to assess fastening systems, then measurement precision of ignition hazard is improved, but productivity of design cycle decreases
Solution Approach 1:
The computational model allows design teams to perform safety assessments during the early design phase, before physical prototypes are manufactured. By inputting material properties and geometry parameters, the model predicts ignition hazards and identifies potential issues early in the design process, allowing corrections to be made before committing to physical manufacturing. This preliminary assessment capability accelerates the overall design cycle while maintaining precision through iterative refinement of the model.
Solution Approach 2:
The patent enables dynamic evaluation of multiple design scenarios by rapidly adjusting input parameters such as material properties, fastener configurations, and lightning strike conditions. The computational model can evaluate numerous design variations in seconds, allowing design teams to optimize fastening systems for minimum ignition risk while exploring multiple configuration options, thereby increasing design productivity without sacrificing assessment precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Reduces the need for extensive testing by accurately predicting ignition hazards, allowing for early assessment of fastening systems and reducing costs and lead times in the design cycle.
Implementation Method 1
high levels of current from a lightning strike may be undesirably concentrated where two panels are joined together by a metal fastener
Implementation Method 2
determining a quantity of volatiles generated within the interface volume following the lightning strike event
Implementation Method 3
determining a total pressure generation within an interface volume based on the resolved heating and the determined quantity of volatiles
Data Source
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AI summary
A method is presented for determining a likelihood of an ignition hazard. The method comprises receiving a current waveform for a lightning strike event at a conductive member that forms an interface with a decomposable member. Material parameter inputs for the conductive member and the decomposable member are received. Based at least on one or more of the received material parameter inputs and an energy from the current waveform, a heating of the decomposable member is resolved, and a quantity of volatiles within the interface volume are determined. A total pressure generation within the interface volume is determined. A probability of ignition hazard by the lightning strike event is output based on a comparison of the total pressure generation and a containment pressure threshold for the interface volume.