Moment Engineering specializes in airframe development, also referred to as aircraft primary structures or aerostructures, with expertise in structural analysis, dynamics, and aeroelasticity.
Technical Capabilities
Our capabilities are described below. More information can be seen by clicking the arrow by the category.
Finite Element Model Development
- FEM development for loads, flutter, and stress analysis
- Coarse loads and flutter FEMs (beam or shell based)
- Intermediate or full detailed stress FEMs
- Nastran format bulk data files
- Mass modeling
- Distributed or lumped mass models
- Mass and inertia properties for loads, aeroelastic, or 6dof analyses
- Nastran static, buckling, modal, dynamics response, random vibration, flutter, aeroelastic response solutions
- Femap API development
- Finite element model debugging
- Model correlation against GVT results
Static and Dynamic Aeroelasticity (Flutter)
- Aeroelastic flutter predictions for main surfaces (e.g. wings, vertical tail) or control surfaces,
- Classic Vfg (Speed-frequency and Speed-damping) diagrams to identify aeroelastic mode behavior and critical crossing speeds
- Mode divergence assessment (dynamic approach)
- Nastran PK method or Zona Zaero G method analysis
- Designing against panel flutter with classic design guidelines or analysis
- Design modifications to prevent or mitigate flutter in the envelope
- Static aeroelasticity
- Evaluation of flex to rigid ratios/ control surface reversal
- Based on level of acceptability, isolate critical contributors to knockdowns, possibly leading to stiffness requirements
- Aerodynamic panel model development
- Panel modeling and splining to structural model, including Zaero body modeling
- Doublet Lattice Method/ Zona6 for subsonic (M<1)
- Zona7 for supersonic applications (M>1)
- Static aeroelasticity – flex-to-rigid ratio studies to evaluate acceptability and isolate critical contributors to knockdowns, possibly leading to stiffness requirements
- Sensitivity analysis to parameter variations or failures for certification requirements or general risk assessment
- Aeroservoelastic predictions for gain and phase margins in the presence of control laws
- Tool development for any of the above
- Certification level analysis towards Part 23/25 or ASTM F3093: Standard Specification for Aeroelasticity Requirements
Airframe Ground Test Development
- Coupon, Element, Full Scale structural test predictions and correlations
- Control surfaces
- Moment of inertia testing
- Free play testing against MIL spec requirements
- Stiffness testing (load loop)
- Tap testing
- Ground Vibration Testing for modal parameters
- Structural Mode Interaction Testing (aka Structural Coupling Testing) for airframe and control system interactions
Flight Flutter Testing
- Instrumentation layout and sensor selection (accelerometers)
- Digital signal processing for frequency response (PSDs, FRFs, etc) during excitation (i.e. frequency sweeps)
- Real time monitoring of safety of test sensors during sweeps
- Determination of modal parameters (mode frequency, damping) in-flight
- Post test analysis, including trending of modal parameters for continued safe envelope expansion
- Experience with rotation vane flutter exciters
Structural Development
- Development of program-specific testing requirements tailored to risk, cost, timeliness, certification goals, including coupon, element, component, assembly, to full scale tests
- Stress analysis of parts and assemblies for composites or metallics
- Analysis of bonded or bolted joints
- Weight reduction initiatives – identification of weight-saving opportunities
External Loads Development
- Experience with applying ASTM F3116: Standard Specification for Design Loads and Conditions, a modern means of compliance for 14 CFR FAR Part 23 Airworthiness Standards: Normal Category Airplanes
- Panel model generation and splining to structural model
- Load case downselection
- Loads database audit
- Internal loads process development
- Application of external loads to more detailed stress models and coordination with stress teams
- Generation of local cases such as internal pressure, fuel pressures, thermal loads, component loads (e.g. control surface loads)
Technical Assurance and Optimization
Independent review for all of the above topics can also be provided to ensure your technical decisions are robust, compliant, and optimized.
Independent Analysis Auditing
- Analysis review – Unbiased in-depth critique of existing analysis processes against industry standards and best practices, tailored to program goals
- Design review – commentary on designs from load path to aeroelastic implications
- Data Interpretation – making sense of complex data sets to extract actionable insights
- Documentation review – ensuring that technical approaches meet all relevant standards and/or certification regulatory requirements, including gap analysis
Risk Assessment and Mitigation
- Reviewing potential risks in design and analysis and proposing mitigation strategies
- Test plan review
- Sensitivity assessment to assumptions such as material or mass properties and their affect on outputs
- Evaluation of paths to risk reduction from testing or analysis procedures
- Communication of risks and risk reduction pathways to management
- Sourcing of experts for various niche topics
Technology Roadmapping
- Process optimization based on available resources, timelines, and goals
- Industry software downselection for airframe analysis tools, based on needs and cost.
- Comparisons of tools, including Femap, Nastran, Advanced Nastran, vs Patran/Apex. Simcenter Nastran vs MSC Nastran, Abaqus vs Nastran, Python vs Matlab, Nastran vs Zaero, Nastran vs open source conversations.
Engineering Knowledge Transfer
- Direct 1:1 or 1:many training for personal development
- Third party training recommendations (classes, workshops, conferences, etc)
- Recommendations for industry standard texts and papers for process benchmarking