How do you handle complex geometries and materials in FEM for aircraft design?

Finite element method (FEM) is a powerful tool for solving structural dynamics problems in aircraft design. It can handle complex geometries and materials that are difficult to model with other methods. But how do you use FEM effectively and accurately? In this article, we will cover some basic concepts and tips for FEM for structural dynamics in the context of aircraft design.

1 What is FEM?

FEM is a numerical technique that divides a complex structure into smaller and simpler elements. Each element has a set of equations that describe its behavior and interactions with other elements. By solving these equations, you can obtain the displacements, stresses, strains, and modes of the structure. FEM can handle nonlinearities, large deformations, and material properties that vary with temperature, pressure, or frequency.

Add your perspective

2 Why use FEM for structural dynamics?

Structural dynamics is the study of how structures respond to dynamic loads, such as vibrations, shocks, and impacts. These loads can affect the performance, safety, and durability of aircraft. FEM can help you analyze the dynamic response of aircraft structures in various scenarios, such as landing, takeoff, maneuvering, gusts, and crashes. FEM can also help you design and optimize aircraft structures to reduce weight, improve stiffness, and enhance damping.

Add your perspective

George Edmond

Principal Technical Project Manager
Report contribution
Dynamic analysis is not new, and should be assessed with a but of caution. The bounds between linear and nonlinear analysis are not clear cut. In these scenarios an iterative approach is a more robust method. Rather than try to capture the complete assessment in one analysis.

Like

3 How to choose elements for FEM?

When deciding on elements for your structure in FEM, you should take into account the geometry, material, and loading of your structure. Generally, higher-order elements are better for curved or irregular geometries as they can better capture the shape. Smaller elements should be used for regions with high stress gradients for more accurate results. Compatible elements should be used for interfaces between different materials or regions to ensure continuity and avoid spurious modes.

Add your perspective

Cmdr (Dr.⁹) Reji Kurien Thomas , FRSA, MLE℠

I Empower Sectors as a Global Tech & Business Transformation Leader| Stephen Hawking Award 2024| Harvard Leader | UK House of Lord's Awardee | Fellow Royal Society | CyberSec | CCISO CISM CCNP-S CEH
Report contribution
Utilising advanced meshing techniques to accurately represent intricate geometries Selecting appropriate element types (e.g., tetrahedral for complex shapes, hexahedral for regular geometries) Incorporating material properties that capture the anisotropic or non-linear behaviour of advanced composites Conducting sensitivity analyses to determine the influence of mesh density on the results Choosing elements for FEM requires – Understanding the stress characteristics of the component Considering the computational efficiency; higher-order elements for regions needing precision, lower-order for less critical areas Matching the element type to the material's behaviour and the geometry's complexity

Like

4 How to validate FEM results?

Validating your results is an important aspect of FEM. Validation involves comparing your FEM results with experimental data or analytical solutions to evaluate the accuracy and reliability of your model. This process can help you identify and address errors, uncertainties, and assumptions in your FEM model. Common validation methods include performing a convergence study to ensure independence of the mesh size and refinement, conducting a sensitivity analysis to measure how results vary with different parameters and inputs, and performing a modal analysis to compare the natural frequencies and mode shapes of your structure with the FEM model.

Add your perspective

George Edmond

Principal Technical Project Manager
Report contribution
There can be a number of different methods to validate or “Check Stress” the results from the FEM model: · Re-analyses the load scenario using a different FEM tool and different personnel, and back check and validate the original FEM results. · Re-analyses the load scenario by another method, such as with hand calculation say using Roarks and MathCad as your reference and analysis tools, and back check and validate the original FEM results. · Undertake Physical testing of the load scenario, with strain gauges, and back check and validate the original FEM results. Either way, you need to do at least two independent methods to remove analysis risk, with the Physical test checking and underwriting your assessment.

Like

5 How to improve FEM efficiency?

FEM can be computationally expensive and time-consuming, especially for large and complex structures. To improve the efficiency and speed of your FEM analysis, you can use symmetry or periodicity to reduce the size and complexity of your model. Alternatively, you can use substructuring or superposition to divide your model into smaller and simpler parts, then combine them later. Additionally, parallel computing or cloud computing can be utilized to distribute your FEM calculations among multiple processors or machines.

Add your perspective

How do you handle complex geometries and materials in FEM for aircraft design?

1

2

3

4

5

1 What is FEM?

2 Why use FEM for structural dynamics?

3 How to choose elements for FEM?

4 How to validate FEM results?

5 How to improve FEM efficiency?

Aircraft Design

Rate this article

Thanks for your feedback

More articles on Aircraft Design

More relevant reading