Accelerate Virtual Prototyping and Design Processes with Finite Element Analysis

At a Glance:

An overview of the fundamentals of Finite Element Analysis (FEA) and its importance in aerospace component design.
A look at how FEA software enables aerospace engineers to simulate the results of tests in a precise and efficient manner.

Since the invention of the airplane, aerospace industries around the world have evolved at a rapid pace. From toy planes to jumbo jets, the design process required to develop these technologies has become increasingly more complex. With this increase of complexity, however, has come a myriad of ways for engineers to precisely and efficiently improve their design processes.

One such method is Finite Element Analysis, or FEA, which has become an invaluable engineering tool. FEA software allows designers to simulate and virtually test designs under various real-life conditions before physical prototypes are manufactured. This allows for a significant reduction in both cost and development time.

This article provides an overview of the fundamentals of FEA, discusses its importance in aerospace component design and illustrates its application with real-world examples. It will also address common mistakes made when attempting FEA and highlight software tools widely used in aerospace applications.

What is Finite Element Analysis?

To understand what FEA is about, one must first develop an understanding of the Finite Element Method (FEM). Fundamentally, FEM is a numerical technique used to solve problems in engineering and mathematical physics, such as how structures behave under stress, heat or other physical phenomena. It does so by subdividing (known as discretizing) graphically generated models into small “elements” of geometrically simple shapes—such as triangles—that create a so-called “mesh.”

For each of these elements, polynomial equations are formed using the governing equations of physics—modelled as partial differential equations (PDEs)—that describe the behavior of an object in a particular environment. The contributions from each element create a system of equations, which can then be solved simultaneously using sparse matrix solvers to simulate an accurate description of how the original model reacts when subject to specific loads or stresses in real life.

FEA describes applications of the FEM and forms the basis for several software that professionals in engineering industries use to solve real-life problems.

Why is FEA Important in Aerospace Component Design?

As the world’s most popular form of international travel, airplanes must be tested rigorously to ensure structural integrity and the safety of those on board. Consequently, each component of an airplane —from the frame to the landing gear—must be put through a variety of tests. Instead of painstakingly creating a physical model and manually applying stress tests to it, FEA software allows engineers to simulate the results of these tests in a precise and efficient manner.

Additionally, specialized versions of FEA software can be modified to target specific areas of component optimization. For example, engineers can use FEA to minimize the mass of an airplane’s landing gear while maintaining its structural integrity, ultimately helping to reduce manufacturing costs and overall weight during flight. FEA can also be used in similar ways to optimize wing dimensions, cabin seating arrangements and other parts of an airplane.

How is FEA Used in Aerospace?

While FEA in aerospace contexts is widely documented and quite commonly used, its importance and vitality to the field is perhaps best acknowledged using a real-life example.

Suppose an aerospace engineering firm was tasked with designing and developing a small airplane for private use before the age of computers and FEA software. To try and account for all of the loads the aircraft might experience during takeoff, flight and landing, the firm would have had to recreate a large number of scenarios in real-life that their prototypes will be subject to. Each design would stressed until the point of failure, leading to more prototypes being created, higher costs and more time spent on testing. Ultimately, each scenario would represent a separate and costly test.

Obviously, it is impractical and very expensive to try and test every design against every possible load case or stress. There must be a way to be able to “weed out” bad designs and proceed with only strong ones that are likely to pass every test thrown at them.

This is where FEA software comes into play. Current software only needs certain parameters—such as the airplane’s dimensions, the material used in manufacturing, takeoff/landing and cruising speeds and other conditions it will face during flight—to give an accurate description of how a model might fail or deform.

Instead of potentially building and testing 10 prototypes and moving forward with just one, engineers might now test a fewer number of theoretical prototypes and build one that is very likely to pass tests that it was less certain to pass previously. This offers the advantage of saving money, time and energy that otherwise would have gone towards building and testing more prototypes.

Of course, like before, real-life stress tests still must be performed to ensure that airplane components can withstand forces experienced during operational use, such as bending wings at extreme angles or exerting heavy loads on landing gear during takeoff/landing procedures. The difference now is that instead of running these tests for every single idea, tests are run to confirm the results of simulations on only the most promising prototypes.

Common Mistakes When Using FEA

FEA is a complicated technique that can output incorrect results if used incorrectly. One notable mistake engineers can make is failing to create an optimal mesh of finite elements during the discretization process. Like Goldilocks and her porridge, creating a mesh that is “just right” is crucial to maintaining the efficiency of the FEM. Elements that are created too large can lead to inaccurate results, while elements that are too small increase computational time and problem complexity.

Another pitfall FEA engineers might encounter is not adding enough constraints to the problem. When replicating a real-life scenario into an FEA problem, constraining the system is what allows the FEM to solve systems of equations via sparse matrix solvers.

Specifically, this means introducing boundary conditions such as restricting the way a wing might bend, or how a joint in a landing gear might be able to rotate. These restrictions limit the number of degrees of freedom in the system, which helps FEA avoid infinite loops during matrix solving or producing incorrect results.

Commonly Used FEA Software

As a tool frequently used by engineers in a variety of disciplines, there are several popular forms of FEA software. For aerospace engineering in particular, these include ANSYS (known for thermal, structural and fluid simulations); Nastran (structural analysis); and Abaqus (solving nonlinear problems).

FEA is an extremely vital part of the modern aerospace industry, enabling engineers to prioritize safety while developing efficient and robust designs. By breaking down complex structures into manageable elements, FEA provides key insights into loads and stresses an aircraft might face during flight.

With proper use, FEA software allows aerospace engineers to push the boundaries of flight performance and reliability, all while saving time and resources in the development process.