Real life systems are often far too complex to analyse using simple, rule based formulas.
Historically, engineers have dealt with this problem by validating designs with laboratory testing, applying extremely conservative factors of safety, or simple trial and error. As computational power has increased in recent years, engineering simulations which mimic real life behaviour have become a far more relevant (and cost saving) alternative to these techniques. Finite Element Analysis is a type of engineering simulation with uses a numerical technique called the Finite Element Method (FEM). FEA can be used to simulate the real-life behavior of complex machines or structures.
Finite Element Method
The finite element method subdivides a large complex system into a ‘mesh’ comprised of (often millions) simpler parts called ‘finite elements’. The user will determine their boundary conditions, for example a set of elements assumed to be in contact with the ground will be prevented from moving in that direction. Finally loading conditions are approximated based on the assumed usage conditions and then the behavior of the finite elements is then calculated.
By calculating the behavior of each of the elements and adding them together its possible to get an approximation of the overall behavior of the entire part. Computing the behavior of each finite element involves lengthy calculations, and with modern finite element analysis packages easily generating over 1,000,000 elements modern FEA problems are impossible to solve by hand, and even extremely powerful computers can take hours to solve these complex calculations.
Perhaps the most important thing to mention when talking about FEA is that (like all numerical models) it will only ever produce an approximate solution. Some people will insist that if FEA produces a solution then it will reflect reality completely, in reality many approximations are made by both the user and the computer and there are many things that affect how close the simulation is to reality. Some things that may dictate the accuracy of the solution include:
- The size of the individual finite elements
- The software package chosen
- The geometry of the part
- Material properties of the part
- Loading conditions
- Boundary conditions
- Type of element used
- Other factors
Knowing how to manipulate these factors to produce an accurate and reliable result can take users of FEA years of study and experience. Although FEA is often ‘good enough’ and margins of safety are included, FEA should always be supported by other forms of evidence such as test data, or hand calculations where it is possible to do so.
Rapallo is here to help
Rapallo has a team of Engineers experienced in the Finite Element Method, and the use of FEA packages. Contact us now to find out what we can do to assist your team with any of its FEA needs.