FINITE ELEMENT ANALYSIS: THE MAIN ADVANTAGES

INTRODUCTION

The Finite Element Analysis (FEA)  is a computer simulation tecnique used in the engineering analyzes in the structural, thermal, fluid dynamics and electomagnetic field.

It is based on the Finite Element Method (FEM), which allowas to solve systems of partial differential equation (PDE). It consists in dividing a system into small and simple entities, called finite element. The space is then discretized through the construction of a mesh: a grid divides the model into nodes and elements. The method then moves on to the definition of an equations system, which describe the entire problem. These are solved in an approximated way, making sure to minimize the error.

A FEM simulation therefore allows you to simulate an experimental test in a virtual environment. It is then possible to evaluate the structural performance of your product in terms of stability, strength, elasticity and stiffness. The finite element technique allows you to respond quickly, using an analytical method and with extreme precision, to the main structural design needs such as:

• define the type and quantity of material needed
• identify critical or weak points of the structures
• check stress and deformation states
• derive displacements, deformations and tensions
• evaluate the mass distributions
• define the failure points

The main advantages deriving from this reside in the possibility of reducing:

• the number of physical prototypes, thus reducing the costs associated with the development of a product;
• the time to market, because in a virtual environment, changes to the geometry take just a few minutes.

Following this logic, it is understandable why in the last decade the number of tools that allow simulations to be carried out has increased significantly. Furthermore, these software have evolved allowing to manage boundary conditions (loads and constraints) more and more complete and types of analysis more and more complex.

The three fundamental phases of the FEM simulation

Regardless of the software used, a FEM analysis is a process divided into three main phases:

• pre-processing, i.e. the definition of the finite element model, composed of geometry (mesh) and boundary conditions (loads and constraints);
• processing, or the actual analysis, with the solution of the finite element problem by a solution software (solver);
• post-processing, where the solution to the problem is elaborated and represented, typically with tables of values ​​or graphs and images.

The pre-processing phase is particularly critical as regards the reliability of the results.

The discretization of the system through the mesh is important, composed of finite elements such as triangles and quadrilaterals for 2D domains, tetrahedra and hexahedron for 3D domains. The geometry is then divided into basic elements which constitute the support point for the mathematical solution of the problem.

In the image on the left the 3D model of the component, in the image on the right the discretized component through the subdivision into elements and the definition of the mesh.

It is therefore clear that the quality of the mesh can sometimes significantly influence the results obtained. This is because each element is characterized by a certain number of nodes with a certain degree of freedom (DOF) which, depending on the constraints, the applied loads and the characteristics of the material, will undergo displacements and consequently will define the deformation of the model being simulated.

Conclusions

As we have seen, the fact of being able to simulate virtual prototypes directly on your PC brings inevitable advantages.

Obviously, for an analysis to be reliable, it is necessary that the boundary conditions are well defined and that the software adopted is able to simulate the phenomenon correctly. In addition to this, it should also be considered that tools become powerful only if placed in the correct hands: do not underestimate important aspects such as knowledge of the subject and training on the instrument.