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Finite Element Analysis (FEA) is a tool used for the evaluation of structures and systems, providing an accurate prediction of a component’s response subjected to thermal and structural loads. Structural analyses include all types of steady or cyclic loads, mechanical or thermal. Thermal analyses include convection, conduction, and radiation heat transfer, as well as various thermal transients and thermal shocks.
FEA is used to analyze complex geometries, whereas very simple ones (for example, a beam) can be analyzed using hand calculations. For a structure subjected to a load condition (thermal, mechanical, vibratory, etc.) its response (deflection, stress, etc.) can be predicted and measured against acceptable defined limits. In the most simplest terms, this is a factor of safety, which is the ratio of the stress in a component, to the allowable stress of the material. If a factor of safety is too small, the possibility of failure becomes unacceptably large; on the other hand, if the factor is unneccesarily large, the result is a uneconomical or nonfunctional design. For the majority of structural and machine applications, factors of safety are specified by design specifications or codes written by committees of experienced engineers, such as the American Institute of Steel Construction (design & construction of structural steel for buildings) and the American Concrete Institute (building codes requirements for reinforced concrete).
Thus, the element equations cannot be solved alone to render the solution over each element. Instead, all the equations from all the elements over the entire structure need to be solved simultaneously. This task can only be performed by computers. It is noteworthy that, as the structure is broken into a larger number of elements, a greater number of simultaneous equations need to be solved. Thus, typically, results for more complex structures require more computing power. Typically finer meshes are used in the locations where the highest stress or heat flow may exist, allowing quicker solutions to what would otherwise take longer computation time.Finite element analysis is often used to verify design integrity and identify critical locations on components without having to build the part or assembly. The analysis is done by modeling the structure into thousands of small pieces (finite elements). Breaking the entire structure into such small peices or “elements” is called discretization. The solution to the governing equations is closely approximated within each element, resulting in a number of equations that need to be solved for every element. However, each element interacts with its neighbors, i.e., each element’s response tightly depends on that of its neighbors, and the responses of their neighbors to those of other neighbors, and so forth.
To see more on finite element analysis, see Nastran FEA Software Simulation Demo Video.
FEA was largely developed in the 1950’s by aerospace engineers to design better aircraft structures. Since then, aided by the rapid growth of computing power, the method has continually developed, and is now the tool of choice for technical analysis by mechanical, civil, biomechanical, and other engineers.
- It is a very accurate tool used for failure analysis purposes.
- Used to quantify design defects, fatigue, buckling, and code compliance.
- Can be used to distinguish between failures due to design deficiencies, materials defects, fabrication errors, and abusive use.
- It provides quantified results previously based on metallurgical and mechanical testing.
- It provides excellent visual aids and animations easily understood by juries.
Historical Note: Early FEA code development followed hardware progress. ANSYS was first released in 1970, running on $1,000,000 CDC, Univac, and IBM mainframe computers which were much less powerful than today’s PC’s. A Pentium PC could solve that 5,000 x 5,00 matrix system in a few minutes, instead of days as in the past.
We have successfully used finite element analysis to evaluate the structural integrity of equipment, as well as in supporting litigation in State, Federal, and International courts. For a description of our sample cases, see Portfolio. For a partial list of components we have worked on, see Components.