Advanced engineering (FEA)
- Modal analysis
After carefully modelling the model’s stiffness and fixing scheme, a modal analysis can be performed where the natural vibration modes can be determined along with their frequency [eigenvalues], deformed shape [eigenvectors] and mode participation factor.
These results allow our clients to target or avoid certain resonant frequencies in their designs and give them insights on how the design will respond to dynamic loads.
- Harmonic analysis
SDEA_Engineering Solutions has ample experience performing both full harmonic analyses (where a frequency sweep in a specified range is performed) and frequency response analyses (where the natural vibration modes can be targeted and checked with a modal superposition calculation).
In these analyses, a sinusoidal excitation is introduced and the variable response at each frequency is obtained, obtaining peak stresses and displacements.
These harmonic loads can be input either in or out of phase and with a specified damping characterisation.
- Response spectrum and random vibration analyses
For some applications, the vibration load is not pure sinusoidal but rather a sum of a series of sinusoidal components. In these cases, a statistical model is used to deal with random vibrations, where the vibration is characterised through a mean, standard deviation and probability distribution and a large number of cycles is taken into account.
To measure the power intensity of a vibration, the power spectral density (PSD, measured in g2/Hz) is used. The RMS (Root Mean Square) value of the acceleration is the qualitative measure for vibration intensity.
Seismic loading, as an example of random vibration, is an important concern for many structures such as public buildings in earthquake prone areas or buildings with high security requirements such as nuclear power plants. SDEA_Engineering Solutions has experience in assessing structures in high risk environmental areas, as well as in the design of tuned liquid dampers (TLD) which help to alleviate the response in slender stack structures.