Resumo:
Welding processes may cause undesirable residual stresses and their detection is possible using
different methods. Some residual stress detection methods or techniques are destructive or semidestructive,
therefore not always applicable. Some methods are non-destructive, such as X-ray
diffraction, neutron diffraction, and ultrasound. However, they are complex and high cost. One
possible non-destructive method to detect welding residual stresses, lower cost than the current
techniques, is being studied by some researchers. This method is based in the phenomenon
which a structure natural frequencies vary when welding residual stress is applied. It consists
in measuring the structure natural frequencies after welding, and comparing them to natural
frequency values considered ideal values. These ideal values are obtained from finite element
method simulation. However, the welding process simulation is not trivial; it implies at least
four finite element analysis which can be executed in different manners. Different researchers
have been developing studies with different types of structures, materials and results. The aim
of this study is to analyze which parameters can improve Finite Element Method (FEM) model
performance for obtaining simulation results closer to experiments. In this study, five models
were developed and validated with experimental studies. It was observed that models using
2D shell elements generate better results than models using 3D solid elements. In addition,
it was observed that the symmetry technique which can be used in plate simulations leads to
significant lower computational times, but affect modal results and, in addition, do not generate
natural frequency values for all vibrational modes; therefore, the symmetry technique should
be avoided in this type of analysis. The birth and death technique, which simulates filler metal
deposition, was also analyzed and it was concluded that this technique has small effect in the
results. Finally, this work proposes an interpolation technique for the natural frequency values
to evaluate the modal results variation due to welding residual stresses.
