Implementing High Frequency Mechanical Impact in Industrial Components: A Case Study

A recently more used method of improving weld quality at the weld transition to the plate called HFMI (High Frequency Mechanical Impact) has been investigated and tried on two demonstrators, a bogie beam in an articulated hauler and a dipper arm in an excavator, see fig. 1. The designs of the beams have been made so that thinner plates can be used and higher material strength can be utilized. Such an approach needs to make use of local based analysis methods and in this case the effective notch method was used. Recently made research has suggested SN-curves where the use of HFMI in combination with different material yield strengths are described and these FAT values have been used to develop allowed stress levels in the beams to fulfill the life requirements. All this resulted in components which were 24% and 18% lighter using plate thicknesses of 8-12 mm in material yield 700 MPa. They were then produced and tested in a rig to verify the designs. The results imply that the HFMI treatment is a very promising method to build lighter welded structures, however, the design needs to take some new considerations into account to succeed.