24 J. P. Winkel et al. Fig. 3.16 Multi-shaker support beams, trolleys, and manual chain hoists Fig. 3.17 Shaker support attachments To support attachment of the portable shakers to these hoists, a standard lifting hardware setup was created. This lifting hardware setup, shown in Fig. 3.17, consisted of (order from shaker to hoist): swivel hoist rings fastened to the four corners of the portable shaker trunnions, four-leg cable bridles, and finally a bungee cord link along with a loosely fitted safety strap. The loosely fitted lifting strap was put in place because the bungee cord links were not load tested. Therefore, to ensure safety, the lifting straps would not allow the shakers to fall if the bungees were to break. Normally, turnbuckles would be used between the swivel hoist rings and the four-leg cable bridles so that the shaker orientation could be accurately set, however, the lab did not own enough of these for this research and a decision was made to not utilize them in this first phase. Looking back, they would have been helpful to have and are strongly suggested to be used in the future. 3.7 Traditional Fixed Based Modal Test The test article FEM that was correlated using the free-free test data documented in previous sections was constrained at all the fastener locations using RBE2 spiders. The modal analysis was performed to identify the target modes that would be extracted in the fixed based testing. Figure 3.18 shows the frequencies, associated modal effective mass, and the deformation shapes of the selected target modes.
RkJQdWJsaXNoZXIy MTMzNzEzMQ==