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In the area of modal balancing, it is essential to identify the vibration modes to be balanced in order to obtain the different modal parameters that will allow knowing the correction weight and its position in the balance planes. However, in some cases, a single mode is apparently observed in the polar response diagrams used for this process, which actually contains at least two modes and which, when added vectorially, shows only one apparent mode. In these cases, in addition to the intrinsic errors when using a modal parameter extraction tool, there will be errors in determining the correction weight for the modes, as well as for the placement angle. In this work, an identification methodology is presented which, through the use of coordinate transformation and a modal parameter extraction tool, allows identifying characteristic patterns of close modes in frequency and which, when applied in the study of a system in the field, offers robustness and applicability.

A comparative experimental analysis of three common hemming processes used in the automotive industry is presented. These processes are die hemming, table hemming, and roll hemming. We aim to determine which one of the three processes provides the better quality hemming. The die hemming and table hemming used in this study were performed with custom made tooling and a 35 tonne hydraulic press. Similarly, roll hemming was performed using a custom made workbench with a three-degree of freedom system of rolls. The material used for testing was aluminum sheet (6011); three rolling directions were taken in account: 0°, 45°, and 90° for the manufacture of the samples. Hemming quality was determined from the geometric variables such as: lip high, pre-hemming angle, tool position, roll radius (roll hemming only). As a result, the comparison of roll in/out and wrinkle defects are reported and compared.

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GUR1050 is a medical grade variety of ultra-high molecular weight polyethylene (UHMWPE) intended for use on total joint prosthesis and implants. Probes of this material were characterized on a compression test following ASTM norms and lineaments. Available data from these mechanical tests is fitted on multiple material models. Achieved results on numerical solutions of finite element modeling (FEM) of the tests are discussed, looking for the best one available in order to simulate with accuracy GUR1050 behavior, with specific interest on the load curve results, showing the pertinence of using certain models on different conditions. It was found that the use of a bilinear isotropic hardening model assures the best fit for GUR1050 behavior in uniaxial compression under a constant strain rate.