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Finite element modeling has been used extensively nowadays for predicting the noise and vibration performance of whole engines or subsystems. However, the elastomeric components on the engines or subsystems are often omitted in the FE models due to some known difficulties. One of these is the lack of the material properties at higher frequencies. The elastomer is known to have frequency-dependent viscoelasticity, i.e., the dynamic modulus increases monotonically with frequency and the damping exhibits a peak. These properties can be easily measured using conventional dynamic mechanical experiments but only in the lower range of frequencies. The present paper describes a method for characterizing the viscoelastic properties at higher frequencies using fractional calculus. The viscoelastic constitutive equations based on fractional derivatives are discussed. The method is then used to predict the high frequency properties of an elastomer.

Hydroformed components are replacing stamped parts in automotive frames and front end and roof structures to improve the crash performance of vehicles. Due to the increasing application of hydroformed components, a better understanding of the crash behavior of these parts is necessary to improve the correlation between full-vehicle crash tests and FEM analysis. Accurately predicting the performance of hydroformed components will reduce the amount of physical crash testing necessary to develop the new components and new vehicles as well as reduce cycle time. Virgin material properties are commonly used in FEM analysis of hydroformed components, which leads to erroneous prediction of the full-vehicle crash response. Changes in gauge and material properties during the hydroforming process are intuitive and can be reasonably predicted by using forming simulations. The effects of the forming process have been investigated in the FEA models that are created for crash analyses.

This paper discusses the virtual development process used to support design of a high-tonnage hydroform press. It also discusses the optimized design for structural integrity while achieving low target cost. Other considerations included optimization of setup issues such as press fabrication and assembly. Due to tightly constrained development time, a diverse range of CAE methodologies were used to refine and validate the design. Detailed linear and nonlinear finite element models were developed to provide the required accuracy in the critical regions of the press structure. From these detailed models simplified analytical tools were developed to calculate the key press parameters such as alternating stress and predicted fatigue life. Finite element models were validated with physical strain gage measurements from an array of strain gages installed on the production presses.

The effect of multiple braze furnace exposures has been questioned by many because the rework of brazed parts is a common practice in manufacturing. However, there are process controls that limit the number of exposures for an assembly due to known issues with multiple exposures. A common concern deals with the effect of multiple braze furnace exposures on the structural integrity of the base material of the components. Another concern regards the effect of multiple exposures on the structural integrity of the braze joint itself. This paper details experimental results of a physical study to investigate these questions. The material forms used are seam-welded tube and a thin-wall stamped component, both made from 304L stainless steel. The copper paste used in the study has an industry designation of ANSI/AWS A5.8 - BCu-1a.

The scope of this paper is to determine the affects that non-petroleum based fuels such as: rapeseed methyl ester (RME) and soy methyl ester (SME) have on thermoset elastomers. The thermoset elastomers that have been evaluated are NBR (Nitrile Butadiene Rubber), NBR/PVC (Nitrile Butadiene Rubber & Polyvinyl Chloride), Epichlorohydrin homo- (Homopolymer of Epichlorohydrin), co- (Copolymer of Epichlorohydrin), ter- (Terpolymer of Ecpichlorohydrin), and Di-, and ter FKM (Fluorinated Rubber). The different elastomers have been subjected to aging in neat fatty acid methyl esters, RME and SME, at a variety of durations and temperatures. The effects of this exposure on the properties of thermoset elastomers are described in this paper.