Search Results

The durability certification is one of the critical paths of a mass production vehicle project. For structural components, the development and the execution of experimental tests supported by finite element method (FEM) became mandatory for implementation time reduction, especially when on-board diagnoses (OBD) legislation turns even small cracks in severe structural failures. This job aims to show a simulation method of structural efforts in an exhaust system on a test bench. The exhaust pipe is previously analyzed with FEM and the critical points are instrumented with strain gage in vehicles. The strains are measured and its values reproduced in a dynamometer bench using a shaker with adjustable amplitudes. Therefore, difficulties to reproduce temperature and strain were overcome and the test shows repeatability. The variation of shaker device amplitude makes it possible to define the life cycle curve of the part.

The present article shows the influence of the measurement method on a transversal section of exhaust system, downstream of the manifold, the dimensional and the acoustics package simulation. For this task the same system section was instrumented with five different configurations; the values of backpressure were measured on maximum power and used as data for the GTPOWER software to make a virtual simulation of acoustics intensity as a function of engine speed. Therefore it was possible to compare the virtual curves with the real measured values of acoustics intensity. Due to the stream lines influence of the analyzed section, we obtained different values of backpressure and curves of acoustics intensity. Finally, it is shown the measured value of backpressure which has the best correlation with the real measurement and identifies the measurement method with piezo ring as the best configuration.

The present article shows the effect of the mass and friction reduction inside the engine over the carbonic gas emission reduction in the atmosphere. Authors have confirmed that the mass reduction and low friction in the internal components of the OTTO cycle engine, achieved by exhaust and admission valves re-dimensioning and sealer's substitution can help to reduce fuel consumption and, consequently, CO2, the main greenhouse effect gas. It is exposed and discussed different measurements of torque and power curves, friction power, and specific fuel consumption compared in the same engine without the proposed improving actions.

In spite of the changes in vehicle performance, one of the current challenges is to get components applicable to different vehicles with no changes in the project. Simulations made with specific numerical programs enable this process of unifying components, for different platforms, to be applied to the exhaust system. The projects proposed, based on the results obtained with the simulation programs, were tested experimentally. It was proven that the results of the simulation proposals correlated to the experimental results. This ultimately provided simplification to the project, with gains in logistics and productivity. Besides the technological process involved, possibilities to reduce costs can also be considered.