Search Results

Components of an automatized transmission system were improved by using techniques of finite element numerical simulation and topology optimization, in order to achieve mass saving and higher performance. Numerical simulations have being applied more frequently during the components design, once the models become more sophisticated, higher computational capacity is available and more precise material properties can be determined. In this paper, a good correlation between the simulation models and the experimental tests was achieved through the material properties determination by means of the impulse excitation technique. This impulse excitation technique consists of a non-destructive test for the dynamic elasticity modulus and material damping through the vibration natural frequencies. The test specimens are evaluated by an impulsive mechanical excitation and the response acoustic signal is collected by a microphone and processed in a conventional computer.

In the current Brazilian air intake manifold market, most of the small car applications use the reinforced polyamide PA 6.6 GF30 as base material. The glass fiber (30%) guarantees the required mechanical resistance, necessary once the manifold is assembled on the engine and is subjected to considerable vibration levels. Air intake manifolds were developed using a new chemically recycled material recuperated from yarn production process, called Technyl ECO, which represents a reduction of 4.3 kg of CO₂ equivalent per 1 kg of polyamide produced. This material can replace the current one, once it has the same formulation (PA 6.6 GF30) and similar mechanical resistance. Moreover, it represents a cost saving up to 10% in the raw material. The air intake manifolds injected with the recycled material were subjected to the mechanical validation tests under severe conditions of accelerated aging at temperature of 140°C and thermal shock with abrupt temperature change from -40°C to 120°C.

Several projects in engineering involve rotating parts submitted to bending loads, which can result in the material heating. This thermal load happens due to energy loss caused by the material damping. This heat source can be great enough to make the component reach high temperatures and, consequently, risk its performance or even its resistance. A theoretical approach, considering that part of the mechanical energy is converted to thermal energy, implies that the maximum temperature found in a uniform rotary beam is linear dependent with the rotating speed and is directly proportional to the square of the applied load. This work intends to present some results acquired from an experiment performed in a fatigue test machine and also validate the theoretical formulation. Stainless steel (316L) specimens were painted with matte black ink to improve their emissivity. The temperature was measured via a FLIR thermographic infrared camera.

The crankshaft dynamic behavior of internal combustion engines are deeply influenced by its geometry and modal parameters. The modal density of a 6 cylinder crankshaft is high and, therefore, it is necessary the evaluation of its several modal parameters during the crankshaft development. This paper presents the calculation of modal parameters such as: natural frequencies, modal shapes and damping factors; of a 6 cylinder in line crankshaft from a Diesel engine. Two approaches are conducted, firstly, a numeric calculation based on finite element method to collect the free body shape modes and its natural frequencies, respectively. Successively, an experiment is realized by the use of an electro-dynamic shaker to excite the structure, and accelerometers to measure the acceleration in 21 interest points of crankshaft geometry. The 3 directions FRFs are presented for each point, and also, the estimation of modal parameters obtained by tools like CMIF, Stabilization Diagram and Polymax.