- I work as a researcher in vibration and acoustics of aerospace systems in Institute of Aeronautics and Space (IAE, Sã... moreI work as a researcher in vibration and acoustics of aerospace systems in Institute of Aeronautics and Space (IAE, São José dos Campos, Brazil) since 2004. Also I am a Professor at graduate program of Space Science and Technology at Aeronautics Institute of Tecnology (ITA, São José dos Campos, Brazil) since 2013.edit
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On the design of combustion chambers for liquid and solid propelled rocket the presence of acoustic modes is an important feature to be considered. These modes can cause instabilities on the burning process and should be well known during... more
On the design of combustion chambers for liquid and solid propelled rocket the presence of acoustic modes is an important feature to be considered. These modes can cause instabilities on the burning process and should be well known during the design stage. An acoustic cavity simulating a combustion chamber was analyzed by the finite element method and the results are compared to experimental results. The effect of placing Helmholtz resonators into the chamber is also analyzed.
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While attached to a launch vehicle, satellites are subjected to intense dynamic loads throughout the flight, mainly at lift-off. Part of the vibrations is due to the propulsion system and is transmitted along the launch vehicle to the... more
While attached to a launch vehicle, satellites are subjected to intense dynamic loads throughout the flight, mainly at lift-off. Part of the vibrations is due to the propulsion system and is transmitted along the launch vehicle to the satellite by the payload adaptor fitting (PAF). This paper analyzes the influence of interstage sections and PAF damping on the acceleration response of the payload to launcher longitudinal vibrations. Simple mass-spring-damper models were used, considering the satellite and the stages as rigid bodies connected by springs and dampers. The satellite response to an oscillating force applied on the first stage was evaluated. The results show that when the damping in the inter-stage is high, the launch vehicle moves as a single mass, exciting the satellite as a moving base. If the damping is low, the stages move separately and the satellite will be excited by higher frequency modes. Moreover, lower PAF damping lead to higher accelerations at the second mode frequency and lower accelerations at higher frequencies, while the interstages damping showed little influence on the response around the second mode frequency but a direct effect on higher frequencies. The study was performed by implementing the models in a MATLAB routine.
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This paper presents a data acquisition and analysis system based on a computer sound card for measuring and processing random vibration signals. This system turns the computer into a two-channel measurement instrument which provides... more
This paper presents a data acquisition and analysis system based on a computer sound card for measuring and processing random vibration signals. This system turns the computer into a two-channel measurement instrument which provides sample rate, simultaneous sampling, frequency range, filters and others essential capabilities required to perform random vibrations measurements. An easy-to-use software was developed for vibration monitoring and analysis, including facilities for data recording, digital signal processing and real time spectrum analyzer. Since the tasks of vibration data acquisition frequently require expensive hardware and software, this versatile system provides students a very accurate and inexpensive solution for experimental studying mechanical vibrations.
Satellite launchers are submitted to severe acoustic loads mainly during lift-off where SPL achieve, at the upper parts, values within the range of 140-160 dB. Such an excitation can damage embedded elements, if energy attenuation... more
Satellite launchers are submitted to severe acoustic loads mainly during lift-off where SPL achieve, at the upper parts, values within the range of 140-160 dB. Such an excitation can damage embedded elements, if energy attenuation measures are not adopted. In view of managing the PLF vibro-acoustic environment, numerical techniques are applied to predict elasto-acoustic behavior. This manuscript presents a numerical study on the design of acoustic insulation for the VLS-1 fairing compartment. An excitation profile based on the literature is applied on a SEA coupled model of this structural-acoustic system and absorbing materials are added to the model. Two parameters of the absorbing material layer are analyzed: thickness and covered area. Two NCT modeling approaches are used to simulate the effect of blanketing the VLS-1 fairing: acoustic materials Biot's parameters, given by the manufacturer, and material samples absorption coefficient, measured in a Kundt Tube. Results show t...