Modern telecommunication satellites can benefit from the features of fiber optic sensing wrt to mass savings, improved performance and lower costs. Within the course of a technology study, launched by the European Space Agency, a fiber optic sensing system has been designed and is to be tested on representative mockups of satellite sectors and environment.
Modern telecommunication satellites can benefit from the features of fiber optic sensing wrt to mass savings, improved performance and lower costs. Within the course of a technology study, launched by the European Space Agency, a fiber optic sensing system has been designed and is to be tested on representative mockups of satellite sectors and environment.
Laser lift-off processes have been observed during structuring CIS thin film solar cells with ultra-short laser pulses, if a
Mo film on glass is irradiated from the glass substrate side. To investigate the underlying physical effects, ultrafast
pump-probe microscopy is used for time- and space resolved investigations. The setup utilizes a 660 fs-laser pulse at a
wavelength of 1053 nm that is split up into a pump and a probe pulse. The pump pulse ablates the thin film, while the
frequency doubled probe pulse illuminates the ablation area after an optically defined delay time of up to 4 ns. For longer
delay times, a second electronically triggered 600 ps-laser is used for probing. Thus, the complete ultra fast pulse
initiated ablation process can be observed in a delay time range from femtoseconds to microseconds.
First experiments on the directly induced ablation of molybdenum films from the glass substrate side show that
mechanical deformation is initiated at about 400 ps after the impact of the pump laser pulse. The deformation continues
until approximately 15 ns, then a Mo disk shears and lifts-off with a velocity of above 70 m/s free from thermal effects.
Satellite mechanical performance is to be further enhanced e.g. by active launch vibration attenuation, and even more so
by in-orbit micro-vibration and shape control and possibly also significant shape morphing. This puts stringent
requirements on the actuators and their materials, such as high resolution of possibly large strokes, or a very broad
operational temperature range going down to -150°C or even lower. The discussion also shows the need to consider the
host material and structure together with the actuator as a highly interacting system. This holds to a considerable extent
also for integrated fiber optic sensors used for strain and temperature monitoring.
Large satellites are equipped with hundreds of sensors for temperature measurement. The large amount of
sensors is expensive in terms of integration effort and mass in the case conventional sensors are used. In this
article an integrated fiber optic temperature sensor network for the hot spot detection on satellite sandwich
panels is introduced. The developed sensor system is integrated with only negligible mechanical impact. It is
electro-magnetic immune and decoupled from mechanical loads. In addition to monitoring hotspots, the number
and aerial density allows a reliable reconstruction of temperature and displacement fields.
Fiber optic sensors are of interest because of their robustness against environmental disturbances, low drift, and ease of
integration. The relatively high population of measurement points also favors the estimation of displacement and
temperature from discrete data. This together with techniques for integration into structural materials is discussed in the
context of satellite structures.
Very thin shells, shell-membrane and membrane structures offer high actuator authority for controlling their behaviour.
On the other side, special care has to be taken for proper material and structural characterisation and its interaction with
the actuators. In the paper different types of actuators are discussed in the context of precision shell-membrane space
reflectors. For actuation, emphasis is given on piezo-ceramics and electro-active polymers. Special integration,
modelling and testing techniques for smart fibre reinforced shell-membranes and membranes are addressed.
A possible approach to meet the increasing performance requirements of lightweight structures in various engineering
fields is the application of smart structures. One of the functions, which are required, is the observation of the structures'
shape. During operation, however, the monitoring of displacement fields is difficult. This paper discusses the
displacement field estimation of a dynamically excited plate using fiber Bragg grating strain sensors. Using a modal
approach, it is possible to derive a transformation matrix to estimate the displacement field using only a few strain
measurements. To reduce systematic estimation errors due to residual modes, a parameter study was performed and the
sensor location optimized using the condition number of the transformation matrix as an objective function. An
experiment with an optimized sensor configuration including 16 fiber Bragg grating strain sensors was performed to
verify the method and the simulation results.
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