Browsing by Author "Allik, Mari"

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    Characterization of a Temperature Measurement System for Use in Vacuum
    (Tartu Ülikool, 2020) Akintola, Adeyinka Jimoh; Vendt, Riho; Allik, Mari; Jain, Ayush; Tartu Ülikool. Loodus- ja täppisteaduste valdkond
    Thermal vacuum tests must be performed to ensure the survivability of the spacecraft during the development and performance validation stages. To carry out these tests, vacuum compatible temperature sensors are placed on different sub-systems of a spacecraft in a vacuum chamber. For the reliability of this test, the temperature sensors to be used need to be calibrated. This work, therefore, aims at improving the temperature measurement system currently used for thermal vacuum testing at the Tartu Observatory, University of Tartu. A suitable vacuum compatible sensor was selected and calibrated in the climatic chamber using the existing measurement system available at the observatory and a new measurement system introduced in this work. Both measurement systems were characterized, and measurement and uncertainty models were designed and estimated for the measurements carried out both in the climatic chamber and in the vacuum chamber.
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    Software Development for the Mechanical Shock Testing System at Tartu Observatory
    (Tartu Ülikool, 2016) Allik, Mari; Allik, Viljo; Tilk, Teet; Vendt, Riho; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Tehnoloogiainstituut
    Components used in space are subject to high frequency and high amplitude mechanical shocks that occur during the launch and separation phases of the space vehicles. Shock testing is done to ensure that components can withstand the shock events. A shock can be described by an acceleration and time history, but in shock testing it is difficult to manage and quantify shocks by only looking at the acceleration and time history of a shock. Instead, a shock response spectrum is used, which plots the peak accelerations of multiple single degree of freedom systems with their own unique frequencies over a range of frequencies, usually from 100 Hz to 10 000 Hz. The shocks that occur in space can reach up to acceleration levels of 10 000 g’s. The main objective of this work was to develop a software application for the mechanical shock testing system at Tartu Observatory. The shock testing system at Tartu Observatory consists of a resonant plate, pendulum hammer, guiding rod, weights and a data acquisition module with acceleration sensors. The software was developed in Microsoft Visual Studio .NET 2003 using the C++ programming language and external libraries. The software is required to acquire the data from the sensors connected to the data acquisition module and process and plot it. The shock response spectrum and acceleration-time histories can be plotted. An important aspect of shock testing is to be able to recreate shocks of various levels. If the shock testing system manages to do this, the system is considered reliable. To test the reliability of the system, the developed software was tested by performing shock testing on test objects and plotting the results.