Examining the performance of machined springs in foldable rocket wings

The defense industry and space exploration represent the pinnacle of technology today. Rockets, satellites, and other spacecraft used in these fields are formed by bringing together complex systems. However, the most crucial element within this complexity is the precise operation of sensitive components in harmony. One of the most striking examples of this harmony is the foldable rocket fins and foldable satellite panels. The accurate and precise functioning of these parts at the moment they are deployed is of critical importance for the success of space exploration and defense strategies. In this thesis, 10 machined torsion spring samples with different spring constants were produced for use as actuators in the designed foldable rocket fin mechanism. AISI 630 (1.4542) martensitic stainless steel was chosen for the production of the machined springs, and tensile tests of the material were conducted. Machining and profile laser cutting methods were used for the production of the springs, and the effects of these manufacturing methods on the springs' performance were also investigated. The spring constants of the springs were determined through analytical, numerical, and experimental measurements. Subsequently, a test system was designed and manufactured to measure the performance of the springs in foldable rocket fins. The springs were tested in this system, and the fin deployment times were measured to reveal their performance. While the springs produced through machining achieved much more precise dimensions with a tolerance of 0.05 mm, dimensional deviations of up to 0.2 mm occurred in the profile laser cutting method. Additionally, it was observed that softening of the material caused by the laser cutting process led to yielding during torsion tests. However, the laser profile cutting method was found to have an advantage over machining, with a reduction in production time by 3.6 times and cost by 5 times. It was demonstrated that the spring constant and torque values determined through numerical and analytical methods were accurate to over 95% compared to the experimentally measured values. The foldable fin mechanism designed and produced within the scope of the thesis was successfully used to measure the performance of the machined springs. In this context, it was found that the springs providing approximately 11 Nm torque at 135° achieved the target deployment time of 200 milliseconds with an average value of 182.5 milliseconds. The results of the dynamic analysis were found to be 95.4% accurate compared to the deployment times measured in foldable fin tests performed experimentally using high-speed cameras. Thus, it has been shown that dynamic analyses can be successfully used to avoid the costs associated with setting up experimental systems.